Extracorporeal blood pump, heart-lung machine, method for operating an extracorporeal blood pump and method for operating a heart-lung machine

Description

[0001] The invention relates to an extracorporeal blood pump, a heart-lung machine, a method for operating an extracorporeal blood pump and a method for operating a heart-lung machine.

[0002] The heart, the central organ of the circulatory system, is a hollow muscle with two chambers that pumps blood through the circulatory system by contracting and relaxing. Its left chamber (left ventricle) pumps blood through the arterial blood vessels of the circulatory system to the blood capillaries of the body's periphery. The blood returns to the right ventricle through the venous blood vessels. From there, it is pumped through the pulmonary arteries into the pulmonary circulation (lesser circulation) to the lungs, and then returns to the left ventricle via the pulmonary veins. The lesser circulation is located in the chest.

[0003] In cases of heart disease, patients may find themselves in a situation where artificial circulatory support becomes the only possible and therefore life-sustaining therapy.

[0004] Heart-lung machines replace the vital circulatory functions of blood flow and gas exchange, for example, during cardiac surgery. Heart-lung machines can also be used to stabilize patients with heart or lung failure for several days. This is referred to as extracorporeal membrane oxygenation (ECMO) or extracorporeal life support (ECLS). In this procedure, blood is withdrawn from the patient via minimally invasive cannulas, processed, and returned to the patient.

[0005] WO 2009 / 024308 A1 discloses an electric linear drive, in particular for a pumping system of an artificial heart.

[0006] EP 2 523 702 A1 discloses an arrangement with a blood pump and a gas exchanger for extracorporeal membrane oxygenation.

[0007] Document WO02 / 30267 discloses an extracorporeal blood pump for pumping and displacing blood, the blood pump comprising two blood chambers and a mechanical drive unit, the drive unit being arranged between the blood chambers, one blood chamber comprising a membrane, a blood inlet channel and a blood outlet channel, characterized in that the blood outlet channels of both blood chambers are connected to each other.

[0008] The document US5232434 discloses an extracorporeal blood pump for sucking in and displacing blood, wherein the blood pump has a blood chamber and a mechanical drive unit, wherein the drive unit is adjacent to the blood chamber, wherein the blood chamber has a membrane, a blood inlet channel and a blood outlet channel, wherein the drive unit has a gas inlet and a gas outlet as well as two pressure chambers, wherein each pressure chamber has an active surface, in particular an active surface is a membrane, wherein a blood chamber is separated from a pressure chamber by a membrane, wherein the drive unit is in operative connection to the layer of the membrane.

[0009] Document EP3520833, prior art according to Article 54(3) EPC, discloses an extracorporeal blood pump for sucking in and displacing blood, the blood pump comprising two blood chambers and a mechanical drive unit, each of the blood chambers comprising a membrane, a blood inlet channel and a blood outlet channel, the drive unit being arranged between the blood chambers, the blood outlet channels of both blood chambers being interconnected and a region between the membranes comprising a coupling rod which is adapted to couple the movement of the two membranes to one another.

[0010] The invention is based on the object of providing an improvement or an alternative to the prior art.

[0011] According to a first aspect of the invention, the object is achieved by an extracorporeal blood pump for sucking in and displacing blood, wherein the blood pump has two blood chambers and a mechanical drive unit, wherein the drive unit is arranged between the blood chambers, wherein a blood chamber has a membrane, a blood inlet channel and a blood outlet channel, wherein the blood outlet channels of both blood chambers are connected to one another.

[0012] The following terminology should be explained in this regard: First, it should be expressly pointed out that in the context of this patent application, indefinite articles and numerical expressions such as "one", "two", etc., should generally be understood as "at least" expressions, i.e. as "at least one...", "at least two...", etc., unless it is expressly clear from the respective context or it is obvious or technically necessary for the person skilled in the art that only "exactly one...", "exactly two...", etc. can be meant.

[0013] A "blood pump," often referred to as an "artificial heart," is a device that takes over or supports the function of the heart and is designed to maintain the body's circulation. In particular, a blood pump can be used to support a surgical procedure, particularly to temporarily take over the function of the heart or to support the heart (perioperatively), to take over the function of the heart or to support the heart after a surgical procedure (postoperatively), or otherwise, i.e., not in connection with the surgical procedure, as part of an intervention.

[0014] An "extracorporeal blood pump" is used outside the body.

[0015] A "blood chamber" is a component of a blood pump and is designed to receive the designated blood flow. A blood chamber has a "membrane."

[0016] A "membrane" is a component of a blood pump and a component of a blood chamber. It is designed to change its position and thus the volume of the blood chamber. The designated blood flow is drawn in when the blood chamber volume increases and displaced when the blood chamber volume decreases. In particular, the "membrane" is designed to change its position so that a blood chamber can only have approximately 10% or less of its maximum volume without impairing the material behavior of the blood chamber or the membrane.

[0017] A "drive unit", especially a "mechanical drive unit", is a structural unit that drives a blood pump by means of energy conversion.

[0018] A "blood entry channel" is a channel through which the designated blood flow of an operating blood pump flows into a single blood chamber.

[0019] A "blood outlet channel" is a channel through which the designated blood flow of an operating blood pump flows out of a single blood chamber.

[0020] The state of the art has so far primarily envisaged the use of centrifugal pumps to support cardiac function or to take over the function of the heart. Due to their design, centrifugal pumps can place mechanical stress on the blood during operation due to the comparatively high level of shear stress acting on the blood.

[0021] During practical operation of centrifugal pumps, suction can often occur through cannulas on the inlet side of the centrifugal pump. Due to the pressure-flow characteristics of centrifugal pumps, the suction pressure can increase, leading to a further increase in the shear stress acting on the blood or even to cavitation of the blood, which can cause blood damage.

[0022] Alternatively, diaphragm pumps are used in the state of the art.

[0023] By way of derogation, a specific design of a diaphragm pump is proposed which has two blood chambers and a mechanical drive unit, wherein the drive unit is arranged between the blood chambers, wherein a blood chamber has a diaphragm, a blood inlet channel and a blood outlet channel, wherein the blood outlet channels of both blood chambers are connected to one another.

[0024] In concrete terms, it is conceivable under other construction methods that the two blood chambers have the same nominal volume.

[0025] With a suitable design of the blood pump, undercuts and dead water areas are avoided in the area through which the designated blood flow flows.

[0026] The aspect of the invention presented here can advantageously ensure that the blood-carrying side of the blood pump can be designed in such a way that the blood flow can be guided in a way that is as gentle on the blood as possible.

