ITRM20090523A1 - EQUIPMENT FOR EXTRACORPROOF HEMODIALYSIS PREPARED FOR THE DECONTAMINATION OF LINES AND FILTERS. - Google Patents

Description

EQUIPMENT FOR EXTRACORPOREAL HEMODIALYSIS PREDI-MOVE FOR THE DECONTAMINATION OF LINES AND FILTERS

The present invention relates to an extracorporeal hemodialysis equipment designed for the decontamination of lines and filters. More specifically, the invention relates to a machine for extracorporeal dialysis (or artificial kidney) of the type already in use to carry out the hemodialysis treatment, integrated with a modification to the internal hydraulic circuit and the relative connections, so as to allow performing a decontamination wash of the dialysis filter and disposable lines before their disposal. The invention also concerns the relative operating method for carrying out the cleaning and disinfection cycle.

As is known, dialysis is a chemical-physical process of separation of substances dissolved in a liquid in which a semipermeable membrane is used, which allows the passage of such substances in only one direction. The motion of the substances is of a diffusive type, essentially due to the concentration gradient of the solutes between the two compartments separated by the membrane, but in some cases it is also influenced by the pressure gradient existing between the two compartments, which involves the transit of a certain altitude. of the solvent liquid from one side of the membrane to the other. In the latter case, the motion of the solutes occurs not only by diffusion, but also by convection.

In the medical field, this process is applied in hemodialysis, a physical therapy to replace renal function which is administered to subjects with renal insufficiency in whom this function is severely reduced (uremia), and which is still the only treatment in able to allow such patients to survive, while at the same time guaranteeing a good state of well-being.

In fact, hemodialysis treatment replaces the basic functions of the kidneys which, as known, regulate the water content in the body (removal of excess fluids), remove metabolic waste products from the blood (removal of toxic substances) and help maintain the body's chemicals in balance (electrolyte rebalancing and acid-base rebalancing). In consideration of the porosity of the anisotropic membranes used, the technique used for hemodialysis is ultrafiltration.

From a medical point of view, hemodialysis treatments are divided into two main categories, hemodialysis proper, in which the blood is extracted from the patient, filtered with a semipermeable membrane and reinfused, and peritoneal dialysis, in which it is introduced into the fluid peritoneal cavity that uses the peritoneum (a semipermeable membrane of the human body that surrounds the organs of the abdomen) as a membrane to perform the aforementioned processes. Both categories in turn include different subtypes, depending on the specific application characteristics and the devices and methods used. However, the most widely used method is extracorporeal dialysis, generically known as hemodialysis, which is performed by means of a special equipment, also known as "artificial kidney". This is connected to the patient's blood vessels and the blood extracted by a pump system is passed through it. The blood is suitably filtered, coming into contact with a special dialysis fluid (dialysis solution or dialysis bath) to which it transfers the waste substances, and then it is reintroduced, purified and deprived of excess fluid, into the patient's circulatory system. Each of these treatments is performed on average three times a week, and lasts from 3 to 5 hours.

To perform hemodialysis therapy, access to a vein and an artery, usually in the arm, is required and is done surgically (arteriovenous fistula). The surgical technique consists in the connection (anastomosis) of a donor arterial vessel and an adjacent venous vessel, more often made in a latero-terminal mode, in which the terminal end of the cephalic vein is sutured to the lateral wall of the radial artery. In this way the two vessels guarantee a permanent vascular access through which an adequate blood flow is normally obtained for an effective purification.

The equipment used for extracorporeal hemodialysis is made up of four fundamental elements as a whole:

• the dialysis filter;

• the extracorporeal blood circuit;

• the dialysis fluid circuit;

• the control monitor.

