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In my December 2014 EUBS... more
In my December 2014 EUBS President's column, entitled "Hydrophobicity: the link between bubbles, bubblers and autoimmunity?" (Diving Hyperb Med. 2014;44:185), the text in the first two paragraphs under the subheading "Surfactants act against proteins and cause autoimmune diseases" should have been attributed to: Arieli R. Was the appearance of surfactants in air breathing vertebrates ultimately the cause of decompression sickness and autoimmune disease? Resp Physiol Neurobiol. 2015;206:15-18. This paper was available on-line from November 2014. Dr Arieli accepts that this omission was unintentional on my part and that the promulgation of his theories was done from the best of motives.
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Les redacteurs et les auteurs de ce livre sont un groupe de scientifiques et de medecins possedant une vaste experience et des connaissances approfondies de la physiologie de la plongee et de la theorie de la decompression. Comme... more
Les redacteurs et les auteurs de ce livre sont un groupe de scientifiques et de medecins possedant une vaste experience et des connaissances approfondies de la physiologie de la plongee et de la theorie de la decompression. Comme c'est souvent le cas, il faut un effort collectif pour reussir a faire progresser les connaissances pratiques. Le familier "le tout est plus grand que la somme de ses parties" est souvent vrai et le Groupe de recherche PHYPODE incarne ce concept. En regroupant logiquement les differents elements de la science et de la medecine de la plongee avec des sections provocantes et " matiere a reflexion ", le texte offre des lecons precieuses a ceux qui s'interessent a l'etat actuel de la plongee. Malgre pres de 170 ans de recherche, la nature fondamentale du stress de decompression demeure insaisissable. Comme il est bien decrit dans ce livre, de grands progres ont ete realises en ce qui concerne les elements pratiques permettant de plonger en toute securite. Ce travail est une traduction realisee avec l'intelligence artificielle.
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Doctorat en kinésithérapie et réadaptationinfo:eu-repo/semantics/nonPublishe
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Exposure to acute normobaric hypoxia (NH) elicits reactive oxygen species (ROS) accumulation, whose production kinetics and oxidative damage were here investigated. Nine subjects were monitored while breathing an NH mixture (0.125 FIO2 in... more
Exposure to acute normobaric hypoxia (NH) elicits reactive oxygen species (ROS) accumulation, whose production kinetics and oxidative damage were here investigated. Nine subjects were monitored while breathing an NH mixture (0.125 FIO2 in air, about 4100 m) and during recovery with room air. ROS production was assessed by Electron Paramagnetic Resonance in capillary blood. Total antioxidant capacity, lipid peroxidation (TBARS and 8-iso-PFG2α), protein oxidation (PC) and DNA oxidation (8-OH-dG) were measured in plasma and/or urine. The ROS production rate (μmol·min−1) was monitored (5, 15, 30, 60, 120, 240 and 300 min). A production peak (+50%) was reached at 4 h. The on-transient kinetics, exponentially fitted (t1/2 = 30 min r2 = 0.995), were ascribable to the low O2 tension transition and the mirror-like related SpO2 decrease: 15 min: −12%; 60 min: −18%. The exposure did not seem to affect the prooxidant/antioxidant balance. Significant increases in PC (+88%) and 8-OH-dG (+67%) at ...
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ObjectiveWe aimed to evaluate the feasibility of an online High-Intensity Interval Training (HIIT) program on clinical psychological symptoms in higher education students in the context of the COVID-19 pandemic lockdown.Materials and... more
ObjectiveWe aimed to evaluate the feasibility of an online High-Intensity Interval Training (HIIT) program on clinical psychological symptoms in higher education students in the context of the COVID-19 pandemic lockdown.Materials and MethodsDuring the lockdown, 30 students aged 18–25 years, who had been screened previously with a cut-off score ≥5 in the Generalized Anxiety Disorder-7 (GAD-7) questionnaire, were randomly assigned to either the 4-week HIIT program with three sessions per week conducted through online videos, or a no-intervention control group. The primary outcome was the feasibility assessment. The secondary outcome was a psychological self-report with the 21-items Depression, Anxiety, and Stress Scale (DASS-21). Assessment and intervention were performed in compliance with social distancing rules.ResultsTwo participants in the HIIT were lost to follow-up, leaving 13 participants vs. 15 in the control group. We observed high adherence (87%) and complete safety for men...
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Introduction: Scuba diving represents stressful event for cardiovascular system. Breathing with compressed air, hyperbaric environment and microbubbles formation are the main factors are the most influencing factors for pulmonary... more
Introduction: Scuba diving represents stressful event for cardiovascular system. Breathing with compressed air, hyperbaric environment and microbubbles formation are the main factors are the most influencing factors for pulmonary circulation. Hypothesis: The aim of the study was to evaluate the change in morphology and function of the right heart after scuba dive with compressed air. Methods: Ten healthy sport divers (2 woman, 8 men, average age 42.1 ± 4.1 yrs., 21-52yrs) performed one scuba dive with compressed air (the depth was 20 meters, bottom tine 20 minutes, one safety stop at 3 m, water temperature 15°C). Echocardiography was performed just before and immediately after the dive, and every 60 minutes after surfacing with the aim to evaluate the presence of microbubbles (iVivid, GE). Results: After the dive, left atrium, right ventricle and inferior vena cava diameters significantly decreased (LA: 30.4±2.1 vs. 27.1±1.2 mm, p<0.05; RV: 27.8±2.1 vs. 25.2±1.1mm, p<0.05; IVC: 19.3±1.1 vs. 17.6±0.9 mm, p...
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Previous studies suggest that altered gravity levels during parabolic flight maneuvers affect spatial updating. Little is known about the impact of the experimental setting and psychological stressors associated with parabolic flight... more
Previous studies suggest that altered gravity levels during parabolic flight maneuvers affect spatial updating. Little is known about the impact of the experimental setting and psychological stressors associated with parabolic flight experiments on attentional processes. To address this gap, we investigated the level of alertness, selective and sustained attention in 1 and 0 g using a Go/No-Go Continuous Performance Task. We also identified several parameters associated with the experimental set-up of a parabolic flight that could be expected to affect attentional processing. These included the use of scopolamine, sleep quality prior to the flight day, participant’s stress level as well as mood and anxiety state before and after the parabolic flight. We observed a deterioration in attentional processing prior to the first parabola that was further aggravated in weightlessness and returned to baseline after the last parabola.Reaction Time,HitandFalse Alarm Ratewere moderately correla...
Research Interests: Psychology, Cognition, Attention, Medicine, Anxiety, and 10 moreHuman, Mood, Microgravity, DDC, ANXIETY, Alertness, Scopolamine, Parabola, Education Physique, and Adverse effects
We report Blood Oxygen Level Dependent (BOLD) signal changes recorded in the brain of an elite breath-hold diver during voluntary dry long breath-hold by means of fMRI. An independent component analysis (ICA) method was applied to extract... more
We report Blood Oxygen Level Dependent (BOLD) signal changes recorded in the brain of an elite breath-hold diver during voluntary dry long breath-hold by means of fMRI. An independent component analysis (ICA) method was applied to extract brain areas that are putatively involved in the apnea process network. We discuss the hypothesis that these BOLD signal variations express the functional adaptive diving response under long apnea at rest. This is a preliminary report, which results are promising for large series investigations.
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Research Interests: Physiology, Environmental Science, Medicine, Diving, Humans, and 6 moreNitrogen, Helium, Oxygen, Breathing, Education Physique, and Heliox
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Introduction: The SARS-CoV2 pandemic has led to an worldwide shortage of Personal Protection Devices (PPD) for medical and paramedical personnel. Adaptation of commercially available snorkel masks to serve as full face masks has been... more
Introduction: The SARS-CoV2 pandemic has led to an worldwide shortage of Personal Protection Devices (PPD) for medical and paramedical personnel. Adaptation of commercially available snorkel masks to serve as full face masks has been proposed. Even not formally approved as PPD, they are publicized on social media as suitable for this use. Concerns about actual protection levels and risk of carbon dioxide (CO2) accumulation while wearing them for extended periods made us perform a systematic testing of various brands, in order to verify whether they are as safe and effective as claimed. Methods: A “fit” test was performed, analogous to gas mask testing. Respiratory safety was evaluated by measuring end-tidal CO2 and oxygen saturation while wearing the masks in rest and during physical exercise. Masks were tested with 3D adaptors to mount regular bacterial-viral ventilator filters when available, or with snorkel openings covered with N95/FFP2 cloth. Results: Modified masks performed r...
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Research Interests: Cognition, Medicine, Diving, Humans, Air, and 7 moreNitrogen, Respiration, Oxygen, Adult, Breathing, Task Performance and Analysis, and Decompression
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Research Interests: Psychology, Medicine, Hypergravity, Microgravity, Arousal, and 3 moreAlertness, G, and Education Physique
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Divers Alert Network Europe has created a database with a large amount of dive-related data that has been collected since 1993 within the scope of the Diving Safety Laboratory citizen science project. The main objectives of this study are... more
Divers Alert Network Europe has created a database with a large amount of dive-related data that has been collected since 1993 within the scope of the Diving Safety Laboratory citizen science project. The main objectives of this study are the grouping divers by their health information and revealing significant differences in diving parameters using data mining techniques. Due to the methodology of the project, data cleaning was performed before applying clustering methods in order to eliminate potential mistakes resulting from inaccuracies and missing information. Despite the fact that 63% of the data were lost during the cleaning phase, the remaining 1,169 “clean” diver data enabled meaningful clustering using the “two-step” method. Experienced male divers without any health problems are in Cluster 1. Male and female divers with health problems and high rates of cigarette smoking are in Cluster 2; healthy, overweight divers are in Cluster 3. There are significant differences in te...
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Venous gas emboli (VGE) are often quantified as a marker of decompression stress on echocardiograms. Bubblecounting has been proposed as an easy to learn method, but remains time-consuming, rendering large dataset analysis impractical.... more
Venous gas emboli (VGE) are often quantified as a marker of decompression stress on echocardiograms. Bubblecounting has been proposed as an easy to learn method, but remains time-consuming, rendering large dataset analysis impractical. Computer automation of VGE counting following this method has therefore been suggested as a means to eliminate rater bias and save time. A necessary step for this automation relies on the selection of a frame during late ventricular diastole (LVD) for each cardiac cycle of the recording. Since electrocardiograms (ECG) are not always recorded in field experiments, here we propose a fully automated method for LVD frame selection based on regional intensity minimization. The algorithm is tested on 20 previously acquired echocardiography recordings (from the original bubble-counting publication), half of which were acquired at rest (Rest) and the other half after leg flexions (Flex). From the 7,140 frames analyzed, sensitivity was found to be 0.913 [95% C...
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The main objective of the CADDY project is to replace a human buddy diver with an autonomous underwater vehicle and add a new autonomous surface vehicle to improve monitoring, assistance, and safety of the diver's mission. However,... more
The main objective of the CADDY project is to replace a human buddy diver with an autonomous underwater vehicle and add a new autonomous surface vehicle to improve monitoring, assistance, and safety of the diver's mission. However, the use of robots underwater may also bring additional safety requirements. Within the scope of this research, the existing vehicles that will be adapted for the purposes of the CADDY project were evaluated regarding safety issues. This will mainly focus on the vehicles' maneuvering capabilities as an indicator of whether the vehicles are safe to be used for interaction with divers. The hazards of ancillary equipment such as scaling lasers and acoustic modems were addressed as well. The design requirements, as well as the formal hazard identification and risk assessments guideline (HIRA) is developed in the beginning of the project to provide operational safety for each manned diving operation. All the CADDY vehicles are modified in order to comply with the design rules for safety. In fact, by the end of February 2015, 44 dives were conducted with a cumulative dive time of 1545 minutes without any accident. The HIRA and the diving methodology are proven to be effective means of safety.
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Hyperoxia causes oxidative stress. Breath-hold diving is associated with transient hyperoxia followed by hypoxia and a build-up of carbon dioxide (CO₂), chest-wall compression and significant haemodynamic changes. This study analyses... more
Hyperoxia causes oxidative stress. Breath-hold diving is associated with transient hyperoxia followed by hypoxia and a build-up of carbon dioxide (CO₂), chest-wall compression and significant haemodynamic changes. This study analyses variations in plasma oxidative stress markers after a series of repetitive breath-hold dives. Thirteen breath-hold divers were asked to perform repetitive breath-hold dives to 20 metres' depth to a cumulative breath-hold time of approximately 20 minutes over an hour in the open sea. Plasma nitric oxide (NO), peroxinitrites (ONOO⁻) and thiols (R-SH) were measured before and after the dive sequence. Circulating NO significantly increased after successive breath-hold dives (169.1 ± 58.26% of pre-dive values; P = 0.0002). Peroxinitrites doubled after the dives (207.2 ± 78.31% of pre-dive values; P = 0.0012). Thiols were significantly reduced (69.88 ± 19.23% of pre-dive values; P = 0.0002). NO may be produced by physical effort during breath-hold diving....
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Background: World Rugby Union laws are constantly evolving towards stringent injury-prevention, particularly for contested scrums, since front row players are most at risk of cervical spine injuries. Recently, some countries have also... more
Background: World Rugby Union laws are constantly evolving towards stringent injury-prevention, particularly for contested scrums, since front row players are most at risk of cervical spine injuries. Recently, some countries have also introduced tailored training programs and minimum performance requirements for playing in the front row. Nevertheless, these approaches lack an objective assessment of each cervical muscle that would provide protective support. Objective: Since front row players are the most at risk for cervical spine injuries due to the specific type of contact during scrums, the purpose of this study was to ascertain whether significant differences exist in neck muscle size and range of motion between front row players and players of other positions, across playing categories. Study design: Cross-sectional controlled laboratory study. Methods: 129 sub-elite male subjects from various first-team squads of Belgian Rugby clubs were recruited. Subjects were grouped according to age: Junior (J) < 19 years old, Senior (S) 19 to 35 years old and Veteran (V) > 35 years old; as well as playing position: Front row players (J = 10, S = 12, V = 11 subjects), (Rest of the) pack (J = 12, S = 12, V = 10), backs (J = 10, S = 11, V = 11). An age-matched control group of non-rugby players was also recruited (J = 10, S = 10, V = 10).For each subject, the total neck circumference (NC) and the cervical range of motion (CROM) were measured. In addition, the thickness of the trapezius (T), splenius capitis (SCa), semispinalis capitis (SCb), semispinalis cervicis (SPC), sternocleidomastoid muscles (SCOM), and the total thickness of all four structures (TT), were measured using ultrasonography. Results: In each age category, compared to controls, rugby players were found to have decreased CROM, an increase in neck circumference (NC), and increased total thickness (TT), trapezius (T), semispinalis capitis (SCb) and sternocleidomastoid muscles (SCOM) sizes. For junior players, the thickness of the semispinalis cervicis (SPC) was also increased compared to controls. The CROM was decreased in front row players compared to pack and back players for all age categories; Front row seniors also showed an increase in trapezius (T), splenius capitis (SCa), semispinalis capitis (SCb) and total thickness (TT), compared to back players. Conclusion: In regard of the differences in cervical values found between player positions, the implementation of both range of motion and echography muscle thickness assessments could serve to create an additional measurement for all front row players, that could complement current pre-participation screening used by rugby federations by objectively monitoring muscular size and motion amplitude around the cervical spine.