[0027] This can advantageously ensure that the forces acting on the blood remain comparatively low and that all areas of the blood pump are always washed out by the blood.

[0028] This can advantageously prevent blood cells from being damaged and blood from clotting.

[0029] This can advantageously result in a particularly blood-protecting and energetically efficient blood pump, which can allow the designated blood flow to flow back into the body through a cannula.

[0030] Preferably, the blood entry channels of both blood chambers are connected to each other.

[0031] In a suitable embodiment, the two blood entry channels are connected in a Y-arrangement so that the designated blood flow can be divided between both blood chambers.

[0032] The advantage of this is that the blood can be withdrawn from the body with only one cannula and that the designated blood flow is pumped in a particularly blood-friendly manner in the blood pump.

[0033] Optionally, a connecting area of ​​the blood outlet channels has a backflow restrictor.

[0034] The following terminology should be explained: A "connecting area" is an area in which the designated partial blood flows from both blood chambers flow together again.

[0035] A "backflow restrictor" refers to a component designed to allow blood to flow through with a low pressure loss in one flow direction and a high pressure loss in the opposite flow direction. In particular, the pressure loss in the backflow direction is so high that backflow can be prevented. A backflow restrictor preferably represents a closure for a designated blood flow in one flow direction, while a designated blood flow can pass through the backflow restrictor almost unhindered in the other flow direction, in particular, can pass through it unhindered. In a sense, a backflow restrictor has the properties of an adjustable closure, which is opened or closed depending on the designated flow direction.

[0036] For example, it is conceivable that the blood outlet channels are brought together in a connecting area from both sides, similar to a so-called Y-arrangement.

[0037] With a suitable design, this prevents blood from flowing back into the other blood chamber when a designated blood flow is ejected. In a preferred embodiment, the backflow restrictor is designed so that the designated blood flow flows well around it on both sides, ensuring that the backflow restrictor is always thoroughly rinsed.

[0038] This can advantageously ensure that the blood pump has a high energy efficiency.

[0039] In addition, it can be advantageously achieved that the backflow restrictor and the connection area are well washed out by a designated blood flow, thus preventing the formation of thrombi.

[0040] Furthermore, it can be advantageously achieved that blood can reach the blood chamber via the blood outlet channel during suction.

[0041] According to the invention, the drive unit has a gas inlet and a gas outlet as well as a pressure chamber, wherein the pressure chamber is separated from a blood chamber by a membrane, wherein the drive unit is operatively connected to the layer of the membrane.

[0042] The following terminology should be explained: A "gas inlet" is an inlet for a gaseous fluid. A designated gas flow flows through the gas inlet in such a way that gas flows into the drive unit.

[0043] A "gas outlet" is an outlet for a gaseous fluid. A designated gas flow flows through the gas outlet so that gas flows out of the drive unit.

[0044] A "pressure chamber" is a chamber designed to allow a designated gas flow. A pressure chamber has an "active surface." This "active surface" is designed to change its position, allowing energy to be converted. In particular, an active surface can be a membrane separating a blood chamber and a pressure chamber.

[0045] For example, it is conceivable that the blood pump is powered by gas, which releases energy into the bloodstream in the drive unit.

[0046] In a suitable manner, the gas flow may be provided by a supply unit.

[0047] According to the invention, a pressure chamber is arranged adjacent to a blood chamber. The pressure chamber and blood chamber are separated from each other only by the membrane.

[0048] The drive unit can thus be operatively connected to the position of the membrane. In particular, increasing the pressure in the pressure chamber can shift the position of the membrane toward the blood chamber.

[0049] In particular, by reducing the pressure in the pressure chamber, the position of the membrane can be shifted towards the pressure chamber.

[0050] In a suitable design of the drive unit, this has an operative connection to the position of the membrane, which includes end position detection of the membrane.

[0051] In this suitable embodiment, the drive unit is thus able to detect when the membrane has reached its respective end position and its movement should be stopped or reversed.

[0052] This can advantageously ensure that the drive unit can obtain the necessary energy for sucking in and displacing the blood from a gas stream.

[0053] Furthermore, it can be advantageously achieved that the active connection to the position of the membrane prevents damage to the membrane, enables energy-optimized suction and displacement of the blood and contributes to the most blood-sparing treatment of the blood in the blood pump.

[0054] Another advantage is that suction of the cannulas into the blood vessels, a common problem when using blood pumps, can be prevented, since the described system, thanks to the pneumatically operated drive unit, has a suction limit defined by a relationship between the pressure of the operating gas, the pressure on the discharge side, and the suction pressure on the inlet side. This eliminates the need for the complex alarms and safety devices of conventional systems using pressure sensors.

[0055] Optionally, the drive unit has two pressure chambers, with each pressure chamber adjacent to a blood chamber via a membrane.

[0056] In a preferred embodiment, a designated blood stream is ejected in one blood chamber while being aspirated on the other side.

[0057] If the blood pump is suitably designed, the gas flow will alternately pressurize a membrane.

[0058] For example, it is conceivable that after a work cycle and / or reaching a diaphragm end position, the gas pressure in the pressure chamber is reduced and the other pressure chamber is pressurized with gas so that both diaphragms now move in opposite directions.

[0059] This has the advantage that the blood pump can be operated with a constant gas flow, which means that no external circuitry is necessary.

[0060] Furthermore, it can be advantageously achieved that a designated gas flow only needs to have one pressure level.

[0061] According to a second aspect of the invention, the object is achieved by an extracorporeal blood pump for sucking in and displacing blood, wherein the blood pump has a blood chamber and a mechanical drive unit, wherein the drive unit is adjacent to the blood chamber, wherein the blood chamber has a membrane, a blood inlet channel and a blood outlet channel, wherein the drive unit has a gas inlet and a gas outlet as well as two pressure chambers, wherein each pressure chamber has an active surface, in particular an active surface is a membrane, wherein a blood chamber is separated from a pressure chamber by a membrane, wherein the drive unit is in operative connection to the layer of the membrane.

[0062] The state of the art has so far primarily envisaged the use of centrifugal pumps to support cardiac function or to take over the function of the heart. Due to their design, centrifugal pumps can place mechanical stress on the blood during operation due to the comparatively high level of shear stress acting on the blood.

[0063] Alternatively, diaphragm pumps are used in the state of the art.

