DE2501552A1 - DEVICE FOR Bypassing the blood circulation in the heart and lungs - Google Patents

Description

PATENT LAWYERS

Dlpi.-Ing. P. WiRTH Dr. V. SCHMLED-KOWARZIT \ g. G. DANNENBERG Dr. P. WEINHOLD Dr. D. ί

281134 β FRANKFURTAM MAIN

TELEPHONE (0611)

287014 GR. ESCHENHgIMER STRASSE 39

15th January 1975
Da / -mr- ,, -

Baxter Laboratories ₉ Inc "Morton Grove j Illinois / USA

Device for bypassing the blood circulation

Heart and lungs

The invention relates to controls of the blood flow rate for systems provided with pumps and oxygen enrichment devices and, in particular, systems which respond to the venous blood supply for safeguarding against seasonal air for use in cardiac surgery and for partial support of the cardiopulmonary area _{or the like}

In general, a device is ι for bypassing the blood stream through the heart and Lunge.eine medical device _s used in the surgery of the heart vessels, the intensive treatment 'and surgical follow-up and is connected to the human body to the blood refresh and to pump and thus certain To take over functions of the heart and lungs, often with partial or complete bypassing of part of the bloodstream "

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The device receives venous blood (blood, dem Oxygen is missing) from the human cycle, oxygenated and warms the blood and circulates it with a r opening rate increases again, which corresponds to the venous output, Lungs and heart are relieved.

lia © üaägshungsvorriehtung for partial support. is used, for example, during the Herz = -In ^ ensi "/ ebandlung patients ₃ who suffered sinsa H-srs infarct

;, Bsi which a bargain the heart muscle ^ sgen insufficient BlutzufiAm died isto The tots'Muskel is sew soft and difficult su because he einrsissto easy Muscle kmm, wedges, if the patient is kept quiet and the ventricles only minimal pressure Sindo exposed defect such treatment may arise an aneurysm, "in which the softened muscle swells and forms blood accumulations which the lumps" or * clotting _o tend the tendency to develop such a Aneurismastexm UVSTOh ¥ ermin alteration of Pumpbelästung of the heart with Tsil ^ eisem Stützsyst'em to a be brought minimum "in typical case scarred bswo healed by the affected infarct tissue and gains in a few weeks zurückρ its resilience and during this time has the bypass Yorriehtung work continuously ₀ Recent developments where> n ^ Pi MPAN-OxygenatiDnsausrüstungenj as membrane Oxygenator @ a ₉ with hot longevity "limited. Elut = gradation effects feesi long-term = T © ilstützi ing won such pawn possible

In the ¥ @ rgangenh @ it, technicians have the blood- g durefe (DKjgenations ^ Puiapsjstem © for ^ a relatively © it ₉ about less than four hours ^ during surgery Long-term, and even when used, human error can create significant problems.

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The ones resulting from security, costs and flexibility Conflicts must be reduced * in order to have a satisfactory system for relieving the stress on the heart and lungs. Desirable traits include responsiveness on the delivery rate under the action of gravity, minimum Blood degradation and reliability in long-term use, In addition, the blood should be exposed to the air as little as possible and excessive gas formation should be avoided or at least be displayed.

In the practical implementation of a partial support system, numerous requirements must be taken into account. For example, the device or system for bypassing the heart and lungs experiences a load when the blood is returned to the body. This load is variable because the flow resistance to the system can increase if, for example, the arteries contract, or decrease if the arteries expand. Even so, the bypass device should generally deliver a constant flow rate to the body circulation that is equal to the venous output. In the past, the return flow or supply rate was controlled as a function of the central venous pressure or return flow pressure. Cf. eg Turina, et. Al ·., But ⁿ An Automatic Cardiopulmonary Bypass Unit for Use in Infants ", The Journal of Thoracic and Cardiovascular Surgery, 63" (February 1972), page 263, 264. The venous pressure is an inaccurate Measure for the blood flow and can fluctuate very considerably with constant blood flow, depending on the physical condition of the patient.

A device is used to draw blood from the circulatory system to bypass the flow through the heart and lungs.

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Generate excessive negative pressure or suction in such a way that the veins collapse but still produce a substantial and essentially uniform blood flow, to effectively relieve the patient's heart and lungs. A system that uses negative pressure in a Caval cannula

describes ^e / essay by 'Turina et al.,; "Servo-controlled Perfusion Unit With Membrane Oxygenator for Extended Cardiopulmonary Bypass", Biomedical Engineering (March 1963) pages 102-107. However, this Turina system is quite complicated and expensive due to the Use of "sensors" and servomotors for a number of controls and thus not only extremely expensive, but also more prone to failure.