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Molecular oxygen (O2) is one of the four most important elements on Earth (alongside carbon, nitrogen and hydrogen); aerobic organisms depend on it to release energy from carbon-based molecules [...]
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Hyperbaric oxygen therapy (HBOT) is a therapeutical approach based on exposure to pure oxygen in an augmented atmospheric pressure. Although it has been used for years, the exact kinetics of the reactive oxygen species (ROS) between... more
Hyperbaric oxygen therapy (HBOT) is a therapeutical approach based on exposure to pure oxygen in an augmented atmospheric pressure. Although it has been used for years, the exact kinetics of the reactive oxygen species (ROS) between different pressures of hyperbaric oxygen exposure are still not clearly evidenced. In this study, the metabolic responses of hyperbaric hyperoxia exposures for 1 h at 1.4 and 2.5 ATA were investigated. Fourteen healthy non-smoking subjects (2 females and 12 males, age: 37.3 ± 12.7 years old (mean ± SD), height: 176.3 ± 9.9 cm, and weight: 75.8 ± 17.7 kg) volunteered for this study. Blood samples were taken before and at 30 min, 2 h, 24 h, and 48 h after a 1 h hyperbaric hyperoxic exposure. The level of oxidation was evaluated by the rate of ROS production, nitric oxide metabolites (NOx), and the levels of isoprostane. Antioxidant reactions were assessed through measuring superoxide dismutase (SOD), catalase (CAT), cysteinylglycine, and glutathione (GSH)....
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We investigated the effects of intermittent long-term stretch training (5 weeks) on the architectural and mechanical properties of the muscle–tendon unit (MTU) in healthy humans. MTU’s viscoelastic and architectural properties in the... more
We investigated the effects of intermittent long-term stretch training (5 weeks) on the architectural and mechanical properties of the muscle–tendon unit (MTU) in healthy humans. MTU’s viscoelastic and architectural properties in the human medial gastrocnemius (MG) muscle and the contribution of muscle and tendon structures to the MTU lengthening were analyzed. Ten healthy volunteers participated in the study (four females and six males). The passive stretch of the plantar flexor muscles was achieved from 0° (neutral ankle position) to 25° of dorsiflexion. Measurements were obtained during a single passive stretch before and after the completion of the stretching protocol. During the stretch, the architectural parameters of the MG muscle were measured via ultrasonography, and the passive torque was recorded by means of a strain-gauge transducer. Repeated-measure ANOVA was applied for all parameters. When expressed as a percentage for all dorsiflexion angles, the relative torque valu...
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Hypoxia, even at non-lethal levels, is one of the most stressful events for all aerobic organisms as it significantly affects a wide spectrum of physiological functions and energy production. Aerobic organisms activate countless molecular... more
Hypoxia, even at non-lethal levels, is one of the most stressful events for all aerobic organisms as it significantly affects a wide spectrum of physiological functions and energy production. Aerobic organisms activate countless molecular responses directed to respond at cellular, tissue, organ, and whole-body levels to cope with oxygen shortage allowing survival, including enhanced neo-angiogenesis and systemic oxygen delivery. The benefits of hypoxia may be evoked without its detrimental consequences by exploiting the so-called normobaric oxygen paradox. The intermittent shift between hyperoxic-normoxic exposure, in addition to being safe and feasible, has been shown to enhance erythropoietin production and raise hemoglobin levels with numerous different potential applications in many fields of therapy as a new strategy for surgical preconditioning aimed at frail patients and prevention of postoperative anemia. This narrative review summarizes the physiological processes behind th...
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In this study, the metabolic responses of hypoxic breathing for 1 h to inspired fractions of 10% and 15% oxygen were investigated. To this end, 14 healthy nonsmoking subjects (6 females and 8 males, age: 32.2 ± 13.3 years old (mean ± SD),... more
In this study, the metabolic responses of hypoxic breathing for 1 h to inspired fractions of 10% and 15% oxygen were investigated. To this end, 14 healthy nonsmoking subjects (6 females and 8 males, age: 32.2 ± 13.3 years old (mean ± SD), height: 169.1 ± 9.9 cm, and weight: 61.6 ± 16.2 kg) volunteered for the study. Blood samples were taken before, and at 30 min, 2 h, 8 h, 24 h, and 48 h after a 1 h hypoxic exposure. The level of oxidative stress was evaluated by considering reactive oxygen species (ROS), nitric oxide metabolites (NOx), lipid peroxidation, and immune-inflammation by interleukin-6 (IL-6) and neopterin, while antioxidant systems were observed in terms of the total antioxidant capacity (TAC) and urates. Hypoxia abruptly and rapidly increased ROS, while TAC showed a U-shape pattern, with a nadir between 30 min and 2 h. The regulation of ROS and NOx could be explained by the antioxidant action of uric acid and creatinine. The kinetics of ROS allowed for the stimulation o...
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Oxygen is a powerful trigger for cellular reactions and is used in many pathologies, including oxidative stress. However, the effects of oxygen over time and at different partial pressures remain poorly understood. In this study, the... more
Oxygen is a powerful trigger for cellular reactions and is used in many pathologies, including oxidative stress. However, the effects of oxygen over time and at different partial pressures remain poorly understood. In this study, the metabolic responses of normobaric oxygen intake for 1 h to mild (30%) and high (100%) inspired fractions were investigated. Fourteen healthy non-smoking subjects (7 males and 7 females; age: 29.9 ± 11.1 years, height: 168.2 ± 9.37 cm; weight: 64.4 ± 12.3 kg; BMI: 22.7 ± 4.1) were randomly assigned in the two groups. Blood samples were taken before the intake at 30 min, 2 h, 8 h, 24 h, and 48 h after the single oxygen exposure. The level of oxidation was evaluated by the rate of reactive oxygen species (ROS) and the levels of isoprostane. Antioxidant reactions were observed by total antioxidant capacity (TAC), superoxide dismutase (SOD), and catalase (CAT). The inflammatory response was measured using interleukin-6 (IL-6), neopterin, creatinine, and urat...
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Background: This study aimed to observe the effects of a fast acute ascent to simulated high altitudes on cardiovascular function both in the main arteries and in peripheral circulation. Methods: We examined 17 healthy volunteers, between... more
Background: This study aimed to observe the effects of a fast acute ascent to simulated high altitudes on cardiovascular function both in the main arteries and in peripheral circulation. Methods: We examined 17 healthy volunteers, between 18 and 50 years old, at sea level, at 3842 m of hypobaric hypoxia and after return to sea level. Cardiac output (CO) was measured with Doppler transthoracic echocardiography. Oxygen delivery was estimated as the product of CO and peripheral oxygen saturation (SpO2). The brachial artery’s flow-mediated dilation (FMD) was measured with the ultrasound method. Post-occlusion reactive hyperemia (PORH) was assessed by digital plethysmography. Results: During altitude stay, peripheral oxygen saturation decreased (84.9 ± 4.2% of pre-ascent values; p < 0.001). None of the volunteers presented any hypoxia-related symptoms. Nevertheless, an increase in cardiac output (143.2 ± 36.2% of pre-ascent values, p < 0.001) and oxygen delivery index (120.6 ± 28.4...
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Effect of varying deep stop times and shallow stop times on precordial bubbles after dives to 25 msw (82 fsw). Bennett PB, Marroni A, Cronje FJ, Cali-Corleo R, Germonpre P, Pieri M, Bonuccelli C, Leonardi MG, Balestra C. Effect of varying... more
Effect of varying deep stop times and shallow stop times on precordial bubbles after dives to 25 msw (82 fsw). Bennett PB, Marroni A, Cronje FJ, Cali-Corleo R, Germonpre P, Pieri M, Bonuccelli C, Leonardi MG, Balestra C. Effect of varying deep stop times and shallow stop times on precordial bubbles after dives to 25 msw (82 fsw). Undersea Hyperb Med 2007; 34(6):399-406. In our previous research, a deep 5-min stop at 15 msw (50 fsw), in addition to the typical 3-5 min shallow stop, significantly reduced precordial Doppler detectable bubbles (PDDB) and "fast" tissue compartment gas tensions during decompression from a 25 msw (82 fsw) dive; the optimal ascent rate was 10 msw (30 fsw/min). Since publication of these results, several recreational diving agencies have recommended empirical stop times shorter than the 5 min stops that we used, stops of as little as 1 min (deep) and 2 min (shallow). In our present study, we clarified the optimal time for stops by measuring PDDB wi...
Introduction: Heart rate variability (HRV) during underwater diving has been infrequently investigated because of environment limitations and technical challenges. This study aims to analyze HRV changes while diving at variable hyperoxia... more
Introduction: Heart rate variability (HRV) during underwater diving has been infrequently investigated because of environment limitations and technical challenges. This study aims to analyze HRV changes while diving at variable hyperoxia when using open circuit (OC) air diving apparatus or at constant hyperoxia using a closed-circuit rebreather (CCR). We used HRV analysis in time and frequency domain adding nonlinear analysis which is more adapted to short-time analysis and less dependent on respiratory rate (Sinus respiratory arrhythmia).Materials and Methods: 18 males, 12 using OC (30 mfw for 20 min) and 6 using CCR (30 mfw for 40 min.). HRV was recorded using a polar recorder. Four samples of R-R intervals representing the dive were saved for HRV analysis. Standard deviation of normal-to-normal intervals (SDNN), square root of the mean squared differences between successive RR intervals (rMSSD), and average RR intervals (RR) in time-domain; low frequency (LF) and high frequency (...
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Background: Despite evolution in decompression algorithms, decompression illness is still an issue nowadays. Reducing vascular gas emboli (VGE) production or preserving endothelial function by other means such as diving preconditioning is... more
Background: Despite evolution in decompression algorithms, decompression illness is still an issue nowadays. Reducing vascular gas emboli (VGE) production or preserving endothelial function by other means such as diving preconditioning is of great interest. Several methods have been tried, either mechanical, cardiovascular, desaturation aimed or biochemical, with encouraging results. In this study, we tested mini trampoline (MT) as a preconditioning strategy. Methods: In total, eight (five females, three males; mean age 36 ± 16 years; body mass index 27.5 ± 7.1 kg/m2) healthy, non-smoking, divers participated. Each diver performed two standardized air dives 1 week apart with and without preconditioning, which consisted of ±2 min of MT jumping. All dives were carried out in a pool (NEMO 33, Brussels, Belgium) at a depth of 25 m for 25 min. VGE counting 30 and 60 min post-dive was recorded by echocardiography together with an assessment of endothelial function by flow-mediated dilatio...
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Oxygen is a powerful trigger for cellular reactions, but there are few comparative investigations assessing the effects over a large range of partial pressures. We investigated a metabolic response to single exposures to either normobaric... more
Oxygen is a powerful trigger for cellular reactions, but there are few comparative investigations assessing the effects over a large range of partial pressures. We investigated a metabolic response to single exposures to either normobaric (10%, 15%, 30%, 100%) or hyperbaric (1.4 ATA, 2.5 ATA) oxygen. Forty-eight healthy subjects (32 males/16 females; age: 43.7 ± 13.4 years, height: 172.7 ± 10.07 cm; weight 68.4 ± 15.7 kg) were randomly assigned, and blood samples were taken before and 2 h after each exposure. Microparticles (MPs) expressing proteins specific to different cells were analyzed, including platelets (CD41), neutrophils (CD66b), endothelial cells (CD146), and microglia (TMEM). Phalloidin binding and thrombospondin-1 (TSP), which are related to neutrophil and platelet activation, respectively, were also analyzed. The responses were found to be different and sometimes opposite. Significant elevations were identified for MPs expressing CD41, CD66b, TMEM, and phalloidin bindi...
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Impaired flow mediated dilation (FMD), an index of vascular stress, is known after SCUBA diving. This is related to a dysfunction of nitric oxide (NO) availability and a disturbance of the redox status, possibly induced by... more
Impaired flow mediated dilation (FMD), an index of vascular stress, is known after SCUBA diving. This is related to a dysfunction of nitric oxide (NO) availability and a disturbance of the redox status, possibly induced by hyperoxic/hyperbaric gas breathing. SCUBA diving is usually performed with a mask only covering “half face” (HF) and therefore forcing oral breathing. Nasal NO production is involved in vascular homeostasis and, as consequence, can significantly reduce NO possibly promoting vascular dysfunction. More recently, the utilization of “full-face” (FF) mask, allowing nasal breathing, became more frequent, but no reports are available describing their effects on vascular functions in comparison with HF masks. In this study we assessed and compared the effects of a standard shallow dive (20 min at 10 m) wearing either FF or a HF mask on different markers of vascular function (FMD), oxidative stress (ROS, 8-iso-PGF2α) and NO availability and metabolism (NO2, NOx and 3-NT an...
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Background and Objective: Several cases of central serous chorioretinopathy (CSC) in divers have been reported in our medical retina center over the past few years. This study was designed to evaluate possible changes induced by SCUBA... more
Background and Objective: Several cases of central serous chorioretinopathy (CSC) in divers have been reported in our medical retina center over the past few years. This study was designed to evaluate possible changes induced by SCUBA diving in ophthalmic parameters and especially subfoveal choroidal thickness (SFCT), since the choroid seems to play a crucial role in physiopathology of CSC. Materials and Methods: Intraocular pressure (IOP), SFCT, pachymetry, flow-mediated dilation (FMD), blood pressure, and heart rate were measured in 15 healthy volunteer divers before diving, 30 and 60 min after a standard deep dive of 25 m depth for 25 min in a dedicated diving pool (NEMO 33). Results: SFCT reduces significantly to 96.63 ± 13.89% of pre-dive values (p = 0.016) 30 min after diving. It recovers after 60 min reaching control values. IOP decreases to 88.05 ± 10.04% of pre-dive value at 30 min, then increases to 91.42 ± 10.35% of its pre-dive value (both p < 0.0001). Pachymetry show...
