Introduction: The EPIC Study implemented the national EMS TBI Guidelines in a massive, statewide ... more Introduction: The EPIC Study implemented the national EMS TBI Guidelines in a massive, statewide initiative (>11,000 providers trained, 133 agencies). While implementation was not associated with improved survival to discharge in moderate or critically-severe TBI in the primary (all-age) study, the adjusted odds of survival doubled in severe TBI and tripled in severe, intubated TBI. We now report the preplanned pediatric subgroup analysis (“EPIC4Kids”-NIH R01NS071049). Methods: Multisystem, intention-to-treat study using a before/after controlled design in patients with moderate to critically severe TBI. Interventions: Prevention/treatment of hypoxia, hypotension, and hyperventilation by EMS providers. Inclusion: Age<18; CDC Barell Matrix Type 1; 1/07-6/15. Severity subgroups [Head Region Severity Score (IDC-based AIS equivalent)]: Moderate=1-2; Severe=3-4; Critical=5-6. The pre-implementation (P1) and post-implementation (P3) cohorts were compared using logistic regression (F...
Objective: Little is known about End-Tidal CO 2 monitoring using nasal cannula sensors (NC-CO 2 )... more Objective: Little is known about End-Tidal CO 2 monitoring using nasal cannula sensors (NC-CO 2 ) in non-intubated patients. Objective: To describe the patterns of NC-CO 2 seen during the EMS care of spontaneously breathing major Traumatic Brain Injury (TBI) patients. Methods: Continuous NC-CO 2 data (Philips MRx™ monitors) were evaluated from non-intubated, major (moderate, severe, critical) TBI cases (4/13-5/17) in the EPIC TBI Study (NIH 1R01NS071049). Descriptive statistics were used to evaluate case and NC-CO 2 attributes. Results: Included were 92 cases [median age = 50 (range 10-91; 66% male)]. Median respiratory rate (RR) was >15/min in 87% of cases and >20/min in 53%. The highest median RR was 39. Sixteen cases (17%) had a median NC-CO 2 <20 mmHg, 37% (34) were 20-29, 18% (17) were 30-34, 25% (23) were 35-45. Two cases (2%) were 45-50, which has not been noted in this population previously. No case had a median NC-CO 2 >50. Several common NC-CO 2 patterns emerge...
Introduction: Little is known about prehospital availability and use of medications to treat pati... more Introduction: Little is known about prehospital availability and use of medications to treat patients from hazardous materials (hazmat) medical emergencies. The aim of this study was to identify the availability and frequency of use of medications for patients in hazmat incidents by paramedics with advanced training to care for these patients.Methods: A prospectively validated survey was distributed to United States paramedics with advanced training in the medical management of patients from hazmat incidents who successfully completed a 16-hour Advanced Hazmat Life Support (AHLS) Provider Course from 1999 to 2017. The survey questioned hazmat medication availability, storage, and frequency of use. Hazmat medications were considered to have been used if administered anytime within the past 5 years. For analyses, medications were grouped into those with hazmat indications only and those with multiple indications.Results: The survey email was opened by 911 course participants and 784 o...
Background: Cardiopulmonary resuscitation (CPR) quality is strongly linked to outcomes following ... more Background: Cardiopulmonary resuscitation (CPR) quality is strongly linked to outcomes following out-of-hospital cardiac arrest (OHCA). However, manual CPR quality varies and has risk to providers. We hypothesized that use of a mechanical CPR device might provide higher quality CPR than manual CPR during the technically challenging periods of OHCA resuscitation such as packaging, loading, and transporting patients. Methods: Cases of OHCA at a single site from 10/2008-10/2016 were identified. Two CPR quality metrics, chest compression fraction (CCfr) and CC rate (CCra), measured using accelerometer-based technology (E & X-Series), were compared between 3 groups: packaging (terminal 5 minutes on scene), loading (terminal 3 minutes on scene), and transport. Mechanical CPR was performed using (AutoPulse®, ZOLL Medical) while most cases of manual CPR were performed with real-time audiovisual chest compression feedback enabled (Real CPR Help®). To compare manual CPR [metronome rate of 100...
