DE2345994A1 - BLOOD CIRCUIT OUTSIDE THE BODY - Google Patents

Description

Dr. F. Zumsteln sen. · Dr. E. Assmann Dr. R. Koenigsberger - Dlpl.-Phys. R. Holzbauer - Dr. F. Zumsteln Jun.

PATENT LAWYERS

CHECK ACCOUNT: MUNICH 91139

BANK ACCOUNT: BANKHAUS H. AUFHÄUSER

8 MUNICH 2,

SC 4131

RHONE-POULENC S.A., Paris, France

The blood circuit outside the body

The present invention relates essentially to an outside the body's arranged blood circuit connecting a diaphragm blood oxygenator device to a patient's vascular system connects, for pulmonary, cardiac or cardiopulmonary support or for the corresponding replacement.

There are known extracorporeal blood circuits located where two circulation pumps are used, which are arranged in series on both sides of a blood oxygenator with _r membrane. Maintaining a predetermined pressure in the oxygenator, which is necessary to keep the blood in the form of thin films of constant thickness, however, requires either a line for partially returning the arterial blood to the oxygenator or complicated regulation systems.

The present invention relates to a blood circuit which is arranged outside the body and which has an oxygenator device by means of two pumps for connecting blood with membrane to the vascular system of a patient, its operation at the same time simple and safe and which in particular does not require a compensatory bypass for the blood flow rates.

409812/0993

A circuit for blood has now been created which is arranged outside the body and which is a blood oxygenator device with a membrane connects to the vascular system of a patient and at least two peristaltic pumps or pumps with a hose or tubular membrane and has flaps arranged in series on either side of the oxygenator. This circle is characterized by that the pump body of each of the pumps has an inner useful volume between two limit values, which is essentially the blood pressure at the inlet of the pump is proportional, this inner useful volume being a maximum for the pump arranged at the inlet of the oxygenator and is minimal for the pump arranged at the outlet of the oxygenator, namely for a pressure at the inlet of each pump within an area above or below 20 mm Hg from atmospheric pressure.

In the following the invention with reference to the figures of the drawing, which are shown schematically without a specific scale, as an example an embodiment of the invention and the characteristic Curves of the pumps used show, explained in more detail i ^ earth. It demonstrate:

3 shows a schematic view of an exemplary embodiment of a circle according to the invention, arranged outside the body, for blood and

FIG. 2 shows the delivery rate / pressure characteristic curve of a peristaltic pump which can be used in the circuit according to the invention, and FIG

3 shows a set of flow rate / pressure characteristics of two pumps which are arranged on either side of the Dlutoxygenator.

The term oxygenator for blood or blood oxygenator, which is a common one The term is intended here to denote an exchanger for respiratory gas, i.e. an exchanger of oxygen, however also of carbon dioxide, water vapor and nitrogen and possibly gases or vapors with medicinal and / or anesthetic

409812/0993

IAD ORiQlNAL

_ ~ X -

table effects. It is also a heat exchanger.

From Fig. 1 it can be seen that the arranged outside the body Circuit for blood a blood oxygenator 1 of conventional design, which has at least one membrane 2, with the veno-arterial System of a patient connects.

A cannula 3 is inserted into the caudal vena cava, for example. A cannula is preferably used which has a non-occluding bulge at its end. That bulge can consist of three radial elastic arms 5, which are supported on the venous walls and keep them locally at a distance, whereby the opening of the cannula is kept free. Such Cannula prevents occlusion of the vein and decreases the flow rate through it. The arms can advantageously be retractable be introduced through a side branch of smaller caliber (e.g. the femoral vein), which is severed for this purpose to be able to.

The cannula 3 is with the entrance of the blood oxygenator 1 through a flexible line 7, for example made of silicone elastomer, connected, in which a first pump 6 of the peristaltic type or with a tubular or hose membrane and valves (also "ventricular pump" called) is arranged.

A flexible line 11, also made of silicone elastomer, connects the outlet of the blood oxygenator 1 with a cannula inserted into an artery 9 or preferably with a bulbous one Prosthesis 8 attached to the artery, generally a femoral artery, is sewn on. In this line 11 is a second pump 10, also of the peristaltic type or with a hose or tubular membrane with flaps.