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PurposeA reduction in ambient pressure or decompression from scuba diving can result in ultrasound-detectable venous gas emboli (VGE). These environmental exposures carry a risk of decompression sickness (DCS) which is mitigated by... more
PurposeA reduction in ambient pressure or decompression from scuba diving can result in ultrasound-detectable venous gas emboli (VGE). These environmental exposures carry a risk of decompression sickness (DCS) which is mitigated by adherence to decompression schedules; however, bubbles are routinely observed for dives well within these limits and significant inter-personal variability in DCS risk exists. Here, we assess the variability and evolution of VGE for 2 h post-dive using echocardiography, following a standardized pool dive in calm warm conditions.Methods14 divers performed either one or two (with a 24 h interval) standardized scuba dives to 33 mfw (400 kPa) for 20 min of immersion time at NEMO 33 in Brussels, Belgium. Measurements were performed at 21, 56, 91 and 126 min post-dive: bubbles were counted for all 68 echocardiography recordings and the average over ten consecutive cardiac cycles taken as the bubble score.ResultsSignificant inter-personal variability was demonstrated despite all divers following the same protocol in controlled pool conditions: in the detection or not of VGE, in the peak VGE score, as well as time to VGE peak. In addition, intra-personal differences in 2/3 of the consecutive day dives were seen (lower VGE counts or faster clearance).ConclusionsSince VGE evolution post-dive varies between people, more work is clearly needed to isolate contributing factors. In this respect, going toward a more continuous evaluation, or developing new means to detect decompression stress markers, may offer the ability to better assess dynamic correlations to other physiological parameters.
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Although many factors contributing to inert gas narcosis onset and severity have been put forward, the available evidence is not particularly strong. Using objective criteria, we have assessed brain impairment associated with narcosis... more
Although many factors contributing to inert gas narcosis onset and severity have been put forward, the available evidence is not particularly strong. Using objective criteria, we have assessed brain impairment associated with narcosis under various environmental diving conditions. 40 volunteers performed a no-decompression dive (33 m for 20 min) either in a dry chamber, a pool or open sea. They were assessed by critical flicker fusion frequency before the dive, upon arriving at depth, 5 min before ascent, on surfacing and 30 min post-dive. Compared to the pre-dive value, the mean value of each measurement was significantly different. An increase of flicker fusion to 105.00±0.69% when arriving at depth is followed by a decrease to 94.05±0.65%. This impairment persists when surfacing and 30 min post-dive, decreasing further to 96.36±0.73% and 96.24±0.73%, respectively. Intragroup comparison failed to demonstrate any statistical difference. When objectively measured narcosis may not be influenced by external factors other than pressure and gas. This might be of importance for training to avoid any over- or underestimation of the severity of narcosis based only on subjective symptoms.
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Inert gas accumulated after multiple recreational dives can generate tissue supersaturation and bubble formation when ambient pressure decreases. We hypothesized that this could happen even if divers respected the currently recommended... more
Inert gas accumulated after multiple recreational dives can generate tissue supersaturation and bubble formation when ambient pressure decreases. We hypothesized that this could happen even if divers respected the currently recommended 24-hour pre-flight surface interval (PFSI). We performed transthoracic echocardiography (TTE) on a group of 56 healthy scuba divers (39 male, 17 female) as follows: first echo - during the outgoing flight, no recent dives; second echo - before boarding the return flight, after a multiday diving week in the tropics and a 24-hour PFSI; third echo - during the return flight at 30, 60 and 90 minutes after take-off. TTE was also done after every dive during the week's diving. Divers were divided into three groups according to their 'bubble-proneness': non-bubblers, occasional bubblers and consistent bubblers. During the diving, 23 subjects never developed bubbles, 17 only occasionally and 16 subjects produced bubbles every day and after every d...
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Germonpré, P. et al.: Influence of SCUBA diving on asymptomatic isolated pulmonary bulla. Europ J Underwater i-iyperbaric Med 2006, 7(4): 79-85. Pulmonary blebs and bu]lae are generally considered an absolute contra-indication for SCUBA... more
Germonpré, P. et al.: Influence of SCUBA diving on asymptomatic isolated pulmonary bulla. Europ J Underwater i-iyperbaric Med 2006, 7(4): 79-85. Pulmonary blebs and bu]lae are generally considered an absolute contra-indication for SCUBA diving, because of a high estimated risk for pulmonary overpressure syndrome due to air-trapping inside the bulla. This is primarily based on a number of retrospective studies
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Flying after diving may increase decompression sickness risk (DCS), but strong evidence indicating minimum preflight surface intervals (PFSI) is missing. On return flights after a diving week on a live-aboard, 32 divers were examined by... more
Flying after diving may increase decompression sickness risk (DCS), but strong evidence indicating minimum preflight surface intervals (PFSI) is missing. On return flights after a diving week on a live-aboard, 32 divers were examined by in-flight echocardiography with the following protocol: 1) outgoing flight, no previous dive; 2) during the diving week; 3) before the return flight after a 24-h PFSI; and 4) during the return flight. All divers completed similar multiple repetitive dives during the diving week. All dives were equivalent as to inert gas load and gradient factor upon surfacing. No bubbles in the right heart were found in any diver during the outgoing flight or at the preflight control after a 24-h PFSI following the diving week. A significant increase in the number and grade of bubbles was observed during the return flight. However, bubbles were only observed in 6 of the 32 divers. These six divers were the same ones who developed bubbles after every dive. Having obse...
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Hypoxia is the natural trigger for endogenous EPO production but recently the use of intermittent hyperoxia to stimulate EPO has been postulated and this phenomenon has been called the "normobaric oxygen paradox" (NOP). The... more
Hypoxia is the natural trigger for endogenous EPO production but recently the use of intermittent hyperoxia to stimulate EPO has been postulated and this phenomenon has been called the "normobaric oxygen paradox" (NOP). The "NOP" is a mechanism by which oxygen regulates the expression of the Hypoxia Inducible Factor 1 alpha (HIF-1α). The HIF-1α-depending gene regulation is responsible for many different genetic expressions including EPO and VEGF. It has been proposed that relative changes of oxygen availability rather than steady state hypoxic or hyperoxic conditions, play an important role in HIF transcriptional effects. According to this hypothesis, the cell interprets the return to normoxia after a hyperoxic event as an oxygen shortage, and induces HIF-1-regulated gene synthesis, including EPO. Being both a hormone and a cytokine, the actual actions of EPO are complex; its clinical utility has been postulated for neuroprotection and cardioprotection. The preci...
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Our study's aim is to show how a five-week stretch training protocol, based on passive stretching, can change muscle performance during a drop jump (stretch shortening cycle). This study observes in 8 healthy subjects (four males and... more
Our study's aim is to show how a five-week stretch training protocol, based on passive stretching, can change muscle performance during a drop jump (stretch shortening cycle). This study observes in 8 healthy subjects (four males and four females), the effect of a 5-week passive stretch training protocol on the stretch shortening cycle (SSC) during the performance of a drop jump, and identify the architectural changes in the muscle. Subjects underwent measurements of their drop jump performance 3 times before, and 3 times after, the stretch training protocol. For the muscle tendon unit (MTU), changes were measured using the Hawkins and Hull's model. In order to calculate the length changes in the MTU, we measured the ankle and knee angles. For changes in the fascicle, the pennation angle and the thickness of the gastrocnemius medialis (GM) muscle were measured. After the 5-week stretch training protocol, a significant increase in flexibility was observed in the fascicle duri...
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In our previous research, a deep 5-min stop at 15 msw (50 fsw), in addition to the typical 3-5 min shallow stop, significantly reduced precordial Doppler detectable bubbles (PDDB) and "fast" tissue compartment gas tensions... more
In our previous research, a deep 5-min stop at 15 msw (50 fsw), in addition to the typical 3-5 min shallow stop, significantly reduced precordial Doppler detectable bubbles (PDDB) and "fast" tissue compartment gas tensions during decompression from a 25 msw (82 fsw) dive; the optimal ascent rate was 10 msw (30 fsw/min). Since publication of these results, several recreational diving agencies have recommended empirical stop times shorter than the 5 min stops that we used, stops of as little as 1 min (deep) and 2 min (shallow). In our present study, we clarified the optimal time for stops by measuring PDDB with several combinations of deep and shallow stop times following single and repetitive open-water dives to 25 msw (82 fsw) for 25 mins and 20 minutes respectively; ascent rate was 10 msw/min (33 fsw). Among 15 profiles, stop time ranged from 1 to 10 min for both the deep stops (15 msw/50 fsw) and the shallow stops (6 msw/20 fsw). Dives with 2 1/2 min deep stops yielded t...
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Scuba divers with patent foramen ovale (PFO) may be at risk for paradoxical nitrogen gas emboli when performing maneuvers that cause a rebound blood loading to the right atrium. We measured the rise and fall in intrathoracic pressure... more
Scuba divers with patent foramen ovale (PFO) may be at risk for paradoxical nitrogen gas emboli when performing maneuvers that cause a rebound blood loading to the right atrium. We measured the rise and fall in intrathoracic pressure (ITP) during various maneuvers in 15 divers. The tests were standard isometric exercises (control), forceful coughing, knee bend (with and without respiration blocked), and Valsalva maneuver (maximal, gradually increased to reach control ITP, and as performed by divers to equalize middle ear pressure). All the maneuvers, as well as the downward slope of ITP at the release phase, were related to the control value. ITP levels were significantly higher than the standard isometric effort during a breath-hold knee bend (172%, P < 0.001), cough (133%, P < 0.05), and maximal Valsalva (136%, P < 0.05) whereas "usual" Valsalva maneuvers produced ITPs significantly lower than the standard (28%, P < 0.001). The downward slope of the pressure ...
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The aim of this study was to evaluate the effect of a single, shallow, swimming pool scuba dive on pulmonary function in divers with asthma as compared to controls. Opinions concerning the risks of diving with asthma are still... more
The aim of this study was to evaluate the effect of a single, shallow, swimming pool scuba dive on pulmonary function in divers with asthma as compared to controls. Opinions concerning the risks of diving with asthma are still contradictory and inconclusive in the diving community. Baseline pulmonary function tests (PFTs) were performed on a group of 22 divers with asthma and on a control group of 15 healthy divers. The same PFTs were repeated within 10 minutes after a single pool dive, at 5 metres' depth for 10 minutes. PFTs were measured using a portable Jaeger SpiroPro™ device. Student's paired t-tests and linear mixed effects model comparisons and interactions within the groups were used in the data analysis. Divers with asthma initially presented significantly lower values of FEV1/FVC%* (P < 0.01), FEF25* (P < 0.01), FEF50* (P < 0.001), FEF75* (P < 0.01) and FEF25-75* (P < 0.001) compared to controls. There were significant reductions in FEV1 (P < 0.01...
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The existence of a right-to-left shunt may increase the likelihood of micro-embolism by allowing a flux of bubbles under hyperbaric conditions. The aim of the study was to measure the relationship between these shunts and bubbles in 10... more
The existence of a right-to-left shunt may increase the likelihood of micro-embolism by allowing a flux of bubbles under hyperbaric conditions. The aim of the study was to measure the relationship between these shunts and bubbles in 10 consecutive subjects using trans-thoracic and trans-esophageal echocardiography. In video frames, all cardiac chambers were segmented and bubbles were analyzed by our proposed method and two other methods. The relationship with bubbles and shunts was divided into three classes: no bubbles, 1-20 bubbles, &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;20 bubbles and measured over 2160 frames. Our sensitivity was 100% and our specificity was between 90.1% and 96.4%. There were 4.32-23.78 bubbles/frame in the left atrium according to our method. After the automatic analysis, shunts were graded double-blinded by two cardiologists. Consequently, we noted that aperture size does not necessarily reflect how active the right-to-left shunt is. Instead, our proposed decay curves constitute a better tool for determining functionality.
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We examined whether the improvement of impaired NO-dependent vasorelaxation by exercise training could be mediated through a BH4-dependent mechanism. Male spontaneously hypertensive rats (SHR, n = 20) and Wistar-Kyoto rats (WKY, n = 20)... more
We examined whether the improvement of impaired NO-dependent vasorelaxation by exercise training could be mediated through a BH4-dependent mechanism. Male spontaneously hypertensive rats (SHR, n = 20) and Wistar-Kyoto rats (WKY, n = 20) were trained (Tr) for 9 weeks on a treadmill and compared to age-matched sedentary animals (Sed). Endothelium-dependent vasorelaxation (EDV) was assessed with acetylcholine by measuring isometric tension in rings of femoral artery precontracted with 10(-5) M phenylephrine. EDV was impaired in SHR-Sed as compared to WKY-Sed (p = 0.02). Training alone improved EDV in both WKY (p = 0.01) and SHR (p = 0.0001). Moreover, EDV was not different in trained SHR than in trained WKY (p = 0.934). Pretreatment of rings with L-NAME (50 μM) cancelled the difference in ACh-induced relaxation between all groups, suggesting that NO pathway is involved in these differences. The presence of 10(-5) M BH4 in the organ bath significantly improved EDV for sedentary SHR (p = 0.030) but not WKY group (p = 0.815). Exercise training turned the beneficial effect of BH4 on SHR to impairment of ACh-induced vasorelaxation in both SHR-Tr (p = 0.01) and WKY-Tr groups (p = 0.04). These results suggest that beneficial effect of exercise training on endothelial function is due partly to a BH4-dependent mechanism in established hypertension.
