FR2695038A1 - Transportable artificial kidney for emergency dialysis treatment - has closed circulation circuit dialysis bath with tubes connecting reservoir to input of dialysis machine, and output to reservoir through pump - Google Patents

Abstract

The artificial kidney includes components necessary for kidney dialysis, and includes a closed circulation circuit (11,12) dialysis bath which uses a predetermined quantity of pure water for a dialysis session. The bath is prepared the bath from dissolved chemical powders before commencement of dialysis. The volume of water lost by the patient is measured by reading the volume of water in the reservoir (4). A thermostatically controlled heater resistance (9) is located in the bath (4). The closed circuit circulation system uses silicone tubes or equivalent which can be heated to more than 120 deg C for sterilising purposes by means of boiling water or hot air. A first tube (11) connects the reservoir (4) to an input if the dialysis machine (1) and a second tube (12) connects the output of the machine (1) to the reservoir (4) through a pump (2). USE/ADVANTAGE - For emergency use. Simple construction and easy to maintain.

Description

 The present invention relates to an autonomous hemodialysis device.

 Hemodialysis, commonly called "artificial kidney", covers a process of purification of the blood, by osmosis phenomenon, which consists in eliminating organic waste (urea, creatinine, uric acid, etc ...) and hydroelectric overloads (water and mineral salts) which are no longer eliminated naturally due to a renal deficiency, and to normalize the hydroelectrolytic balance of the plasma.

 This phenomenon of osmosis is carried out in a device with semipermeable membranes called a dialyzer, between the blood liquid of a patient and a solution of electrolytic composition close to that of the extracellular liquid, obtained by diluting a concentrate in 1 ' ultra-pure water. This requires in particular to organize an extracorporeal circulation of the patient 's blood to allow it to meet with the dialysis bath.

For hemodialysis to be carried out successfully, it is necessary to have an apparatus which makes it possible to ensure:
- a suitable concentration of the dialysis bath in the basic product that the concentrate contains (generally acetate or bicarbonate)
- maintaining the temperature of the dialysis bath near the temperature of the human body (37 OC)
- circulation of the dialysis bath at the appropriate flow rate and at the transmembrane pressure in the dialyzer
- possible elimination of air bubbles in the circulation circuits, in particular of the blood
- the return of purified blood to the patient's body under suitable pressure
Existing hemodialysis machines meet these conditions, but requiring a complex implementation of bulky, heavy, fragile, expensive equipment, as well as an important infrastructure. Indeed, on the one hand these devices use bath concentrates dialyzes which are heavy to transport, bulky to store, and whose dilution is carried out and regulated as the hemodialysis is carried out by automatic means by continuously incorporating ultrapure water, thus requiring a permanent source of ultrapure water, taking into account the consumption of the apparatus and the duration of a hemodialysis. On the other hand, these devices use a series of complex devices for operating automation and electronic controls, which require a stabilized and reliable power supply.

 This leads to the fact that existing devices are extremely expensive to manufacture, use, and maintain. In addition, their complexity requires, in the event of a maintenance problem, the intervention of persons qualified in the techniques employed, and who are not within the competence of the medical profession.

 All these drawbacks mean that existing devices are only accessible to large structures, with high financial potential, and calling for maintenance, to qualified non-medical personnel trained by the manufacturers. For these reasons, they are in practice unusable in countries where economic and / or technological development does not allow these conditions to be met, as well as in emergency situations.

 The aim of the present invention is to propose a simple device which is easy to maintain, at least by medical personnel, and which, for its operation, does not require a source of continuous supply of purified water, nor of stabilized electrical supply. . The invention also aims to propose a device which takes up little space compared to existing devices, which can operate independently, which is easily transportable, and which can be easily installed at the place of use.

 According to its main characteristic, the present invention relates to a hemodialysis device of the type comprising means suitable for ensuring the meeting, in a dialyzer (1) provided with semi-permeable membranes, of a circulation in a closed circuit (13), ( 14) of a patient 's blood liquid and of a closed circuit circulation (11), (12) of a dialysis bath between the said dialyzer (1) and a reservoir (4) containing a predetermined volume of the said bath dialysis.