The blood flow rate and its changes are indicative of the patient's physical condition and it would therefore be desirable to monitor blood flow rate. The doctor may find it appropriate to increase the return flow rate: or lower it. An increase in the inflow rate beyond the venous delivery rate often requires an additional one Blood supply to the system or device. It would therefore be advantageous to have a bypass device available to have the blood flow in addition to the amount of blood coming from the patient's circulatory system can feed. ·

The amount of blood in the circulation of a newborn or an infant is particularly critical »For example, can hyaline membranes damage the lungs alveoli of infants β When this occurs, the lining of the lungs is impermeable to oxygen and carbon dioxide. As an infant with this disease will not have adequate oxygen

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In the past, treatment has been carried out by increasing the concentration and pressure of the oxygen supplied to the infant. * Although the disease is often cured after this procedure, other serious conditions caused by the toxic effects of oxygen, such as . retrolental fitiroplasia, "which destroys the retina. Using a bypass device, however, allows the lungs to heal. Controlling blood volume is essential because the hyaline disease is typical of underweight infants, generally less than 2500 g and with a total blood volume from only 150 to 300 cm ⁵ .

It is therefore desirable to have available a heart and lung bypass device that is safe and reliable is responsive to gravity feed and allows volume change. . ■ =

Generally speaking, a bypass device for the heart and lungs of the human circulation according to the invention comprises an air-free collection device of variable volume for a patient's blood supplied by gravity and a transducer coupled to this device which emits a signal responsive to the blood volume which is related to the supply rate. After the blood discharged from the collecting device has been oxygenated and heated, the blood is fed back to the patient via a pump coupled to this device at a flow rate which is controlled by the transducer signal in such a way that it is returned to the patient supplied flow

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is essentially the same as the rate of delivery of that Patient.

According to a preferred embodiment of the invention is a first flexible bag that can collapse, switched on to prevent blood flowing in under heavy forces to record. The GDR bag can collapse and become air-free, making any blood-gas interface practical is avoided. Since the bag is also flexible, it prevents that it sucks in air when it is deflated, thus avoiding a vent embolism in the circulatory system.

A standpipe extending from the bag is coupled to a gas pressure responsive transducer. The standpipe forms a limited volume of gas, the pressure of which acts on the converter. Changes in the blood flow rate in the bag, which appear as changes in the volume in the bag, result in fractional changes in the volume of gas, with corresponding changes in pressure, which are greatly increased compared to the changes in volume in the bag. A second flexible, collapsible bag is provided which acts generally as a buffer zone and from which revitalized blood is supplied from the patient's body. The revitalization device generally comprises a pump, a membrane oxygenator and a heat exchanger, and this device is interposed between the first and second bags. A return flow path between the second bag and the first bag provides for the return flow of part of the blood stream, relieving the second bag of excess pressure and ensuring equilibrium of the flow rates. A main variable speed pump connected to the second gouge

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is used to deliver a controlled flow of blood from the second bag to a human circulation. To regulate the pump speed is used by a controller responsive to the converter signal, which controls the main pump in a Rate that tends to increase the volume of blood in the first bag for a given blood collection rate on one to maintain a predetermined value so that the blood return rate substantially coincides with the rate of venous Blood flow is maintained. The setting of the control can be operated manually by a supervising doctor, so as to instantly change the flow rate without. turn off the automatic system.

Furthermore, according to the invention, the device can also have a Containers for ... "contain a blood supply. The blood from the container can be selectively added to the first bag to increase the total blood volume, that circulates in the combined circulatory and bypass system- " A valved one. Tube can be used to draw off an excess amount of blood when the flow is predetermined Exceeds values.

The invention is explained in more detail below with reference to the drawing, for example. ■.

Fig. 1 is one of a block diagram and a simplified one schematic representation. combined reproduction a bypass device for the circulation through the heart and lungs with a flow control according to the invention.