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Research Interests: Injury Prevention, Adolescent, Diving, Case Report, Humans, and 15 moreFemale, Male, Cluster Analysis, Hearing Loss, Medical Physiology, Hierarchical Clustering, Aged, Middle Aged, Adult, Hyperbaric Oxygenation, Diving Medicine, Indexation, Decompression Sickness, Bayes Theorem, and Bayesian Information Criterion
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Face aux Livres 11/08/2015: Interview avec Eric Bouancheaux (cliquez ici pour ecouter) De plus en plus d’organisations reconnaissent la superiorite du QE (quotient emotionnel) sur le QI. Les modeles de “leaders” sous les traits d’un CEO... more
Face aux Livres 11/08/2015: Interview avec Eric Bouancheaux (cliquez ici pour ecouter) De plus en plus d’organisations reconnaissent la superiorite du QE (quotient emotionnel) sur le QI. Les modeles de “leaders” sous les traits d’un CEO glacial ou d’un commercial sanguin ont vecu. L’humain se place desormais au centre de toute entreprise et pour cela, il doit savoir apprecier l’autre au moins autant pour ce qu’il est que pour ce qu’il fait. Car qui dit humain dit humaniser. La cle ? Communiqu’agir ! Facile a dire : comment maitriser les rouages de l’interaction avec ses semblables ? En suivant le parcours offert dans ces pages ! Les auteurs ont decrypte pour vous tous les codes de la communication en partant de sa source : le cerveau. Et pour vous aider a positiver, ils vous revelent la langue des mots, de la voix et du corps. Et leur mode d’emploi. Resolument tourne vers le developpement personnel, ce package de la relation a soi et a l’autre aborde les matieres de facon tres ludique et les agrementent de nombreuses illustrations et meme d’une BD. Totalement revise et mis a jour, le contenu de cette seconde edition est augmente de plusieurs index permettant d’encore mieux localiser les pepites qu’elle contient. Vous savez ne pas posseder deux chances de faire une premiere bonne impression ? Et qu’a cet egard, un acte de communication bien pose laisse peu de marge a l’erreur ? Alors, donnez-vous les moyens de bâtir un rapport sain et realiste avec votre entourage : gardez ce guide pratique a portee de main. Un ouvrage qui vous veut du bien, c’est rare, non ? Dans la presse RTBF Viva Cite: La Vie du Bon Cote avec Sylvie Honore: http://www.rtbf.be/radio/podcast/player? id=2026506&channel=vivacite •
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Objectifs Determiner si une prehydratation 90 min avant une plongee sous-marine diminue la formation de bulles et evaluer les modifications hemodynamiques et hydriques de l'organisme ainsi que les variations de la tension... more
Objectifs Determiner si une prehydratation 90 min avant une plongee sous-marine diminue la formation de bulles et evaluer les modifications hemodynamiques et hydriques de l'organisme ainsi que les variations de la tension superficielle plasmatique associees. Methodes 8 plongeurs militaires ont participe a l'etude (36 ± 6 ans, IMC = 23,2 - 26,1 kg.m -2 ). Chacun d'eux a realise 2 plongees (30m, 30min, 9min a 3m) dont une etait precedee par une phase d'hydratation de 60min (protocole 1) tandis que l'autre etait sans boisson prealable (protocole 2). La solution a boire etait constituee de 30g de sucre et de 2g de sel (1300 ml, osmolarite = 324 mOsml -1 ). Les parametres hemodynamiques, une pesee, le recueil des urines et des prelevements sanguins ont ete collectes avant et apres hydratation et apres plongee. L'activite bullaire a ete mesuree par Doppler precordial jusqu'a 90min apres les plongees. Resultats Le score de bulles a ete significativement plus bas apres prehydratation (p<0,031). Le volume plasmatique a augmente de 3,5 % apres boisson puis est revenu a un niveau normal apres la plongee pour le protocole 1, tandis qu'il a diminue de 2,2 % apres plongee pour le protocole 2. Les differences de volemie post-plongee entre les 2 protocoles etaient tres significatives (p<0,007). La perte relative de poids apres plongee etait plus importante pour le protocole 2 que pour le protocole 1 (-2,4% versus -0,5%, p<0,016) avec une reduction de la balance hydrique pour la plongee precedee d'hydratation due a une meilleure retention d'eau (p<0,05). Nous n'avons pas retrouve de differences significatives dans la mesure de la tension superficielle du plasma avant/apres hydratation et apres plongee pour les 2 protocoles. Conclusion L'ingestion de 1300 ml d'un solute legerement hypertonique avant une plongee a permis de diminuer le niveau de bulles vasculaires circulantes produites lors de la decompression. Ce protocole de prehydratation limiterait la deshydratation post-plongee et empecherait l'hypovolemie associee. Dans cette etude, la tension superficielle du plasma ne semble pas etre modifiee par l'hydratation ou la plongee.
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Le but de cette étude était de tester les e ets des stimulations réflexes podales (SRP) sur l&amp;#39;architecture du sommeil chez des sujets atteints de troubles nocturnes. Durant leurs 3 nuits au Laboratoire du sommeil, chaque sujet... more
Le but de cette étude était de tester les e ets des stimulations réflexes podales (SRP) sur l&amp;#39;architecture du sommeil chez des sujets atteints de troubles nocturnes. Durant leurs 3 nuits au Laboratoire du sommeil, chaque sujet (n = 10) a reçu une séance de SRP de 20 mn. Elles sont été pratiquées de manière aléatoire en nuit 2 ou
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Renal (paratubular) tissue hypoxia is the only known physiological trigger for Erythropoietin (EPO) produc-tion. For this experiment, we hypothetised that another triggering mechanism might exist, unrelated to absolute renal tissue... more
Renal (paratubular) tissue hypoxia is the only known physiological trigger for Erythropoietin (EPO) produc-tion. For this experiment, we hypothetised that another triggering mechanism might exist, unrelated to absolute renal tissue hypoxia. We tested a group of healthy ...
Left Ventricular Mechanics in Behcet’s Disease: A Speckle Tracking Echocardiographic Study. S. Demirelli, H. De girmenci, H. Bilen, E. Ermis, H. Duman, A. Arisoy, E.M. Bakirci, E. _ Ipek, L. Askin, M.H. Tas. Department of Cardiology,... more
Left Ventricular Mechanics in Behcet’s Disease: A Speckle Tracking Echocardiographic Study. S. Demirelli, H. De girmenci, H. Bilen, E. Ermis, H. Duman, A. Arisoy, E.M. Bakirci, E. _ Ipek, L. Askin, M.H. Tas. Department of Cardiology, Erzurum Education and Research Hospital, Erzurum, Turkey; Department of Cardiology, Erzincan Universty, Erzincan, Turkey; Department of Dermatology, Faculty of Medicine, Erzurum University, Erzurum, Turkey; Department of Cardiology, Rize State Hospital, Rize, Turkey; Department of Cardiology, Corum Education and Research Hospital, Corum, Turkey; Department of Cardiology, Faculty of Medicine, Erzurum University, Erzurum, Turkey.
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Scuba and breath-hold divers are compared to investigate whether endothelial response changes are similar despite different exposure(s) to hyperoxia. 14 divers (nine scuba and five breath-holding) performed either one scuba dive (25m/25... more
Scuba and breath-hold divers are compared to investigate whether endothelial response changes are similar despite different exposure(s) to hyperoxia. 14 divers (nine scuba and five breath-holding) performed either one scuba dive (25m/25 minutes) or successive breath-hold dives at a depth of 20 meters, adding up to 25 minutes of immersion time in a diving pool. Flow-mediated dilation (FMD) was measured using echography. Peripheral post-occlusion reactive hyperemia (PORH) was assessed by digital plethysmography and plasmatic nitric oxide (NO) concentration using a nitrate/nitrite colorimetric assay kit. The FMD decreased in both groups. PORH was reduced in scuba divers but increased in breath-hold divers. No difference in circulating NO was observed for the scuba group. Opposingly, an increase in circulating NO was observed for the breath-hold group. Some cardiovascular effects can be explained by interaction between NO and superoxide anion during both types of diving ending to less N...
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Seddon F, Thacker J, Jurd K, Loveman G. Effects of Valsalva manoeuvres and the ‘CO 2 -off’ effect on cerebral blood flow. Diving and Hyperbaric Medicine. 2014 December;44(4):187-192.) Introduction: Previous research has shown that a rapid... more
Seddon F, Thacker J, Jurd K, Loveman G. Effects of Valsalva manoeuvres and the ‘CO 2 -off’ effect on cerebral blood flow. Diving and Hyperbaric Medicine. 2014 December;44(4):187-192.) Introduction: Previous research has shown that a rapid drop in inhaled carbon dioxide (CO 2 ) partial pressure reduces cerebral blood flow and may induce faintness – the ‘CO 2 -off’ effect. The aims of this study were to investigate the effects of performing Valsalva manoeuvres while experiencing the ‘CO 2 -off’ effect and whether symptoms occur that are sufficient to jeopardise submarine tower escape. Methods: Twenty male volunteers, mean (SD) age 34.7 (8.5) years each completed three tests. The first test was to perform Valsalva manoeuvres breathing air. The second and third tests involved breathing a high CO 2 mix (5% CO 2 /16% O 2 / 79% N 2 ) for 1 h prior to switching to breathe O 2 and performing Valsalva manoeuvres, or switching to breathe air for 1 min then O 2 and performing Valsalva manoeuvre...
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Introduction: Divers with a patent Foramen Ovale (PFO) have an increased risk for decompression sickness (DCS) when diving with compressed breathing gas. The relative risk increase, however, is difficult to establish as the PFO status of... more
Introduction: Divers with a patent Foramen Ovale (PFO) have an increased risk for decompression sickness (DCS) when diving with compressed breathing gas. The relative risk increase, however, is difficult to establish as the PFO status of divers is usually only determined after a DCS occurrence.Methods: This prospective, single-blinded, observational study was designed to collect DCS data from volunteer divers after screening for right-to-left shunt (RLS) using a Carotid Doppler test. Divers were blinded to the result of the test, but all received a standardized briefing on current scientific knowledge of diving physiology and “low-bubble” diving techniques; they were then allowed to dive without restrictions. After a mean interval of 8 years, a questionnaire was sent collecting data on their dives and cases of DCS (if any occurred).Results: Data was collected on 148 divers totaling 66,859 dives. There was no significant difference in diving data between divers with or without RLS. D...
Depending on the oxygen partial pressure in a tissue, the therapeutic effect of oxygenation can vary from simple substance substitution up to hyperbaric oxygenation when breathing hyperbaric oxygen at 2.5–3.0 ATA. Surprisingly, new data... more
Depending on the oxygen partial pressure in a tissue, the therapeutic effect of oxygenation can vary from simple substance substitution up to hyperbaric oxygenation when breathing hyperbaric oxygen at 2.5–3.0 ATA. Surprisingly, new data showed that it is not only the oxygen supply that matters as even a minimal increase in the partial pressure of oxygen is efficient in triggering cellular reactions by eliciting the production of hypoxia-inducible factors and heat-shock proteins. Moreover, it was shown that extreme environments could also interact with the genome; in fact, epigenetics appears to play a major role in extreme environments and exercise, especially when changes in oxygen partial pressure are involved. Hyperbaric oxygen therapy is, essentially, “intermittent oxygen” exposure. We must investigate hyperbaric oxygen with a new paradigm of treating oxygen as a potent stimulus of the molecular network of reactions.
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Inflammation is an adaptive response to both external and internal stimuli including infection, trauma, surgery, ischemia-reperfusion, or malignancy. A number of studies indicate that physical activity is an effective means of reducing... more
Inflammation is an adaptive response to both external and internal stimuli including infection, trauma, surgery, ischemia-reperfusion, or malignancy. A number of studies indicate that physical activity is an effective means of reducing acute systemic and low-level inflammation occurring in different pathological conditions and in the recovery phase after disease. As a proof-of-principle, we hypothesized that low-intensity workout performed under modified oxygen supply would elicit a “metabolic exercise” inducing a hormetic response, increasing the metabolic load and oxidative stress with the same overall effect expected after a higher intensity or charge exercise. Herein, we report the effect of a 5-week low-intensity, non-training, exercise program in a group of young healthy subjects in combination with the exposure to hyperoxia (30% and 100% pO2, respectively) or light hypoxia (15% pO2) during workout sessions on several inflammation and oxidative stress parameters, namely hemogl...
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Introduction: The SARS-CoV2 pandemic has led to an worldwide shortage of Personal Protection Devices (PPD) for medical and paramedical personnel. Adaptation of commercially available snorkel masks to serve as full face masks has been... more
Introduction: The SARS-CoV2 pandemic has led to an worldwide shortage of Personal Protection Devices (PPD) for medical and paramedical personnel. Adaptation of commercially available snorkel masks to serve as full face masks has been proposed. Even not formally approved as PPD, they are publicized on social media as suitable for this use. Concerns about actual protection levels and risk of carbon dioxide (CO2) accumulation while wearing them for extended periods made us perform a systematic testing of various brands, in order to verify whether they are as safe and effective as claimed. Methods: A ‘fit’ test was performed, analogous to gas mask testing. Respiratory safety was evaluated by measuring end-tidal CO2 and oxygen saturation while wearing the masks in rest and during physical exercise. Masks were tested with 3D adaptors to mount regular bacterial-viral ventilator filters when available, or with snorkel openings covered with N95/FFP2 cloth. Results: Modified masks performed r...
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Oxygenation conditions are crucial for growth and tumor progression. Recent data suggests a decrease in cancer cell proliferation occurring after exposure to normobaric hyperoxia. Those changes are associated with fractal dimension. The... more
Oxygenation conditions are crucial for growth and tumor progression. Recent data suggests a decrease in cancer cell proliferation occurring after exposure to normobaric hyperoxia. Those changes are associated with fractal dimension. The purpose of this research was to study the impact of hyperoxia on apoptosis and morphology of leukemia cell lines. Two hematopoietic lymphoid cancer cell lines (a T-lymphoblastoid line, JURKAT and a B lymphoid line, CCRF-SB) were tested under conditions of normobaric hyperoxia (FiO2 > 60%, ± 18h) and compared to a standard group (FiO2 = 21%). We tested for apoptosis using a caspase-3 assay. Cell morphology was evaluated by cytospin, microphotography after coloration, and analysis by a fractal dimension calculation software. Our results showed that exposure of cell cultures to transient normobaric hyperoxia induced apoptosis (elevated caspase-3) as well as significant and precocious modifications in cell complexity, as highlighted by increased fractal dimensions in both cell lines. These features are associated with changes in structure (pycnotic nucleus and apoptosis) recorded by microscopic analysis. Such morphological alterations could be due to several molecular mechanisms and rearrangements in the cancer cell, leading to cell cycle inhibition and apoptosis as shown by caspase-3 activity. T cells seem less resistant to hyperoxia than B cells.