Advantageously, the artery is slit in the longitudinal direction, and the prosthesis 8 is sewn obliquely to the edges of the slot, the inclination preferably in the direction of flow is made. The two sides of the prosthesis remain under

409812/0993

BATH ORIGINAL

- Ii -

the effect of arterial pressure at a distance from each other. After removing the prosthesis, the artery is closed in the usual way Method.

A peristaltic auxiliary pump 13, which is connected to the suction line 7 of the Pump 6 connected, allows the peripheral end of vein 4 to drain additional amounts of blood to the outside of the body Introduce the circuit from a blood source, such as the container 16, to compensate for any loss of blood, and optionally introducing medicinal fluids such as heparin.

Since the one shown as an example is located outside the body Blood circuit is a veno-arterial type circuit, it is It is necessary to keep three different pressures under control: the blood pressure at the inlet of the pump 6, the pressure in the oxygenator and the patient's arterial pressure to maintain desired V / er.

A manometer 17 is arranged in the line 7 directly at the inlet of the pump 6. This manometer advantageously measures the Blood pressure through the walls of the flexible line 7, which reduces the risk of blood coagulation. As a manometer you can for example that in the French patent specification 71. * J388l use as described. As can be seen from the following, knowing the blood pressure at the inlet of the pump 6 enables to know their throughput.

A manometer Ik makes it possible to determine the blood pressure in the oxygenator. In addition, a device 21 for determining the arterial pressure of the patient makes it possible to maintain this at the desired level by influencing, if necessary, the blood volume with the aid of the container 16 and the pump 13 or the vascular resistance of the patient.

The blood is said to be in the patient at a temperature close by of 37 C. For this purpose one arranges, for example on the line 11 heating and temperature control devices

409812/0393

^"5 - 234599Λ

for the blood. The heating devices advantageously exist from a heating element which has an electrical resistance 18, which surrounds the line 11 or is preferably arranged in its wall. This heating element can, for example, be an element that described in French patent 71 · ^ 6 ^ 08 Be kind.

In general, heat sensors 19 and 20 of the usual type are used, which are located upstream of the heating element and at the location of the heating element 18 orders. The sensor 19 enables the heating of the blood to be monitored (and, if necessary, to be regulated). The feeler 20 makes it possible to avoid local overheating of the blood which occurs during a reduction or a momentary standstill of the Blood flow can occur.

The inner walls which are in contact with the blood preferably have of the various elements forming the circle (pump body, cannulas and, in particular, connecting lines) a smooth one Organosilicon coating, which is applied according to the method described in DOS 2 206.

■ o ^v

The circuit works schematically in the following way: The venous blood flows out of the caudal vena cava, in which there is a pressure in has close to atmospheric pressure, through a cannula 3 and the line 7 up to the first peristaltic pump 6. This leads the blood into the oxygenator 1 with membrane at a sufficient pressure to exceed the flow resistance of the device. squirm. Ground the oxygenator tubes intended for the blood kept filled, and the blood films are kept at substantially constant thickness, with the blood pressure at a predetermined, the range indicated by the pressure gauge 1 * 1 is maintained. That oxygenated blood is taken up at the outlet of the oxygenator by a second peristaltic pump 10, which brings it to a pressure which enables its introduction into the arterial system of the patient through the prosthesis 8 after suitable heating in the line 11.

409812/0993

The average blood flow shared by the two pumps is delivered through the patient's veins. This Throughput should be able to vary in such a way that any increase in venous pressure is avoided, which could disturb the patient (especially acute pulmonary edema). In order to avoid this, it is then advisable to check the throughput of the pumps 6 and 10 to increase or decrease against it, if the venous pressure becomes too low, resulting in a collapse of the veins or venous Could lead to cavities.

For this purpose one uses pumps whose body a depending on the blood pressure offers variable internal volume at the inlet, which is generally the case with pumps of the peristaltic type or pumps with tubular or tubular membrane and flaps is not the case. According to the invention if pumps are used that offer an internal groove volume in the range of the blood pressure actually occurring at the inlet, which is essentially proportional to the blood pressure at the inlet of the pump.