The dialysis filter constitutes the functional unit of the artificial kidney. As shown in Figures 1 and 2 of the attached drawings, which respectively illustrate and with different symbols, the first the extracorporeal blood circuit, and the second the entire haemofiltration apparatus, the dialysis filter (4) is interposed between the arterial line (3 ), connected to the patient's artery, and the venous line (5), through which the purified blood returns to the patient's own vein. To achieve the desired purification, blood recirculates hundreds of times between the patient and the dialysis filter during each dialysis session. From the point of view of the technological realization, the dialysis filter can be of different types, but in any case it consists of a semipermeable membrane connected at the inlet with the arterial tract (3) of the blood circuit and at the outlet with the venous tract (5) of said circuit, which is crossed in countercurrent, on the other side, by the dialysis liquid (this passage is not shown in Figure 1, which illustrates only the blood circuit, but is illustrated in Figure 2, which shows, from the shell side of the filter dialyzer (4), the inlet and outlet ducts of the dialysis fluid.

The lines of both sections, arterial and venous, are made up of a series of small-caliber flexible tubes, made of plastic material, which are replaced after each session, between one patient and the next. The progression of blood in the extracorporeal circuit is ensured by a peristaltic pump, (7) in Figure 2 (Figure 1, in parallel, shows with (3b) the section of arterial line that is inserted into the peristaltic pump, which can sometimes be made of a different material than the rest of the arterial line). Blood flow is maintained by the pump at around 250-350ml / min.

The sterility of the dialysis filter and of the whole extracorporeal circuit is obtained by sterilization with ethylene oxide or with gamma rays. The incoagulability of the blood in the extracorporeal circuit in general and in the dialysis filter in particular is ensured by washing these structures, in the circuit preparation phase, with a heparin solution, and by the administration of heparin during the hemodialysis session.

As regards the dialysis liquid circuit (of which only the part that passes through the filter (4) is shown in Fig. 2), it contains a solution consisting essentially of mains water (subjected to a demineralization process chemistry by passing through ion exchange resins), mineral salts, osmotically active substances and buffer substances (generally acetate or bicarbonate). This solution contains sodium, potassium, calcium, magnesium, chloride, acetate and glucose. Once through the filter, with a reverse flow direction with respect to the blood, the dialysis fluid is sent directly to the drain. Furthermore, a second pump is inserted on the dialysis fluid circuit (suction pump, not visible in Fig. 2) which has the function of creating a negative pressure, thus allowing the direct removal by ultrafiltration of excess water subtracted from the blood. of the patient.

Finally, the monitor (8 in Fig. 2) is an equipment equipped with sophisticated devices aimed at two essential tasks, which are the preparation of the dialysis fluid and the control of some essential parameters for the conduct of the dialysis session in conditions of efficacy and safety for the patient, such as warming of dialysis fluid, detection of blood leaks across membranes, temperature control of both dialysate and blood, continuous control of dialysis fluid composition. These parameters are displayed, during the various operations, on video 9. Modern equipment is equipped with numerous servo control systems: flows, temperatures, ultrafiltration, conductivity, pH are all quantities measured by sensors located along the extracorporeal circuit. There are patient-specific sensors that continuously measure certain biological and hemodynamic variables, such as body temperature, blood volume or urea variations, allowing accurate intradialytic monitoring. For volume control (total volume of blood present in the body), the most important variables are ultrafiltration and sodium concentration in the dialysate (dialysis fluid). For example, an increase in the sodium concentration in the dialysate raises osmolarity and favors the mobilization of liquids from the extra-vascular compartment, minimizing volume variations.

By way of example only, Figure 3 of the attached drawings, also relating to the current state of the art, shows an example of an internal hydraulic circuit of a hemodialysis monitor (8), where, in particular, the inlet of the liquid is visible. sterilant (10), the cold water inlet (11), the mixing point (12) of the sterilant with the lukewarm water (heated by passing through the heat exchanger (13)) the "blue" connector (14) of the dialysis filter (4), the “red” connector (15) of the same filter and the drain (16) of the used sterilant. (It should be noted that according to the international convention it is envisaged to indicate with "red" the arterial side of the circuit, on the side of the blood sample, and with "blue" the venous side of the circuit, on the side of reinfusion.)