Background: Recent studies have shown that prehospital systolic blood pressure (SBP) is strongly ... more Background: Recent studies have shown that prehospital systolic blood pressure (SBP) is strongly associated with mortality across a remarkably wide range (far above 90 mmHg) in traumatic brain injury (TBI). Furthermore, in TBI research, trial enrollment and risk-adjustment are highly dependent upon accurate documentation of BP. Our preliminary work identified potential discrepancies between EMS-documented vs. actual measured BP. Objective: In major TBI, evaluate concordance between SBP documented in EMS patient care records (PCR) and actual, monitor-recorded SBP. Methods: A subset of major TBI cases (mod/severe/critical) in the EPIC TBI Study (NIH 1R01NS071049) were analyzed (3/13-7/18). Cases from 6 EMS agencies reporting continuous monitor data (Philips MRx™) were included. All monitor data available for this analysis were displayed and accessible to the providers during EMS care. We compared the lowest PCR-documented SBP to the monitor-recorded value in each patient. Results: Inc...
Background: Little is known about the ventilatory aspects of overdose-related OHCA (OD-OHCA). We ... more Background: Little is known about the ventilatory aspects of overdose-related OHCA (OD-OHCA). We compared maximum ETCO2 (mETCO2; each patient’s highest CO2 level) and mean for each recorded minute of CPR in OD-OHCA to that of respiratory (R-OHCA) and cardiac (C-OHCA) arrests. Methods: Continuous CO2 data (Zoll E/X series monitors) were obtained from 3 Arizona EMS agencies. Cases had at least 3 min of recorded CO2 during CPR. Arrests were classified as OD-OHCA by EMS and/or hospital documentation. Any drug OD was included (e.g., opioids, mixed). C-OHCA and R-OHCA cases were randomly chosen for comparison. The groups were compared using Fisher’s exact test or Chi-squared for categorical and Kruskal-Wallis for continuous variables. Results: Included were 263 subjects (37 OD-OHCA, 157 C-OHCA and 69 R-OHCA; median age 61, 64% male, 1/10-12/18) with 10,271 min of data [median resuscitation interval 37 min (IQR 29, 47)]. Mean ETCO2 (SD): OD-OHCA [41 mmHg (24)]; R-OHCA [40 (23)], C-OHCA [30...
BACKGROUND The Emergency Medical Services for Children State Partnership Program, as well as the ... more BACKGROUND The Emergency Medical Services for Children State Partnership Program, as well as the Institute of Medicine report on pediatric emergency care, encourages recognition of emergency departments (EDs) through categorization and verification systems. Although pediatric verification programs are associated with greater pediatric readiness, clinical outcome data have been lacking to track the effects and patient-centered outcomes by implementing such programs. OBJECTIVE To describe pediatric mortality rates prior to and after implementation of a pediatric emergency facility verification system in Arizona. METHODS This was a cross-sectional study conducted using data from ED visits between 2011 and 2014 recorded in the Arizona Hospital Discharge Database. The primary outcome measure was the mortality rate for ED visits by patients under 18 years old. Rates were compared prior to and after facility certification by the Arizona Pediatric Prepared Emergency Care program. RESULTS The total number of ED visits by children during the study period was 1,928,409. Of these, 1,127,294 were at facilities undergoing certification. For hospitals becoming certified, overall ED mortality rates were 35.2 deaths/100,000 ED visits (95% confidence interval [CI] 29.5-41.7) in the precertification analysis and 34.4 deaths/100,000 ED visits (95% CI 30.4-38.9) in the postcertification analysis. The injury-related ED visit mortality rate for certified hospitals showed a decrease from 40.0 injury-related deaths/100,000 ED visits (95% CI 28.6-54.4) in the precertification analysis to 25.8 injury-related deaths/100,000 ED visits (95% CI 18.7-34.8) in the postcertification analysis. CONCLUSION The implementation of the Arizona pediatric ED verification system was associated with a trend toward lower mortality. These results offer a platform for further research on pediatric ED preparedness efforts and their effects on improved patient outcomes.