 The fact of planning to organize the circulation of the dialysis bath in a closed circuit makes it possible, in a particularly advantageous manner, to no longer have recourse, either to a continuous supply of purified water, or to an automatic dosing system for the dilution of a concentrate during the hemodialysis process, or a complicated system for determining the mass of water withdrawn from the patient.

 In fact, according to the invention, the dialysis bath solution is prepared, prior to hemodialysis, from powdered dialysate, for instant use, and from a predefined volume of purified water, so as to respect easy the prescribed concentration of active ingredient in the dialysis bath. The organization of the circulation of the dialysis bath in a closed circuit is not detrimental to the result of the hemodialysis provided that the starting volume and the concentration of active principles are adapted with the dialysis time and with the weight of the patient. In practice, a 20 liter tank (4) will be replaced every two hours.

 In addition, this circulation in a closed circuit advantageously makes it possible not to have recourse to complex means for measuring the weight loss in water of the patient. This is directly visualized by increasing the volume of dialysis bath in the reservoir (4) as the hemodialysis process proceeds. This increase in volume and the modification of the concentration of the dialysis bath to which it leads are negligible on the efficiency of hemodialysis. The reservoir (4) according to the invention is advantageously made of transparent or translucent material and has a volume graduation over a portion of its surface, to allow such viewing.

 Another characteristic of the device according to the invention is the advantageous use of dialysate in powder form. This makes it possible to considerably reduce the mass transported, and consequently the costs of transport, storage and preparation. The use of powder is made possible by the organization in a closed circuit of the dialysis bath and by the extemporaneous preparation and all at once of the solution of this dialysis bath. Indeed, in conventional devices, the use of continuous dilution leads to the need to use a concentrate in liquid form, because the use of powders would require even more complex equipment to ensure precise dosing, mixing and homogeneous dilution during the hemodialysis process.

 In addition, the closed circuit circulation of the dialysis bath avoids the need, as is the case with existing apparatus, for powerful heating means for rapidly carrying the purified water, coming from a continuous supply of cold water. , at the appropriate operating temperature, approximately 37 C. The preparation of the dialysis bath is carried out with a predetermined quantity of softened or ultrapure water, as the case may be, brought to a temperature close to 37 C by means of heating independent of 1 'device, the latter ensuring maintenance at this temperature by a thermostat immersion heater (9).

According to the invention, other advantageous characteristics of the device are the following:
- Said closed circuit circulation means of said dialysis bath are formed using silicone tubes, a first tube (11) connecting said reservoir (4) to a dialysis bath inlet of said dialyzer (1) and a second tube (12) connecting a dialysis bath outlet of said dialyzer (1) to said reservoir (4) by passing through a first pump (2) preferably of the peristaltic type;
- Said closed circuit circulation means of said dialysis bath comprise, on each of the tubes, preferably near their entry into said reservoir (4), a device (7), (7 ') for closing by crushing the tube allowing adjusting the desired vacuum to remove the desired amount of water from the patient 's blood, through the membranes of the dialyzer (1); this circuit, comprising a minimum of seals, prevents the development of germs and is easily sterilized with boiling water.

- The device comprises thermostated heating means (9) of the volume contained in said tank, preferably constituted by a heating resistor of the heat sink type; reheating in said tank at one time avoids the need for a degassing system constantly in operation to remove the gases dissolved in the inlet water of conventional devices;
- The device comprises means for measuring the temperature (10), the flow rate (8), and the pressure (6) of the dialysate circulating in said first (11) and second (12) tubes; a thermometer (10) being preferably placed on the path of said first tube (11), and a pressure gauge (6) and a flow meter (8) being preferably placed on the path of said second tube (12) upstream of said first pump (2);
The blood circuit does not differ from that of existing devices and comprises the means for circulating in a closed circuit said blood fluid, consisting of pipes made of biocompatible plastic material, a first pipe (13) connecting a blood sampling point of the patient to a blood inlet of said dialyzer (1) by passing a second peristaltic pump (3) and a second pipe (14) connecting a blood outlet of said dialyzer (1) to a point of blood return of the patient by passing through a bubble trap (15 ). This circuit also includes a pressure gauge (5) for controlling the pressure at which the blood is re-injected into the patient's body, the connection for the physiological saline infusion (16) and the injection of anticoagulant (17 ).