Between one hemodialysis session and the next, it is mandatory to carry out a washing and disinfection cycle of the hemodialysis monitor circuits, to avoid viral and / or bacterial contamination between one patient and the next. This in addition, of course, to the normal cycles of periodic washing and disinfection of the equipment, which take place on a daily and weekly basis, and which have a more specific function of maintenance of the equipment itself and of the various accessory devices.

The professional figure of the dialysis operator is particularly exposed to the danger of contracting infectious diseases; in fact, a part of dialysis patients are anti-HCV positive, and anti-HIV positive and HbsAg positive patients are occasionally present. In total, the main risks of contamination are from HIV, hepatitis B and C (HBV, HCV) and other pathogenic germs, such as Pseudomonas aeruginosa and Staphylococcus aureus.

For this reason, preventive training is currently of great importance to minimize the risk, the implementation of epidemiological surveillance policies for infectious diseases and, above all, the application by operators of standard, universal precautions, such as:

• the use of gloves for any direct patient assistance maneuver that may involve contact with blood or other biological liquids, and when handling sharp instruments;

• the change of gloves after the assistance of each patient or when they break, and as soon as possible in case of visible contamination;

• washing hands after the assistance of each patient or in any case after any accidental contact with blood or other biological liquids and after removing gloves, avoiding eating and putting hands to mouth or eyes during work and touching objects present in the environment (telephone, handles, taps) when wearing potentially contaminated gloves;

• the use of protective gowns, masks, goggles and protective face shields during care maneuvers that may involve the emission of droplets or splashes of blood or other biological fluids, for example when placing dialysis needles;

• maximum attention in avoiding punctures or cuts when using needles or sharp edges; the needles must not be re-capped, bent, broken or removed from the supports, but disposed of in resistant containers available near the places where the needles or the cutting edges themselves are used.

Despite the awareness and application of the aforementioned prevention rules, particularly critical areas are identified, where the risk of contracting an infectious disease for the operator is particularly high. One of these “high risk areas for the hemodialysis technician” is that relating to the replacement, after the treatment cycle, of the lines and disposable filters of the machinery.

Disposable hemodialysis devices, i.e. the lines and the filter, are contaminated during use by the dialysis process, and also undergo mechanical stress due to the crushing repeatedly exerted by the rollers of the blood pumps on the corresponding points of the lines. At the end of the dialysis cycle, the stress suffered is such that it can compromise the integrity of the lines used. According to the procedure, the dialysis operators at the end of the session manually remove these devices (filters and lines), with the consequent risk of contamination by the blood fluid of the dialysed patient.

Furthermore, from an environmental point of view, it should be noted that disposable hemodialysis devices (filters and lines), contaminated by the dialysis process, are considered infectious risk material: their disposal involves storage in special containers for transport and subsequent incineration, with consequent considerable costs to be incurred.

In the normal management of an equipment for extracorporeal dialysis, therefore, the current procedure involves the following succession of phases:

a) end of patient X's dialysis session;

b) manual removal of the filter and lines (potentially infected) by the operator;

c) cleaning and disinfection cycle of the internal circuits of the hemodialysis monitor;

d) disposal of the filter and lines as special infectious risk waste;

e) start of the dialysis session of patient Y.

In the light of the foregoing, it is evident that the removal of the disposable lines of a hemodialysis device between one session and the next and their elimination among the hospital waste at infectious risk constitutes a delicate problem in the management of hemodialysis treatment, and the present invention the aim is precisely to provide a solution to this problem.

For this purpose it is proposed to intervene with limited modifications to the extracorporeal hemodialysis equipment of the generally known type and to create the conditions for washing and disinfecting the filter and the lines together with the cleaning and disinfection cycle of the internal circuits of the hemodialysis monitor, integrating lines and filter, after use, in the same disinfection circuit as the internal lines of the monitor. Only after disinfection will it be possible to manually remove the filter and lines, with no more infectious risk for the operator.

