Control for non-occlusive blood pumps

Abstract

The invention relates to an open- and closed-loop control unit for a non-occlusive blood pump for extracorporeal circulation support and to a system comprising such an open- and closed-loop control unit and to a corresponding method. Thus, an open- and closed-loop control unit (48) for a non-occlusive blood pump (40) for extracorporeal circulation support is proposed, which is configured to receive a flow value (10) for extracorporeal circulation support, to receive a measurement of an arterial pressure (12) of a supported patient (38) over a predetermined time period and an ECG signal (14), to determine a mean arterial pressure (16) for extracorporeal circulation support or of a supported patient from the measurement of the arterial pressure (12) and to determine an energy equivalent pressure (18) from the flow value (10) and the arterial pressure (16). The open- and closed-loop control unit (48) is further configured to determine a required value (14) of at least one pulse parameter (20) of the blood pump (40) from the mean arterial pressure (16), the energy equivalent pressure (18) and the ECG signal to achieve a ratio of the energy equivalent pressure (18) to the mean arterial pressure (16). The ratio is greater than 1.0. The control unit (48) is further configured to adjust the pulse parameter (20) from the ECG signal (14).

Description

TECHNICAL FIELD

[0001] The present invention relates to a control unit for a non-occlusive blood pump for extracorporeal circulation support and to a system comprising such a control unit and to corresponding program steps. BACKGROUND

[0002] If the pumping capacity or the pumping function of the heart fails, cardiogenic shock can occur, due to a reduced cardiac output or ejection volume, which can generally lead to a reduced perfusion or blood flow to end organs such as the brain, the kidneys and the vascular system. This acute heart failure leads to an acute blood deficiency of the tissue and organs, which leads to an oxygen deficiency, also called hypoxia, which can lead to damage to the end organs. In most cases, this cardiogenic shock occurs as a complication of an acute myocardial infarction (AMI: Acute Myocardial Infarction) or heart attack, and is therefore one of the most common causes of death in myocardial infarction. In Germany alone, around 350,000 people are affected by myocardial infarction every year, of which around 10% develop cardiogenic shock.

[0003] Furthermore, cardiogenic shock can be a complication of surgical treatment, for example bypass surgery, or can be due to insufficient or impaired lung function and conduction system dysfunction, structural heart disease or myocardial inflammatory processes. Despite factors such as early revascularization, administration of positive inotropic drugs and mechanical support, the mortality rate for cardiogenic shock remains above 50%.

[0004] In order to improve the patient's condition, circulation or life support systems have been developed which provide mechanical support and can be quickly connected to the circulation to improve blood flow and perfusion of organs including the coronary arteries of the heart and to prevent hypoxic states. For example, a system has been developed in which a balloon is introduced invasively into the aortic region and is controlled so as to be rapidly inflated with, for example, helium gas during the diastolic phase of the cardiac cycle, in order to improve blood flow to the myocardial tissue at this stage. This system is known under the term "Intra-Aortic Balloon Counterpulsation" (IABP). However, the effect of this system is very limited, in particular because only blood which is not sufficiently oxygenated during cardiogenic shock is transported into the coronary arteries. Therefore, compared to a drug setting using, for example, positive inotropic drugs or catecholamines, this procedure does not provide a significant improvement.

[0005] Furthermore, extracorporeal support systems are known, which are based on the fact that blood is taken from, for example, the right atrium or the vena cava through a cannula that has been inserted into the femoral vein and returned to the patient by means of a perfusion cannula inserted into the femoral artery via a membrane ventilator, wherein the membrane ventilator decarburizes, i.e. removes carbon dioxide, and oxygenates the blood. Such a system is also known by the term "extracorporeal membrane oxygenation" (ECMO).

[0006] Although this improves the perfusion of the organs, the perfusion is continuous both in systole and diastole, so that this arrangement causes a retrograde blood flow opposite to the actual ejection direction of the heart, thereby increasing the afterload. In this way, the heart is less hindered in its ejection and emptying, while the heart has to do more muscle work, so that the oxygen supply needs to be increased. This is particularly disadvantageous for a heart that has already been damaged by a myocardial infarction. Therefore, such a system is primarily used in the case of cardiac arrest or deliberate bypass of the patient's own heart capacity, for example during surgical applications or interventions. In order to reduce the afterload of a beating heart, the patient can also be given medication by administering so-called vasopressors, which dilate or widen the blood vessels, thereby reducing the resistance and the afterload. However, in these cases, the existing cardiac output of the patient is not therapeutically supported, but is replaced by the system.

[0007] Furthermore, the blood flow of the heart's coronary arteries, which normally supplies the myocardium with sufficient oxygen, usually occurs in the diastolic phase of the cardiac cycle and thus depends on the corresponding emptying of the left ventricle. If the filling pressure of the left ventricle at the end of systole or at the beginning of diastole is as low as possible, the coronary arteries can dilate their lumen as much as possible in order to increase the blood flow rate and the oxygen supply. The percutaneous femoral-femoral connection of the extracorporeal circulation system and the resulting retrograde blood flow reduces the emptying of the left ventricle, so that this system is also disadvantageous for the perfusion of the coronary arteries. Furthermore, the flow rate of the blood pump can be adjusted in such a way that the blood flow closes the aortic valve. Because the blood is also pumped from the pulmonary veins via the right atrium into the left ventricle and can not escape, the pressure in the left ventricle is further increased in this case, which can further reduce the perfusion of the coronary arteries. In other words, the auxiliary perfusion, which is beneficial for the end organs, has an adverse effect on the coronary artery perfusion.