Pumps such as those described in French patent specification 69.36805 are preferably used as peristaltic pumps.

The two peristaltic pumps 6 and 10 connected in series are, are generally driven synchronously at one and the same speed or at different speeds to the deliver the same average throughput. They preferably always have the same speeds as one another and are for this purpose advantageously mounted on the same drive shaft. These speeds can be adjustable, but it is often of interest maintain a constant speed.

The peristaltic pumps can also be rotated at the same speed by a separate motor, but with the same speed Speed / voltage characteristics are operated, fed by a common (fixed or adjustable) voltage source for each motor will.

409812/0993 _BÄD

It is also possible to use pumps with tubular or tubular diaphragms and flaps, either automatic or preferential have controlled inlet flap. The controlled exit flap can be of the same type as the entry flap. These Pumps can be connected to different pulse generators, which are synchronized to the same frequency, or preferably to one be connected to a common pulse generator.

The peristaltic pumps shown in Fig. 1 are preferably made from a flexible peristaltic tube made of silicone elastomer, which is held taut between two fixed points and rotating rollers. The peristaltic tube has the generally an elliptical cross-section between the rollers which is more or less flattened depending on the pressure at the inlet of the pump is on. At constant speed, the throughput is a function of the pressure at the input of the pump, which is clear from the Throughput / suction pressure characteristic of such a pump, as shown in Fig., Can be seen.

It can be seen that at an operating pressure P. at the inlet of the pump, the pump is between two limit values P and P _n ; provides a throughput (L between two limit values Q and Q.). The! throughput Q. in this range is essentially proportional to the inlet pressure P ..

In the following, P and P ^ denote the minimum useful pressure and the maximum useful pressure at the inlet of the pump. Likewise, with Ci and Q _v, the corresponding minimum and maximum. Usable throughputs called.

The minimum useful throughput Q _n is obtained when the pressure at the inlet ao is low so that the hose collapses, with the walls lying opposite one another resting against one another. The cut of the hose takes the shape of a dumbbell from much lower suction pressures at the inlet of the pump, the cross-section of the hose decreases even more, which corresponds to a rapid change in the slope of the curve.

409812/0993

• AD ORIGINAL

The maximum useful throughput Q ,, is obtained when the pressure is on The entrance of the pump is quite high, with the hose assuming a circular cross-section. In addition, the "Do not expand the hose, which requires considerably higher pressures and also corresponds to a rapid change in the slope of the curve.

In the one shown in Fig. 1 located outside the body Blood circulation, the flow rate of the pump β varies for a given level depending on the venous pressure. Since the venous pressure at the Place the cannula 3 is close to atmospheric pressure and since the blood pressure at the inlet of the pump 6 from this through the Flow resistances of the intermediate line 5 differs, where he partially is compensated by the difference in the height of the cannula 3 and the pump> 6, the pressure is generally lower than At-

atmospheric pressure. In general, a pump 6 is also selected, the flow rate / pressure characteristic of which is in a range of preferably lower pressures than atmospheric pressure. In Fig. 3, the characteristic curve of the pump 6 is shown. The useful range of the curve lies between points B and B _M , the useful pressure limits, which correspond to P f and Pw, - for example, in this case both of them are both less than atmospheric pressure (point 0 on the abscissa). Like the maximum throughput, the pressure P ", - is proportional to the speed of the pump 6.

It is advantageous that the maximum mean pressure P _{? / I (} - is slightly less than atmospheric pressure, generally less than 20 mm Hg and preferably less than 10 mm Hg below atmospheric pressure. This condition is realized with a pump whose peristaltic hose with thinner Wandung- in the rest state has a circular cross-section (between the rollers if it is represented by a rotary pump with rollers, as shown in Fig. 1, treated) has. This IJutzquerschnitt is maximum and providing maximum Mutzdurchsatz Q "f · For a Blood pressure P ^ ara inlet of the pump 6 between P r and P _Mr

409812/0993

BATH ORIGINAL

is equivalent to. When the pressure Pg equals the minimum useful pressure P _m g, the peristaltic tube flattens even further, and its cross-section becomes almost zero: the throughput decreases to the minimum useful throughput Q _m g

The pump 10 _3, which is connected in series with the pump β, delivers exactly the same average throughput. The throughput of the pump 10 is therefore determined by that of the pump 6, which in turn depends on the venous pressure.