The decontamination of the lines and filters carried out according to the method proposed by the invention could, with a simple on-site sterilization process, allow the disposal of used lines and filters as solid urban waste and no longer as special infectious risk waste.

The procedure to be implemented between one hemodialysis cycle and the next, in light of the proposed modification, is modified as follows:

A. end of patient X's dialysis session;

B. cleaning and disinfection cycle of the internal circuits of the hemodialysis monitor, lines and filter;

C. manual removal of the filter and lines (no longer at infectious risk) by the operator;

D. disposal of the filter and lines as municipal solid waste;

E. Beginning of patient Y's dialysis session

According to the invention, a hemodialysis monitor of those already in current use for extracorporeal dialysis can be modified by introducing two further connection points accessible on one of the external panels of the machine, equipped with two luer-lock connections, to provide additional access to the machine's internal hydraulic circuit. Luer lock couplings or fittings are currently used and well known in the sector, as well as uniquely defined by their denomination.

These attachments, which according to the aforementioned convention are preferably one in red and the other blue, indicating that one must be connected to the disposable arterial line and the other to the venous one, are shaped so that they can be coupled with corresponding fittings luer locks which are provided for this purpose at the extremity of the arterial and venous lines, on the side where they connect to the patient. Specifically, the arterial disposable line is preferably equipped with a female luer lock fitting at its end, while the corresponding connection provided on the monitor panel according to the invention is a male red luer lock connection. Similarly, at the end of the disposable venous line there is preferably provided, according to the invention, a female luer lock connection, intended to be inserted, in the corresponding blue luer lock connection provided on the equipment.

The connection of the aforementioned fittings with the disposable arterial and venous lines of the blood circuit, after dialysis, allows the whole line to be inserted, with the dialysis filter interposed between them, into the hydraulic circuit of the monitor, to integrate in the washing and disinfection also these elements before eliminating them ..

The proposed modification also provides that corresponding points of the internal hydraulic circuit on which the red luer lock and blue luer lock ducts are connected are made in specific positions of the circuit, so as not to interfere with the already consolidated operation of the machine during the cycle. washing.

It should be noted that each company producing hemodialysis monitors has particular characteristics in the relative hydraulic circuits: the modification proposed according to the invention applies to elements that are common to all the best known hemodialysis monitors, and is potentially applicable to all models and brands.

Therefore, the specific object of the present invention is a control monitor (8) of an apparatus for extracorporeal hemodialysis comprising

an internal hydraulic circuit for the preparation and management of a dialysis liquid and one or more liquids with sterilizing and / or disinfectant functions,

instruments and videos for the control of parameters relating to the conduct of a hemodialysis session; And

attachments and connections for connection to an extracorporeal blood circuit, consisting of disposable arterial (3) and venous (5) lines and a dialysis filter (4);

characterized in that it also comprises a first and a second connection (22 and 23) suitable for integrating said disposable arterial (3) and venous (5) lines with said filter (4) interposed, in the hydraulic circuit of the monitor (8) during the washing phase following a dialysis session, said first connection (22) being connectable with the end of said arterial line (3) and said second connection (23) being connectable with the end of said venous line (5) ,

the internal hydraulic circuit of the monitor (8) being hydraulically connectable to said first connection (22) at a point downstream of the mixing point of water and sterilant liquid and upstream of the inlet to said filter 84) (between A and B) .

In the proposed control monitor, the internal hydraulic circuit can be hydraulically connected to said second connection (23) at a point downstream of the last solenoid valve before the discharge point (between C and D).

Said control monitor is preferably further provided with two caps (24 and 25) for closing the access to the filter (4) from the side of the dialysate passage in the hemodialysis phase (mantle side). Said first and second connections (22 and 23) provided on the monitor are two male luer lock connections.

According to a preferred solution, in the control monitor said first connection (22) is a red male luer lock and said second connection (23) is a blue male luer lock.