According to the preferred embodiment shown in FIG. 1 of a bypass device generally designated 10

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for the circulation through the heart and lungs according to the invention is located below the blood collection point the circulatory system of a patient (indicated schematically by a. Rectangle) a generally designated 12 Catching device that is intended to be thrown away after a single use and is used under the effect of gravity to absorb supplied venous blood from the patient's circulation. A standpipe 14 containing a gas space is connected to the interior of the containment device and extending vertically to a pressure responsive one Converter 16 which is in operative connection with the interior of the standpipe 14 at its upper end. The Auifiangeinrichtung 12 includes a first flexible bag 18, of the collapsible type, and one at an inlet of the bag 18 connected tube 20 for venous Blood. The bag 18 and the tube 20 can be made and made of a wide variety of materials in the embodiment made of surgical quality neoprene and of the type intended to be discarded after a single use. The thickness or wall thickness of the Bag 18 ,. which is preferably clear or translucent, is sufficient to hold a substantial amount of blood without risk of tearing ^> the piercing at Contact with other objects. In this case, however, the bag 18 is sufficiently flexible to allow the shape to be adapted its walls to allow the absorbed blood volume, which practically eliminates a blood-gas interface and allowing the bag to collapse completely when all blood is removed therefrom. One on top of the bag 18 The provided outlet connection 19 can be closed by a clip "21" when all air is out of the inside of the bag is delivered.

The standpipe 14 is preferably a rigid and transparent one or translucent tubular shaped element of

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surgical quality. Since the inner tube 14 a small volume has, compared with the volume of the bag 18 and the blood can take certain prior heights therein ", it bestirnt a limited volume of gas 22 within a cylindrical ^K ammer 23, which via a sterile barrier 24 a within the chamber 23 Applies pressure to transducer 16. An increase in blood flow in bag 18 causes "a. Expansion of the bag and thereby causes the level of the blood in the standpipe 14 to rise and the gas volume 22 to decrease. The reduction in the trapped gas volume 22 causes a pressure increase which is transmitted to the transducer 16 via the barrier 24. Small proportional changes in blood flow rate into the 'bag 18,' the. result in only small proportional changes in the volume of the blood in the bag, cause major proportional changes in the pressure of the gas volume 22 “In this way, the combination of the collecting device 12 with the standpipe 14 and the transducer 16 results in an extremely sensitive device for measuring and displaying changes in the venous flow rate .

During the transducer 16 on the rate of blood flow the patient emits a signal related to the bag 18, does not necessarily need this signal in relation to one Signal that would be obtained if, for example, a patient's central venous pressure was monitored would. Rather, the invention aims to provide a more accurate display of the venous flow rate, as a patient's blood pressure varies with changes in the volume of blood in the patient's circulatory system or with others Can change parameters.

A device 28 for revitalizing and oxygenating

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is intended for the continuous revitalization of the Blood including oxygen transfer to oxygen deficient Blood and the warming of the blood that has been partially cooled by the patient since it was drawn. the Device 28 generally includes a pump 30 driven by a motor 32. The pump 30 is in series with a membrane oxygenator and a heat exchanger 34 with the pump 30 pushing blood through the membrane oxygenator and heat exchanger 34. The engine 32 or the pump 30 may be a roller blood pump, in the blood between a membrane and a surface, the one forms a cylindrical chamber, is conveyed by rotating rollers that rest against the membrane and the surface.

A second flexible pouch 36 corresponding to the first pouch 18 can be made deflated and is preferred transparent or translucent. The flow passing through the oxygenator 28 becomes the second Bag 36 supplied via a line 37, for the purpose of continuously supplying this bag 36 with freshly revitalized, i.e. oxygenated and warmed blood. The second bag 36 also helps keep irregular or pulsating To dampen or buffer flows of blood which is returned to the patient by means of a main pump 38, For reliable circulation under all conditions, the pump 38 becomes constant at a somewhat slower speed driven as the pump 30 so that the pump 38 does not operate without a supply of blood. Although in the exemplary embodiment two flexible bags 18, 36 are described, be here loading. notes that within the scope of the invention, a single, sub-

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divided bag can be used. The property the fully collapsible bag not only limits the occurrence of blood-gas interfaces, but does so also helps avoid massive air embolisms. Should it happen for any reason that the one or , the other of the two bags 18, 36 becomes bloodless and collapses, no air that could leak into the bypass device 10 can be pumped into the patient's circulatory system.

A return flow path is formed by a hose 39 which connects the second bag 36 to the first bag 18 and provides a pressure relief to equalize the pressure between the two bags. Without the return flow path t-jürde easily overpressure arise in the second bag 36 because the pump 30 works at a greater rate than the main pump 38.

The main pump 38 is preferably a roller blood pump which is connected to the second bag 36 to return the oxygenated and warmed blood to the patient's circulation. The main pump 38 maintains a blood flow rate that is invariable against fluctuating resistances or loads applied by the patient circuit 4 to the pump 38, regardless of the fact that the resistances or loads on the patient circuit vary with the patient's physical condition a contraction - increased resistance in the patient's circulatory system, but blood is still returned to the patient at a rate independent of his physical condition.