The pumps 6 and 10 are generally substantially in the placed at the same height as the oxygenator, the assembly that comes from pumps 6 and 10 and the oxygenator is generally used arranged below the patient at an adjustable height in order to partially compensate for the flow resistance upstream of the pump -6 and thus adjust the blood flow rate to the desired mean value.

It is necessary to control the blood pressure in the oxygenator in one to maintain a predetermined pressure range in order to allow the blood film to be of substantially constant thickness in contact with the membranes and maintains an adjusted pressure gradient through the thickness of the membranes.

For a blood oxygenator that consists of a pile of alternating If there is membranes and spacers, the choice can be made, in this oxygenator, the relative blood pressure, measured by means of of the manometer 14, at a predetermined interval, for example between 0 and 200 mm Hg.

If you keep the oxygen pressure in this oxygenator below atmospheric If the pressure is maintained, the pressure difference is always between positive for the blood and oxygen, which enables the use of microporous membranes with increased gas throughput and also a good removal of bubbles from the blood itself in the Allows paIXe of foam or small bubbles. This will a bladder remover made for you. The French

409812/0993

© AD ORrQINAU

- ίο -

The membranes described in patent specification 1,568,130 are particularly suitable good for this purpose. In addition, the upright «!! 'keeping this positive pressure difference to avoid that the membranes stick together randomly, a glue that is difficult to pick up.

If, on the other hand, the blood pressure is much higher than that of oxygen the blood can tear the membrane or overcome the hydrophobicity of the microporous membranes and permeate them. <-U * ingen, for example under a pressure of 800 mm Hg.

The blood pressure in the oxygenator can be maintained in a selected range by means of a pump 10, the flow rate / pressure characteristic of which extends in a range of pressures substantially above atmospheric pressure. In Fig. 3, the characteristic of a pump 10 C <Jtfaigt. The maximum range of the characteristic lies between the points C, _n and Cp ,, whereby the extreme useful pressures, which _{correspond to P 10} and P ^ ₁₀ , for example in this case both are both above atmospheric pressure.

Eu is advantageous that the minimum useful pressure Pj ₁₁₁₀ equal to atmospheric pressure or slightly above atmospheric pressure, generally less than. 20 mm Hg and preferably less than 10 mm H [j; above atmospheric pressure. This condition is implemented with a pump, the peristaltic tube of which has a flattened cross-section in the idle state, this cross-section being virtually minimal and enabling a minimal useful throughput Q ₁₀ . The hose of the pump 10 has fairly thin walls so that the maximum useful throughput Qm ₁₀ * ^ ^re i ^nen maximum useful pressure Pm ₁₀ * is generally below 200 mm Hg above atmospheric pressure and preferably in the order of 50 mm Hg above atmospheric pressure , is achieved. For each throughput determined by the pump 6, the hose of the pump 10 thus has a more or less flattened cross-section, corresponding to the pressures at the outlet of the oxygenator between 0 and, for example, 50 mm Hg above atmospheric pressure. The maximum pressure at the inlet of the Oxyßonator depends on the flow resistances in the latter

409812/0993

SAD ORIGINAL

which is generally below 100 mm Hg for blood flow rates in the Of the order of 600 ml / min in an oxygenator with an upper

2
area of 0.5 m.

To be sure that the average blood pressure in the oxygenator remains in the correct range at all times, two conditions must be met at the same time.

The first condition is that the maximum useful flow rate of the pump 10, which is arranged at the outlet of the oxygenator, above that which is arranged at the inlet of the oxygenator pump 6.

Since, according to the invention, the pumps 6 and 10 are generally synchronized are driven, this condition can optionally be met by the following means:

One can run the pump 10 at a speed with a fixed percentage Drive above that of the pump 6. You can in the Palle a peristaltic pump with rotor, equip the pump 10 with a rotor with a diameter larger than that of the pump 6. Preferably the two pumps have identical rotors equipped that rotate at the same speed as a result of a common men shaft, these rotors on different hoses act and wherein the inner diameter of a cross section of the hose of the pump 10 is greater than that of a cross section of the The hose of the pump 6 is. Of course, you can take several of these measures combine with each other.