Prehospital emergency care : official journal of the National Association of EMS Physicians and the National Association of State EMS Directors, Jan 8, 2017
Low body temperatures following prehospital transport are associated with poor outcomes in patien... more Low body temperatures following prehospital transport are associated with poor outcomes in patients with traumatic brain injury (TBI). However, a minimal amount is known about potential associations across a range of temperatures obtained immediately after prehospital transport. Furthermore, a minimal amount is known about the influence of body temperature on non-mortality outcomes. The purpose of this study was to assess the correlation between temperatures obtained immediately following prehospital transport and TBI outcomes across the entire range of temperatures. This retrospective observational study included all moderate/severe TBI cases (CDC Barell Matrix Type 1) in the pre-implementation cohort of the Excellence in Prehospital Injury Care (EPIC) TBI Study (NIH/NINDS: 1R01NS071049). Cases were compared across four cohorts of initial trauma center temperature (ITCT): <35.0°C [Very Low Temperature (VLT)]; 35.0-35.9°C [Low Temperature (LT)]; 36.0-37.9°C [Normal Temperature (N...
The tongue participates in a range of complex oromotor behaviors, including mastication, swallowi... more The tongue participates in a range of complex oromotor behaviors, including mastication, swallowing, respiration, and speech. Previous electromyographic studies of the human tongue have focused on respiratory-related tongue muscle activities and their role in maintaining upper airway patency. Remarkably, the activities of human hypoglossal motor units have not been studied during the execution of voluntary maneuvers. We recorded single motor unit activity using tungsten microelectrodes in the genioglossus muscle of 10 healthy human subjects performing both slow tongue protrusions and a static holding maneuver. Displacement of the tongue was detected by an isotonic transducer coupled to the lingual surface through a customized lever arm. For protrusion trials, the firing rate at recruitment was 13.1 ± 3 Hz and increased steeply to an average of 24 ± 6 Hz, often with very modest increases in tongue protrusion. For the static holding task, the average firing rate was 16.1 ± 4 Hz, which...
The respiratory central pattern generator distributes rhythmic excitatory input to phrenic, inter... more The respiratory central pattern generator distributes rhythmic excitatory input to phrenic, intercostal, and hypoglossal premotor neurons. The degree to which this input shapes motor neuron activity can vary across respiratory muscles and motor neuron pools. We evaluated the extent to which respiratory drive synchronizes the activation of motor unit pairs in tongue (genioglossus, hyoglossus) and chest-wall (diaphragm, external intercostals) muscles using coherence analysis. This is a frequency domain technique, which characterizes the frequency and relative strength of neural inputs that are common to each of the recorded motor units. We also examined coherence across the two tongue muscles, as our previous work shows that, despite being antagonists, they are strongly coactivated during the inspiratory phase, suggesting that excitatory input from the premotor neurons is distributed broadly throughout the hypoglossal motoneuron pool. All motor unit pairs showed highly correlated acti...
Although studies of the principal tongue protrudor muscle genioglossus (GG) suggest that whole mu... more Although studies of the principal tongue protrudor muscle genioglossus (GG) suggest that whole muscle GG electromyographic (EMG) activities are preserved in nonrapid eye movement (NREM) sleep, it is unclear what influence sleep exerts on individual GG motor unit (MU) activities. We characterized the firing patterns of human GG MUs in wakefulness and NREM sleep with the aim of determining 1) whether the range of MU discharge patterns evident in wakefulness is preserved in sleep and 2) what effect the removal of the “wakefulness” input has on the magnitude of the respiratory modulation of MU activities. Microelectrodes inserted into the extrinsic tongue protrudor muscle, the genioglossus, were used to follow the discharge of single MUs. We categorized MU activities on the basis of the temporal relationship between the spike train and the respiration cycle and quantified the magnitude of the respiratory modulation of each MU using the eta (η2) index, in wakefulness and sleep. The major...
Although respiratory muscle motor units have been studied during natural breathing, simultaneous ... more Although respiratory muscle motor units have been studied during natural breathing, simultaneous measures of muscle force have never been obtained. Tongue retractor muscles, such as the hyoglossus (HG), play an important role in swallowing, licking, chewing, breathing, and, in humans, speech. The HG is phasically recruited during the inspiratory phase of the respiratory cycle. Moreover, in urethane anesthetized rats the drive to the HG waxes and wanes spontaneously, providing a unique opportunity to study motor unit firing patterns as the muscle is driven naturally by the central pattern generator for breathing. We recorded tongue retraction force, the whole HG muscle EMG and the activity of 38 HG motor units in spontaneously breathing anesthetized rats under low-force and high-force conditions. Activity in all cases was confined to the inspiratory phase of the respiratory cycle. Changes in the EMG were correlated significantly with corresponding changes in force, with the change in...