[0064] In contrast, a specific design of a diaphragm pump is proposed, which comprises a blood chamber and a drive unit, wherein the drive unit has two pressure chambers. One pressure chamber is connected to the blood chamber via the diaphragm. The other pressure chamber is positioned laterally next to the first pressure chamber.

[0065] In a suitable embodiment, the blood pump allows cyclical suction and displacement of blood with the blood chamber, wherein the drive unit can be operated according to the first aspect of the invention.

[0066] In a suitable design, the second pressure chamber has a different type of effective surface instead of the membrane used according to the first aspect.

[0067] This can advantageously ensure that the blood pump with a blood chamber can be operated in a particularly blood-friendly manner and that the drive unit can obtain the necessary energy for sucking in and displacing the blood from a gas stream.

[0068] Furthermore, it can be advantageously achieved that the active connection to the position of the membrane prevents damage to the membrane, enables energy-optimized suction and displacement of the blood and contributes to the most blood-sparing treatment of the blood in the blood pump.

[0069] Another advantage is that suction of the cannulas into the blood vessels, a common problem when using blood pumps, can be prevented, since the described system, thanks to the pneumatically operated drive unit, has a suction limit defined by a relationship between the pressure of the operating gas, the pressure on the discharge side, and the suction pressure on the inlet side. This eliminates the need for the complex alarms and safety devices of conventional systems using pressure sensors.

[0070] Another advantage of this is that the blood pump can be operated with a constant gas flow, which means that no external circuitry is necessary.

[0071] Furthermore, it can be advantageously achieved that a designated gas flow only needs to have one pressure level.

[0072] Preferably, a blood chamber has a rotationally symmetrical region.

[0073] This can advantageously ensure that the forces acting on the designated blood flow due to the geometry of the blood chamber can reach as low a homogeneous level as possible.

[0074] Furthermore, it can be advantageously achieved that the flow field inside a blood chamber can be designed to be as gentle on the blood as possible.

[0075] This can also advantageously ensure that the blood pump has a high energy efficiency.

[0076] Optionally, a blood inlet channel and a blood outlet channel are arranged predominantly in the circumferential direction on the rotationally symmetrical area of ​​a blood chamber.

[0077] This can advantageously ensure that the forces acting on the blood remain comparatively low and that all areas of the blood pump are always washed out by the blood.

[0078] This can advantageously prevent blood cells from being damaged and blood from clotting.

[0079] This can advantageously result in a particularly blood-protecting and energetically efficient blood pump.

[0080] Preferably, a blood inlet channel has a backflow throttle.

[0081] In an advantageous embodiment, the blood inlet channel has a backflow throttle which is designed to prevent blood from flowing against the designated flow direction of the blood.

[0082] Particularly preferably, the backflow restrictor is designed in such a way that it is particularly well washed out by the designated blood flow.

[0083] This can advantageously ensure that blood flows through the blood inlet channel when displaced in a blood chamber.

[0084] In addition, it can advantageously prevent the formation of thrombi at the backflow throttle.

[0085] This can also advantageously ensure that the blood pump has a high energy efficiency.

[0086] Optionally, the drive unit has a gas inlet valve and a gas outlet valve as well as a switching device, wherein the gas inlet valve and the gas outlet valve have a closed position and an open position with respect to a gas flow path, wherein the switching device has two switching end states, in particular the switching device has exactly two switching states.

[0087] The following terminology should be explained: A "gas inlet valve" is a component for shutting off or regulating the flow of gas. A closure element in the gas inlet valve is moved, reducing or interrupting the flow. Specifically, the gas inlet valve is designed to allow gas to flow into the pressure chamber.

[0088] A "gas outlet valve" is a component used to shut off or regulate the flow of gas. A closure element in the gas outlet valve is moved, reducing or interrupting the flow. Specifically, the gas outlet valve is designed to allow gas to flow into the pressure chamber.

[0089] A "switching device" is a mechanical assembly that can effect a different switching state. The switching device switches the gas inlet and outlet valves shortly before the diaphragm's end position is reached, thereby pressurizing the other pressure chamber.

[0090] "Bistability" refers to the property of a system that can assume two possible stable states, but can only change from one to the other in response to an external stimulus. These systems are then called bistable systems.

[0091] A "membrane end position" or "effective surface end position" refers to the designated reversal point of a membrane position or effective surface position.

[0092] In particular, the switching device is designed to be bistable and can therefore only assume discrete positions in the respective end positions.

[0093] A "gas flow path" is a path taken by a designated gas flow.

[0094] A "closing position" is the position of a valve, in particular a gas inlet valve and / or a gas outlet valve, in which the flow of gas is prevented.

[0095] An "open position" is the position of a valve, in particular a gas inlet valve and / or a gas outlet valve, in which gas flow is possible.

[0096] A "switching end state" is a stable switching state that is reached after a completed switching state of a bistable switching system.

[0097] In a particularly preferred embodiment, the switching device is designed such that the switching device switches between the two possible switching end states when a diaphragm end position is reached and thus, when the switching device is actuated, the valve positions change to the other switching end state, whereby the gas pressure in the pressure chamber is reduced when a diaphragm end position is reached and the other pressure chamber is pressurized with gas, so that both diaphragms or active surfaces now move in opposite directions.

[0098] Thus, in a suitable embodiment, the membrane end position can be reached in particular when a blood chamber has only about 10% or less of its maximum volume.

[0099] Thus, the connected active surfaces and / or membranes can move in the opposite direction after an operation by changing the pressurized pressure chamber by switching via the switching device.

[0100] The advantage of this is that a blood pump can be achieved which operates mechanically autonomously and is not dependent on electronics or external specifications.

[0101] Furthermore, it can be advantageously achieved that there is no impairment of the material behavior of the blood chamber or the membrane.

[0102] This also has the advantage that the blood pump can be operated with a constant gas flow, which means that no external circuitry is necessary.

[0103] Preferably, a switching end state for a blood chamber has the gas inlet valve in the open position and the gas outlet valve in the closed position or the gas inlet valve in the closed position and the gas outlet valve in the open position.

[0104] This can advantageously achieve that one pressure chamber is filled with gas and the other pressure chamber is emptied of gas.

[0105] This can advantageously result in a blood pump that operates mechanically autonomously and is not dependent on electronics or external specifications, and the blood pump can be operated with a constant gas flow, which means that no external circuitry is necessary.

[0106] Furthermore, it can be advantageously achieved that the blood pump achieves a high degree of energetic efficiency.

[0107] Optionally, the switching device has a magnet.

[0108] For example, an arrangement of magnets is conceivable in which a pair of magnets in the central position has the maximum repulsion force, whereby a bistable switching device can be achieved.