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Exercise generates reactive oxygen species (ROS), creating a redox imbalance towards oxidation when inadequately intense. Normobaric and hyperbaric oxygen (HBO) breathed while not exercising induces antioxidant enzymes expression, but... more
Exercise generates reactive oxygen species (ROS), creating a redox imbalance towards oxidation when inadequately intense. Normobaric and hyperbaric oxygen (HBO) breathed while not exercising induces antioxidant enzymes expression, but literature is still poor. Twenty-two athletes were assigned to five groups: controls; 30%, or 50% O2; 100% O2 (HBO) at 1.5 or 2.5 atmosphere absolute (ATA). Twenty treatments were administered on non-training days. Biological samples were collected at T0 (baseline), T1 (end of treatments), and T2 (1 month after) to assess ROS, antioxidant capacity (TAC), lipid peroxidation, redox (amino-thiols) and inflammatory (IL-6, 10, TNF-α) status, renal function (i.e., neopterin), miRNA, and hemoglobin. At T1, O2 mixtures and HBO induced an increase of ROS, lipid peroxidation and decreased TAC, counterbalanced at T2. Furthermore, 50% O2 and HBO treatments determined a reduced state in T2. Neopterin concentration increased at T1 breathing 50% O2 and HBO at 2.5 ATA...
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The term “normobaric oxygen paradox” (NOP), describes the response to the return to normoxia after a hyperoxic event, sensed by tissues as oxygen shortage, and resulting in up-regulation of the Hypoxia-inducible factor 1α (HIF-1α)... more
The term “normobaric oxygen paradox” (NOP), describes the response to the return to normoxia after a hyperoxic event, sensed by tissues as oxygen shortage, and resulting in up-regulation of the Hypoxia-inducible factor 1α (HIF-1α) transcription factor activity. The molecular characteristics of this response have not been yet fully characterized. Herein, we report the activation time trend of oxygen-sensitive transcription factors in human peripheral blood mononuclear cells (PBMCs) obtained from healthy subjects after one hour of exposure to mild (MH), high (HH) and very high (VHH) hyperoxia, corresponding to 30%, 100%, 140% O2, respectively. Our observations confirm that MH is perceived as a hypoxic stress, characterized by the activation of HIF-1α and Nuclear factor (erythroid-derived 2)-like 2 (NRF2), but not Nuclear Factor kappa-light-chain-enhancer of activated B cells (NF-κB). Conversely, HH is associated to a progressive loss of NOP response and to an increase in oxidative str...
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Hyperbaric oxygen (HBO₂) therapy and use of enriched air can result in oxidative injury affecting the brain, lungs and eyes. HBO₂ exposure during diving can lead to a decrease in respiratory parameters. However, the possible effects of... more
Hyperbaric oxygen (HBO₂) therapy and use of enriched air can result in oxidative injury affecting the brain, lungs and eyes. HBO₂ exposure during diving can lead to a decrease in respiratory parameters. However, the possible effects of acute exposure to oxygen-enriched diving on subsequent spirometric performance and oxidative state in humans have not been recently described recently. We aim to investigate possible effects of acute (i) hyperbaric and (ii) hyperbaric hyperoxic exposure using scuba or closed-circuit rebreather (CCR) on subsequent spirometry and to assess the role of oxidative state after hyperoxic diving. Spirometry and urine samples were obtained from six well-trained divers (males, mean ± SD, age: 43.33 ± 9.16 years; weight: 79.00 ± 4.90 kg; height: 1.77 ± 0.07 meters) before (CTRL) and after a dive breathing air, and after a dive using CCR (PO₂ 1.4). In the crossover design (two dives separated by six hours) each subject performed a 20-minute session of light under...
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Bubble formation during scuba diving might induce decompression sickness. This prospective randomised and double-blind study included 108 advanced recreational divers (38 females). Fifty-four pairs of divers, 1 breathing air and the other... more
Bubble formation during scuba diving might induce decompression sickness. This prospective randomised and double-blind study included 108 advanced recreational divers (38 females). Fifty-four pairs of divers, 1 breathing air and the other breathing nitrox28 undertook a standardised dive (24 ± 1 msw; 62 ± 5min) in the Red Sea. Venous gas bubbles were counted (Doppler) 30-&amp;amp;lt;45 min (early) and 45-60 min (late) post-dive at jugular, subclavian and femoral sites. Only 7% (air) vs. 11% (air28®) (n.s.) were bubble-free after a dive. Independent of sampling time and breathing gas, there were more bubbles in the jugular than in the femoral vein. More bubbles were counted in the air-group than in the air28-group (pooled vein: early: 1845 vs. 948; P = 0.047, late: 1817 vs. 953; P = 0.088). The number of bubbles was sex-dependent. Lastly, 29% of female air divers but only 14% of male divers were bubble-free (P = 0.058). Air28® helps to reduce venous gas emboli in recreational divers. The bubble number depended on the breathing gas, sampling site and sex. Thus, both exact reporting the dive and in particular standardising sampling characteristics seem mandatory to compare results from different studies to further investigate the hitherto incoherent relation between inert gas bubbles and DCS.
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Backround: Nitrogen narcosis impairs cognitive function, a fact relevant during SCUBA-diving. Oxygen-enriched air (nitrox) became popular in recreational diving, while evidence of its advantages over air is limited. Compare effects of... more
Backround: Nitrogen narcosis impairs cognitive function, a fact relevant during SCUBA-diving. Oxygen-enriched air (nitrox) became popular in recreational diving, while evidence of its advantages over air is limited. Compare effects of nitrox28 and air on two psychometric tests. In this prospective, double-blind, open-water study, 108 advanced divers (38 females) were randomized to an air or a nitrox-group for a 60-min dive to 24 m salt water. Breathing gas effects on cognitive performance were assessed during the dive using a short- and long-term memory test and a number connection test. Nitrox28 divers made fewer mistakes only on the long-term memory test (p = 0.038). Female divers remembered more items than male divers (p &amp;amp;lt; 0.001). There were no significant differences in the number connection test between the groups. Likely owing to the comparatively low N2 reduction and the conservative dive, beneficial nitrox28 effects to diver performance were moderate but could contribute to diving safety.
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Previous studies have shown vascular dysfunction of main conductance arteries and microvessels after diving. We aim to evaluate the impact of bubble formation on vascular function and haemostasis. To achieve this, we used a vibration... more
Previous studies have shown vascular dysfunction of main conductance arteries and microvessels after diving. We aim to evaluate the impact of bubble formation on vascular function and haemostasis. To achieve this, we used a vibration preconditioning to influence bubble levels without changing any other parameters linked to the dive. Twentty-six divers were randomly assigned to one of three groups: (1) the "vibrations-dive" group (VD; n = 9) was exposed to a whole-body vibration session 30 min prior the dive; (2) the "diving" group (D; n = 9) served as a control for the effect of the diving protocol; (3) The "vibration" protocol (V; n = 8) allowed us to assess the effect of vibrations without diving. Macro- and microvascular function was assessed for each subject before and after the dive, subsequently. Bubble grades were monitored with Doppler according to the Spencer grading system. Blood was taken before and after the protocol to assess any change of ...
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Purpose: Since non-provocative dive profiles are no guarantor of protection against decompression sickness, novel means including pre-dive "preconditioning" interventions, are proposed for its prevention. This study investigated... more
Purpose: Since non-provocative dive profiles are no guarantor of protection against decompression sickness, novel means including pre-dive "preconditioning" interventions, are proposed for its prevention. This study investigated and compared the effect of pre-dive oxygenation, pre-dive whole body vibration or a combination of both on post-dive bubble formation. Methods: Six healthy volunteers performed 6 no-decompression dives each, to a depth of 33 mfw for 20 min (3 control dives without preconditioning and 1 of each preconditioning protocol) with a minimum interval of 1 week between each dive. Post-dive bubbles were counted in the precordium by two-dimensional echocardiography, 30 and 90 min after the dive, with and without knee flexing. Each diver served as his own control. Results: Vascular gas emboli (VGE) were systematically observed before and after knee flexing at each post-dive measurement. Compared to the control dives, we observed a decrease in VGE count of 23.8...
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Aiding women during delivery is a constant concern nowadays, particularly aiming to reduce the fetus expulsion time. The available technical aids are very variable depending upon ethno-anthropological variables. Physical therapy is able... more
Aiding women during delivery is a constant concern nowadays, particularly aiming to reduce the fetus expulsion time. The available technical aids are very variable depending upon ethno-anthropological variables. Physical therapy is able to offer some tools through muscle relaxation and respiratory management. Our study focuses on the pelvimetric analysis during the contraction of the musculus obturatorius internus. Its muscular contraction
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Commentaries on Viewpoint: Why predominantly neurological DCS in breath-hold divers?Commentaries on Viewpoint: Why predominantly neurological DCS in breath-hold divers?Commentaries on Viewpoint: Why predominantly neurological DCS in breath-hold divers?Commentaries on Viewpoint: Why predominantly ...more
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Breath-hold diving is both a recreational activity, performed by thousands of enthusiasts in Europe, and a high-performance competitive sport. Several... more
Breath-hold diving is both a recreational activity, performed by thousands of enthusiasts in Europe, and a high-performance competitive sport. Several &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;disciplines&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; exist, of which the &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;no-limits&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; category is the most spectacular: using a specially designed heavy &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;sled,&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; divers descend to extreme depths on a cable, and then reascend using an inflatable balloon, on a single breath. The current world record for un-assisted descent stands at more than 200 m of depth. Equalising air pressure in the paranasal sinuses and middle-ear cavities is a necessity during descent to avoid barotraumas. However, this requires active insufflations of precious air, which is thus unavailable in the pulmonary system. The authors describe a diver who, by training, is capable of allowing passive flooding of the sinuses and middle ear with (sea) water during descent, by suppressing protective (parasympathetic) reflexes during this process. Using this technique, he performed a series of extreme-depth breath-hold dives in June 2005, descending to 209 m of sea water on one breath of air.
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Decompression illness (DCI)/dysbaric disorders represent a complex spectrum of pathophysiological conditions with a wide variety of signs and symptoms related to dissolved gas and its subsequent phase change. Any significant organic or... more
Decompression illness (DCI)/dysbaric disorders represent a complex spectrum of pathophysiological conditions with a wide variety of signs and symptoms related to dissolved gas and its subsequent phase change. Any significant organic or functional decrement in individuals who have recently been exposed to a reduction in environmental pressure (i.e., decompression) must be considered as evidence of DCI until proven otherwise. However, apart from the more obvious acute manifestations, individuals who have experienced repetitive exposures (e.g., commercial or professional divers and active recreational divers) may also develop sub-acute or chronic manifestations sub-clinically - insidious, even if subtle, and almost symptomless. It is, in fact, generally accepted that sub-clinical forms of DCI exist, with little or no reported symptoms, and that these may cause changes in the bones, the central nervous system and the lungs. All this has led us to analysing &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;decompression stress&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;, the actual way of understanding decompression. Current research into decompression sickness (DCS) is focused on biological markers that can be detected in the blood. Investigators are exploring the potential association between decompression stress and the presence of membrane microparticles (membrane-bound vesicles shed from a variety of cell types) in the blood. Microparticle levels increase in association with many physiological disease states as well as with the shearing stress caused by bubbles in the blood. The working hypothesis is that certain microparticles (possibly induced by inert gas bubbles) may initiate, be a marker of or contribute to the inflammatory response that leads to DCS. This investigation goes beyond the pure bubble model. While bubbles in the blood certainly play a key role in the development of DCS, their presence or absence does not reliably predict DCS symptom onset. Investigating this process at the molecular level may teach us a great deal more about DCS, providing insights that we hope will improve the effectiveness of both prevention and treatment. Approaches to evaluating decompression stress have considered a wide range of &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;markers&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;: different physiological changes after the dive (flow mediated dilatation reduction, blood pressure); personal susceptibility (VO2max, age); environmental factors (altitude, temperature); various physiological states (dehydration, increased vascular resistance as well as bubble counts, predictive decompression models, etc., etc. All this shows how far today&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s approach to decompression is removed from &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;traditional&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; understanding. It reflects both the need to consider the phenomenon of decompression in a different way than previously and the advances in knowledge over the past 20 years of diving science research. The 14 researchers who have been working for three years under the PHYPODE European Project reached a point where they felt the need to publish a new book in English to allow divers to learn more about the modern approaches to understanding decompression and its problems. Almost every young scientist participating in the PHYPODE project had the responsibility of writing a chapter. This was by no means a simple job considering the different linguistic origins of this group of young researchers, many of whom had their own doctoral theses or research programmes to complete in parallel. Authors also…
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Pulmonary blebs and bullae are generally considered an absolute contra-indication for scuba diving, because of a high estimated risk of pulmonary overpressure syndrome due to air-trapping inside the bulla. This is primarily based on a... more
Pulmonary blebs and bullae are generally considered an absolute contra-indication for scuba diving, because of a high estimated risk of pulmonary overpressure syndrome due to air-trapping inside the bulla. This is primarily based on a number of retrospective studies and case reports; formal prospective evidence of a higher risk is lacking. We present three cases where a pulmonary bulla was radiographically shown to increase in diameter, seemingly related to scuba diving activity, and causing ultimately a barotraumatic diving accident. These cases provide pathophysiological clues as to how even an isolated, non-ventilated bulla can be the cause of pulmonary barotrauma. The most likely mechanism for this phenomenon is a &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;stretching&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; of the bulla upon ascent from the dive: after a period of compression (Boyle&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s Law), there is a gradual diffusion of air through the bulla wall, with restoration to its initial size by the end of the dive. Upon ascent, the air diffuses only slowly out of the bulla, causing a temporary increase in diameter and stretching of the bulla wall. This repeated stretching causes the bulla to grow gradually. At one point, the cyst wall may become critically thin and rupture during the ascent.
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The focus in this new title is on PFO (Patent Foramen Ovale) as a risk factor in diving and thus the text is concerned primarily with dissolved gas and the subsequent aberrant distribution of those venous bubbles in the presence of a... more
The focus in this new title is on PFO (Patent Foramen Ovale) as a risk factor in diving and thus the text is concerned primarily with dissolved gas and the subsequent aberrant distribution of those venous bubbles in the presence of a natural and common anatomical variant of cardiac development. The prevalence of PFO is about 25% in the general population and several respectable investigators have studied this problem and feel that PFO should be considered a definite risk factor for the development of decompression sickness.