 The mode of implementation and use of the apparatus produced according to this invention will now be described in more detail, the essential constituent elements of which are shown diagrammatically in the figure below, in order to better understand the characteristics. essential and advantages, it being understood however that this embodiment is chosen by way of example and that it is in no way limiting.

 Preparation of the dialysis bath circuit.

The tank (4) must be well dried, free from all humidity, and well sealed, to avoid any possible development of germs since the last use. Otherwise, rinse with boiling water for a few minutes, then dry with a hair dryer until there are no more traces of moisture.

Pour ultrapure water heated to 37 ° C (or simply potable water, softened, in the case of acute renal failure) in the tank (4) up to the line of 20 liters. Then pour the dialysate powder for instant use, stirring with a glass or stainless steel stirrer. The powder dissolves easily.

Switch on the thermostatically controlled heating (9) to maintain the dialysate at 370 C by shaking, from time to time, manually or mechanically.

Open the two tube closing devices (7) and (7 ') on the device. The silicone tubes (11) and (12) are connected together by a quick coupling, excluding the dialyzer (1), and contain boiled water, cooled from the last use. This water, during the new dialysis, serves as a relay for the new sterilization with boiling water of the dialysate circuit. The end of the tube (11) is immersed in boiling water and the end of the tube (12) in a disposal container. The pump (2) is started for 5 minutes at very slow speed. Thus the circuit of the dialysis bath, made of silicone, is sterilized. Then the end of the tube (11) is placed in the reservoir (4), the water remaining in the tubes is removed, the end of the tube (12) is also placed in the tank, and the speed of the pump (2) is increased to better mix the solution of the dialysis bath in the tank. The dialysis bath circuit is ready to operate.

 Assembly of the blood circuit.

The principles of this circuit are identical on all devices, only the models and the lengths of the routes are different.

Mount the dialyzer (1) on its support. Mount the hose (13), or arterial line to the blood pump (3) and connect to the "artery" input of the dialyzer (1). Connect its two small lines to a bottle, or bag, of physiological saline (16) and to a 30 ml syringe (17) filled with heparin diluted beforehand.

Mount the pipe (14), or venous line, by connecting it to the "vein" inlet of the dialyzer. Also connect the venous pressure gauge (5).

Completely fill the lines (13) (14) and the dialyzer (1) with physiological saline by running the blood pump (3).

 Connection of blood and dialysate circuits.

Stop the dialysate pump (2). Connect the tube (11) to the dialysate inlet, on the vein side, of the dialyzer (1). Connect the tube (12) with the dialysate outlet, on the "artery" side of the dialyzer (1). Restart the dialysate pump (2).

When the thermometer (10) indicates 370C, the heating by immersion heater also stops. The device is then ready to replace the physiological serum in the lines with the patient's blood, and hemodialysis begins.

 Settings during use.

In terms of temperature, the device allows a difference range from 360C to 380C. Beyond that, an audible alarm system will operate.

The negative pressure, or negative pressure in the dialysate circuit is regulated by two taps (7) and (7 ') because the pump (2) constantly draws in the circuit. When the tap (7) is closed a little, the pressure gauge (6) starts to drop. To stabilize this negative pressure, without reducing the desirable flow rate in exchange with the blood circuit in the dialyzer (1), we need another tap (7 ') so that the flow meter (8) always indicates between 400 at 500 ml per minute.

