JPS5829463A - Method and apparatus for adding oxygen to blood by using air permeable diaphragm - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for diffusively oxygenating blood across a ventilated diaphragm.

In the case of diffusive blood oxygenation, oxygen reaches the blood without forming bubbles.

For example, in the case of cardiac surgery, the necessary oxygen supply to the patient is maintained by direct supply of oxygen to the blood, so-called blood oxygenation. In this case, at the same time excess carbon dioxide is expelled from the blood. This blood oxygenation takes place outside the patient's body by so-called oxygenation. Blood oxygenation methods and devices are known per se. Furthermore, during the aforementioned surgery, the patient's body temperature is simultaneously maintained at the desired level by extracorporeal thermoregulation of his blood. In this case, the patient's body temperature is generally first lowered rapidly at the beginning, that is, before the main surgery, and then the patient's body temperature is maintained at this low temperature during the surgery, and then returned to normal body temperature after the surgery. be. Cooling of the blood is carried out, for example, by introducing a tube into which only the patient's blood, or a portion thereof that has been lysed, is completely immersed in ice water. The maintenance of a low body temperature and the rewarming of the patient's blood after surgery, as well as the above-mentioned pre-operative cooling, can be carried out with likewise known heat exchangers developed specifically for these purposes.

It is likewise known to produce blood oxygenators and heat exchangers made of hollow fibers or hollow fibers, tubular films or flat films or thin films and in the form of so-called modules. It is known that the supply of oxygen to the blood and the removal of carbon dioxide from the blood take place throughout the diaphragm of an oxygenator constructed as a hollow fiber, hollow fiber, tube or film and that the blood of the patient is The cooling, temperature conditioning and warming of the mixture takes place in a second device, a heat exchanger, for example with water having a suitable temperature.

In this case, blood flows entirely on one side of the diaphragm of the device, and oxygen and water on the other side. In the case of hollow fiber diaphragms, blood generally flows through the interior of the hollow fibers.

A disadvantage of this known method is that, in particular due to the presence of the two devices mentioned above, the blood volume to be maintained outside the patient's body and the foreign body contact surface that comes into contact with the blood are relatively large, and therefore the two devices are constantly monitored. The problem lies in the fact that the respective units themselves can cause trouble and that not only the oxygenator but also the heat exchanger in most cases must be disposed of after use.

The object of the invention was therefore to eliminate all the disadvantages which arise when using disposable diaphragm acid accumulators and disposable or reusable heat exchangers of the type described above.

In order to completely solve this problem, a type of heat exchanger is used, in which the supply of oxygen to the blood and the removal of carbon dioxide from the blood are carried out by the diffusion of the above-mentioned gases through a diaphragm, and the cooling and heating of the blood is carried out by at least one heat exchanger. , a method for extracorporeal oxygenation and temperature regulation of the blood of a patient, in which the heat transfer from the blood to the fluid or vice versa is carried out with oxygen conducted in the circuit as an indirect heat carrier and to the blood. It is proposed that the oxygen supply to the blood and the removal of carbon dioxide from the blood take place simultaneously with the heat transfer, and that the oxygen supply to the blood, the removal of carbon dioxide from the blood and the heat transfer take place by the same diaphragm.

Therefore, the method of the invention requires only one diaphragm unit (module) capable of performing gas exchange and heat transfer.

In this case, the amount of oxygen to the blood f'8 can be controlled by using an appropriate oxygen pressure, while the amount of heat to be transferred can be controlled by adjusting the appropriate oxygen temperature and/or the appropriate amount of oxygen passing through the transfer unit. It can be adjusted by For this purpose, a suitably designed circulation system for the oxygen circuit and the usual temperature, pressure and metering devices and control devices are provided. For cooling, temperature regulation and warming of oxygen (these can be carried out, for example, with water at a suitable temperature).

Customary, suitably designed heat exchangers can be used for this purpose. The form, configuration and design of this heat exchanger are as follows:
This is simplified because the heat exchanger does not unavoidably come into contact with blood, as in known methods, and therefore does not have to be discarded after use.

Therefore, in order to carry out the method of the invention, conventional equipment is required for the total removal of carbon dioxide from the oxygen circuit, a device for replenishing the oxygen received from the oxygen circuit by the patient's blood, a pump for circulating the patient's blood. In addition, the above-mentioned safety devices are required.