Decompression sickness (DCS) is a systemic disorder assumed due to gas bubbles, but additional factors are likely to play a role. Circulating microparticles, vesicular structures with diameters of 0.1 to 1.0 µm, have been implicated but... more
Decompression sickness (DCS) is a systemic disorder assumed due to gas bubbles, but additional factors are likely to play a role. Circulating microparticles, vesicular structures with diameters of 0.1 to 1.0 µm, have been implicated but data in human divers has been lacking. We hypothesized that the number of blood-borne annexin V-positive microparticles (MPs) and neutrophil activation assessed as surface myeloperoxidase (MPO) staining would differ between SCUBA divers suffering from DCS versus asymptomatic divers. Blood was analyzed from 280 divers who had been exposed to maximum depths from 7 to 105 meters; 185 were control/asymptomatic divers and 90 were diagnosed with DCS. Elevations of MPs and neutrophil activation occurred in all divers but normalized within 24 hours in those who were asymptomatic. MPs bearing the following proteins: CD66b, CD41, CD31, CD142, CD235 and von Willebrand factor were between 2.4 and 11.7-fold higher in blood from divers with DCS versus asymptomatic...
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Vasodilation of the peripheral arteries during reactive hyperaemia depends in part on release of nitric oxide from endothelial cells. Previous studies mainly employed a fingertip tonometric device to derive pulse wave amplitude (PWA) and... more
Vasodilation of the peripheral arteries during reactive hyperaemia depends in part on release of nitric oxide from endothelial cells. Previous studies mainly employed a fingertip tonometric device to derive pulse wave amplitude (PWA) and PWA hyperaemic changes. An alternative approach is based on photoplethysmography (PPG). We sought to evaluate the correlates of digital PPG PWA hyperaemic responses as a measure of peripheral vascular function. The Flemish Study on Environment, Genes and Health Outcomes (FLEMENGHO) is a population-based cohort study. Respondents were examined at one centre in northern Belgium. For this analysis, our sample consisted of 311 former participants (53.5% women; mean age 52.6 years; 43.1% hypertensive), who were examined from January 2010 until March 2012 (response rate 85.1%). Using a fingertip PPG device, we measured digital PWA at baseline and at 30 s intervals for 4 min during reactive hyperaemia induced by a 5 min forearm cuff occlusion. We performed...
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Intermittent prenatal exposure to hypoxia is associated with postnatal alteration in cardiac and endothelial functions. Hyperoxic exposure has significant effects on the cardiovascular system including bradycardia, vasoconstriction and... more
Intermittent prenatal exposure to hypoxia is associated with postnatal alteration in cardiac and endothelial functions. Hyperoxic exposure has significant effects on the cardiovascular system including bradycardia, vasoconstriction and endothelial dysfunction. The impact of intermittent prenatal hypoxia on cardiac rhythm control during mild hyperoxic conditions is unclear. Thus, expression of hyperoxic bradycardia during normobaric and hyperbaric hyperoxia was investigated telemetrically (PA-C40,
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Research Interests: Risk assessment, Diving, Prospective studies, Humans, Blood Pressure, and 19 moreBlood sampling, Male, Bubble, Medical Physiology, Risk factors, Middle Aged, Far Infrared, Adult, Public health systems and services research, Time Factors, Pulse Pressure, Hyperbaric Oxygenation, Risk Factors, Risk Assessment, Decompression Sickness, Heat Shock Protein, Decompression, Systolic blood pressure, and Brachial artery
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&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp... more
&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;Cutis Marmorata&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; skin symptoms after diving, most frequently in the form of an itching or painful cutaneous red-bluish discoloration are commonly regarded as a mild form of decompression sickness (DCS), and treated with oxygen inhalation without reverting to hyperbaric recompression treatment. It has been observed that the occurrence of Cutis Marmorata is frequently associated with the presence of a Patent Foramen Ovale (PFO) of the heart, and indeed, with a properly executed contrast echocardiographic technique, these patients have an almost 100% prevalence of PFO. Only occasionally, Cutis Marmorata is accompanied by other symptoms of DCS. These symptoms usually are in the form of visual distortions, vertigo, or mild, vague but generalized cerebral dysfunction (such as abnormal fatigue, clumsiness, concentration problems). The pathogenesis of these other manifestations is clearly emboligenic, and we hypothesize that Cutis Marmorata is also a manifestation of gas bubbles embolizing the brain stem: the site of autonomic nervous system regulation of skin blood vessel dilation and constriction. The consequences of this hypothesis are that Cutis Marmorata skin decompression sickness should no longer be considered a mild, innocuous form but rather a serious, neurological form and treated accordingly.
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Breath-hold diving-induced hemoptysis (BH-DIH) has been reported in about 25% breath-hold divers (BHD) and is characterized by dyspnea, coughing, hemoptysis and chest pain. We investigated whether eNOS G894T, eNOS T786C and ACE... more
Breath-hold diving-induced hemoptysis (BH-DIH) has been reported in about 25% breath-hold divers (BHD) and is characterized by dyspnea, coughing, hemoptysis and chest pain. We investigated whether eNOS G894T, eNOS T786C and ACE insertion/deletion I/D genetic variants, are possible BH-DIH risk factors. 108 experienced healthy instructor BHDs with the same minimum requirements (102 male, six female; mean age 43.90 ± 7.49) were studied. We looked for different eNOS G894T, eNOS T786C and ACE insertion/ deletion genetic variants between BH-DIH-positive and BH-DIH-negative subjects to identify the variants most frequently associated with BH-DIH. At least one BH-DIH episode was reported by 22.2% of subjects, while 77.7% never reported BH-DIH. The majority of BH-DIH-positive subjects showed eNOS G894T (p = 0.001) and eNOS-T786C (p = 0.001) genotype "TT" (high-risk profile). Prevalence of BH-DIH was higher in subjects with eNOS G894T TT genotype (50%) than in subjects with GT (9.5%...
Research Interests: Diving, Humans, Female, Male, Clinical Sciences, and 4 moreGenotype, Adult, Breath Holding, and Hemoptysis
We have previously suggested a classification of DCI using multivariate statistics to assess naturally associated clusters of signs and symptoms based on 1929 cases reported by hyperbaric chambers to the Divers Alert Network from 1999 to... more
We have previously suggested a classification of DCI using multivariate statistics to assess naturally associated clusters of signs and symptoms based on 1929 cases reported by hyperbaric chambers to the Divers Alert Network from 1999 to 2003. The aim of this study is to validate the reliability of the previous work by applying three different alternative clustering methods, by comparing the results of Two-step clustering analysis with the Perceived Severity Index (PSI) and to confirm the characteristics of patient clusters using association rules.
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La facilitation de la circulation de retour est essentielle dans la prise en charge des patients souffrant d'insuffisance veineuse. Nous avons testé; l'effet des techniques de gymnastique hypopressive sur la circulation veineuse... more
La facilitation de la circulation de retour est essentielle dans la prise en charge des patients souffrant d'insuffisance veineuse. Nous avons testé; l'effet des techniques de gymnastique hypopressive sur la circulation veineuse fémorale. Nous avons étudié 13 sujets par échographie-Doppler et mesuré certains paramètres hémodynamiques. Les résultats montrent une augmentation de la circulation de retour, couplée à une chute de la pression dans la veine fémorale. Cette étude souligne l'efficacité des manoeuvres hypopressives dans le cadre de la prise en charge de patients souffrant d'insuffisance veineuse.
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Decompression sickness (DCS) in divers is caused by bubbles of inert gas. When DCS occurs, most bubbles can be found in the venous circulation: venous gas emboli (VGE). Bubbles are thought to be stabilized by low molecular weight... more
Decompression sickness (DCS) in divers is caused by bubbles of inert gas. When DCS occurs, most bubbles can be found in the venous circulation: venous gas emboli (VGE). Bubbles are thought to be stabilized by low molecular weight surfactant reducing the plasma-air surface tension (γ). Proteins may play a role as well. We studied the interrelations between these substances, γ and VGE, measured before and after a dry dive simulation. VGE of 63 dive simulations (21-msw/40-minute profile) of 52 divers was examined 40, 80, 120 and 160 minutes after surfacing (precordial Doppler method) and albumin, total protein, triglycerides, total cholesterol and free fatty acids were determined pre- and post-exposure. To manipulate blood plasma composition, half of the subjects obtained a fat-rich breakfast, while the other half got a fat-poor breakfast pre-dive. Eleven subjects obtained both. VGE scores measured with the precordial Doppler method were transformed to the logarithm of Kisman Integrate...
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Breath-hold diving-induced hemoptysis (BH-DIH) has been reported in about 25% breath-hold divers (BHD) and is characterized by dyspnea, coughing, hemoptysis and chest pain. We investigated whether eNOS G894T, eNOS T786C and ACE... more
Breath-hold diving-induced hemoptysis (BH-DIH) has been reported in about 25% breath-hold divers (BHD) and is characterized by dyspnea, coughing, hemoptysis and chest pain. We investigated whether eNOS G894T, eNOS T786C and ACE insertion/deletion I/D genetic variants, are possible BH-DIH risk factors. 108 experienced healthy instructor BHDs with the same minimum requirements (102 male, six female; mean age 43.90 ± 7.49) were studied. We looked for different eNOS G894T, eNOS T786C and ACE insertion/ deletion genetic variants between BH-DIH-positive and BH-DIH-negative subjects to identify the variants most frequently associated with BH-DIH. At least one BH-DIH episode was reported by 22.2% of subjects, while 77.7% never reported BH-DIH. The majority of BH-DIH-positive subjects showed eNOS G894T (p = 0.001) and eNOS-T786C (p = 0.001) genotype "TT" (high-risk profile). Prevalence of BH-DIH was higher in subjects with eNOS G894T TT genotype (50%) than in subjects with GT (9.5%...
Research Interests: Diving, Humans, Female, Male, Clinical Sciences, and 4 moreGenotype, Adult, Breath Holding, and Hemoptysis
Measurement of inert gas narcosis and its degree is difficult during operational circumstances, hence the need for a reliable, reproducible and adaptable tool. Although being an indirect measure of brain function, if reliable, critical... more
Measurement of inert gas narcosis and its degree is difficult during operational circumstances, hence the need for a reliable, reproducible and adaptable tool. Although being an indirect measure of brain function, if reliable, critical flicker fusion frequency (CFFF) could address this need and be used for longitudinal studies on cortical arousal in humans. To test the reliability of this method, the comparison between CFFF and three tests (Math-Processing Task, Trail-Making Task, and Perceptual Vigilance Task) from the Psychology Experiment Building Language battery (PEBL) were used to evaluate the effect of 10 minutes of 100% normobaric oxygen breathing on mental performance in 20 healthy male volunteers. Breathing normobaric oxygen significantly improved all but one of the measured parameters, with an increase of CFFF (117.3 ± 10.04% of baseline, P < 0.0001) and a significant reduction of time to complete in both the math-processing (2,103 ± 432.1 ms to 1,879 ± 417.5 ms, P = 0...
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In spite of many modifications to decompression algorithms, the incidence of decompression sickness (DCS) in scuba divers has changed very little. The success of stage, compared to linear ascents, is well described yet theoretical changes... more
In spite of many modifications to decompression algorithms, the incidence of decompression sickness (DCS) in scuba divers has changed very little. The success of stage, compared to linear ascents, is well described yet theoretical changes in decompression ratios have diminished the importance of fast tissue gas tensions as critical for bubble generation. The most serious signs and symptoms of DCS involve the spinal cord, with a tissue half time of only 12.5 minutes. It is proposed that present decompression schedules do not permit sufficient gas elimination from such fast tissues, resulting in bubble formation. Further, it is hypothesized that introduction of a deep stop will significantly reduce fast tissue bubble formation and neurological DCS risk. A total of 181 dives were made to 82 fsw (25 m) by 22 volunteers. Two dives of 25 min and 20 min were made, with a 3 hr 30 min surface interval and according to 8 different ascent protocols. Ascent rates of 10, 33 or 60 fsw/min (3, 10,...
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The effects of fatigue on the electromyographic (EMG) reflex activities were compared during sustained voluntary contractions and contractions evoked by electrical stimulation (30 Hz) in the human first dorsal interosseus (FDI). Short... more
The effects of fatigue on the electromyographic (EMG) reflex activities were compared during sustained voluntary contractions and contractions evoked by electrical stimulation (30 Hz) in the human first dorsal interosseus (FDI). Short latency (SL), medium latency (ML) and long latency (LL) reflex responses to a ramp-and-hold stretch of the muscle were recorded and analysed in 27 healthy subjects of both sexes. The amplitude of the reflex components was normalized as function of the amplitude of the surface action potential (SAP) recorded in response to the supramaximal stimulation of the motor nerve. The results indicate that for a similar reduction of force, SL and ML are significantly reduced after fatigue induced by voluntary contractions but they are not when the fatigue test is performed by electrical stimulation at the motor point. In voluntary fatigue experiments, the LL component showed no significant decrease below control values, but an enhancement was observed during elec...
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... İsmail Burak Parlak1, S.Murat Egi1,2, Ahmet Ademoğlu3, Peter Germonpré2, Özlem Batukan Esen4, Salih Aydın5, Serap Tekin4, Costantino ... PFO&amp;amp;#x27;nun büyüklüğü ve yeri transkateter yerleştirilmesi için incelenmelidir [1],... more
... İsmail Burak Parlak1, S.Murat Egi1,2, Ahmet Ademoğlu3, Peter Germonpré2, Özlem Batukan Esen4, Salih Aydın5, Serap Tekin4, Costantino ... PFO&amp;amp;#x27;nun büyüklüğü ve yeri transkateter yerleştirilmesi için incelenmelidir [1], [7], [9]. Kabarcık geçişi ve sayımı PFO değerlendirilmesinde ...