In a recent study (Huang YH et al. Respir Physiol Neurobiol 143: 1–8, 2004), we showed that prena... more In a recent study (Huang YH et al. Respir Physiol Neurobiol 143: 1–8, 2004), we showed that prenatal nicotine exposure (PNE) increased the frequency of spontaneous apneic events on the first 2 days of life in unanesthetized neonatal rats. Here we test the hypothesis that PNE blunts chemoreceptor reflexes. Ventilatory responses to three levels each of hypoxia (inspired O2 fraction: 16, 12, and 10%) and hypercapnia (3, 6, and 9% inspired CO2 fraction, all in 50% O2, balance N2), and one level each of combined hypoxia-hypercapnia (H/H; 12% inspired O2 fraction/5% inspired CO2 fraction) and hyperoxia (50% O2, 50% N2) were recorded with head-out plethysmography in neonatal rats exposed to either nicotine ( N = 12) or physiological saline ( N = 12) in the prenatal period. Recordings were made on postnatal day 1 (P1), P3, P6, P9, P12, and P18, in each animal. The change in ventilation in response to hypoxia was blunted in PNE animals on P1 and P3, but there were no other treatment effects....
Background: End-Tidal CO2 (ETCO2) monitoring is valuable in the management of traumatic brain inj... more Background: End-Tidal CO2 (ETCO2) monitoring is valuable in the management of traumatic brain injury (TBI). In intubated patients it helps prevent hyper/over-ventilation. In non-intubated patients, placing a sensor in the nares allows accurate monitoring of respiratory rate and has other promising uses (e.g. monitoring ETCO2 trends in worsening TBI, COPD, etc). Study Objective: To identify how accurately EMS providers document ETCO2, we compared the values recorded in EMS patient care records (PCR) to monitor data in non-intubated TBI patients. Methods: Cases from 6 EMS agencies reporting continuous monitor data (Philips MRx) in the EPIC Study (NIH 1R01NS071049) were evaluated (4/13-3/17). All ETCO2 data available for this post-hoc review were displayed and accessible to the EMS providers during care. Concordance was defined in two ways (for both highest and lowest ETCO2): ≤5 and ≤3 mmHg difference between the monitor data and PCR-documented values. Results: 106 cases were included ...
Introduction: The EPIC Study implemented the national EMS TBI Guidelines in a massive, statewide ... more Introduction: The EPIC Study implemented the national EMS TBI Guidelines in a massive, statewide initiative (>11,000 providers trained, 133 agencies). While implementation was not associated with improved survival to discharge in moderate or critically-severe TBI in the primary (all-age) study, the adjusted odds of survival doubled in severe TBI and tripled in severe, intubated TBI. We now report the preplanned pediatric subgroup analysis (“EPIC4Kids”-NIH R01NS071049). Methods: Multisystem, intention-to-treat study using a before/after controlled design in patients with moderate to critically severe TBI. Interventions: Prevention/treatment of hypoxia, hypotension, and hyperventilation by EMS providers. Inclusion: Age<18; CDC Barell Matrix Type 1; 1/07-6/15. Severity subgroups [Head Region Severity Score (IDC-based AIS equivalent)]: Moderate=1-2; Severe=3-4; Critical=5-6. The pre-implementation (P1) and post-implementation (P3) cohorts were compared using logistic regression (F...
Objective: Little is known about End-Tidal CO 2 monitoring using nasal cannula sensors (NC-CO 2 )... more Objective: Little is known about End-Tidal CO 2 monitoring using nasal cannula sensors (NC-CO 2 ) in non-intubated patients. Objective: To describe the patterns of NC-CO 2 seen during the EMS care of spontaneously breathing major Traumatic Brain Injury (TBI) patients. Methods: Continuous NC-CO 2 data (Philips MRx™ monitors) were evaluated from non-intubated, major (moderate, severe, critical) TBI cases (4/13-5/17) in the EPIC TBI Study (NIH 1R01NS071049). Descriptive statistics were used to evaluate case and NC-CO 2 attributes. Results: Included were 92 cases [median age = 50 (range 10-91; 66% male)]. Median respiratory rate (RR) was >15/min in 87% of cases and >20/min in 53%. The highest median RR was 39. Sixteen cases (17%) had a median NC-CO 2 <20 mmHg, 37% (34) were 20-29, 18% (17) were 30-34, 25% (23) were 35-45. Two cases (2%) were 45-50, which has not been noted in this population previously. No case had a median NC-CO 2 >50. Several common NC-CO 2 patterns emerge...