[0109] This advantageously allows for the creation of a bistable and mechanically autonomous blood pump with a high energy efficiency.

[0110] Preferably, the switching device comprises a lever mechanism.

[0111] The following terminology should be explained: A "lever gear" is a gear made up of rods, whereby the rods predominantly form a kinematic chain.

[0112] This advantageously allows for the creation of a bistable and mechanically autonomous blood pump with a high energy efficiency.

[0113] Optionally, the switching device has a link with a spring-loaded roller.

[0114] The following terminology should be explained: A "link" is a gear element that has a slot, a web, or a groove. In or on the link there is a sliding block that is positively guided on both sides, to which the link's movement is transmitted.

[0115] A "spring-loaded roller" is a roller whose movement is influenced by the force of a spring.

[0116] This advantageously allows for the creation of a bistable and mechanically autonomous blood pump with a high energy efficiency.

[0117] According to the invention, a region between the membranes has a coupling rod, in particular the coupling rod is connected to the active surfaces, in particular the coupling rod is connected to a membrane and another active surface.

[0118] The following terminology should be explained: A "coupling rod" is a component that is designed to couple the movement of two active surfaces or of an active surface and a membrane or of two membranes.

[0119] In a particularly preferred embodiment, the end position of a membrane is transferred to the control method of the blood pump, in particular the position of the membrane affects the position of the coupling rod and the coupling rod switches the switching device when the end position of a membrane is reached, so that the valve positions switch to the other switching end state and so when one membrane end position is reached the gas pressure in the pressure chamber is reduced and the other pressure chamber is pressurized with gas, so that both membranes or active surfaces now move in opposite directions.

[0120] Thus, in a suitable embodiment, the membrane end position can be reached in particular when a blood chamber has only about 10% or less of its maximum volume.

[0121] Thus, the piston and thus the connected active surfaces and / or membranes can move in the opposite direction after an operation by changing the pressurized pressure chamber by switching via the switching device.

[0122] Furthermore, it can be advantageously achieved that there is no impairment of the material behavior of the blood chamber or the membrane.

[0123] This also has the advantage that the blood pump can be operated with a constant gas flow, which means that no external circuitry is necessary.

[0124] Optionally, the coupling rod has a hollow space inside.

[0125] This advantageously allows the coupling rod to have a gas flow inside under certain conditions. Thus, a hollow coupling rod can be used to create part of a bypass.

[0126] Preferably, the coupling rod has a first component and a second component, wherein the first component and the second component are connected by a spring.

[0127] This advantageously allows the coupling rod components to change their distance from each other when a force defined by the spring is reached. This eliminates the need for the effective surfaces of the pressure chambers to move synchronously.

[0128] Thus, when a pressure ratio defined by the spring between the pressure chambers is exceeded, a movement of the active surfaces that would otherwise be coupled by the coupling rod can be decoupled.

[0129] Optionally, the coupling rod has a valve which is designed to allow a designated gas flow to flow through the cavity in the coupling rod and then through the valve in the coupling rod and via a bypass out of a pressure chamber.

[0130] The following terminology should be explained: A "valve" is a component used to shut off or regulate the flow of fluids. In valves, a closing element is moved, thereby reducing or interrupting the flow.

[0131] A "bypass" is a flow channel through which a designated gas stream can flow. Specifically, a bypass allows gas to escape from a pressure chamber without having to go through the gas outlet valve. The bypass is therefore an alternative channel for the escape of gas contained in a pressure chamber.

[0132] In a suitable embodiment, the valve is opened passively when a pressure ratio between the two pressure chambers is reached, allowing gas to flow out of the pressurized pressure chamber via the bypass.

[0133] In an advantageous embodiment, the components of the coupling rod are connected by a spring. If the pressure ratio in the pressure chambers exceeds a value defined by the preload of a spring located inside the coupling rod, the valve opens, allowing gas to flow out of the pressurized pressure chamber via the bypass.

[0134] This can advantageously provide an additional protective device for limiting intake.

[0135] Preferably, the bypass has a closure device.

[0136] The following terminology is used: A "closure device" comprises a mechanical closure element configured to open a path, close a path, or throttle a flow along the path, in particular to partially close the path. In particular, a closure device is configured to open a bypass, close a bypass, or throttle a bypass, in particular to partially close it.

[0137] This advantageously allows the valve on the coupling rod to be locked by actuating a locking device. This can disable the valve's function.

[0138] It should be expressly pointed out that the subject matter of the second aspect can be advantageously combined with the subject matter of the first aspect of the invention.

[0139] According to a third aspect of the invention, the object is achieved by a heart-lung machine for conveying and processing blood, wherein the heart-lung machine has a blood supply and a blood discharge, wherein the heart-lung machine has a blood pump according to one of the preceding claims.

[0140] It is understood that the advantages of a blood pump for sucking in and displacing blood according to a first or second aspect of the invention as described above extend directly to a heart-lung machine for pumping and processing blood.

[0141] The heart-lung machine preferably has an oxygenator.

[0142] The following terminology should be explained: An "oxygenator" is a medical device that enriches blood with oxygen and removes carbon dioxide from the blood. An oxygenator is used for gas exchange in the blood.

[0143] The advantage of this is that the function of the lungs can be replaced.

[0144] The heart-lung machine optionally has a dialyzer.

[0145] The following terminology should be explained: A "dialyzer" is a medical device designed to carry out a substance exchange in the blood.

[0146] The advantage of this is that the function of the kidney can be replaced.

[0147] Preferably, the heart-lung machine has a filter.

[0148] The following terminology should be explained: A "filter" is a medical device designed to retain particles from the blood.

[0149] This can advantageously achieve that the blood can be cleaned of unwanted particles.

[0150] Optionally, the heart-lung machine has a gas supply, in particular an oxygen supply.

[0151] The following terminology should be explained: A "gas supply" is an assembly designed to provide a gas flow.

[0152] The advantage of this is that a heart-lung machine can be continuously supplied with oxygen and energy.

[0153] According to a fourth, unclaimed, aspect of the invention, the object is achieved by a method for operating an extracorporeal blood pump according to a first and / or second aspect of the invention.

[0154] The following terminology should be explained: A "blood supply" is a connection between the patient and the blood pump assembly, which is designed to be perfused by blood.

[0155] A "blood outlet" is a component through which a designated blood flow leaves the blood pump assembly and which is designed to be flowed through by blood.