[0008] Another problem of many mechanical support systems is that they do not provide a blood flow that corresponds to normal physiological blood flow, i.e. a pulsatile blood flow. Although systems employing pulsatile or non-occlusive blood pumps are known and can improve perfusion of end organs, the negative impact on afterload and the corresponding reduction of coronary perfusion has not been sufficiently addressed so far. The possibility to provide sufficient perfusion of end organs and at the same time to improve coronary perfusion is very limited due to also variable high heart rates and corresponding short duration of the respective phase. At best, the usually low blood flow or the short pulsatile perfusion is adjusted or set to account for possible fluctuations, but this is a fixed setting and does not allow for an optimized perfusion according to the physiological state.

[0009] Therefore, there is a need to optimize the characteristics of the blood flow provided by a blood pump in such a way that it adapts to the physiological condition of the patient and provides an optimization of the perfusion of end organs and coronary arteries. SUMMARY

[0010] Based on this technical background, it is an object of the present application to be able to improve the perfusion of coronary arteries during extracorporeal circulation support.

[0011] The object is achieved by the solution of the present application. Preferred embodiments are defined in the description and the drawings.

[0012] Therefore, a control unit for a non-occlusive blood pump for extracorporeal circulation support is proposed, the control unit being configured to receive a flow value of the extracorporeal circulation support, to receive a measurement of an arterial pressure of a supported patient over a predetermined time period and an ECG signal, to determine a mean arterial pressure of the extracorporeal circulation support or of the supported patient from the measurement of the arterial pressure and to determine an energy equivalent pressure from the flow value and the arterial pressure, and to determine a required value of at least one pulse parameter of the blood pump from the mean arterial pressure, the energy equivalent pressure and the ECG signal to achieve a ratio of the energy equivalent pressure to the mean arterial pressure being greater than 1.0. The control unit is further configured to set the pulse parameter from the ECG signal.

[0013] For example, the control unit can control one or more pump drives or pump heads of a non-occlusive blood pump present in an extracorporeal circulation or life support system.

[0014] The blood pump can be arranged for oxygen enrichment and decarboxilation, i.e. removal or reduction of carbon dioxide, of the blood. For example, the blood pump can be fluidly connected with an oxygenator or a membrane fan provided in an extracorporeal circulation support system, e.g. connected to a venous access by a venous cannula or to an arterial access by an arterial cannula, for pumping or facilitating blood circulation in order to provide blood flow from a side of lower pressure to a side of higher pressure. In this way, an extracorporeal oxygen enrichment and improved oxygen supply of the blood for a patient can be provided. These features can be further improved by a non-occlusive blood pump with pulsatile characteristics and by an energy equivalent pressure to mean arterial pressure ratio, in particular in view of perfusion of coronary arteries and target organs. By setting a predetermined ratio, the control unit is independent of a defined or predetermined value of the pulse parameter. In particular, the pulse parameter can be directly adjusted and optimized to physiological requirements of the respective patient.

[0015] For example, the non-occlusive blood pump can be magnetically coupled to a pump drive of an electric motor to allow torque transfer. A centrifugal pump, such as a rotor pump or an impeller pump, can be used as a non-occlusive blood pump, e.g. a centrifugal pump or a semi-axial pump, also referred to as a diagonal pump. While a centrifugal pump can generate high pressure at low flow rates, a diagonal pump can generate high flow rates at low pressure, which meets general requirements of a pulsatile blood pump system, in particular for extracorporeal circulation support and respiratory support of cardiogenic shock. For example, by providing high flow rates at low pressure heads quickly, an improved and more precise synchronization based on ECG signals can be achieved.

[0016] In contrast to a roller pump or an occlusive blood pump, a rotor pump can not build up pressure and release pressure at a given point in time. However, by varying the rotational speed of the rotor blades or impeller, a low pressure can be built up, which is transferred forward as flow, and has the advantage of precise pulsation without additional components such as valves. Furthermore, due to the small size of the rotor blades / impeller, low inertia can be achieved, so that very precise control and precise pulse transfer at any rotational speed can be achieved.

[0017] Since human organs and cells naturally detect and process dynamic flow and pressure changes, they also react differently to different flow profiles. In particular, in the vascular endothelium, which forms the innermost layer of blood vessels, mechanical transduction and signal transmission occur in response to shear stress and pulse pressure, regulating functions such as apoptosis, angiogenesis, atherosclerosis and systemic blood pressure. In this regard, the non-occlusive blood pump has the additional advantage of providing pulsatile blood flow, which reduces mechanical and / or thermal stress on blood cells, in particular prevents destruction of red blood cells and activation of platelets.

[0018] In general, pulsatile blood flow also improves microcirculation in vital organs, improves vascular compliance, reduces positive inotropic support, increases cerebral oxygen saturation, increases urine excretion and reduces gastrointestinal bleeding rates, which generally leads to a reduction in the time a patient spends in the hospital.

[0019] The blood pump can be connected to the venous access by means of a venous cannula and to the arterial access by means of an arterial cannula for pumping or conveying blood, thereby providing blood flow from the low pressure side to the high pressure side. The blood pump is preferably formed as a disposable or single-use item and fluidically separated from the corresponding pump drive and can be easily coupled, for example, via a magnetic coupling. The control unit actuates the motor of the pump drive and is configured to be able to adjust the speed of the rotor blades of the blood pump such that the blood pump generates a wavy flow corresponding to pulsatile blood flow.

[0020] Furthermore, the pulse amplitude can be defined by varying the rotational speed, which can be input at the control unit and optionally added to the basic flow. For example, the basic flow can be predefined, wherein the respective pulse causes an increase in the total blood flow. This results in an average flow which is calculated by the control unit accordingly. For example, the blood pump can be configured to provide a blood flow of between approximately 0.1 l / min and approximately 8 l / min at a speed of between approximately 50 RPM and approximately 10,000 RPM, wherein the pulsatile flow is obtained by a rotational speed variation. Preferably, a blood flow of between approximately 0.5 l / min and approximately 5.0 l / min, for example between 1 l / min and 2.5 l / min, in order to prevent coagulation and an increase in afterload and to achieve the desired flow to provide sufficient organ oxygenation, i.e. a sufficient number of oxygen-saturated red blood cells.