The present invention also comprises a washing and decontamination process of a hemodialysis control monitor (8) together with the relative arterial (3) and venous (5) lines and the filter (4) interposed between them comprising, as described in the preceding claims, wherein after a hemodialysis session said lines (3 and 5) and said filter (4) are connected to the hydraulic circuit of the monitor (8) by means of said first and second connections (22 and 23).

The specific features of the invention, as well as the advantages of the same and the related operating methods, will be more evident with reference to the detailed description presented by way of example below, in which:

Figure 1 schematically shows the blood circuit of an extracorporeal hemodialysis process according to the known art;

Figure 2 schematically shows an entire extracorporeal dialysis apparatus according to the known art;

Figure 3 shows an example of an internal hydraulic circuit of an extracorporeal hemodialysis monitor according to the known art;

Figures 4 and 5 show respectively an example of a male and female luer lock fitting or connection, respectively, of the type used in the present invention;

Figure 6 shows a control monitor modified according to the invention;

Figure 7 shows a connected luer lock port;

Figure 8 shows an example of a modified hydraulic circuit according to the invention.

EXAMPLE

By way of example, the hydraulic circuit of the Formula BELLCO hemodialysis monitor is shown below, also explaining in a universal way the interval where it is possible to apply the changes according to the invention.

With the proposed modification, illustrated in Figure 6 of the attached drawings, two male luer lock connections 22 and 23 (red and blue) connected to the internal hydraulic circuit are created on the front panel of the hemodialysis monitor. In accordance with the international convention that provides for the red color to indicate the arterial blood circuit (sampling) and the blue color to indicate the venous one (return), the red luer lock will have the function of entering the disinfectant liquid (clean) to the disposable circuit. to be disposed of (lines and filter), while the blue luer lock will have the function of discharging the disinfectant liquid (dirty) used for the disinfection cycle.

The choice of positioning the luer locks 22 and 23 on the front panel, and not on the side panels of the monitor, arises from needs of practicality / comfort for the operator: for the same reasons, a different choice is at the discretion of the monitor manufacturer positioning of the luer locks on one of the side panels.

With regard to the blue 23 luer lock, it is at the discretion of the monitor manufacturer to decide whether to let the (dirty) disinfectant liquid used for the disinfection cycle flow out, connected to the monitor's hydraulic circuit, or through an autonomous duct not connected to the monitor's hydraulic circuit. .

At the end of the dialysis process the lines 2 and 5 are disconnected from the patient, which according to the invention have female luer lock connections (shown by way of example in Figure 5 of the attached drawings) and are connected to the male luer lock connectors (22 and 23) specially created on the front panel of the machine. The relative connection is shown by way of example in Figure 7 of the attached drawings.

Disconnect the dialysate (dialysis fluid) connectors from the filter and reposition on the monitor, specifically on the so-called Hansen positioning block, shown at 18 in Figures 2 and 6.

Two caps (24 and 25) are then inserted on the filter 4 (shell side) in place of the dialysate connectors, and the simultaneous cleaning and disinfection cycle of the internal circuits of the hemodialysis monitor (8), of the lines (3 and 5) and filter (4).

It should be noted that the new luer lock connections (22 and 23) positioned on the front panel of the hemodialysis monitor will be the access route to the internal hydraulic circuit only at the start of the cleaning and disinfection cycle, as the monitor software (8 ) provides for the appropriate opening of two solenoid valves (not shown) positioned on the back of the new luer locks (22 and 23) on the front panel, which allow the inclusion of the lines (3 and 5) and of the filter (4) in the cleaning and disinfection.

Microbiological tests of efficacy and preliminary results

The modification proposed according to the present invention was preliminarily tested with pilot tests of microbiological efficacy.

In such tests, the use of a modified hemodialysis apparatus according to the invention was tested in the presence of the following pathogenic microorganisms: gram + and gram- bacteria, fungi and spores, as well as HBV viruses (hepatitis B virus) and HIV.