The second condition is that the minimum useful flow rate of the pump 10, which is arranged at the outlet of the oxygenator, is less than the minimum! Tut ζ through at ζ of the pump 6, which is at the inlet of the oxygenator is arranged is. For this purpose, a hose with a more flexible wall than that of the hose can be used for the pump 10 of pump 6. The cross-section of the hose flattened by a pressure close to atmospheric pressure forms the Pump 10 a dumbbell with a smaller cross-section than that of the hose of the pump 6 for the minimum useful pressure upstream

409812/0993

BATH ORIGINAL

of this. One chooses for the pump 10 a hose that is essentially flat in the idle state and, if necessary, to the limit shape To achieve a dumbbell, a tube of lower rigidity than that of the circular tube of the pump 6 in the idle state. You can use a hose with thinner walls than for the pump 6 and thin walls and a flat one for the pump 10 Combine shape.

It should be noted that, according to the invention, the two above-mentioned Can meet conditions at the same time.

In practice, when a stable state and a satisfactory circulation flow rate outside the body has been achieved, it is advantageous to reduce blood trauma to reduce the speed of the pump 6 in order to set its actual flow rate to about 4/5 of the maximum flow rate. One comparable · turns to this end, the display of the pressure gauge 17> which allows to determine the actual throughput.

The peristaltic pumps are generally used in cardiac or cardiopulmonary replacement preferred. With the supportive However, application is a competitive influence between the more or less pulsed throughput of such pumps and that from the pulsations of the patient's heart to be feared.

If you want to take advantage of the diastolic pause to introduce the blood from the circle outside the body and to avoid competing interference between the latter and the patient's heart, it is therefore preferred to use pumps to use, the delivery of which is synchronized with the cardiac cycle can be. These pumps are generally chosen from the menibran pumps adapted to the blood circulation. You are under called ventricular pumps or pumps with Hose or tubular membrane and flaps are known. Advantageously pumps as described in French patent specification 72.07863 are used.

409812/0993

BAD OkJGfNAL

These pumps have upstream and downstream controlled flaps. The maximum volume of the arterial chamber which the pump 10 forms is at most 50 % and preferably at most 20 % above the maximum volume of the venous chamber which the pump 6 forms. The generally rigid housings of these pumps are advantageously connected in opposite phase to one and the same pulsation generator.

The onset of systole can be indicated either by an electrocardiographic signal or, preferably, by reducing the patient's arterial pressure below a certain threshold . The suction and discharge pressures of one or the other pump can be regulated by adjusting the pressures of the gaseous propellant fluid. One has an operational journey which is comparable to that of peristaltic pumps with a throughput which depends on the pressure upstream.

As with the latter, an introduction is also possible to prevent air by choosing a vertical arrangement with the blood flowing from top to bottom and the air so is caught at the point of the feed flap, which cannot be completely shut off.

The use of two pumps with a hose or tubular membrane and flaps and a pluid pulsation generator, such as described in French patent specification 72.06812, is particularly useful for resuscitation in the ambulance or in the helicopter advantageous as they do not require electrical energy and only with the help of the relaxation of oxygen, which is used for purging of the oxygenator used x ^ ird can be operated. In this In case, the gas monitor can be omitted and simply flushed in; Open circuit replaced after relaxation to drive the pumps will. With an oxygen cylinder of 0.5 rrr there is sufficient independence with minimal weight and minimal Space requirement reached.

An assembly has been described which is connected to the veno-arterial

409812/0993

BATH ORIGINAL

A patient's system is connected, but is the same assembly Can be used for veno-venous or arterio-venous circulation outside the body. In this latter case it is .Only the pump 6 absolutely necessary, which is at its maximum Flow works (it acts as a flow limiter), and you adjust the latter by adjusting the speed of the pump a.

The circle outside the body can be arranged in parallel have several auxiliary assemblies, each of which consists of a blood oxygenator between two pumps 6 and 10. Such Auxiliary assemblies are connected to the main circuit shown in FIG. 1 by valves 22 and 23. They can be put into operation or short-circuited to quickly meet variable patient needs.