[0021] A further advantage of pulsatile blood flow is the generation of pulse energy, which is generated by the change in pressure over time with respect to the flow gradient. Thus, by multiplying the respective integrals, the hemodynamic work is obtained, which, divided by the flow integral, gives the energy equivalent pressure, also known as "Energy Equivalent Pressure" (EEP). The ratio is mathematically expressed by the following formula:

[0022]

[0023] wherein the blood flow (f) and the pressure (p) are considered over a time interval from ti to t2.

[0024] The energy-equivalent pressure corresponds to the blood pressure of the patient and is based on the idea that the hemodynamic energy is transmitted from the aortic root to the periphery by axial movement of the blood flow and elastic movement of the aortic wall. Thus, the energy-equivalent pressure can also be transformed into surplus hemodynamic energy, also referred to as "Surplus Hemodynamic Energy" (SHE), which preferably represents the energy of a single pulse and corresponds to the additional energy generated by the pulsatile flow in relation to the non-pulsatile or basal flow. Thus, both the energy-equivalent pressure and the surplus hemodynamic energy provide a quantifiable measure for the support of the circulation and / or the heart.

[0025] In order to improve the constant blood flow and to increase the blood pressure of the patient, the energy-equivalent pressure should be higher than the mean arterial pressure (MAP). In other words, a ratio of the energy-equivalent pressure to the mean arterial pressure of at least 1.0 or greater than 1.0 (e.g., > 1.0 and < 1.25) would result in providing physiological blood flow. Thus, a pulse contribution is calculated that results in an increase of the mean arterial pressure. For example, the pulse contribution can be at least 5 mmHg and preferably lies in a range of approximately 10 mmHg to 20 mmHg. Thus, the pulse provided by the control unit should be understood as a physiological or quasi-physiological pulse.

[0026] For example, due to the pulsatile blood flow or the pulsatility of the blood pump, the energy-equivalent pressure can even be higher compared to a constant blood flow at the same mean arterial pressure, such that an improved blood flow is provided to the distal blood vessels. Thus, the difference in the energy-equivalent pressure is an indicator for the higher mean pressure that is required for the non-pulsatile flow to generate the same blood flow.

[0027] Correspondingly, the energy-equivalent pressure can be determined by the control unit, wherein the flow value provided by the blood pump can be manually entered, e.g., via the rotational speed of the rotor blades, and only a measurement of the arterial pressure is required. The mean arterial pressure can also be determined by averaging these values.

[0028] The arterial pressure is preferably input into the control unit via an interface in communication with at least one pressure sensor. Preferably, the pressure measurement is carried out upstream of the blood pump, downstream of the blood pump and / or downstream of an oxygenator or a membrane ventilator arranged in the extracorporeal circulation system and connected to the blood pump. The pressure measurement of the arterial pressure of the supported or assisted patient is preferably carried out in the patient's body, for example at the tip of an arterial cannula, for example in the patient's aorta, or by means of another pressure measurement probe which can be positioned at any preferred location in the aorta. Alternatively, the measurement can also be carried out on the femoral artery and / or the iliac artery or the radial artery. Furthermore, the pressure measurement can also be carried out using a non-invasive pressure sensor (without direct blood contact) or an invasive pressure measurement with blood contact at the tube end or at the arm of the patient set.

[0029] The flow value and the arterial pressure can be detected in a non-invasive manner and can be received by the control unit, for example by detecting the flow value via the speed of the rotor blades and / or by detecting the arterial pressure from the patient via a non-invasive "schlauchschenkel" or in the extracorporeal circulation system. The circulation system can be configured in a compact manner and can reduce its complexity. For the patient, this means that the size of the inserted cannula can be smaller and the surgical intervention can be carried out in a less invasive manner.

[0030] From the determined energy equivalent pressure and the determined mean arterial pressure, the control unit can determine a corresponding ratio and adjust the pulse parameters of the blood pump accordingly in order to achieve a desired ratio greater than 1.0. This can be carried out iteratively and preferably continuously, so that the influence of the changed blood pump pulse parameters on the patient's physiological condition is taken into account and the relationship between the energy equivalent pressure and the mean arterial pressure is not dependent on a fixed value of the pulse parameters and can therefore be optimized.

[0031] The preferred ratio is greater than 1.1 in order to further improve the therapeutic support of the patient. For example, a determined ratio of 1.0 can require an increase in the energy equivalent pressure and / or a decrease in the mean arterial pressure and a first change in the pulse parameters can result in a ratio of 1.05, while a second change in the pulse parameter values can result in a ratio of 1.15, so that no further change in the pulse parameters is required. Furthermore, the ratio can also be 1.15 to 1.25, for example approximately 1.2, for example during resuscitation of the patient when the mean arterial pressure of the patient is in the lower range, for example in the case of a cardiac arrest.

[0032] Furthermore, the value of the pulse parameter is also adjusted based on an ECG signal, preferably a heart rate. Preferably, the ECG signal is a characteristic ECG signal that allows the control unit to synchronize with the blood pump, so that the signal corresponding to the value of the pulse parameter can be output periodically or cyclically from the control unit to the pump drive or the blood pump. For example, the ECG signal or the corresponding region in the electrical excitation system can be characteristic of the systole or diastole of the heart, so that the setting or adjustment of the pulse parameter and the actuation of the motor can take place at predetermined points in time and at predetermined phases, and without any overlap with other phases.

[0033] By synchronizing the pulses with the ECG signal, a pulsatile blood flow is provided that corresponds to the cardiac cycle of the patient. This allows the pulse rate of the blood pump to be adjusted to the heart rate of the patient and, if necessary, to other physiological parameters of the patient, so that, for example, in the case of tachycardia, the pulse parameters can be changed so that the pulses do not overlap or interfere with the phase of the unintended pulses of the cardiac cycle. However, the required ratio between the energy equivalent pressure and the mean arterial pressure still ensures sufficient perfusion of the coronary arteries and end organs within the physiological limits and the pumping properties.