Introduction: Little is known about prehospital availability and use of medications to treat pati... more Introduction: Little is known about prehospital availability and use of medications to treat patients from hazardous materials (hazmat) medical emergencies. The aim of this study was to identify the availability and frequency of use of medications for patients in hazmat incidents by paramedics with advanced training to care for these patients.Methods: A prospectively validated survey was distributed to United States paramedics with advanced training in the medical management of patients from hazmat incidents who successfully completed a 16-hour Advanced Hazmat Life Support (AHLS) Provider Course from 1999 to 2017. The survey questioned hazmat medication availability, storage, and frequency of use. Hazmat medications were considered to have been used if administered anytime within the past 5 years. For analyses, medications were grouped into those with hazmat indications only and those with multiple indications.Results: The survey email was opened by 911 course participants and 784 o...
Background: Cardiopulmonary resuscitation (CPR) quality is strongly linked to outcomes following ... more Background: Cardiopulmonary resuscitation (CPR) quality is strongly linked to outcomes following out-of-hospital cardiac arrest (OHCA). However, manual CPR quality varies and has risk to providers. We hypothesized that use of a mechanical CPR device might provide higher quality CPR than manual CPR during the technically challenging periods of OHCA resuscitation such as packaging, loading, and transporting patients. Methods: Cases of OHCA at a single site from 10/2008-10/2016 were identified. Two CPR quality metrics, chest compression fraction (CCfr) and CC rate (CCra), measured using accelerometer-based technology (E & X-Series), were compared between 3 groups: packaging (terminal 5 minutes on scene), loading (terminal 3 minutes on scene), and transport. Mechanical CPR was performed using (AutoPulse®, ZOLL Medical) while most cases of manual CPR were performed with real-time audiovisual chest compression feedback enabled (Real CPR Help®). To compare manual CPR [metronome rate of 100...
Background: Recent studies have shown that prehospital systolic blood pressure (SBP) is strongly ... more Background: Recent studies have shown that prehospital systolic blood pressure (SBP) is strongly associated with mortality across a remarkably wide range (far above 90 mmHg) in traumatic brain injury (TBI). Furthermore, in TBI research, trial enrollment and risk-adjustment are highly dependent upon accurate documentation of BP. Our preliminary work identified potential discrepancies between EMS-documented vs. actual measured BP. Objective: In major TBI, evaluate concordance between SBP documented in EMS patient care records (PCR) and actual, monitor-recorded SBP. Methods: A subset of major TBI cases (mod/severe/critical) in the EPIC TBI Study (NIH 1R01NS071049) were analyzed (3/13-7/18). Cases from 6 EMS agencies reporting continuous monitor data (Philips MRx™) were included. All monitor data available for this analysis were displayed and accessible to the providers during EMS care. We compared the lowest PCR-documented SBP to the monitor-recorded value in each patient. Results: Inc...
Background: Little is known about the ventilatory aspects of overdose-related OHCA (OD-OHCA). We ... more Background: Little is known about the ventilatory aspects of overdose-related OHCA (OD-OHCA). We compared maximum ETCO2 (mETCO2; each patient’s highest CO2 level) and mean for each recorded minute of CPR in OD-OHCA to that of respiratory (R-OHCA) and cardiac (C-OHCA) arrests. Methods: Continuous CO2 data (Zoll E/X series monitors) were obtained from 3 Arizona EMS agencies. Cases had at least 3 min of recorded CO2 during CPR. Arrests were classified as OD-OHCA by EMS and/or hospital documentation. Any drug OD was included (e.g., opioids, mixed). C-OHCA and R-OHCA cases were randomly chosen for comparison. The groups were compared using Fisher’s exact test or Chi-squared for categorical and Kruskal-Wallis for continuous variables. Results: Included were 263 subjects (37 OD-OHCA, 157 C-OHCA and 69 R-OHCA; median age 61, 64% male, 1/10-12/18) with 10,271 min of data [median resuscitation interval 37 min (IQR 29, 47)]. Mean ETCO2 (SD): OD-OHCA [41 mmHg (24)]; R-OHCA [40 (23)], C-OHCA [30...