To carry out the method of the invention, any suitable diaphragm for diffusive blood oxygenation can be used, as long as sufficient heat transfer is ensured. Sufficient heat transfer can be achieved by suitably defining the diaphragm thickness in the desired manner. In conventional diaphragms, the diaphragm area required for oxygen transfer is generally thicker than that required for heat transfer, so for this reason additional diaphragm surface is required for combined heat transfer. It's unnecessary.

Very good results have been obtained, for example, with diaphragms made of polyzolopyrene, polyamide or those having a microporous cellular polymer structure as described in DE-A-2737745, with a thickness in the range from 3 to 300 μm. achieved. In this case, diaphragms present as hollow fibers or hollow fibers are advantageous, in particular those described in EP-A-2833493. The pore size of the diaphragm is advantageously less than 2 μm in order to prevent the penetration of bacteria, since the use of this type of bacteria-resistant diaphragm ensures the sterility of the oxygen circuit. This is because it is not necessary. The use of a hydrophobic diaphragm prevents leaching of water and proteins from the blood. It is therefore advantageous to render the originally hydrophilic diaphragm hydrophobic in advance by methods known per se. However, the method of the present invention is not limited to the diaphragm type and material described above.

The device for carrying out the method of the invention includes the necessary devices known per se, such as a circulation device for the patient's blood and the oxygen conducted through the circulation, a carbon dioxide absorption device, a heat source for total cooling or heating of the blood. of the type having an exchanger, a diaphragm for enriching the blood with oxygen and removing carbon dioxide from the blood, and conduits for the blood carried in the circulation and the oxygen carried in the circulation; According to the invention, the heat exchanger is arranged in the oxygen circulation, and the heat transfer efficiency of the diaphragm for supplying oxygen to the blood, removing carbon dioxide from the blood, and cooling or heating the blood is determined by the diaphragm of the heat exchanger. At least it's exactly the same dog size. The heat transfer efficiency of the diaphragm is influenced by the blood throughput, the oxygen throughput, the temperature difference across the diaphragm, the thickness of the diaphragm, and the heat transfer ratio of the diaphragm.

To manufacture the only diaphragm unit necessary for the device of the invention, a diaphragm in the form of a tallatrate, a tubular film or a hollow fiber or hollow fiber made of the above-mentioned materials, as well as other suitable materials, is used. can do. In this case, they are present in modular form and can therefore be used or connected to the equipment for this purpose easily and even without special knowledge, even by an amateur, and after use can be dismantled and removed without problems. Embodiments are advantageous.

In the case of the device considered here, the largest possible diaphragm area is accommodated in a small volume, and -
Since it is desirable to be able to construct exchangeable units for single-cut use as small and as inexpensively as possible, the invention provides that the hollow fibers have an inner diameter in the range from 150 to 450 μm and a wall thickness in the range from 3 to 300 μm. It is advantageous to use modules made of hollow fibers with Hollow fibers of this type can accommodate an effective exchange area of, for example, 5 m' in a casing having a volume of 200 cd. The length of the hollow fiber is on the blood side (inside the hollow fiber)
should not be too large to avoid unnecessarily high pressure drop at. This length advantageously lies in the range from 50 to 500 lengths.

The flow of oxygen conducted in the circuit surrounding the hollow fibers of the exchange unit is transverse to the longitudinal axis of the hollow fibers, i.e. blood and oxygen flow crosswise. is advantageous. This makes it possible to significantly simplify the design of the module or the module housing.

However, if desired, the blood and oxygen can flow countercurrently or countercurrently to each other. Mixed forms of the above-mentioned fluid forms are also possible. In any case, care should be taken that the oxygen conducted in the circuit flows around the hollow fibers at a high velocity in order to ensure sufficient heat transfer efficiency. Therefore, the hollow fibers should be spaced sufficiently apart from each other in order to achieve the high throughput required for this purpose. Therefore, the spacing between adjacent hollow fibers should be about 2 to 2 times their diameter. This also applies substantially to replacement units manufactured from separate molded diaphragms as described above.

The inventive method and the inventive device combine mass and heat transfer in a single exchange surface (diaphragm), compared to known methods and devices that are reusable for blood temperature regulation. As a result, the volume of blood held outside the patient's body and the contact surface with foreign objects that come into contact with the blood are significantly smaller, requiring only one device for monitoring, and the parts that came into contact with the patient's blood are discarded after use. The big advantage of reusable heat exchangers is that they do not need to be re-cleaned and sterilized in a costly manner. have

The invention will now be described in detail with reference to the illustrated embodiments.