[0156] In the unclaimed method, the blood is sucked in in a first method step by moving the membrane in the blood pump and a backflow throttle in the blood inlet channel opening as a result, wherein the blood flows into the blood chamber through the blood inlet channel, in a second method step the backflow throttle at the blood inlet channel of the blood chamber closes and the blood is displaced from the blood chamber in a third method step by moving the membrane, wherein the backflow throttle at the blood inlet channel prevents or reduces a backflow of blood through the blood inlet channel and the blood flows out of the blood pump through the blood outlet channel, wherein the movement of the coupling rod acts on the membrane and influences a movement of the membrane.

[0157] The advantage of this is that the blood pump is particularly energy-efficient and gentle on the blood.

[0158] In addition, it can be advantageously achieved that all areas through which a designated blood flow flows are washed out particularly well, so that no thrombi can form in the blood pump.

[0159] Optionally, the blood is alternately sucked in and displaced by two blood chambers, whereby one blood chamber alternately sucks in blood and the other blood chamber displaces blood, whereby the backflow restrictor in the connecting area of ​​the blood outlet channels prevents or attenuates a backflow of blood into a blood chamber through a blood outlet channel.

[0160] This can advantageously achieve a pulsatile suction and displacement of blood, whereby the blood pump can be operated with a constant gas flow, thus eliminating the need for external circuitry.

[0161] Another advantage of this is that the blood pump is particularly energy-efficient and gentle on the blood.

[0162] In addition, it can be advantageously achieved that all areas through which a designated blood flow flows are washed out particularly well, so that no thrombi can form in the blood pump.

[0163] Preferably, the movement of the coupling rod acts on the membrane and influences a movement of the membrane.

[0164] This advantageously allows a pressure chamber to always be supplied with positive pressure and never with negative pressure. The pressure chamber pressurized at that time determines the movement and drags the membrane or active surface of the opposite pressure chamber along, so that no negative pressure is required to release the gas.

[0165] This coupling can advantageously enable the blood pump to be operated with a constant gas flow, thus eliminating the need for external circuitry.

[0166] Optionally, the drive unit is operated with gas, whereby the gas flows into the drive unit through a gas inlet, whereby the gas flows out of the drive unit through a gas outlet, whereby a differential pressure between the blood chamber and the pressure chamber acts on the membrane and influences a movement of the membrane.

[0167] This advantageously makes it possible to provide the energy supply of the blood pump by a gas flow, which makes a particularly simple and robust blood pump possible.

[0168] Preferably, the gas flows through a gas inlet into the drive unit and then through an open gas inlet valve into a pressure chamber, wherein the gas outlet valve of this pressure chamber is closed, so that the pressure in the pressure chamber increases and influences the movement of the membrane, whereby the membrane moves directly or with a time delay towards the blood chamber.

[0169] This can advantageously achieve that the pressure chamber which displaces a membrane and thus also the blood flow in the adjacent blood chamber can be operated with gas pressure, i.e. it can draw its energy from the pressure of the supplied gas.

[0170] Optionally, the gas flows out of a pressure chamber through a gas outlet valve and then out of the drive unit through a gas outlet, whereby the gas inlet valve of this pressure chamber is closed, so that the pressure in the pressure chamber is reduced and influences the movement of the membrane, whereby the membrane moves directly or with a time delay towards the pressure chamber.

[0171] This can advantageously ensure that the gas used to operate the drive unit can leave the blood pump again.

[0172] Preferably, the gas flows alternately into a first pressure chamber while gas flows out of a second pressure chamber, and the switching device switches the gas inlet valve and the gas outlet valve when a diaphragm end position or an effective surface end position is reached, so that gas flows into the second pressure chamber while gas flows out of the first pressure chamber.

[0173] This advantageously makes it possible to create a blood pump with a pulsatile suction and displacement of blood, whereby the blood pump can be operated with a constant gas flow, thus eliminating the need for external circuitry.

[0174] Optionally, the switching device is switched in bistable switching states, so that after a switching operation only one pressure chamber has a gas connection with the gas inlet and the other pressure chamber has a gas connection with the gas outlet.

[0175] This advantageously ensures that the blood pump cannot get stuck between the designated switching states, which would impair its function or even cause it to fail. The blood pump operates mechanically autonomously with bistable switching states and is not dependent on an external controller, thus advantageously achieving particularly safe and robust behavior of a blood pump.

[0176] Preferably, the gas flows out of a pressure chamber via the valve when the differential pressure between the pressure chambers is exceeded.

[0177] This can advantageously provide an additional safety device to limit suction, thus reducing risks when using a blood pump.

[0178] Optionally, the closure device closes the bypass so that no gas or only a reduced gas flow can flow through the valve.

[0179] This can advantageously be achieved by deactivating the protective function provided by the bypass and the associated valve in favor of a higher pump performance.

[0180] According to a fifth, unclaimed, aspect of the invention, the object is achieved by a method for operating a heart-lung machine according to the third aspect of the invention.

[0181] Here, the blood pump of the heart-lung machine is operated using a method according to the fourth aspect of the invention.

[0182] Advantageously, this can ensure that the advantages of a method for operating a blood pump according to a fourth aspect of the invention as described above extend directly to a method for operating a heart-lung machine.

[0183] Optionally, the blood is fed to the blood pump and subsequently to the oxygenator and / or the filter and / or the dialyzer.

[0184] The advantage of this approach is that the blood drawn from the patient can be enriched with oxygen, freed from carbon dioxide and unwanted particles, and a metabolic exchange can take place in the blood. Thus, the functions of the heart, lungs, and kidneys can be partially or completely replaced.

[0185] The invention will be explained in more detail below using exemplary embodiments with reference to the drawings. Fig. 1 schematically shows a heart-lung machine, Fig. 2 schematically shows a blood pump, Fig. 3 schematically shows a switching device, Fig. 4 schematically shows an embodiment of a coupling rod arrangement with valve and bypass, Fig. 5 schematically shows a blood pump with bypass and closure device, Fig. 6 schematically shows a connecting area of ​​the blood outlet channels and Fig. 7 schematically shows a blood chamber unit with blood inlet channel, blood outlet channel and backflow throttle.

[0186] The heart-lung machine 1 in Figure 1 essentially consists of a blood pump 2, an oxygenator 3 and a supply unit 4.

[0187] The blood pump 2 essentially consists of a drive unit 5 and two blood chambers 6, 7.

[0188] A designated blood flow (not shown) flows in a designated blood flow entry direction 8 in a blood supply 9 from the patient (not shown) towards the blood pump 2.