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A variable speed motor 40 drives the main pump 38 at a controllable blood flow rate as desired in response to a signal from, a generally designated 42 control device or setting device for the Förderia te is issued. The control device can be a simple amplifier circuit be that emits an interfering signal to the variable Speed operating pump motors to drive at a rate equal to or equivalent to the venous blood flow; According to a preferred embodiment only by way of example, the control device 42 has an amplifier circuit 44, a servomotor 46 with a downstream speed min- / 48, one with the speed min- ^ mechanical coupled, variable or potentiometer resistor 50 and an adjusting knob on its shaft 52 on. The control device 42 serving to adjust the flow rate responds to a signal ■ of the converter 16 in order to transmit a signal from the potentiometer 50 to the motor 40, the signal from a voltage source 51 to operate the main pump 38 at a flow rate commensurate with the volume of blood in the first bag 18 corresponds. The volume of blood in the bag 18 is maintained at a predetermined level so that the return flow rate to the patient is essentially the same as the venous blood output. The adjustment knob 52 can can be used to manually override the automatic flow rate controller 42 and thereby the To influence the flow rate of the main pump 38 in addition. The amplifier circuit 44 amplifies a bipolar to zero related signal of the converter 16 in order to produce a signal sufficient to drive the servo motor 46. This Signal is bipolar in that it can represent deviations from a zero position in any of two directions, accordingly either a pressure increase at the transducer 16 by

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the volume of gas 22 or a pressure drop due to this Gas volume. To initially set up the device, the pressure of the gas volume 22 can be equalized with the environment are through a closable outlet (not shown) on the cylinder 23, which is closed, when a desired blood level is reached in the standpipe 14. The servo motor 46 rotates in accordance with FIG Polarity of the transducer signal and turns the potentiometer 50 corresponding to the volume of blood in the bag 18 which is sensed by the transducer 16.

The speed reducer 48 may be a gear train that is placed between the servo motor 46 and the potentiometer 50 is switched on and the angular rotation of the potentiometer 50 relative to the rotation of the servo motor 46 decreases and thereby an adjustable increase within the device results. The growth is stopped, in order to obtain time for changes in the pumping rate of the main pump 38 to accommodate blood volume changes caused by the converter 16 can be determined to influence and further rotation of the servomotor without significant overdriving of the potentiometer 50.

The setting of the potentiometer 50 determines the speed of the pump motor 40 and thereby again the flow rate of the main pump 38. An adjustable resistor 54 in the circuit of the motor 40 allows a further adjustment to the pumping rate of the pump 30; higher than that of the To hold the main pump 38, so that there is a reverse flow from the second bag 36 to the first bag 18 and the main pump 38 does not operate without a supply of blood.

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On a scale 53 adjacent to the setting knob 52 the particular value of the flow rate for which the main pump 38 is being driven is displayed. The adjustment knob 52 can be rotated by hand using the torque supplied by the servo motor 46 via the reduction gear 48 is overdriven. A slip clutch or a friction clutch between the reduction gear 48 and the Potentiometer 50 is suitable for a larger torque motor 46, but such an arrangement would do the trick Adjustment knob 52, if released, does not return to its corresponding correct setting permit.

An .Auslaßstutzen 56, the outer surface of which is hermetic is sealingly connected to the second bag 36, can be closed by a clip 57, so that the bag is evacuated in the same way as the first bag 18 can be made. ·,

A container 58 is provided for receiving and holding an excess amount of blood from the device 10 and at the same time serves to increase the blood volume in the bypass device 10 by delivering blood to the second bag 36 through a valve 59 Main pump 38 outgoing line can be used to draw blood from the bypass device. Valves 59, 60 for adding blood to container 58 and releasing blood to bypass device 10 can be manually operable or of the type operated by an electrical signal can be actuated. For example, in the article by Turina et al. in the March · 73 issue of Biomedical Engineering "described a servo system for perfusion flow.

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A cardiotomy tube (not shown) can also be connected to the container 58 as a source of blood. The cardiotomy line is used to remove blood that collects near the veins and veins that have been cut during surgery. The blood aspirated from the patient is in a foamy state, and a defoamer (not shown) is usually used to reduce the foamy state of the blood before it is supplied to the container 5S.