In FIG. 1, only those parts which are important for understanding the invention are shown, while other conventional devices known per se, such as measuring devices and adjusting devices, have been omitted for the sake of clarity. The parts shown in FIG. 1 are: I the patient, 2 the blood circulation conduit connected to the patient, 3 the blood circulation pump, 41i the combined mass/heat-transfer unit, 5 is an oxygen circulation conduit, 6 is a heat exchanger, 7 is an oxygen circulation device, 8 is a carbon dioxide absorption device, and 9 is an oxygen supply port.

The device operates as follows: the blood of the patient I is returned to the patient's body by means of a blood circulation pump 3 through a combined substance/heat exchanger 4 . Oxygen is guided in the circuit via the oxygen circulation line 5 by the oxygen circulation device 7 and is conveyed through the carbon dioxide absorption device 8, the heat exchanger 6 and the combined mass/heat transfer unit 4. heat exchanger 6
Therein, the oxygen transported in the circuit is adjusted to the temperature required to achieve the desired blood or body temperature of the patient 1, for example by means of a sol of cold or hot water or other liquid media. The heating or cooling of the oxygen can also be carried out in other ways, for example using electrical heating or cooling devices. Furthermore, instead of only one heat exchanger 6 as shown in FIG. 1, it is also possible to use two devices of the same type, one for heating the oxygen. and the other can be used for cooling the oxygen. In the case of a combined substance-heat transfer unit 4, the oxygen enrichment of the patient's blood by heat transfer between oxygen and blood as well as the diffusion of oxygen across the diaphragm of the device 4 as well as the Removal of carbon dioxide from the patient's blood is effected by diffusion of carbon dioxide into the oxygen from the patient's blood through the diaphragm. Subsequently, the carbon dioxide recovered in the oxygen of the circuit is removed from the oxygen in a carbon dioxide absorber. Oxygen consumed by the patient can be continuously replenished into the circulatory system 5 via the connection 9.

In this case, all control and monitoring of the process is advantageously carried out using temperature, pressure, throughflow measurement and control devices, etc., which are not shown. The heat recovered or released from the oxygen in the exchange unit 4 is supplied or extracted again as the oxygen flows through the heat exchanger 6.

FIG. 2 is a cross-sectional and enlarged view of the heat exchanger of FIG. 1. In this embodiment of the combined heat-mass exchange unit according to the invention, the diaphragm is connected to the casing 11.
It consists of a hollow fiber bundle 10 arranged within. The casing is composed of a blood distribution chamber 12, a blood collection chamber 13% oxygen distribution chamber 14, and an oxygen collection chamber 15. The blood chamber is fluid-tightly isolated from the oxygen chamber. The basic structure of this type of diaphragm oxygenation unit is well known per se, so it will not be described in detail. It should only be noted that in the preferred embodiment for the process according to the invention, which is shown in FIG. Transmission efficiency is achieved. Furthermore, the direction of oxygen and blood flow is indicated by arrows. The flow type achieved in this case is a so-called crossflow.

As can be seen from FIG. 3, it is particularly advantageous to use a hollow fiber bundle 10 with a completely square cross-section and to arrange this fiber bundle in a housing 10 whose central part is likewise designed squarely. One thing has been proven. This embodiment is extremely effective in achieving the required exchange efficiency.

In the embodiment shown in FIG. 1, a plurality of heat exchangers 6
The heat exchangers 6 can be used for cooling the oxygen or for warming the oxygen.

In this case, one part can be connected for this purpose and the other part for control purposes.

EXAMPLE Below, Figure 2 of a combined substance-heat transfer unit is capable of reducing the body temperature of a patient to 28°C within 10 minutes and later raising it again to 37°C within 20 minutes. and FIG. 3 shows data of the embodiment described in detail. For this purpose, the required amount of oxygen passing through the exchanger is 780n in the cooling stage? /h1 heating stage is 600 ma/h.

During the cooling stage, the oxygen maintains a temperature of 2°C and during the warming stage, at a temperature of 5°C.
It has a temperature of 0°C. The amount of blood pumped through the exchange unit was 4 tons per minute. Cooling and heating of the oxygen took place with water at the corresponding temperature.