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Post decompression records in echocardiography are considered to detect micro bubbles and to survey unexplained decompression sickness which is commonly examined by standardized methods such as dive computers and tables. In this study,... more
Post decompression records in echocardiography are considered to detect micro bubbles and to survey unexplained decompression sickness which is commonly examined by standardized methods such as dive computers and tables. In this study, existent bubbles are detected on transthoracic echicardiografic frames recorded after recreational diving. Bubble detection is performed by Artificial Neural Networks which are trained using bubbles with different
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Many divers report less fatigue following dives breathing enriched air nitrox (EANx) compared with breathing air. A reduction of post-dive fatigue with EANx would suggest a pathological origin, possibly the presence of asymptomatic... more
Many divers report less fatigue following dives breathing enriched air nitrox (EANx) compared with breathing air. A reduction of post-dive fatigue with EANx would suggest a pathological origin, possibly the presence of asymptomatic nitrogen bubbles in the body after a dive. We studied fatigue in 219 healthy divers performing either an air (n = 121) or EANx32 (oxygen 32%, nitrogen 68%; n = 98) dive to 21.2 ± 4 metres' sea water for 43.3 ± 8.6 minutes in tropical open-water conditions. Divers were assessed pre-dive and 30-60 minutes after surfacing using a visual analog scale (VAS) of fatigue and critical flicker fusion frequency (CFFF). The two groups were comparable in sex ratio, age and diving experience. The change in perceived fatigue level after a single dive was significantly lower when EANx was breathed compared to air dives (VAS; P < 0.001). Compared to pre-dive, CFFF decreased by 6% in the air group (P < 0.01) but increased by 4% in the EANx group (P < 0.05). Th...
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Pulmonary blebs and bullae are generally considered an absolute contra-indication for scuba diving, because of a high estimated risk of pulmonary overpressure syndrome due to air-trapping inside the bulla. This is primarily based on a... more
Pulmonary blebs and bullae are generally considered an absolute contra-indication for scuba diving, because of a high estimated risk of pulmonary overpressure syndrome due to air-trapping inside the bulla. This is primarily based on a number of retrospective studies and case reports; formal prospective evidence of a higher risk is lacking. We present three cases where a pulmonary bulla was radiographically shown to increase in diameter, seemingly related to scuba diving activity, and causing ultimately a barotraumatic diving accident. These cases provide pathophysiological clues as to how even an isolated, non-ventilated bulla can be the cause of pulmonary barotrauma. The most likely mechanism for this phenomenon is a 'stretching' of the bulla upon ascent from the dive: after a period of compression (Boyle's Law), there is a gradual diffusion of air through the bulla wall, with restoration to its initial size by the end of the dive. Upon ascent, the air diffuses only slo...
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Stretch reflex responses in three elbow flexor muscles - the brachioradialis and the short and long heads of the biceps brachii - were studied during different motor tasks. The motor tasks were iso-velocity (8 deg/s) elbow flexion... more
Stretch reflex responses in three elbow flexor muscles - the brachioradialis and the short and long heads of the biceps brachii - were studied during different motor tasks. The motor tasks were iso-velocity (8 deg/s) elbow flexion movements in which the muscles performed shortening or lengthening contractions, or were isometric contractions. Care was taken to maintain constant background electromyographic (EMG) activity in the brachoradialis muscle at a 50-deg elbow angle across the tasks by changing the magnitude of the initial load. During each task, mechanical perturbations (duration 170 ms) were applied at pseudorandom intervals when the elbow angle was 50 deg. The magnitude of the perturbation was varied across tasks in order to induce an elbow extension velocity of 80 deg/s over the first 50 ms after the onset of perturbation. The stretch reflex EMG responses in all muscles varied across the three tasks, despite a constant EMG level and similar perturbation-induced angular velocity in the direction of elbow extension. In particular, both the short- and long-latency reflex EMG components were reduced during the lengthening contractions. Further, the task-dependent variations in the early (M2) and the late (M3) components of the long-latency reflex were different, i.e., the magnitude of M3 was considerably enhanced during the shortening task as compared with that of M2. These findings suggest that central modification was responsible for the task-dependent modulation of late EMG responses.
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The current practice of mechanical ventilation comprises the use of the least inspiratory O2 fraction associated with an arterial O2 tension of 55 to 80 mm Hg or an arterial hemoglobin O2 saturation of 88% to 95%. Early goal-directed... more
The current practice of mechanical ventilation comprises the use of the least inspiratory O2 fraction associated with an arterial O2 tension of 55 to 80 mm Hg or an arterial hemoglobin O2 saturation of 88% to 95%. Early goal-directed therapy for septic shock, however, attempts to balance O2 delivery and demand by optimizing cardiac function and hemoglobin concentration, without making use of hyperoxia. Clearly, it has been well-established for more than a century that long-term exposure to pure O2 results in pulmonary and, under hyperbaric conditions, central nervous O2 toxicity. Nevertheless, several arguments support the use of ventilation with 100% O2 as a supportive measure during the first 12 to 24 hrs of septic shock. In contrast to patients without lung disease undergoing anesthesia, ventilation with 100% O2 does not worsen intrapulmonary shunt under conditions of hyperinflammation, particularly when low tidal volume-high positive end-expiratory pressure ventilation is used. In healthy volunteers and experimental animals, exposure to hyperoxia may cause pulmonary inflammation, enhanced oxidative stress, and tissue apoptosis. This, however, requires long-term exposure or injurious tidal volumes. In contrast, within the timeframe of a perioperative administration, direct O2 toxicity only plays a negligible role. Pure O2 ventilation induces peripheral vasoconstriction and thus may counteract shock-induced hypotension and reduce vasopressor requirements. Furthermore, in experimental animals, a redistribution of cardiac output toward the kidney and the hepato-splanchnic organs was observed. Hyperoxia not only reverses the anesthesia-related impairment of the host defense but also is an antibiotic. In fact, perioperative hyperoxia significantly reduced wound infections, and this effect was directly related to the tissue O2 tension. Therefore, we advocate mechanical ventilation with 100% O2 during the first 12 to 24 hrs of septic shock. However, controlled clinical trials are mandatory to test the safety and efficacy of this approach.
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Research Interests: Engineering, Education, Diving, Humans, Male, and 4 moreParanasal Sinuses, Seawater, Respiration, and Adult
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Research Interests: Multivariate Statistics, Injury Prevention, Adolescent, Multivariate Analysis, Diving, and 24 moreCase Report, Humans, Female, Male, Cluster Analysis, Young Adult, Hearing Loss, Medical Physiology, Hierarchical Clustering, Aged, Middle Aged, Adult, Public health systems and services research, Retrospective Studies, Reproducibility of Results, Hyperbaric Oxygenation, Aviation and Space History, Diving Medicine, Indexation, Decompression Sickness, Bayes Theorem, Scuba diving safety, Bayesian Information Criterion, and Severity of Illness Index
Research Interests: Risk assessment, Diving, Prospective studies, Humans, Blood Pressure, and 19 moreBlood sampling, Male, Bubble, Medical Physiology, Risk factors, Middle Aged, Far Infrared, Adult, Public health systems and services research, Time Factors, Pulse Pressure, Hyperbaric Oxygenation, Risk Factors, Risk Assessment, Decompression Sickness, Heat Shock Protein, Decompression, Systolic blood pressure, and Brachial artery
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In cardiology, automatic recognition and image analysis still conserve computational challenges in terms of medical guidance and diagnosis. Bubbles or microemboli that circulate into cardiopulmonary system are considered suspicious for... more
In cardiology, automatic recognition and image analysis still conserve computational challenges in terms of medical guidance and diagnosis. Bubbles or microemboli that circulate into cardiopulmonary system are considered suspicious for several medical problems such as decompression sickness, stroke and migraine. The aim of our work is to develop and assess an automatic approach to detect these bubbles that are analyzed
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Our recent study was based on a classification of DCI using multivariate statistics to assess naturally associated clusters of signs and symptoms based on 1929 cases reported by hyperbaric chambers to the Divers Alert Network from 1999 to... more
Our recent study was based on a classification of DCI using multivariate statistics to assess naturally associated clusters of signs and symptoms based on 1929 cases reported by hyperbaric chambers to the Divers Alert Network from 1999 to 2003 [7]. The aim of this study is to validate the ...
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De plus en plus d’organisations reconnaissent la supériorité du QE (quotient émotionnel) sur le QI. Les modèles de “leaders” sous les traits d’un CEO glacial ou d’un commercial sanguin ont vécu. L’humain se place désormais au centre de... more
De plus en plus d’organisations reconnaissent la supériorité du QE (quotient émotionnel) sur le QI. Les modèles de “leaders” sous les traits d’un CEO glacial ou d’un commercial sanguin ont vécu. L’humain se place désormais au centre de toute entreprise et pour cela, il doit savoir apprécier l’autre au moins autant pour ce qu’il est que pour ce qu’il fait. Car qui dit humain dit humaniser. La clé ? Communiqu’agir ! Facile à dire : comment maîtriser les rouages de l’interaction avec ses semblables ? En suivant le parcours offert dans ces pages ! Les auteurs ont décrypté pour vous tous les codes de la communication en partant de sa source : le cerveau. Et pour vous aider à positiver, ils vous révèlent la langue des mots, de la voix et du corps. Et leur mode d’emploi. Résolument tourné vers le développement personnel, ce package de la relation à soi et à l’autre aborde les matières de façon très ludique et les agrémentent de nombreuses illustrations et même d’une BD. Totalement révisé e...
L'eau est une matière plurielle et ambivalente. Symboliquement associée à la purification, cause régulière de multiples ravages humains et écologiques, elle est aussi devenue un vaste terrain de jeu, d'expériences corporelles,... more
L'eau est une matière plurielle et ambivalente. Symboliquement associée à la purification, cause régulière de multiples ravages humains et écologiques, elle est aussi devenue un vaste terrain de jeu, d'expériences corporelles, d'immersions en tous genres. Retenir son souffle pour aller loin, profond, ou simplement rester longtemps immergé, passionne des pratiquants toujours plus nombreux. Il s'agit bien souvent de « se fondre » dans le milieu, repousser ses limites et surtout se reconnecter avec soi-même, explorer son propre corps et se sentir « bien ». L'apprentissage de l'apnée révèle les capacités d'adaptation du corps humain, actualisant des ressources inédites. Elle favorise l'émersion de sensations nouvelles du corps vivant. Les apnéistes apprennent à décoder les réactions du corps en immersion et en hypoxie. Des cultures motrices et matérielles se construisent à travers cette dynamique des corps dans le milieu aquatique. Cet ouvrage regroupe le...
L'eau est une matière plurielle et ambivalente. Symboliquement associée à la purification, cause régulière de multiples ravages humains et écologiques, elle est aussi devenue un vaste terrain de jeu, d'expériences corporelles,... more
L'eau est une matière plurielle et ambivalente. Symboliquement associée à la purification, cause régulière de multiples ravages humains et écologiques, elle est aussi devenue un vaste terrain de jeu, d'expériences corporelles, d'immersions en tous genres. Retenir son souffle pour aller loin, profond, ou simplement rester longtemps immergé, passionne des pratiquants toujours plus nombreux. Il s'agit bien souvent de « se fondre » dans le milieu, repousser ses limites et surtout se reconnecter avec soi-même, explorer son propre corps et se sentir « bien ». L'apprentissage de l'apnée révèle les capacités d'adaptation du corps humain, actualisant des ressources inédites. Elle favorise l'émersion de sensations nouvelles du corps vivant. Les apnéistes apprennent à décoder les réactions du corps en immersion et en hypoxie. Des cultures motrices et matérielles se construisent à travers cette dynamique des corps dans le milieu aquatique. Cet ouvrage regroupe le...
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Vascular gas emboli (VGE) start forming during the degassing of tissues in the decompression (ascent) phase of the dive when bubble precursors (micronuclei) are triggered to growth. The precise formation mechanism of micronuclei is still... more
Vascular gas emboli (VGE) start forming during the degassing of tissues in the decompression (ascent) phase of the dive when bubble precursors (micronuclei) are triggered to growth. The precise formation mechanism of micronuclei is still debated, with formation sites in facilitating regions with surfactants, hydrophobic surfaces or crevices. Ho wever, significant inter-subject variability to VGE exists for the same diving exposure and VGE may even be reduced with a single pre-dive intervention. The precise link between VGE and endothelial dysfunction observed post dive remains unclear and a nitric oxide (NO) mechanism has been hypothesized. Subjects in good physical condition are at lesser risk of VGE and DCS observed post dive. More surprisingly, single pre-dive interventions or 'preconditioning' can influence the VGE observed post dive. Studies in rats have shown that a single bout of exercise 20 h pre dive can reduce post-dive VGE and mortality. In humans, the role of exe...
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Compared with other sports, SCUBA diving remains a relatively safe activity but precisely defining risk is important. Diving databases such as the Diving Safety Laboratory (DSL) collection by Divers Alert Network (DAN) Europe can provide... more
Compared with other sports, SCUBA diving remains a relatively safe activity but precisely defining risk is important. Diving databases such as the Diving Safety Laboratory (DSL) collection by Divers Alert Network (DAN) Europe can provide new insights into the causes of diving accidents, including decompression sickness (DCS) incidence with respect to the dive profile. Data from the DSL shows that in the recreational setting diving with a dive computer may be used by as many as 95% of divers. This points to the need of validating these tools with respect to DCS incidence, a difficult task.
By using dive tables or diving computers, divers are effectively using decompression algorithms to manage the risk of developing decompression sickness (DCS). They dictate the time allowed at each depth before the dive converts from... more
By using dive tables or diving computers, divers are effectively using decompression algorithms to manage the risk of developing decompression sickness (DCS). They dictate the time allowed at each depth before the dive converts from no-decompression dive into a decompression dive, as well as the decompression stops needed for a decompression dive (time to spend at various depths on the way up to the surface). These algorithms are calculations that follow from the principles of a given decompression theory; of these, different ones exist with wildly different approaches. It is clear that the principles of those algorithms are very different in terms of what the mathematical modelling translates to in reality. This highlights that we still do not know exactly how bubbles form and grow in the body and when they trigger DCS.
The sites for formation of microbubbles that are routinely detected precordially by Doppler after a decompression are still a matter of debate. Firstly, microbubbles could form on the endothelial wall of capillaries, at specific... more
The sites for formation of microbubbles that are routinely detected precordially by Doppler after a decompression are still a matter of debate. Firstly, microbubbles could form on the endothelial wall of capillaries, at specific nanometric sites, but the release mechanism of such small emerging entities remains puzzling. They might also be formed from pre-existing gas nuclei present in the blood when favourable local hydrodynamic/supersaturation conditions generate microcavitation and tribonucleation phenomena. Finally, tissues could represent large pools for microbubble formation and amplification. Nevertheless, it remains unexplained as to what the potential driving pathways might be. Knowing that the permeability of most of the blood capillary network is quite low, an alternative is proposed for such transport. The lymphatic system, which drains the interstitial fluid to guarantee the fluid balance of tissues, could allow the transfer of micrometric elements, like stabilized micr...