[0189] Before the designated blood flow (not shown) reaches the blood pump 2, it is divided in a flow divider 10 and flows downstream of the flow divider 10 in two blood inlet channels 11, 12 into a blood chamber 6, 7 each, is pressurized there by the action of the drive unit 5 and leaves the blood pump 2 via a blood outlet channel 13, 14 each.

[0190] At the end of the blood outlet channels 13, 14, the designated blood flow (not shown) flows together in a connecting area 14 and from there further downstream towards the oxygenator 3.

[0191] The designated blood flow enters the oxygenator in the blood flow direction 16 and exits the oxygenator 3 in the blood flow direction 17.

[0192] Downstream of the oxygenator 3, the designated blood flow (not shown) flows through a blood drain 18 back to the patient (not shown).

[0193] The supply unit 4 supplies the blood pump 2, in particular the drive unit 5 of the blood pump 2, with a gas flow (not shown) via a gas supply 19 and thus supplies the blood pump 2 with the energy required for pumping the designated blood flow (not shown).

[0194] The blood pump 20 in Figure 2 essentially consists of two blood chambers 21, 22 and a drive unit 23.

[0195] The drive unit 23 essentially consists of two pressure chambers 24, 25, a gas inlet 26, a gas outlet 27, a gas inlet valve 28, a gas outlet valve 29 and a coupling rod 30.

[0196] The coupling rod 30 has an effective surface 31, 32 at each of its ends.

[0197] The blood chamber 21 is separated from the pressure chamber 24 by the active surface 31 and the membrane 33, so that a fluid (not shown) can neither flow from the blood chamber 21 into the pressure chamber 24 nor from the pressure chamber 24 into the blood chamber 21.

[0198] The blood chamber 22 is separated from the pressure chamber 25 by the active surface 32 and the membrane 34, so that a fluid (not shown) can neither flow from the blood chamber 22 into the pressure chamber 25 nor from the pressure chamber 25 into the blood chamber 22.

[0199] The gas inlet valve 28 can be switched so that a designated gas flow (not shown) can flow via the gas inlet 26 into the pressure chamber 24 or the pressure chamber 25.

[0200] The gas inlet valve 29 can be switched so that a designated gas flow (not shown) can flow from the pressure chamber 24 or the pressure chamber 25 into the gas outlet 27.

[0201] A designated blood flow (not shown) flows into the blood chamber 21 through a blood inlet channel 35 and a return flow throttle 37 and from there flows out of the blood chamber 21 downstream via the blood outlet channel 39.

[0202] A designated blood flow (not shown) flows into the blood chamber 22 through a blood inlet channel 36 and a return flow restrictor 38 and from there flows out of the blood chamber 22 downstream via the blood outlet channel 40.

[0203] The blood pump 20 in Figure 2 can, for example, have the following state. A designated gas flow (not shown) flows in a gas inflow direction 41 through the gas inlet 26 into the drive unit 23. There, the designated gas flow (not shown) flows via the gas inlet valve 28 in the gas flow direction 42 into the pressure chamber 25. Since the gas outlet valve 29 closes the pressure chamber 25, the gas pressure in the pressure chamber 25 increases.

[0204] The gas pressure in the pressure chamber 25 acts on the active surface 32 and the membrane 34 and becomes so high that the active surface 32 and the membrane 34 move in the direction of movement 43, 44 in the direction of the blood chamber 22.

[0205] As a result, the volume of the blood chamber 22 is reduced, the backflow throttle 38 closes and a designated blood flow (not shown) flows in a blood flow direction 45 towards the blood outlet channel 40 and further through the blood outlet channel 40 in the blood flow direction 46 out of the blood pump 20.

[0206] The direction of movement 43, 44 of the active surface 32 is transmitted via the coupling rod 30 to the direction of movement 47, 48 of the active surface 31, so that the active surface 31 and the membrane 33 move in such a way that the volume of the blood chamber 21 increases.

[0207] As a result, a designated blood flow (not shown) is sucked into the blood chamber 21 through the blood inlet channel 35 in the blood inflow direction 49 and further downstream through the return flow throttle 37 which opens as a result in the blood flow direction 50.

[0208] At the same time, the direction of movement 47, 48 of the active surface 31 and the membrane 33 leads to a reduction in the volume of the pressure chamber 24, whereby a designated gas flow (not shown) flows in the gas flow direction 51 through the open gas outlet valve 29 from the pressure chamber 24 into the gas outlet 27 and from there further downstream in the gas outflow direction 52 leaves the drive unit 23.

[0209] The switching device 60 in Figure 3 essentially consists of an upper switching part 61, a lower switching part 62 and the magnets 66, 67, 68, 69.

[0210] The upper switching part 61 and the lower switching part 62 respectively connect the gas inlet valve 63 and the gas outlet valve 64 on the upper and lower sides of the gas inlet valve 63 and the gas outlet valve 64.

[0211] The position of the gas inlet valve 63 and the gas outlet valve 64 determines into which of the pressure chambers 71, 72 a designated gas flow (not shown) flows in or out and is switched via the switching device 60.

[0212] Magnets 66 and 69 with different polarizations are located in the pressure chamber 71. Magnet 66 is connected to the upper switching part 61. Magnet 69 is connected to the active surface 65 and therefore moves with the active surface 65. Since the active surface 65 is connected to the active surface 70 via the coupling rod 73, the coupling rod 73 and the active surface 70 also move in unison.

[0213] Magnets 67 and 68 with different polarizations are located in the pressure chamber 72. Magnet 67 is connected to the lower switching part 62. Magnet 68 is connected to the active surface 70 and therefore moves with the active surface 70. Since the active surface 70 is connected to the active surface 65 via the coupling rod 73, the coupling rod 73 and the active surface 65 also move in unison.

[0214] Magnets 66, 69 and magnets 67, 68 each have a different polarization and therefore attract each other. The attractive force of magnets 66, 69 and magnets 67, 68 depends on the distance between the respective magnets. When magnets 66, 69 or magnets 67, 68 touch, their respective attractive forces are greatest.

[0215] Due to the arrangement of the magnets 66, 67, 68, 69 in combination with the design of the switching device 60 and the attractive force emanating from the magnets 66, 67, 68, 69, Figure 2 The already described kinematics of the blood pump 20 with switching device 60 achieves a bistable design of the switching device 60, so that bistable switching states are possible.