[0034] In comparison to known ECMO systems with continuous blood flow, physiological blood flow and adaptation to the patient's cardiac cycle can be achieved according to the application, and the afterload, i.e. the residual pressure in the aortic region before or during systole, can be kept as low or not increased as possible.

[0035] Furthermore, the pulsatile flow also provides a higher mean arterial pressure and a higher energy equivalent pressure compared to constant or continuous flow and improves the surplus hemodynamic energy. As a result, a higher systemic blood pressure and less positive inotropic support is obtained. This not only improves the perfusion of the coronary arteries and end organs, but can also provide an improved oxygen supply, for example when an oxygenator or a membrane ventilator is provided in the extracorporeal circulation support system. This leads to a relief and recovery of the myocardial tissue that is improved compared to known IABP systems that do not provide any or possibly insufficient extracorporeal circulation support.

[0036] The at least one pulse parameter preferably includes a pulse amplitude, a pump speed or rotational speed, a pump speed change per unit of time, a pulse duration, a systolic pump duration, a diastolic pump duration, a drive wheel deceleration, a drive wheel acceleration, a mean pump flow, a basal flow and / or a peak flow.

[0037] For example, the pulse amplitude and the pump speed can be used to specify the maximum blood flow during the pulse, thereby specifying the average flow. The pump speed is preferably optimized to a maximum value depending on the determined ratio between the energy equivalent pressure and the mean arterial pressure in order to obtain or achieve the desired pulse amplitude. For example, the pulse amplitude can be provided by varying the pump speed, wherein the variation of the pump speed can have a value between 50 rpm and 10,000 rpm, preferably between 1000 rpm and 5000 rpm, particularly preferably between 3000 rpm and 4000 rpm. Thus, the pulsatile blood flow can provide a sufficient average flow, for example between approximately 2 and 3 l / min. The pump speed variation can also optionally be added to the basic flow, wherein the maximum pump speed obtained is defined by the basic speed, the pump speed variation per time unit and the pulse duration.

[0038] Furthermore, the pulse can also be defined by a pulse duration, wherein the pulse duration is preferably between 20 ms and 400 ms. For example, the pulse duration can be approximately 200 ms to provide a sufficient pulse at a normal heart rate. The pulse comprises a systolic pump duration and a diastolic pump duration in which the drive wheel acceleration or the drive wheel deceleration occurs. These phases of the pulse duration can be symmetrical, such that the systolic phase covers approximately 50% of the pulse duration, for example 100 ms.

[0039] However, the systolic phase can also be adapted to the pulse duration, for example if the pulse duration is shortened due to an increased heart rate and the systolic phase is extended even in the case of a shortened pulse duration to provide a sufficient pulse. In this case, the pulse duration is asymmetrical, for example the systolic phase comprises approximately 60% or approximately 70% of the pulse duration. In order to prevent an increased blood flow even after the pulse duration, the drive wheel deceleration can also be increased during the diastolic phase. Conversely, the drive wheel acceleration can also be increased during the systolic phase to provide a shorter systolic phase and a sufficient speed adjustment. In this case, for example, the systolic phase can comprise approximately 30% or approximately 40% of the pulse duration.

[0040] Thus, the blood pump can also be controlled or regulated in shorter time intervals, thereby providing a sufficient perfusion without an undesired overlap of the pulse with a specific phase of the cardiac cycle. Thus, this can reduce or even prevent an undesired afterload.

[0041] To further increase the pulse duration and the pulse energy, the speed reached during the pulse can be passively decelerated (without active braking) or actively braked. For example, in the case of active braking, a four-quadrant control can be provided, in which four transistors are arranged mirror-symmetrically and form an H-bridge with one p-channel and one n-channel. The respective activation of the transistors enables the reversal of the current direction by means of a brushless DC motor, so that the motor of the pump drive can be switched in both opposite directions and deceleration can accordingly be actively achieved by means of a reversal of the current direction.

[0042] Furthermore, the blood pump can also be controlled in such a way that a negative blood flow is achieved at the end of the pulse. This causes a suction to occur, for example, which is synchronized in such a way that it occurs during the systole in order to further reduce the afterload.

[0043] The cardiac ejection volume, which can be determined by means of an impedance measurement, can also be provided as a further guiding variable for the pulse. For example, the impedance can be determined using a pressure sensor provided in the extracorporeal circulation support system, for example an integrated pressure sensor, or by measuring the impedance in the chest region of the patient using a transcutaneous sensor or a probe placed in the esophagus.

[0044] The required values of the pulse parameters can also be determined depending on a predefined mean arterial pressure and / or a predefined energy equivalent pressure. Alternatively or additionally, this can be determined depending on a measured cardiac ejection volume, stroke volume and / or ejection fraction.

[0045] For example, predefined threshold values can be stored in the control unit, which correspond to basic values of vital parameters or physiological conditions of the patient. In other words, physiological limits for the energy equivalent pressure and the mean arterial pressure can thus be provided, which can be absolute values and / or patient-specific values. For example, the mean arterial pressure can be predefined by the dosage of catecholamines and / or the body volume or body weight of the supported patient. Furthermore, for example, a high heart rate of the supported patient can require a reduction of the mean arterial pressure, so that the pulse parameters are limited to a corresponding maximum energy equivalent pressure. These values can still be actively defined by current measured values of vital parameters, for example via an interface with a communicatively connected ECG device.

[0046] In order to receive the required flow value for the energy equivalent pressure, the control unit can also be configured to be able to determine the flow value depending on an input blood pump speed or automatically based on received flow measurement values.