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Vascular gas bubbles are considered the principal element in decompression sickness (DCS) development. Traditionally these bubbles were called VGE (venous gas emboli), however scientific knowledge indicates that similar bubbles may also... more
Vascular gas bubbles are considered the principal element in decompression sickness (DCS) development. Traditionally these bubbles were called VGE (venous gas emboli), however scientific knowledge indicates that similar bubbles may also be present in the arterial circulation, therefore we propose to use “VGE” for “Vascular Gas Emboli”, and we will do so throughout the text. Reduction of VGE production represents an interesting endpoint to decrease decompression stress and DCS risk. Here we will discuss state of the art pre-dive techniques and approaches, commonly known as preconditioning, used to reduce post-dive VGE load and decompression stress. Evidence based approaches clearly show that some types of preconditioning are more potent in VGE reduction, some indecompression stress reduction and there are some with a positive impact on both. Nevertheless, further research is required to investigate the mechanisms underlying these positive effects.
Decompression illnesses (DCI), or as they are called more scientifically: dysbaric disorders, represent a complex spectrum of pathophysiological conditions with a wide variety of signs and symptoms related to dissolved gas and its... more
Decompression illnesses (DCI), or as they are called more scientifically: dysbaric disorders, represent a complex spectrum of pathophysiological conditions with a wide variety of signs and symptoms related to dissolved gas and its subsequent phase change.1,2 Any significant organic or functional dysfunction in individuals who have recently been exposed to a reduction in environmental pressure (i.e., decompression) must be considered as possibly being caused by DCI until proven otherwise. However, apart from the more obvious acute manifestations of a single, sudden decompression, individuals who have experienced repetitive exposures (e.g. commercial or professional divers and active recreational divers) may also develop sub-acute or chronic manifestations, even if subtle and almost symptomless.3 It is generally accepted that there exist sub-clinical forms of decompression sickness (DCS), with little or no reported symptoms, and that these may cause changes in the bones, the central n...
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The aim of this study was to evaluate the effect of a single, shallow, swimming pool scuba dive on pulmonary function in divers with asthma as compared to controls. Opinions concerning the risks of diving with asthma are still... more
The aim of this study was to evaluate the effect of a single, shallow, swimming pool scuba dive on pulmonary function in divers with asthma as compared to controls. Opinions concerning the risks of diving with asthma are still contradictory and inconclusive in the diving community. Baseline pulmonary function tests (PFTs) were performed on a group of 22 divers with asthma and on a control group of 15 healthy divers. The same PFTs were repeated within 10 minutes after a single pool dive, at 5 metres' depth for 10 minutes. PFTs were measured using a portable Jaeger SpiroPro™ device. Student's paired t-tests and linear mixed effects model comparisons and interactions within the groups were used in the data analysis. Divers with asthma initially presented significantly lower values of FEV1/FVC%* (P < 0.01), FEF25* (P < 0.01), FEF50* (P < 0.001), FEF75* (P < 0.01) and FEF25-75* (P < 0.001) compared to controls. There were significant reductions in FEV1 (P < 0.01...
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The aim of the study was to observe the effects of dark chocolate on endothelial function after scuba diving. Forty-two male scuba divers were divided into two groups: a control (n = 21) and a chocolate group (n = 21). They performed a... more
The aim of the study was to observe the effects of dark chocolate on endothelial function after scuba diving. Forty-two male scuba divers were divided into two groups: a control (n = 21) and a chocolate group (n = 21). They performed a 33-metres deep scuba-air dive for 20 minutes in a diving pool (Nemo 33, Brussels). Water temperature was 33⁰C. The chocolate group ingested 30 g of dark chocolate (86% cocoa) 90 minutes before the dive. Flow-mediated dilatation (FMD), digital photoplethysmography and nitric oxide (NO) and peroxynitrites (ONOO-) levels were measured before and after the scuba dive in both groups. A significant decrease in FMD was observed in the control group after the dive (91 ± 7% (mean ± 95% confidence interval) of pre-dive values; P < 0.001) while it was increased in the chocolate group (105 ± 5% of pre-dive values; P < 0.001). No difference in digital photoplethysmography was observed between before and after the dives. No variation of circulating NO level w...
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analysis of MRI relationships Palpation of the lateral ptergygoid muscle (LP) is at the centre of a polemics: are we able to reach its fleshy fibres, in view of palpation for diagnostic and/or therapeutic purposes? The position of this... more
analysis of MRI relationships Palpation of the lateral ptergygoid muscle (LP) is at the centre of a polemics: are we able to reach its fleshy fibres, in view of palpation for diagnostic and/or therapeutic purposes? The position of this structure in the pterygo-maxillary fossa makes access difficult. This study proposes an analysis by MRI of the relationships between the anatomic structures and the "palpating" finger. The measurement taken shows that the mode of operation recommended by the different authors does not allow for this palpation.
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Decompression illness (DCI)/dysbaric disorders represent a complex spectrum of pathophysiological conditions with a wide variety of signs and symptoms related to dissolved gas and its subsequent phase change. Any significant organic or... more
Decompression illness (DCI)/dysbaric disorders represent a complex spectrum of pathophysiological conditions with a wide variety of signs and symptoms related to dissolved gas and its subsequent phase change. Any significant organic or functional decrement in individuals who have recently been exposed to a reduction in environmental pressure (i.e., decompression) must be considered as evidence of DCI until proven otherwise. However, apart from the more obvious acute manifestations, individuals who have experienced repetitive exposures (e.g., commercial or professional divers and active recreational divers) may also develop sub-acute or chronic manifestations sub-clinically - insidious, even if subtle, and almost symptomless. It is, in fact, generally accepted that sub-clinical forms of DCI exist, with little or no reported symptoms, and that these may cause changes in the bones, the central nervous system and the lungs. All this has led us to analysing 'decompression stress'...
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Flying after diving may increase decompression sickness risk (DCS), but strong evidence indicating minimum preflight surface intervals (PFSI) is missing. On return flights after a diving week on a live-aboard, 32 divers were examined by... more
Flying after diving may increase decompression sickness risk (DCS), but strong evidence indicating minimum preflight surface intervals (PFSI) is missing. On return flights after a diving week on a live-aboard, 32 divers were examined by in-flight echocardiography with the following protocol: 1) outgoing flight, no previous dive; 2) during the diving week; 3) before the return flight after a 24-h PFSI; and 4) during the return flight. All divers completed similar multiple repetitive dives during the diving week. All dives were equivalent as to inert gas load and gradient factor upon surfacing. No bubbles in the right heart were found in any diver during the outgoing flight or at the preflight control after a 24-h PFSI following the diving week. A significant increase in the number and grade of bubbles was observed during the return flight. However, bubbles were only observed in 6 of the 32 divers. These six divers were the same ones who developed bubbles after every dive. Having obse...
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Our study's aim is to show how a five-week stretch training protocol, based on passive stretching, can change muscle performance during a drop jump (stretch shortening cycle). This study observes in 8 healthy subjects (four males and... more
Our study's aim is to show how a five-week stretch training protocol, based on passive stretching, can change muscle performance during a drop jump (stretch shortening cycle). This study observes in 8 healthy subjects (four males and four females), the effect of a 5-week passive stretch training protocol on the stretch shortening cycle (SSC) during the performance of a drop jump, and identify the architectural changes in the muscle. Subjects underwent measurements of their drop jump performance 3 times before, and 3 times after, the stretch training protocol. For the muscle tendon unit (MTU), changes were measured using the Hawkins and Hull's model. In order to calculate the length changes in the MTU, we measured the ankle and knee angles. For changes in the fascicle, the pennation angle and the thickness of the gastrocnemius medialis (GM) muscle were measured. After the 5-week stretch training protocol, a significant increase in flexibility was observed in the fascicle duri...
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Research Interests: Humans, Female, Male, Proteins, Clinical Sciences, and 6 moreOxygen, Adult, Edema, Time Factors, Protein Denaturation, and Protein Transport
Erythropoiesis is affected during deep saturation dives. The mechanism should be related to a downregulation of serum Erythropoietin (s-EPO) concentration or to a toxic effect of the hyperbaric hyperoxia. We evaluated s-EPO and other... more
Erythropoiesis is affected during deep saturation dives. The mechanism should be related to a downregulation of serum Erythropoietin (s-EPO) concentration or to a toxic effect of the hyperbaric hyperoxia. We evaluated s-EPO and other haematological parameters in 6 scuba divers before, during and after a 14-days guinness saturation dive (8-10 m). Athletes were breathing air at 1.8-2 ATA, under the control of a team of physicians. Serum parameters were measured before diving (T0) and: 7 days (T1), 14 days (T2) after the beginning of the dive and 2 h (T3) and 24 h (T4) after resurfacing. Hgb, and many other haematological parameters did not change whereas Ht, s-EPO, the ratio between s-EPO predicted and that observed and reticulocytes (absolute, percent) declined progressively from T0 to T3. At T4 a significant rise in s-EPO was observed. Hgb did not vary but erythropoiesis seemed to be affected as s-EPO and reticulocyte counts showed. All these changes were statistically significant. The experiment, conducted in realistic conditions of dive length, oxygen concentration and pressure, allows us to formulate some hypotheses about the role of prolonged hyperbarism on erythropoiesis. The s-EPO rise, 24 h after resurfacing, is clearly documented and related to the &amp;amp;quot;Normobaric Oxygen Paradox&amp;amp;quot;. This evidence suggests interesting hypotheses for new clinical applications such as modulation of s-EPO production and Hgb content triggered by appropriate O₂ administration in pre-surgical patients or in some anemic disease.
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The purpose of this study was to define the optimal irradiation conditions of a KTP laser during root planing treatment. The surfaces of 60 single-root human teeth were scaled with conventional instruments before lasing. The pulpal... more
The purpose of this study was to define the optimal irradiation conditions of a KTP laser during root planing treatment. The surfaces of 60 single-root human teeth were scaled with conventional instruments before lasing. The pulpal temperature increase was measured by means of one thermocouple placed in the pulp chamber and a second one placed on the root surface at 1 mm from the irradiation site. The influence of variables of coloration by Acid Red 52 (photosensitizer), scanning speed, dentin thickness, and probe position was analyzed for a constant exposure time of 15 sec and 500 mw (spot size diameter, 0.5 mm). The pulpal temperature was below 3 degrees C for the adjustments. The irradiation on one point of root surface had the following results: The application of photosensitizer on the root surface before lasing produced a 50% higher temperature rise within the pulp than in the case without the application of the photosensitizer. The temperature rise in the pulp chamber was below 3 degrees C with the following settings of 500 mw: PW = 10 msec and PRR &lt; 35; or PW= 20 msec and PRR &lt; 20 Hz. On the other hand, for the same irradiation conditions, the temperature rise on the surface of the root was always below 7 degrees C. However, the temperature increase became higher than 7 degrees C (on the surface of the root) in the case of P &gt; 500 mw, PW &gt; 50 msec and PRR &gt; 10 Hz of root surface or a scanning speed of irradiation of 1 mm/sec for a linear irradiation of 4 mm. The KTP laser may be used safely without thermal damage to pulp and periodontal tissue with respect to the biologically acceptable previously described parameters.
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The axillary arch (AA) is a muscular anatomical variation in the fossa axillaris that has been extensively studied in cadaveric specimens. Within these dissections, different innervations of the AA have been proposed, but this has never... more
The axillary arch (AA) is a muscular anatomical variation in the fossa axillaris that has been extensively studied in cadaveric specimens. Within these dissections, different innervations of the AA have been proposed, but this has never been explored in vivo. Knowledge of the innervation of the AA is required in order to better understand its function (e.g. predisposition for certain sports and/or activities, understanding shoulder injuries in overhead sports). Here, we report on the use of surface stimulodetection electromyography (SSEMG) to resolve the innervation of the AA in 20 subjects (12 women, eight men - mean age of 21.3 ± 2.7 years) with a uni- or bilateral AA. SSEMG of each muscle [M. latissimus dorsi (MLD) and M. pectoralis major] was performed with a four-channel electrostimulation measuring system in order to determine the innervation of the AA. The results showed co-contraction of the MLD in 85% of the subjects after AA stimulation. In the remaining subjects, no specific localized response was observed due to non-specific nerve stimulation, inherent to the proximity of the brachial plexus in these individuals. Our findings demonstrate that SSEMG exploration offers a practical and reliable tool for investigating anatomical aspects of muscle innervation in vivo. Using this approach, we conclude that the AA receives the same innervation as the MLD (the N. thoracodorsalis), and may be considered a muscular extension of the latter.
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There is a limited understanding of the normal function of the pterygoïdeus proprius muscle and the role that this muscle may have in temporomandibular disorders. Despite a well-described anatomical in-vitro approach to this muscle, there... more
There is a limited understanding of the normal function of the pterygoïdeus proprius muscle and the role that this muscle may have in temporomandibular disorders. Despite a well-described anatomical in-vitro approach to this muscle, there are still difficulties in investigating the fossa pterygopalatina. This study reveals an alternative in-vivo approach by magnetic resonance imaging to visualise the muscle in the fossa pterygopalatina on 78 head halves, describe the connections with the musculus temporalis and pterygoïdeus lateralis as well as report the incidence without dealing with the known inconveniences of the dissection approach. The results show an incidence of 12.82% for the musculus pterygoïdeus proprius equally divided between both genders. Two different types of bridging between the musculus temporalis and musculus pterygoïdeus lateralis were also found: (i) 'O' shape (6.41%) and (ii) 'Y' shape (6.41%). This study suggests the use of magnetic resonan...
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Research Interests: Cognitive Science, Multivariate Analysis, Brain Mapping, Humans, Movement, and 17 moreFemale, Male, Reaction Time, Young Adult, Oscillations, Human Brain, Phase Locking, Somatosensory Cortex, Adult, Spectrum analysis, Sensory Gating, Human Brain Mapping, Biological clocks, Fingers, Neurosciences, Median Nerve, and Beta Rhythm
Research Interests:
Objective The purpose of this study was to test the impact of foot reflexology (FR) on sleep architecture in patients suffering from sleeping disorders. Aims Try to improve sleep quality in patients with sleep disorders using the foot... more
Objective The purpose of this study was to test the impact of foot reflexology (FR) on sleep architecture in patients suffering from sleeping disorders. Aims Try to improve sleep quality in patients with sleep disorders using the foot reflexology. Methods A controlled interventional study in which volunteers (nxa0;=xa0;10) were their own control. Each subject received one 20xa0;min FR session during