[0216] The embodiment of a coupling rod arrangement 80 with valve and bypass in Figure 4 (left partial figure shows the embodiment of the coupling rod arrangement 80 with closed valve 81, right partial figure shows the embodiment of the coupling rod arrangement 80 with open valve 81) essentially consists of a valve 81, a coupling rod 82 and a bypass 83.

[0217] The coupling rod 82 has an upper coupling rod component 84 and a lower coupling rod component 85. The upper coupling rod component 84 is firmly connected to the active surface 86. The lower coupling rod component 85 is firmly connected to the active surface 87.

[0218] The upper coupling rod component 84 and the lower coupling rod component 85 are pressed together by a spring 88 at the location of the valve 81. If a force acts on the active surfaces 86, 87 that is greater than the spring force and acts in the opposite direction to the spring force, the valve 81 opens (right-hand part of the figure).

[0219] The upper coupling rod component 84 is hollow inside and has bores 89, 90, which can connect the cavity 91 of the upper coupling rod component 84 with the pressure chamber 92. The arrangement of the bores 89, 90 is designed such that they only expose the cavity 91 of the upper coupling rod component 84 with the pressure chamber 92 when the pressure chamber has more than 50% of its nominal pressure chamber volume.

[0220] The lower coupling rod component 85 is hollow inside and has bores 93, 94, which can connect the cavity 95 of the lower coupling rod component 85 with the pressure chamber 96. The arrangement of the bores 93, 94 is designed such that they only expose the cavity 95 of the lower coupling rod component 85 with the pressure chamber 96 when the pressure chamber has more than 50% of its nominal pressure chamber volume.

[0221] In particular, the coupling rod 82 is designed such that, in no state, do the bores 89, 90 simultaneously connect the cavity 91 of the upper coupling rod component 84 with the pressure chamber 92, and the bores 93, 94 simultaneously connect the cavity 95 of the lower coupling rod component 85 with the pressure chamber 96. This ensures that the cavities 91, 95 of the coupling rod 82 do not equalize the pressure between the pressure chambers 92, 96. In particular, such pressure equalization is excluded.

[0222] If a force 99, 100 acts on the active surfaces 86, 87 that is greater than the spring force and acts in the opposite direction to the spring force, the valve 81 opens (right-hand part of the figure). If the pressure chamber 96 has more than 50% of its nominal pressure chamber volume, a designated gas stream (not shown) flows from the pressure chamber 96 in the gas flow direction 97, 98 through the bore 93, 94 into the cavity 95, through the open valve 81, and further downstream into the bypass 83.

[0223] Alternatively (not shown), a designated gas flow (not shown) flows from the pressure chamber 92 in the gas flow direction (not shown) through the bore 89, 90 into the cavity 91, through the open valve 81 and further downstream into the bypass 83, provided that the force 99, 100 on the active surfaces 86, 87 is greater than the spring force, acts in the opposite direction to the spring force and the pressure chamber 92 has more than 50% of its nominal pressure chamber volume.

[0224] The blood pump 110 in Figure 5 consists essentially of the blood chambers 111, 112 and a drive unit 113.

[0225] The blood chambers 111, 112 each have a blood inlet channel (not shown) and a blood outlet channel 114, 115.

[0226] The drive unit 113 has a gas inlet 116, a gas outlet 117 and a bypass 118, so that a designated gas flow (not shown) can flow into the drive unit 113 in the gas inflow direction 119 through the gas inlet 116 and flow out through the gas outlet 117 in the gas outflow direction 120.

[0227] If the valve 81 inside the drive unit 113 opens, a designated gas flow (not shown) can flow out of the drive unit 113 through the bypass 118.

[0228] The bypass 118 has a closure device 121 which makes it possible to open the bypass 118 so that a designated gas flow (not shown) can flow through the bypass when the valve 81 is opened, to close it so that a designated gas flow (not shown) cannot flow through the bypass when the valve 81 is opened, or to throttle it so that a designated gas flow (not shown) can only flow through the bypass in a throttled manner when the valve 81 is opened.

[0229] The connection area 130 in Figure 6 (left part of the figure and right part of the figure show alternative blood flow paths) consists essentially of the blood outlet channels 131, 132, which meet in the connecting area 130, the blood discharge 133 to the patient (not shown) and a backflow throttle 134.

[0230] A designated blood flow (not shown) can flow out of the blood pump 136 through the blood outlet channel 131 in the blood flow direction 135, then further downstream encounters the connecting region 130, through which the blood flows in the blood flow direction 137, and the return flow restrictor 134, which the blood flows through in the blood flow direction 137. Further downstream, the designated blood flow (not shown) flows from the connecting region 130 in the blood flow direction 138 through the blood discharge 133 back to the patient (not shown).

[0231] A designated blood flow (not shown) can flow out of the blood pump 136 through the blood outlet channel 132 in the blood flow direction 139, then further downstream encounters the connecting region 130, through which the blood flows in the blood flow direction 140, and the return flow restrictor 134, which the blood flows through in the blood flow direction 140. Further downstream, the designated blood flow (not shown) flows from the connecting region 130 in the blood flow direction 141 through the blood discharge 133 back to the patient (not shown).

[0232] The backflow restrictor 134 prevents or dampens any backflow of a designated blood flow (not shown) through the blood outlet channel 131, 132 not connected to the blood-displacing blood chamber (not shown) of the blood pump 136.

[0233] A blood chamber unit 150 in Figure 7(left part of the figure shows a displacement of blood from the blood chamber, right part of the figure shows a suction of blood into the blood chamber) essentially consists of a blood chamber 151, a blood inlet channel 152, a blood outlet channel 153 and a backflow throttle 154.

[0234] When a designated blood flow (not shown) is displaced, the designated blood flow (not shown) flows out of the blood chamber 151 through the blood outlet channel 153 in the blood flow direction 155. This results in a circulating movement 156 of the designated blood flow (not shown) in the blood chamber 151.

[0235] When displacing a designated blood flow (not shown) from the blood chamber 153, the backflow restrictor 154 prevents or restricts the outflow of a designated blood flow (not shown) from the blood chamber 151 through the blood inlet channel 152.