[0047] For example, the pump flow value can correspond to a certain speed, so that the speed entered via the user interface of the control unit will define the pump flow value. Preferably, however, the pump flow value is measured by a flow sensor, so that the currently measured flow speed is received by the control unit to determine the energy equivalent pressure. Since the flow value can still differ for each patient for a predefined speed, the flow sensor can be arranged, for example, in the arterial cannula, in the cannula tip of the venous cannula and / or in the line between the blood pump and the respective tip, so that the flow value can be accurately measured.

[0048] The flow value preferably comprises a patient-specific mean flow, wherein the control unit can also be configured to adjust the mean flow by setting or adjusting the pulse parameters based on the received flow measurement and the mean arterial pressure.

[0049] As described above, the medium flow can be provided, for example, by increasing the rotational speed and the corresponding pulse amplitude. However, since the physiological state and the pathophysiological state of each patient differ, a patient-specific mean flow can be required for each patient. In addition to the flow measurement, which can be provided as described above by a flow sensor arranged in the extracorporeal circulation support system, the optimal mean flow for the patient can also be determined from the mean arterial pressure, so that the flow is set by adjusting the pulse parameters, for example, via the speed of the blood pump.

[0050] This enables an automatic adjustment of the blood pump and the extracorporeal circulation support. In addition to the mean arterial pressure and the flow measurement, other important parameters, for example, the heart rate, the age, the pathologies and other physiological values of the patient, can also be taken into account when determining the optimal mean flow.

[0051] The flow, pressure and pulse characteristic parameters can also be controlled by specifying an EEP value. The current EEP value is displayed on the control console display and can be changed to a target EEP. The display can also be made as an EEP percentage value, which refers to the maximum possible EEP value for the individual patient. The maximum EEP value can be determined individually for each patient using a short empirical algorithm.

[0052] In order to achieve the best synchronization of the pulse with the respective phase of the cardiac cycle, the control unit is preferably configured to determine the heart rate from the ECG signal and to set or adjust the pulse parameters depending on the heart rate. For example, the pulse duration of the pulse can thus be adapted to the heart rate, and the motor or the rotor blades can be actuated at times at which they do not collide with the phases of the cardiac cycle.

[0053] Alternatively, the heart rate can also be determined from pressure measurements, pressure curves, pressure changes, cardiac ejection volume, ejection fraction and / or impedance measurements. The pulse parameters or the setting of the pulse parameters can be adapted accordingly to the heart rate of the patient, for example, by changing the pulse duration and adjusting the speed change.

[0054] The pulse parameters can also optionally be adjusted based on the respective pulse frequency. For example, the pulse parameters can also alternatively be set to only every 2nd or 3rd heartbeat, so that if the heart rate exceeds a cut-off frequency, the pulse rate can also be set to a ratio of 1 :2 or 1 :3 instead of a ratio of 1 :1 to the heart rate. The heart rate can be monitored or evaluated over a predetermined period of time, wherein, for example, a short-term increase in the heart rate does not cause a change in the pulse rate and / or a pulse initially reduced can be reset or increased after the heart rate has normalized.

[0055] In particular, the control unit can be configured to determine an amplitude change from the ECG signal and to adjust the pulse parameters at a predetermined time after the amplitude change.

[0056] For example, the trigger signal can be determined as a P-wave, one or more characteristic features of a P-wave, points or segments, or characteristic features of a QRS complex, and the pulse parameters can be adjusted at a predetermined time after the P-wave, the QRS complex or the R-wave. However, other amplitude changes can also be determined, for example, over a predetermined distance section of the ECG signal or from different points of the ECG signal. Preferably, an R-wave is determined from the ECG signal. The pulse parameters can be set at a predetermined time after the detection of the R-wave, for example, after the detection of the maximum amplitude, which is usually with a delay. Furthermore, the amplitude change can be averaged over a predetermined period of time, so that any deviations or changes can be taken into account when setting or adjusting the pulse parameters.

[0057] The R-wave can be determined, for example, from a patient's surface ECG, but it can also be invasive, for example, via a lead at the tip of a venous drainage cannula in the right atrium or superior vena cava, a lead at the tip of an arterial cannula in the aorta or femoral or iliac artery. Furthermore, the ECG signal can be obtained via an invasive oesophageal probe or via non-invasive pressure sensors on the tube arms, for example, integrated pressure sensors (IPS: Integrated Pressure Sensors) integrated into the tube system.

[0058] The R-wave of the QRS-complex read from the ECG signal can then be used as a trigger signal, wherein the setting of the pump signal or pulse parameters takes place after a pre-defined delay. The delay can be chosen such that the pump signal occurs at the time of a short pressure increase in the aorta, which marks the time of aortic valve closure and thus the beginning of the diastole (dicrotic point). By actuating the motor or pump driver and thus the rotor blades and triggering the pulse at said point in time, the pulsatile blood flow can be delivered via the arterial cannula into the area downstream of the left ventricle and into the aorta. The positioning of the cannula tip and the retrograde orientation thus increase the pulsatile blood flow in the coronary arteries and provide the myocardial tissue with an accordingly improved blood flow without impairing the systemic circulation.

[0059] The pressure increase caused by the pulse must, however, be completed at the beginning of the systole in order to prevent overlap. The pulse duration is accordingly limited, but this is not a problem for a normal frequency of the heart rhythm. There can be, for example, about 300 ms between the detected R-wave and the closing of the aortic valve, and the waiting time between the detected R-wave and the output of the pump signal can be about 200 ms, for example between 150 ms and 250 ms, so that the actuation by the output of the pump signal or pulse parameters can be 100 ms. Although the pump signal is given before the aortic valve is closed, the pump signal is preferably output in such a way that the pulse or pressure level is at the cannula tip when the aortic valve is closed, so that the waiting time with regard to the fluid transport time of the used pump and lines can be taken into account.

[0060] The pulse duration can be about 200 ms, for example 100 ms to 300 ms, wherein the systolic phase of the pulse is about 100 ms when the pulse is emitted symmetrically. In order to obtain sufficient perfusion, the pulse amplitude can be chosen by setting the speed variation between 2500 rpm and 4500 rpm, preferably about 3500 rpm.