BACKGROUND The Emergency Medical Services for Children State Partnership Program, as well as the ... more BACKGROUND The Emergency Medical Services for Children State Partnership Program, as well as the Institute of Medicine report on pediatric emergency care, encourages recognition of emergency departments (EDs) through categorization and verification systems. Although pediatric verification programs are associated with greater pediatric readiness, clinical outcome data have been lacking to track the effects and patient-centered outcomes by implementing such programs. OBJECTIVE To describe pediatric mortality rates prior to and after implementation of a pediatric emergency facility verification system in Arizona. METHODS This was a cross-sectional study conducted using data from ED visits between 2011 and 2014 recorded in the Arizona Hospital Discharge Database. The primary outcome measure was the mortality rate for ED visits by patients under 18 years old. Rates were compared prior to and after facility certification by the Arizona Pediatric Prepared Emergency Care program. RESULTS The total number of ED visits by children during the study period was 1,928,409. Of these, 1,127,294 were at facilities undergoing certification. For hospitals becoming certified, overall ED mortality rates were 35.2 deaths/100,000 ED visits (95% confidence interval [CI] 29.5-41.7) in the precertification analysis and 34.4 deaths/100,000 ED visits (95% CI 30.4-38.9) in the postcertification analysis. The injury-related ED visit mortality rate for certified hospitals showed a decrease from 40.0 injury-related deaths/100,000 ED visits (95% CI 28.6-54.4) in the precertification analysis to 25.8 injury-related deaths/100,000 ED visits (95% CI 18.7-34.8) in the postcertification analysis. CONCLUSION The implementation of the Arizona pediatric ED verification system was associated with a trend toward lower mortality. These results offer a platform for further research on pediatric ED preparedness efforts and their effects on improved patient outcomes.
Prehospital emergency care : official journal of the National Association of EMS Physicians and the National Association of State EMS Directors, Jan 8, 2017
Low body temperatures following prehospital transport are associated with poor outcomes in patien... more Low body temperatures following prehospital transport are associated with poor outcomes in patients with traumatic brain injury (TBI). However, a minimal amount is known about potential associations across a range of temperatures obtained immediately after prehospital transport. Furthermore, a minimal amount is known about the influence of body temperature on non-mortality outcomes. The purpose of this study was to assess the correlation between temperatures obtained immediately following prehospital transport and TBI outcomes across the entire range of temperatures. This retrospective observational study included all moderate/severe TBI cases (CDC Barell Matrix Type 1) in the pre-implementation cohort of the Excellence in Prehospital Injury Care (EPIC) TBI Study (NIH/NINDS: 1R01NS071049). Cases were compared across four cohorts of initial trauma center temperature (ITCT): <35.0°C [Very Low Temperature (VLT)]; 35.0-35.9°C [Low Temperature (LT)]; 36.0-37.9°C [Normal Temperature (N...
The tongue participates in a range of complex oromotor behaviors, including mastication, swallowi... more The tongue participates in a range of complex oromotor behaviors, including mastication, swallowing, respiration, and speech. Previous electromyographic studies of the human tongue have focused on respiratory-related tongue muscle activities and their role in maintaining upper airway patency. Remarkably, the activities of human hypoglossal motor units have not been studied during the execution of voluntary maneuvers. We recorded single motor unit activity using tungsten microelectrodes in the genioglossus muscle of 10 healthy human subjects performing both slow tongue protrusions and a static holding maneuver. Displacement of the tongue was detected by an isotonic transducer coupled to the lingual surface through a customized lever arm. For protrusion trials, the firing rate at recruitment was 13.1 ± 3 Hz and increased steeply to an average of 24 ± 6 Hz, often with very modest increases in tongue protrusion. For the static holding task, the average firing rate was 16.1 ± 4 Hz, which...
The respiratory central pattern generator distributes rhythmic excitatory input to phrenic, inter... more The respiratory central pattern generator distributes rhythmic excitatory input to phrenic, intercostal, and hypoglossal premotor neurons. The degree to which this input shapes motor neuron activity can vary across respiratory muscles and motor neuron pools. We evaluated the extent to which respiratory drive synchronizes the activation of motor unit pairs in tongue (genioglossus, hyoglossus) and chest-wall (diaphragm, external intercostals) muscles using coherence analysis. This is a frequency domain technique, which characterizes the frequency and relative strength of neural inputs that are common to each of the recorded motor units. We also examined coherence across the two tongue muscles, as our previous work shows that, despite being antagonists, they are strongly coactivated during the inspiratory phase, suggesting that excitatory input from the premotor neurons is distributed broadly throughout the hypoglossal motoneuron pool. All motor unit pairs showed highly correlated acti...