Since in the blood circuit according to the invention pumps outside the body used to have a very low level of thermolysis and since any direct return of blood is avoided, the circuit can advantageously last for a long period of time be used. Since the pumps are self-regulating, the circuit is simple, reliable and of considerable safety, in particular compared to the introduction of air, since the pumps as Bubble traps work.

If the blood oxygenator device is equipped with microporous membranes and is traversed by a gas stream at a pressure lower than atmospheric pressure, the bubbles that are accidentally introduced into the blood can be resorbed in front of the entrance to the oxygenator, and the finer the bubbles are, the better . The oxygenator '.tfirkt this regard better than the commonly used bubble traps (gravity or buoyancy bubble traps) _λ these latter so as to act be.sser, the large bubbles are. Under these preferred conditions, one can also refrain from creating such a bubble in the. To build a circle.

409812/0991

ORIGINAL

The following examples serve to further illustrate the invention.

example 1

The circle corresponds to that shown in Fig. 1 with the exception the drive devices of the pumps 6 and 10. These are fed by direct current motors from a common voltage source with speeds that can be set between 0 and 40 rpm are driven. The pumps 6 and 10 are pumps as described in French patent 69-36805. The peristaltic tubes are made of silicone elastomer. The hose of the pump 6 has an inside diameter of 10 mm and an outside diameter of 12.6 mm. The circumference of the rotor with three rollers describes a circle with a diameter of 140 mm. The hose of the pump 10 has an inner diameter of 11.25 mm and an outside diameter of 14.1 mm. The scope of the The rotor describes a circle with a diameter of 1 * 10 mm. The pump 10 is at a height of 50 cm above the blood oxygenator arranged. This consists of two identical assemblies, each with 16 microporous membranes and 7 spacers, stacked on top of one another and clamped between two end plates. The oxygenator is of the type found in the French U.S. Patent 1,597,874. Its exchange surface

is 1 m. In continuous operation
compared to the blood 50 mm Hg.

is 1 m. In continuous operation, its flow resistance is

The circle was used for cardiopulmonary support for a period of 12 hours. At the end of the treatment it was found that the hemolysis level of the blood was below 0.5 % . The blood pressure inside the blood oxygenator was kept in the range of 50 to 150 mm Hg. For an average blood flow rate of 800 ml / min, the exchange was 40 ml of oxygen and 60 ml of carbon dioxide / min.

409812/0993

Example 2

The circuit and pumps 6 and 10 are analogous to those of Example 1 and correspond to FIG. 1. The rotors of pumps 6 and are mounted on a common shaft passed through a single Motor 12, the speed of which can be set between 0 and 40 rpm, is driven. Each rotor has 3 rollers at an angle of 120 °, whereby the two rotors are offset from one another by 60 °.

The hose of the pump 6 has a circular cross-section in the idle state. The inner diameter of the hose is 15 ₃ 8 mm and the outer diameter 20 mm. The hose of the pump 10 is elliptical in the idle state. The large and small inner axes of the ellipse are 2 ^l \ and H mm, respectively. Deformed by the pressure, this hose takes on a circular cross-section with an inner diameter of 16.8 mm and an outer diameter of 20 mm. The usable diameter of the rotors of pumps 6 and 10 is 190 mm. The oxygenator has a menibranal surface of 3 m ² .

This assembly is used to perform a subtotal cardiopulmonary replacement in an adult patient for 52 hours. The blood flow rate is set to an average value of 2 l / min and an average exchange is observed of 130 nl oxygen / min and 150 ml carbon dioxide / min. The printing and hemolysis conditions are the same as in Example 1. A second same assembly is provided ready to use to become if the exchange proves to be inadequate at the moment.