The depression in the dialysate circuit attracts small molecules from the blood, including water, to the reservoir (4). The increase in volume in the graduated tank (4) signifies the loss of volume, or weight of the patient, which one wishes to remove on each dialysis. The adjustment of the depression, indicated by the pressure gauge (6), combined with time, gives the volume of water to be drawn from the patient's body. By knowing the volume of water already drawn into the tank and the time remaining to be dialyzed, the depression is adjusted accordingly. An audible alarm system thus controls the tolerable variation in depression, or negative pressure, by the pressure gauge (6).

After two hours of dialysis, far from being saturated with organic waste, but for performance purposes, we change the tank (4), already used, with a brand new dialysis bath tank heated to 370C like the first . So we can deal with all situations, in body volume, or in dialysis time, starting with an average body weight of 60 kg and an average dialysis time of 4 hours.

From the blood circuit point of view, the adjustment is made with the speed of the pump (3), under the control of the venous pressure manometer which triggers an audible alarm if the tolerance range is exceeded. A bubble trap (15) which has the function of stopping all the air bubbles accidentally entered into the blood circuit, also helps to trigger the alarm when the volume of air is high, causing the desired pressure to be reduced. .

 Storage between the two hemodialysis sessions.

After a hemodialysis session the blood circuit, lines (13) and (14), is discarded, as well as the dialyzer (1).

 The two tubes (11) and (12) of the dialysate circuit connect to each other at the level of the dialyser (1) by a quick coupling. We rinse all these silicone tubes with simple water, then with boiling water and finally we connect the two free ends together to keep this boiled water in its circuit. Only silicone tubes can withstand the high and repeated heat for these heat sterilizations.

The two tanks are then washed and rinsed thoroughly, then dried properly with a hot air dryer until all traces of humidity are absent and finally closed hot with their airtight cap.

Thus germs can not develop in the circuit during the rest time, and in this way it is avoided to carry out disinfection with expensive chemicals, and requiring meticulous rinsing.

Claims (1)

1 / Hemodialysis device, of the type comprising means suitable for ensuring on the one hand the circulation of blood liquid between a patient and a dialyzer (1) provided with semi-permeable membranes; characterized in that it comprises means suitable for organizing, on the other hand, by means of a pump (2) the circulation in a closed circuit of a dialysis bath between said dialyzer (1) and a tank (4) containing a predetermined volume of this dialysis bath, commonly called dialysate. 21 Device according to claim 1, characterized in that said dialysis bath is obtained by dilution, before starting dialysis, of dialysate in the form of powder for instant use, in a predetermined volume of pure water, contained in said tank ( 4), 31 Device according to any one of claims 1 to 2, characterized in that said reservoir (4) is made of transparent or transparent material, provided with a cap ensuring the tightness after sterilization with hot air, and has a volume graduation, at least over a portion of its surface, allowing immediate reading of the volume of water lost by the patient.  41 Device according to any one of claims I to 3, characterized in that it includes thermostatically controlled heating means (9) of the volume contained in said tank (4), preferably constituted by a heating resistor of the immersion-heater type .  5 / Device according to any one of: claims 1 to 4, characterized in that said circulation means in closed circuit of said dialysis bath are formed by means of silicone tubes, or equivalent supporting more than 1200C to allow their sterilization 1 boiling water and hot air, a first tube (11) connecting said reservoir (4) to a dialysate inlet of said dialyzer (1), and a second tube (12) connecting a dialysate outlet of said dialyzer (1 ) to said tank (4) by passing through the pump (2).  6 / Device according to claim 5, characterized in that said tubes (11, 12) ensuring the circulation of the dialysis bath are each provided, preferably near their entry into said tank (4), with a closing device by crushing (7), (7 '), making it possible to adjust the depression to the desired value to remove the desired quantity of water from the patient's blood, through the membranes of the dialyzer (1), avoiding contamination due to of their lack of joints.  7 / Device according to claim 5 or 6, characterized in that it comprises means for measuring the temperature (10), the flow rate (8) and the pressure (6) of the dialysis bath circulating in said first (11 ) and second (12) tubes; a thermometer (10) being preferably placed on the path of said first tube (11), a pressure gauge (6) and a flow meter (8) being preferably placed on the path of said second tube (12) upstream of said first pump ( 2).