The operation of the bypass device 10 for the blood path through the heart and lungs is summarized below. The first flexible bag 18 is generally placed at a lower level than the patient so that blood can flow under the action of gravity. Initially, blood is added to the bag 18 with the clamps 21 and 57 open. The air pressure of the bypass is adjusted for the gas volume 22 and the converter 16 by opening a valve (not shown) or separating the standpipe 14 from the cylinder 23. Blood is added until the level in the standpipe 14 reaches a mark or an initial level 62, after which the standpipe 14 is connected again with the lock 24 and the converter 16. In this way, the pressure in the gas volume 22 is initially matched to that of the surroundings.

Air contained in the first and second bags 18, 36 is forced out, either by hand or by filling the bags 18, 36, whereupon the outlets 19, 56 are closed by the clips 21, 57. In this way, the blood-air interfaces in the bags 18, 36 are minimized.

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Venous blood flows under the action of gravity into the first bag 18, the volume of which then increases accordingly the flow rate of blood flowing through it changes. This volume sets the level in the standpipe 14 and - as already described above - cause proportional Changes in the blood volume of the bag 18 are significantly larger changes in the pressure on the transducer 16. Although the signal of the transducer 16 is generally related to the pressure of the environment, an arrangement with a U-tube (not shown) can be used to obtain a relative pressure so that the converter artificially can be set when the level of the collecting device 12, from that in the embodiment in FIG position shown deviates and, for example, is closer to the level of the patient.

The signal from the converter 16 is fed to the amplifier circuit 44, the signal of which switches on the servomotor 46, the rotates at a speed corresponding to the amplitude of the signal and in a direction determined by the polarity. The servomotor rotates via the reduction gear 48 the potentiometer 50 in the corresponding direction at a lower speed and also the setting knob 52, so that the blood flow rate can be read from the dial 53. As the speed of the main pump 38 by the motor 40 is set, which is controlled by the setting of the potentiometer 50, the level of the blood is set to the starting position 62 returned while slowing down or reversing the direction of the servomotor 46 "It should be noted that that the pump motor 40 continues to operate at or near a substantially constant speed and that the working mode of the device is controlled by the sensitivity setting stabilized on the reduction gear 48

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although other suitable means may be used.

Blood from the first bag 18 is passed by the pump 30 the ptevitalization "or oxygenation device 28 is pumped, with sufficient pressure to pass the blood through the membrane oxygenator and heat exchanger 34 to the second bag 36 to feed. Because the speed of motor 32 is also determined by the setting of potentiometer 50, the pump 30 conveys blood at a flow rate which is above the flow rate of the main pump 38, according to FIG the adjustment of the resistance 54. By the pump 30 induced overpressure in the second bag 36 is over the Hose 39, which serves as a return flow path, is relieved. Blood from the second bag 36 is then pumped through the main pump 38 supplied to the patient's circulation.

It is important for a doctor to be alert to the presence of a low blood volume condition in a patient Is done, this condition can indicate internal bleeding and may require one additional amount of blood is introduced into the entire system. A doctor or assistant who "pointed to such a condition becomes attentive, can now increase the circulating blood volume by opening the container valve 59, whereby Blood can flow into the second bag 36. Also can Physician additionally or instead manually override the setting knob 52, thereby increasing the flow rate of the main pump 38 to the patient's circulatory system will. It should be noted, however, that such an increase in the return flow rate to the patient without refilling can only be run for a limited period of time can without the bags 18 and 36 collapsing.

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The invention thus provides a simple, accurate and sensitive bypass device for the blood circulation through the heart and lungs having a variable rate, "preferably gravity, supplied venous flow." absorbs from a patient's circulation, revitalizes the blood and returns the blood to the circulation, at a rate substantially equal to the venous flow rate but with adjustable blood volume and keeping blood-gas interfaces to a minimum can.

Patent or protection claims

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Claims (10)