[0061] However, at increased heart rates, for example 90 to 130 times per minute, these values can cause the pump outflow to collide with the beginning of the systole or heart ejection. In order to prevent this and to optimize the afterload, the pulse amplitude can be chosen, for example, by setting the speed variation between 1500 rpm and 5000 rpm, and the pulse duration can be in the range of 120 ms to 300 ms. The pulse can be asymmetric, with the systole ranging from about 70% to about 90%. Thus, even in the case of higher heart rates, an afterload reduction and sufficient perfusion of the coronary arteries can be provided.

[0062] Thus, due to the pulsatile blood flow and the adjustment or setting of the impulse parameters based on the R-wave of the QRS signal, an improved blood flow to the myocardium and end organs can be provided, wherein the blood pump and the impulse parameters can be fully adapted to the intrinsic heart rhythm of the patient by appropriate configuration of the control unit. In particular, a diastolic augmentation can be achieved by the impulse application without increasing the afterload too much and keeping it at a level as low as possible.

[0063] The diagonal pump is preferably used as blood pump, the advantage of which is that the flow rate or average flow can be lower at higher pressures at least during diastole, and both pressure and flow rate can be increased during diastole. Thus, the residual pressure after the impulse and before the systole is as low as possible, preferably even negative by the respective control. Furthermore, compared to a centrifugal pump, the diagonal pump has the advantage that the impeller has a smaller circumference and a smaller mass to accelerate, so that it can be accelerated and decelerated faster and, due to the smaller mass inertia, the impulse can be adjusted more finely.

[0064] In addition to the received ECG signal, the control unit can also be configured to receive a measurement of the aortic pressure of the supported patient over a predefined time period and to set the impulse parameters at a predefined aortic pressure and aortic pressure change.

[0065] Thus, the aortic pressure can be used as a verification of the predefined impulse delay and / or impulse duration, wherein a latency of the fluid delivery time can be taken into account. In this way, the user of the extracorporeal circulation support can manually set the exact time of the trigger signal and adjust it to the measured aortic pressure or cardiac output. However, the measured aortic pressure or ejection power can also optionally be used as a feedback for the control unit, wherein the measured aortic pressure or cardiac volume provides a feedback signal that is automatically taken into account when setting the impulse parameters. Thus, the setting or adjustment of the impulse parameters can be further improved and performed iteratively.

[0066] Alternatively, the measured aortic pressure can also replace the ECG signal, wherein the aortic pressure is evaluated by the control unit and wherein the aortic pressure change in the pressure curve is characteristic of a certain cardiac phase of the cardiac cycle. For example, a short rise in aortic pressure after a fall in aortic pressure (dicrotic notch) can indicate the closure of the aortic valve, thus indicating the beginning of the diastolic or filling phase of the heart. For example, such a pressure change can be detected as a dicrotic notch in the pressure curve.

[0067] The control unit is preferably configured to determine the diastolic and systolic phases of the heart of the supported patient from the ECG signal and / or the aortic pressure and to adjust the impulse duration at least in such a way that it ends before the systole.

[0068] While the R-wave of the ECG signal indicates the beginning of the heart contraction or ejection, the short rise in the aortic pressure after the drop in the aortic pressure indicates the closure of the aortic valve, the beginning of the diastole or filling of the heart, as described above. Thus, by combining the ECG signal and the measured aortic pressure, the accuracy of the output of the blood pump control signal can be further improved, so that any ECG interference does not affect the safety of the patient and the functioning of the control unit.

[0069] As described above, the termination of the pulse before the systole is advantageous for reducing the afterload and still allows for a diastolic augmentation with sufficient perfusion of the end organs. Such diastolic augmentation can be achieved, for example, by retrograde blood flow with appropriate cannula positioning, for example with positioning in the aortic region or the femoral artery. However, depending on the patient, a central cannula can also be required to provide antegrade blood flow. In this case, the pulse parameters can alternatively be adjusted during the systole, so that it is pulsed during the systole.

[0070] The above object is also achieved by a system for extracorporeal circulation support of a patient. Thus, the system comprises a venous patient access and an arterial patient access, a non-occlusive blood pump fluidically connected to the venous patient access and the arterial patient access and adapted to provide a blood flow from the venous patient access to the arterial patient access, and an interface for receiving a measurement of an arterial pressure from the patient and an ECG signal. According to the invention, the system further comprises a control unit as described above.

[0071] For fluidically connecting the non-occlusive blood pump to the venous patient access and the arterial patient access, the system can comprise a suction line and a delivery line, each having an inner lumen with an inlet and an outlet opening, respectively, wherein, when the blood pump is operated or actuated, blood can flow from the venous patient access to the arterial patient access via the blood pump. The suction line can also be connected to a fluid reservoir, for example a blood reservoir, via a specific branch, so that additional fluid, for example blood for transfusion or to maintain sufficient blood volume, can be injected to the patient when the system is operated. These lines can be connected to the blood pump via simple connections such as luer connections, and, like the blood pump, are preferably formed as replaceable disposables. The blood pump can be coupled with the pump drive via a pump head, for example by means of a magnetic coupling. This means that the system can be used continuously for several patients while complying with hygiene standards.

[0072] The suction line and the delivery line can also each have a cannula, so that the system comprises a venous cannula and an arterial cannula, which are configured to be inserted into the heart or a heart region of the patient, for example into the right atrium or into the aortic region. This allows the blood collection and delivery to be precisely matched to the anatomy of the heart and to provide pulsatile blood flow directly in the coronary region. Thus, the ejection during systole is not impaired while the perfusion of the coronary arteries during diastole is optimized.