[0236] When a designated blood flow (not shown) is sucked in, the designated blood flow (not shown) flows through the blood inlet channel 152 in the blood flow direction 157 and through the return flow throttle 154 into the blood chamber 151. List of reference symbols used

[0237] 1 Heart-lung machine 2 Blood pump 3 Oxygenator 4 Supply unit 5 Drive unit 6 Blood chamber 7 Blood chamber 8 Blood flow inlet direction 9 Blood supply 10 Flow divider 11 Blood inlet channel 12 Blood inlet channel 13 Blood outlet channel 14 Blood outlet channel 15 Connection area 16 Blood flow direction 17 Blood flow direction 18 Blood discharge 19 Gas supply 20 Blood pump 21 Blood chamber 22 Blood chamber 23 Drive unit 24 Pressure chamber 25 Pressure chamber 26 Gas inlet 27 Gas outlet 28 Gas inlet valve 29 Gas outlet valve 30 Coupling rod 31 Effective area 32 Effective area 33 Membrane 34 Membrane 35 Blood inlet channel 36 Blood inlet channel 37Backflow throttle 38Backflow throttle 39Blood outlet channel 40Blood outlet channel 41Gas inflow direction 42Gas flow direction 43Direction of movement 44Direction of movement 45Blood flow direction 46Blood flow direction 47Direction of movement 48Direction of movement 49Blood inflow direction 50Blood flow direction 51Gas flow direction 52Gas outflow direction 60Switching device 61Upper switching part 62LowerSwitching part 63 Gas inlet valve 64 Gas outlet valve 65 Effective area 66 Magnet 67 Magnet 68 Magnet 69 Magnet 70 Effective area 71 Pressure chamber 72 Pressure chamber 73 Coupling rod 80 Coupling rod assembly 81 Valve 82 Coupling rod 83 Bypass 84 Upper coupling rod component 85 Lower coupling rod component 86 Effective area 87 Effective area 88 Spring 89 Bore 90 Bore 91 Cavity 92 Pressure chamber 93 Bore 94 Bore 95 Cavity 96 Pressure chamber 97 Gas flow direction 98 Gas flow direction 99 Force 100 Force 110 Blood pump 111 Blood chamber 112 Blood chamber 113 Drive unit 114 Blood outlet channel 115Blood outlet channel 116Gas inlet 117Gas outlet 118Bypass 119Gas inflow direction 120Gas outflow direction 121Closing device 130Connecting area 131Blood outlet channel 132Blood outlet channel 133Blood discharge 134Backflow throttle 135Blood flow direction 136Blood pump 137Blood flow direction 138Blood flow direction 139Blood flow direction 140Blood flow direction 141Blood flow direction 150Blood chamber unit 151Blood chamber 152Blood inlet channel153Blood outlet channel 154Return flow restrictor 155Blood flow direction 156Circulation movement 157Blood flow direction

Claims

1. Extracorporeal blood pump for aspiration and displacement of blood, wherein the blood pump has one or two blood chambers and a mechanical drive unit, each of the blood chambers having a membrane, a blood inlet channel and a blood outlet channel, - wherein in the case of the blood pump with one blood chamber, the drive unit is adjacent to the blood chamber, wherein the drive unit has a gas inlet and a gas outlet as well as two pressure chambers, wherein each pressure chamber has an active surface, wherein a blood chamber is separated from a pressure chamber via a membrane, wherein the drive unit is actively connected to the position of the membrane, and wherein an area between the active surface and the membrane has a coupling rod which is designed to couple the movement of the active surface and the membrane to one another; - wherein in the case of the blood pump with two blood chambers, the drive unit is arranged between the blood chambers, the blood outlet channels of both blood chambers are connected to one another and an area between the membranes has a coupling rod which is designed to couple the movement of the two membranes to one another, whereby the drive unit has a gas inlet and a gas outlet as well as a pressure chamber, wherein the pressure chamber is separated from a blood chamber via a membrane, wherein the drive unit is actively connected to the position of the membrane.

2. Extracorporeal blood pump according to claim 1, characterised in that the blood inlet channels of both blood chambers are connected to one another.

3. Extracorporeal blood pump according to one of claims 1 or 2, characterised in that a connecting area of the blood outlet channels has a return flow throttle.

4. Extracorporeal blood pump according to one of the preceding claims, characterised in that the drive unit has two pressure chambers, each pressure chamber being adjacent to a blood chamber via a membrane.

5. Extracorporeal blood pump according to one of the preceding claims, characterised in that a blood chamber has a rotationally symmetrical area.

6. Extracorporeal blood pump according to one of the preceding claims, characterised in that a blood inlet channel and a blood outlet channel are predominantly arranged in the circumferential direction in the rotationally symmetrical area of a blood chamber.

7. Extracorporeal blood pump according to one of the preceding claims, characterised in that a blood inlet channel has a return flow throttle.

8. Extracorporeal blood pump according to one of the preceding claims, characterised in that the drive unit has a gas inlet valve and a gas outlet valve as well as a switching device, wherein the gas inlet valve and the gas outlet valve have a closed position and an open position with respect to a gas flow path, wherein the switching device has two switching end states, in particular the switching device has exactly two switching states.

9. Extracorporeal blood pump according to claim 8, characterised in that a switching end state for a blood chamber has the gas inlet valve in the open position and the gas outlet valve in the closed position or the gas inlet valve in the closed position and the gas outlet valve in the open position.

10. Extracorporeal blood pump according to one of claims 8 or 9, characterised in that the switching device has a magnet.

11. Extracorporeal blood pump according to one of claims 8 to 10, characterised in that the switching device has a lever mechanism.

12. Extracorporeal blood pump according to one of claims 8 to 11, characterised in that the switching device has a gate to a spring-loaded roller.

13. Extracorporeal blood pump according to one of the preceding claims, characterised in that the coupling rod has a cavity inside.

14. Extracorporeal blood pump according to one of the preceding claims, characterised in that the coupling rod has a first component and a second component, wherein the first component and the second component are connected with a spring.

15. Extracorporeal blood pump according to one of the preceding claims, characterised in that the coupling rod has a valve which is designed to allow a designated gas flow to flow through the cavity in the coupling rod and then through the valve in the coupling rod and via a bypass out of a pressure chamber.

16. Extracorporeal blood pump according to claim 15, characterised in that the bypass has a closure device.

17. Heart-lung machine for pumping and processing blood, wherein the heart-lung machine has a blood supply and a blood discharge, characterised in that the heart-lung machine has a blood pump according to one of the preceding claims.

18. Heart-lung machine according to claim 17, characterised in that the heart-lung machine has an oxygenator.

19. Heart-lung machine according to one of claims 17 or 18, characterised in that the heart-lung machine has a dialyser.

20. Heart-lung machine according to one of claims 17 to 19, characterised in that the heart-lung machine has a filter.

21. Heart-lung machine according to one of claims 17 to 20, characterised in that the heart-lung machine has a gas supply, in particular an oxygen supply.