Jan 15, 1,975 Baxter Laboratories, Inc, Da / -mr- jq AO-415 Patent or protection claims Device for bypassing the blood circulation through the heart and lungs for receiving venous blood from a patient's circulation, which is fed in at a variable flow rate, in particular by gravity, for revitalizing the blood and returning it to the circulation at a flow rate that is essentially the same as the flow rate of the venous blood,
characterized by a first flexible container (18) which can collapse on itself, with an inlet for receiving the venous blood, which can be at least partially filled with blood and contains essentially no blood-gas interfaces, and which is sufficiently flexible is to collapse in the event of an emptiness and not to allow suction to develop at the inlet; a second flexible bag (36) which is also collapsible; a return path (39) for blood to flow out of the second container (36) to the first container (18); one inserted between the first and second bags Revitalization device (-28) for continuous Oxygenating and warming the blood from the first bag (18) and then conveying it to the second Bag (36); a main pump connected to the second bag (36) (38) for delivering a flow of blood from the second bag to the patient's circulation with a through a Control signal controlled flow rate; a transducer coupled to the first bag (I8) (16), which emits a signal related to the volume of blood in the first bag *; and one responsive to the blood volume display of the transducer (16) Control device (42) which outputs the control signal (50) for the main pump (38), causing it to operate at a rate 509830/0705 ίο promotes, which strives to keep the blood volume in the first bag (18) at a predetermined level or value and thereby maintaining the flow rate of the blood returned to the patient substantially equal to the flow rate of the dispensed venous blood. 2. Device according to claim 1,
characterized in that the volume of the first bag (18) is determined by the blood contained therein and that a device (23) for gas absorption is connected to the first container (18) and to the converter (16), the volume of which is small compared to the Volume of the first bag (18) and in which blood levels are adjustable, as well as a limited gas volume (22), the pressure of which can be applied to the transducer (16), so that changes in the flow rate appear due to changes in volume in the bag (18) Proportional changes in the gas volume (22) and corresponding changes in pressure result in this bag, which changes are greatly increased compared to the proportional changes in volume in the bag. 3. Device according to claim 2,
characterized gekennze ic h η et that the converter (16) gasaufnehmende device form (22) and the bag (18) is a closed system that are 0ff _ne of the device n (22) for ambient air pressure brought to a reference level which, in the Schliessaides system, serves as a zero mark (62) for the transducer with respect to subsequent fluctuations in blood flow . 509830/0705 4. Device according to one of the preceding claims, characterized in that that a control device (42) for keeping the flow rate supplied to the patient equal to that of the venous Flow rate provided and a device (52) for overriding the control device (42) set flow rate manually. 5. Device according to one of the preceding claims, characterized in that between the second flexible bag (36) and the first flexible bag (18) a ^1-i ückströmv / eg (39) is provided for the pressure equalization between the two bags. · '· 6. Device according to one of the preceding claims, characterized in that the vitalization device (28) has a membrane oxygenator (34), an oxygenator pump (30) and a heat exchanger connected in series and that to the oxygenator pump (30) a flow rate the main pump (38) -responsive device (54), which ensures a higher value of the flow rate of the pump (30) than that of the main pump (38), so that a return flow from the second bag ("36) to the first bag (18) occurs and the main pump (38) does not work without a supply of blood _f . • 4 7. Device, in particular after one of the previously ' going claims, for regulated blood supply to a patient's circulation, characterized by a collection 509830/0705 ί? direction (12) for venous blood discharged from the patient; one coupled to the collecting device and means (16) responsive to the volume of blood therein and providing an indicator for that volume; an oxygenation device coupled to the collecting device (16) (34) to revitalize the blood; and one connected to the collecting device (12) Variable delivery pump (38) for returning blood to the patient with an on display responsive flow rate. 8. Apparatus according to claim 7 _f
characterized geke η e nz I et η, that the collecting device (12) comprises at least one flexible container (18), which is designed for minimal air interfaces blood. 9. Device for bypassing blood circulation through the heart and lungs having a first container to hold drawn blood, a second container for receiving revitalized blood flow from the first container, one connected between the first and the second container Revitalization device with oxygenation pump; furthermore with a return path for blood from the second container to the first container and a main pump connected to the second container for a blood flow to the patient's circulation,
marked by the combination with a transducer (1.6) which responds to the volume of blood in the first """container"("18 ) and is coupled to the latter to provide an indication of the flow rate; 50 9830/07 05 - ir- ■ ■. ".-. monitoring means (52) responsive to the indication of the flow rate for adjusting a flow rate; one between the main pump (38) and the oxygenation pump (3P) switched on device (54) through which the higher flow rate oxygenation pump (30) can be driven as the main pump (38); and a control device (42) for driving the main pump (38) at a rate related to the blood level in the first container (18). 10. Apparatus according to claim 9, characterized, that this has a container (58) for holding a liquid with a higher level than a liquid level in the first container (18) and this container (58) with the first container (18) connecting flow path (36, 39) for a flow to the first container and a valve device (59) via which liquid can be selectively fed from the container (58) to the first container (1.8-) is. attorney: Dannenberg 509830/0705 Blank page