[0073] Furthermore, the blood pump is preferably a diagonal pump as described above. This allows a low flow rate to be provided at a higher pressure or at a higher pressure peak, which is advantageous for precise synchronization with the ECG signal, in particular with the diastolic phase. Furthermore, the impeller of such a diagonal pump has to accelerate a smaller circumference and a smaller mass, so that it can be accelerated and decelerated faster and the pulses can be adjusted more finely. The pump capacity provides the blood flow from the low-pressure side to the high-pressure side, wherein the control unit actuates the motor of the blood pump and is configured to adjust the rotational speed of the rotor blades so that the blood pump accordingly generates a wave-like flow corresponding to the pulsatile blood flow.

[0074] By providing a synchronized pulsatile blood flow, the system can in particular be used to treat the hypoxia of the myocardial tissue caused by, for example, cardiogenic shock, so that the perfusion of the coronary arteries is also improved in a pathophysiological and oxygen supply-reduced state of the myocardium without impairing or while also improving the perfusion of the end organs. Thus, the system provides therapeutic support for the patient's own heart function first. Furthermore, the system can be used to support a catheterization procedure or in the case of a heart attack or cardiac arrest, or in the case of a change or loss of cardiac output, as an artificial replacement and support for the heart function.

[0075] One or more components of the system can still be integrated in one housing. For example, the control unit can be arranged in a control console, which has a user interface for inputting and reading out system settings, in particular for blood pump parameters. For example, the control console can comprise a touchscreen and / or a display with a keyboard, which can be operated by the user. The control unit operates, actuates, controls, adjusts and monitors the blood pump and synchronizes the blood pump with the respective heart cycle of the patient.

[0076] For example, the control unit can record the received ECG signal and the heart rate, wherein the display shows the current ECG signal graphically and the current or average heart rate numerically. Furthermore, features or unique characteristics of the ECG signal can be emphasized or marked in the graphical display, so that in the QRS signal, for example, the detected R wave for outputting the pulse parameters or the pump signal can be marked in the ECG signal. Furthermore, further settings such as the time of the output pulse parameters and the pulse duration can also be displayed in the ECG signal, so that the user can monitor the control and adjustment of the blood pump depending on the physiological condition of the patient.

[0077] For example, the interface can be formed as a sensor box which can be connected to various sensors, such as pressure sensors and ECG devices integrated in the tube system, via connections.

[0078] Preferably, the system further comprises an ECG device communicatively connected to the interface. This allows the system to be used independent of the presence of other components. The ECG unit can also be attached to the control unit to provide a compact system. The ECG device is preferably integrated in a single housing of the system, for example in the form of an ECG card or an ECG module in the sensor box. Alternatively, the control unit can be configured to receive an external ECG signal from a supported patient, for example from a cardiac monitor external to the system. This makes the system more compact.

[0079] Furthermore, the extracorporeal circulation support system can be configured as a portable system so that the patient does not need to be treated at a fixed location and the mobility of the patient is improved. The various components of the system, such as the blood pump, the control unit and optionally the ECG device, can be operated by an integrated battery. Preferably, the non-occlusion blood pump and / or the control unit, more preferably both, are configured for extracorporeal use. Furthermore, the ECG device can preferably be configured for extracorporeal use.

[0080] In order to be able to more accurately acquire and transport pulsatile blood flow, the system preferably comprises at least one cannula for introducing an arterial patient access into the patient as described above and at least one cannula for introducing a venous patient access into the patient as described above. The cannula can also be used to derive the required ECG signal, for example via a lead at the tip of the cannula or the venous drainage cannula in the right atrium or superior vena cava, a lead at the tip of the cannula or at the location of the arterial cannula in the aorta or femoral artery or iliac artery. Thus, for example, the R wave of the QRS signal can be accurately detected and disturbances that can occur with a body surface ECG are avoided as far as possible.

[0081] The cannula for inserting the arterial patient access is preferably adapted to be inserted into the aortic region, for example into the ascending or descending aorta, or into the femoral artery, and / or the cannula for inserting the venous patient access is preferably adapted to be inserted into the right atrium or the vena cava. Depending on the physiological condition of the patient, different cannula sizes and regions of the patient's circulation can be selected.

[0082] Alternatively, the cannula can also be designed as a regular cannula or a dual lumen cannula, for example the cannula can be inserted intercostally to the apex. For example, such a cannula can be used if the insertion into the aortic region is difficult or unfavorable for the patient. Thus, depending on the specific situation of the patient, an intravascular cannula or an intracardiac cannula can be used in the system.

[0083] The system can further comprise an oxygenator or a membrane oxygenator which allows decarboxylation, i.e. removal or reduction of carbon dioxide, and oxygenation of blood drawn from the patient and provides a better oxygen supply to the myocardial tissue compared to known IABP methods. For example, a membrane ventilator such as an iLA membrane ventilator can be provided in the system which can also be operated without a pump and only by the performance of the heart as it has a low resistance. Preferably, the system comprises a relatively flat and angled oxygenator with a superimposed pad compared to the housing. Alternatively, any gas exchanger can be used, for example a round and / or cylindrical oxygenator, for example with a wrapped pad, can also be used. Preferably, the membrane oxygenator is configured to be arranged extracorporeally.

[0084] The above objects are further achieved by a method for controlling a non-occlusive blood pump for extracorporeal circulation support. The method comprises at least the following steps:

[0085] receiving a flow value of the extracorporeal circulation support;

[0086] receiving a measurement of an arterial pressure and an ECG signal of the supported patient over a predefined time period;

[0087] determining a mean arterial pressure of the extracorporeal circulation support or the supported patient based on the measured arterial pressure and determining an energy equivalent pressure based on the flow value and the arterial pressure;

[0088] determining a required value of at least one pulse parameter of the blood pump to achieve a ratio of the energy equivalent pressure to the mean arterial pressure being greater than 1.0 depending on the mean arterial pressure, the energy equivalent pressure and the ECG signal; and

[0089] adjusting the pulse parameter depending on the ECG signal.