409812/0993

Claims (1)

Claims 1. I A blood circuit arranged outside the body that contains a blood oxygenator device with a membrane of the usual type can connect to the vascular system of a patient and at least one arrangement of two pumps of the peristaltic type or with a tubular or tubular membrane and valves in series on both sides of the oxygenator are switched, characterized in that the body of each pump between two limit values Provides internal useful volume which is essentially proportional to the blood pressure at the input of the pump, this internal useful volume maximum for the pump arranged at the inlet of the oxygenator and for the pump arranged at the outlet of the oxygenator Pump is minimal, for a pressure at the inlet of each pump which is in a range of over or under 20 mm Hg as opposed to the atmospheric pressure. 2. The blood circuit arranged outside the body according to claim 1, characterized in that the two pumps have a synchronous drive. 3. The blood circuit arranged outside the body according to claim 1 or 2, characterized in that the internal usable volume offered by the pump arranged at the inlet of the oxygenator is for one Blood pressure at the inlet of this pump is below atmospheric pressure. k. Blood circuit arranged outside the body according to one of Claims 1 to J >> characterized in that the usable internal volume offered by the pump arranged at the outlet of the oxygenator is minimal for a blood pressure at the inlet of this pump above atmospheric pressure. 5 · Blood circuit arranged outside the body according to one of the preceding claims, characterized in that the maximum Only throughput of the pump arranged at the outlet of the oxygenator 409812/0993 pe is greater than the maximum useful throughput at the inlet of the oxygenator arranged pump is. 6. Blood circuit arranged outside the body according to one of the preceding claims, characterized in that the minimum useful throughput of the pump arranged at the outlet of the oxygenator ^ less than the minimum useful throughput at the outlet of the oxygenator arranged pump is. 7. Blood purification arranged outside the body according to one of the preceding claims, characterized in that at least one of the arranged in series on both sides of the oxygenator Pumping is a peristaltic pump with a flow rate responsive to the pressure of the liquid being drawn in. 8. Blood circles arranged outside the body according to one of the The preceding claims, characterized in that at least the pump arranged at the outlet of the blood oxygenator is a pump with a tubular or tubular membrane and flaps. 9. Outside the body arranged blood circuit according to one of claims 1 to 7 » characterized in that the two pumps arranged in series are peristaltic pumps and have identical rotors, which are on the same shaft, which is driven by a single motor with adjustable speed, are arranged. 10. Outside the body arranged blood circuit according to one of the preceding claims, characterized in that the hose of a first pump, which is arranged at the inlet of the oxygenator, has a circular cross-section in the rest state and the hose of a second pump of the same type as the previous one is arranged at the outlet of the oxygenator, has a substantially elliptical cross-section in the rest state, the inner circumference of the hose of the second pump being larger than that of the hose of the first pump. 409812/0993 11. Outside the body arranged blood circuit according to one of the preceding claims, characterized in that in the Oxygenator the blood is separated from the oxygenation gas stream by at least one microporous membrane. 12. Blood circuit arranged outside the body according to claim 11, characterized in that the microporous membrane is water-repellent is. ' 13. Outside the body arranged blood circuit according to one of the preceding claims, characterized in that the inner wall of at least one in contact with the blood Element of the circle has a smooth organosilicon coating. I ¹ I. The blood circuit arranged outside the body according to one of the preceding claims, characterized in that at least one cannula which draws the venous blood has a non-occluding bulge "at its end. 15. Outside the body arranged blood circuit according to one of the preceding claims, characterized in that it is equipped with a Artery is connected by a suturable bulbous prosthesis. 16. The blood circuit arranged outside the body according to one of the preceding claims, characterized in that it has heating devices for the blood and devices for determining the blood temperature, which are at the height and downstream of the heating devices are arranged for the blood. 17. Outside the body arranged blood circuit after a of the preceding claims, characterized in that he has a Has auxiliary pump that has at least one other source of blood or connects medicinal liquids to the suction opening of the pump arranged at the inlet of the blood oxygenator. l3. Blood circuit arranged outside the body according to one of the 409812/0993 preceding claims, characterized in that a manometer is arranged upstream of the at the inlet of the blood oxygenator Pump is provided. 19. Arranged outside the body. Blood circuit according to claim 18, characterized in that the manometer measures the pressure through the wall of a flexible hose. 20. Blood circuit arranged outside the body after a of the preceding claims, characterized in that several Assemblies connected in parallel are provided, each of which has a blood oxygenator between two pumps. 409812/0993 , ■ ** · ♦ Blank page