Although studies of the principal tongue protrudor muscle genioglossus (GG) suggest that whole mu... more Although studies of the principal tongue protrudor muscle genioglossus (GG) suggest that whole muscle GG electromyographic (EMG) activities are preserved in nonrapid eye movement (NREM) sleep, it is unclear what influence sleep exerts on individual GG motor unit (MU) activities. We characterized the firing patterns of human GG MUs in wakefulness and NREM sleep with the aim of determining 1) whether the range of MU discharge patterns evident in wakefulness is preserved in sleep and 2) what effect the removal of the “wakefulness” input has on the magnitude of the respiratory modulation of MU activities. Microelectrodes inserted into the extrinsic tongue protrudor muscle, the genioglossus, were used to follow the discharge of single MUs. We categorized MU activities on the basis of the temporal relationship between the spike train and the respiration cycle and quantified the magnitude of the respiratory modulation of each MU using the eta (η2) index, in wakefulness and sleep. The major...
Although respiratory muscle motor units have been studied during natural breathing, simultaneous ... more Although respiratory muscle motor units have been studied during natural breathing, simultaneous measures of muscle force have never been obtained. Tongue retractor muscles, such as the hyoglossus (HG), play an important role in swallowing, licking, chewing, breathing, and, in humans, speech. The HG is phasically recruited during the inspiratory phase of the respiratory cycle. Moreover, in urethane anesthetized rats the drive to the HG waxes and wanes spontaneously, providing a unique opportunity to study motor unit firing patterns as the muscle is driven naturally by the central pattern generator for breathing. We recorded tongue retraction force, the whole HG muscle EMG and the activity of 38 HG motor units in spontaneously breathing anesthetized rats under low-force and high-force conditions. Activity in all cases was confined to the inspiratory phase of the respiratory cycle. Changes in the EMG were correlated significantly with corresponding changes in force, with the change in...
In a recent study (Huang YH et al. Respir Physiol Neurobiol 143: 1–8, 2004), we showed that prena... more In a recent study (Huang YH et al. Respir Physiol Neurobiol 143: 1–8, 2004), we showed that prenatal nicotine exposure (PNE) increased the frequency of spontaneous apneic events on the first 2 days of life in unanesthetized neonatal rats. Here we test the hypothesis that PNE blunts chemoreceptor reflexes. Ventilatory responses to three levels each of hypoxia (inspired O2 fraction: 16, 12, and 10%) and hypercapnia (3, 6, and 9% inspired CO2 fraction, all in 50% O2, balance N2), and one level each of combined hypoxia-hypercapnia (H/H; 12% inspired O2 fraction/5% inspired CO2 fraction) and hyperoxia (50% O2, 50% N2) were recorded with head-out plethysmography in neonatal rats exposed to either nicotine ( N = 12) or physiological saline ( N = 12) in the prenatal period. Recordings were made on postnatal day 1 (P1), P3, P6, P9, P12, and P18, in each animal. The change in ventilation in response to hypoxia was blunted in PNE animals on P1 and P3, but there were no other treatment effects....
Background: End-Tidal CO2 (ETCO2) monitoring is valuable in the management of traumatic brain inj... more Background: End-Tidal CO2 (ETCO2) monitoring is valuable in the management of traumatic brain injury (TBI). In intubated patients it helps prevent hyper/over-ventilation. In non-intubated patients, placing a sensor in the nares allows accurate monitoring of respiratory rate and has other promising uses (e.g. monitoring ETCO2 trends in worsening TBI, COPD, etc). Study Objective: To identify how accurately EMS providers document ETCO2, we compared the values recorded in EMS patient care records (PCR) to monitor data in non-intubated TBI patients. Methods: Cases from 6 EMS agencies reporting continuous monitor data (Philips MRx) in the EPIC Study (NIH 1R01NS071049) were evaluated (4/13-3/17). All ETCO2 data available for this post-hoc review were displayed and accessible to the EMS providers during care. Concordance was defined in two ways (for both highest and lowest ETCO2): ≤5 and ≤3 mmHg difference between the monitor data and PCR-documented values. Results: 106 cases were included ...
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