The diaphragm surface carrying out the transmission was in the form of a hollow fiber bundle with a square cross section. The hollow fiber bundle had the following dimensions: Length 250 m Outer diameter of the hollow fibers Wall thickness of the 0.6 gourd hollow fibers 0.15 m Center distance between the hollow fibers 1.2 Number of hollow fibers
Approximately 10,700 diaphragm transmission planes
Approximately 5 - height and width of hollow fiber bundle 1
Cross-sectional area of the inlet and outlet for oxygen in the casing of the 24Wr+n transmission unit 3318mm The hollow fibers in the hollow acupuncture bundle are arranged so that the hollow fibers of adjacent rows are offset by &pitch respectively, i.e. directly Hollow fibers that are adjacent to each other are arranged so as to form an equilateral triangle when viewed in cross section.

Experiments were performed in vitro using calf blood held in a receptor. The above value was obtained from the temperature and amount of passage measured at this time. It was done.

The average hourly heat transfer efficiency of the transfer unit was 15,840 J during the cooling phase.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the basic configuration of the device of the present invention, FIG. 2 is an enlarged sectional view of the exchange unit in FIG. 1, and FIG.
FIG. 3 is a plan view of the replacement unit shown in FIG. 4...Transmission device, 5...Oxygen circulation path, 6...Heat exchanger, IO...Hollow fiber (thread) bundle Fig. 1

Claims (1)

[Claims] 1. Oxygen from the elementary circulation path is diffused into the blood through the diaphragm so as not to form bubbles in the blood, and carbon dioxide from the blood is diffused through the diaphragm into the oxygen circulation path, and the blood is at least Indirect heat transfer from the blood to the fluid or vice versa in a method of blood oxygenation using a vented diaphragm by cooling, heating or holding at a predetermined temperature using a single heat exchanger. Oxygen supply to the blood is carried out with oxygen guided through the circulation as a carrier, oxygen supply to the blood and removal of carbon dioxide from the blood simultaneously with heat transfer. A method for oxygenating blood using a breathable diaphragm, characterized in that carbon dioxide removal from the blood and heat transfer are carried out by the same diaphragm. 2. The method according to claim 1, characterized in that the diaphragm is made of polypropylene. 3. A method according to claim 1, characterized in that the diaphragm consists of a microporous cellular polymer structure. 4. The method according to claim 1 or 3, characterized in that the diaphragm consists of a microporous cellular polymer structure as described in DE-A-2737745. 5. The method according to any one of claims 1 to 4, characterized in that the diaphragm consists of a hollow fiber bundle. 6. The method according to any one of claims 41 to 6, characterized by a diaphragm consisting of hollow fibers as described in German Patent Application No. 2833493. 7. Any one of claims 1 to 6 characterized by a diaphragm having a thickness in the range of 3 to 300 μm.
The method described in section. 8. Circulation devices for the patient's blood and oxygen conducted in the circulation, carbon dioxide absorption devices, heat exchangers for cooling or warming the blood, and reservoirs for enriching the blood with oxygen and removing carbon dioxide from the blood. In an apparatus for blood oxygenation using a breathable diaphragm, the heat exchanger (6) is provided with a plum and a conduit for the blood conducted in the circuit and the oxygen transported in the circuit, in which the heat exchanger (6) is connected to the oxygen circuit. (5) and is characterized in that the achievable heat transfer efficiency of the diaphragm of the transfer device (4) is at least the same as that of the heat exchanger (6). Adding device. 9. The device of claim 8, wherein the diaphragm is made of polypropylene. 10. The device of claim 8, wherein the diaphragm comprises a microporous cellular polymer structure. 11. The diaphragm was published in West Germany Special Application Publication No. 273.
11. The device of claim 8 or 10, comprising a microporous cellular polymeric structure as described in '7745. 12 The diaphragm consists of a hollow fiber bundle (10),
An apparatus according to any one of claims 8 to 11. 13. The diaphragm was published in West German Patent Application No. 283
Device according to any one of claims 8 or 10 to 12, consisting of a hollow fiber bundle (10) as described in Patent No. 3,493. 14. Any one of claims 8 to 13, wherein the diaphragm has a thickness in the range of 3 to 300 μm.
Equipment described in Section. 15, hollow fiber or hollow system (10) is 150-45
15. A device according to any one of claims 12 to 14, having an internal diameter in the range 0 [mu]m. 16 Hollow fiber or hollow fiber (10) is 50 to 50
16. A device as claimed in any one of claims 1 to 15, having a length in the range of 0.05 mm. 17 Claims 12 to 1, wherein the distance between two adjacent hollow fibers or hollow fibers (10) is 0.2 to 2 times the diameter of the hollow fibers or hollow fibers (10).
6. The device according to any one of clauses 6 to 6.