Two types of disinfectants in consolidated use were used, by way of example only, in the disinfection operations of hemodialysis monitors:

- sodium hypochlorite at a concentration of 1.1% by weight;

- peracetic acid at 4% by weight.

In both cases a 1:34 dilution of the above concentrations was made, simulating the normal conditions of use, and the following disinfectant-pathogen contact times were adopted:

• HIV: 2.5 min;

• hepatitis B virus: 1 min;

• spores: 5 min;

• Gram + and Gram- bacteria and fungi: 5 min.

Based on the pilot tests, it was confirmed that the method proposed according to the invention produces absolutely effective results in terms of microbiological activity, in compliance with the main CEN (European Committee for Standardization) regulations in force. In particular, a significant logarithmic reduction was confirmed, in line with CEN regulations both in terms of bactericidal, fungicidal, sporicidal and virucidal efficacy.

From the above description it is evident that the modified hemodialysis equipment according to the present invention and the operating procedure implemented with its use allow to achieve the following advantages:

• possibility of including in the cleaning and disinfection process of the monitor hydraulic circuit also lines and filters (disposable) of the extracorporeal circuit, which after this process have a residual bacterial charge harmless for the operator responsible for manual removal of the same; consequently, the risk of lines and filters breaking upon removal, which is significant due to the mechanical stress suffered by these components due to the repeated crushing exerted by the blood pump rollers during the dialysis session, no longer translates into a risk infectious for the operator;

• possibility of safely handling the previously decontaminated lines and filter, with the consequent possibility of inserting them in on-site sterilizers to then be able to dispose of them as solid urban waste rather than special infectious risk waste; this entails potential economic savings, while respecting the regulations on the disposal of medical waste (Presidential Decree no. 254 of 15 July 2003).

The present invention has been described with reference to some of its specific embodiments, but it is to be understood that variations or modifications may be made to it by those skilled in the art without thereby departing from the relative scope of protection.

Claims (1)

CLAIMS 1. Control monitor (8) of an extracorporeal hemodialysis equipment comprising an internal hydraulic circuit for the preparation and management of a dialysis liquid and one or more liquids with sterilizing and / or disinfectant functions, instruments and videos for the control of parameters relating to the conduct of a hemodialysis session; And attachments and connections for connection to an extracorporeal blood circuit, consisting of disposable arterial (3) and venous (5) lines and a dialysis filter (4); characterized in that it also comprises a first and a second connection (22 and 23) suitable for integrating said disposable arterial (3) and venous (5) lines with said filter (4) interposed, in the hydraulic circuit of the monitor (8) during the washing phase following a dialysis session, said first connection (22) being connectable with the end of said arterial line (3) and said second connection (23) being connectable with the end of said venous line (5) , the internal hydraulic circuit of the monitor (8) being hydraulically connectable to said first connection (22) at a point downstream of the mixing point of water and sterilant liquid and upstream of the inlet to said filter 84) (between A and B) . 2. Control monitor according to claim 1, in which the internal hydraulic circuit is hydraulically connectable to said second connection (23) at a point downstream of the last solenoid valve before the discharge point (between C and D). 3. Control monitor according to claims 1 or 2, further provided with two caps (24 and 25) for closing access to the filter (4) from the side of the dialysate passage in the hemodialysis phase (mantle side). Control monitor according to any one of claims 1-3, wherein said first and second connections (22 and 23) provided on the monitor are two male luer lock couplings. Control monitor according to claim 4, wherein said first connection (22) is a red male luer lock and said second connection (23) is a blue male luer lock. 6. Washing and decontamination process of a hemodialysis control monitor (8) together with the relative arterial (3) and venous (5) lines and the filter (4) interposed between them comprising as described in the preceding claims, in which after a hemodialysis session said lines (3 and 5) and said filter (4) are connected to the hydraulic circuit of the monitor (8) by means of said first and second connections (22 and 23).