[0090] Preferably, an R-wave is determined depending on the ECG signal and the pulse parameter is set at a given time after the R-wave as described above. This improves the perfusion of the diastolic coronary arteries and significantly reduces the afterload.

[0091] The following pulse parameters can also be set: pulse amplitude, pump speed, pump speed change per time unit, pulse duration, systolic pump duration, diastolic pump duration, drive wheel deceleration, drive wheel acceleration and / or mean pump flow.

[0092] Furthermore, the diastolic and systolic phase of the heart of the supported patient can be determined from the ECG signal and at least the pulse duration can be adjusted such that it ends before the systolic phase. Thus, the provided pulse and energy equivalent pressure is adapted to the heart rate of the patient and the possible perfusion of the coronary arteries is also optimized accordingly.

[0093] It can also be provided that the value is received via the injection capacity calculated or determined, for example, by means of an impedance measurement or a pressure measurement.

[0094] As mentioned above, depending on the patient, a central cannula can also be required to provide an antegrade blood flow. In this case, the pulse parameters can alternatively be set for the systolic phase such that the pulse is generated for the systolic phase.

[0095] The required value of the pulse parameter can also be determined from a pre-defined target value or a pre-defined target percentage of the energy equivalent pressure.

[0096] Thus, the flow, pressure and / or pulse characteristic parameters can also be controlled by pre-defining a value of the energy equivalent pressure. For example, the current energy equivalent pressure value can be displayed on the control console display and then optionally changed to a target value. It can also be displayed as a percentage of the energy equivalent pressure, which refers to the maximum possible value of the energy equivalent pressure for the individual patient. For example, the maximum value can be determined on a patient-specific basis using a short empirical algorithm.

[0097] Preferably, the method according to the application is performed by a control unit according to the application. More preferably, when the method of the application is applied, the controlled non-occlusive blood pump (40) is fluidically connected to a membrane oxygenator, which is usually arranged extracorporeally. Thus, the oxygen- and / or carbon dioxide-reduced blood of the patient can be guided to the patient as it passes through the membrane oxygenator. The components performing the method steps are usually arranged extracorporeally. Thus, some, multiple or preferably all method steps of the method of the application can be performed non-invasively, i.e. extracorporeally.

[0098] Furthermore, the ratio of the energy equivalent pressure to the mean arterial pressure can also be displayed on the display or monitor. The energy equivalent pressure is preferably displayed in mmHg and / or as a percentage of the maximum achievable value of the energy equivalent pressure. BRIEF DESCRIPTION OF DRAWINGS

[0099] In the following drawing description, preferred embodiments of the application are explained in more detail, in which:

[0100] Figure 1 is a schematic representation of the control logic of a control unit according to the application;

[0101] Figure 2is a schematic representation of an arterial pressure curve and a corresponding flow value curve over a predefined time period;

[0102] Figure 3 is a schematic representation of a pulse output according to the present application;

[0103] Figure 4 is a schematic representation of a system for extracorporeal circulation support according to the present application;

[0104] Figure 5 is a schematic representation of a pulse adjustment based on an ECG signal received at normal frequency heart rate according to the present application;

[0105] Figure 6 is a schematic representation of an overlap of a patient pulse and a support pulse when the heart rate is increased;

[0106] Figure 7A and 7B show examples of respective pulse parameter settings according to the present application and according to Figure 5 and Figure 6 respectively; and

[0107] Figure 8 is a schematic representation of a pulse setting a according to the present application for improving post-reduction afterload. DETAILED DESCRIPTION

[0108] In the following, preferred embodiments will be explained in more detail with reference to the accompanying drawings. In the drawings, corresponding, similar or identical elements are denoted by the same reference signs, and repeated description thereof can be omitted to avoid redundancy.

[0109] Figure 1 The control logic for the control unit is schematically shown, wherein values from the interface 24 are correspondingly input into the control and regulation unit stage 26 and, after processing by the control logic, cause a setting or adjustment of the blood pump stage 28.

[0110] Correspondingly, the control unit is configured to receive via the interface 24 a flow value 10 of the extracorporeal circulation support and measured values of an arterial pressure 12 of the supported patient over a predefined time period and an ECG signal 14. Based on the measured values of the arterial pressure 12, a mean arterial pressure 16 is determined. The mean arterial pressure 16 can be determined either from arterial pressure measurements 12 from the extracorporeal circulation support or from arterial pressure measurements 12 from the patient, e.g. via a tube arm of an arterial access or via an invasive pressure sensor. According to the present embodiment, the mean arterial pressure 16 of the supported patient is determined, e.g. via a radial artery or directly in the aorta.

[0111] Furthermore, a flow value 10 can be obtained via the respective tube arm of the arterial access and provide direct feedback to the control unit regarding the blood flow in the extracorporeal support. For example, the blood flow provided by the non-occlusive blood pump can be input as a rotational speed and can be adapted to the feedback value. In other words, the flow value 10 can be initially set via the respective speed and continuously or periodically corrected according to the current measurement. In this way, any different patient parameters or tube parameters that can cause a change in the flow value 10 at the same blood pump speed can be taken into account.

[0112] The control unit also determines an energy equivalent pressure 18 from the received flow value 10 and the arterial pressure 16. In order to achieve a pulsatile contribution to the mean arterial pressure, a current ratio of the energy equivalent pressure 18 to the mean arterial pressure 16 value is determined in the control unit. For example, this ratio can initially be approximately 1.0, so that no or only a limited pulsatile contribution is achieved by the extracorporeal support. In order to increase the ratio and thus the pulsatile contribution, a required value of at least one pulsatile parameter 20 of the blood pump is determined in the control unit. Not only is the ratio between the energy equivalent pressure 18 and the mean arterial pressure 16 determined iteratively, but also the received ECG signal 14 is taken into account.

[0113] For example, a possible pulse duration can be determined from the ECG signal, which prevents two cardiac phases of a cardiac cycle from overlapping during the setting of the pulsatile parameter 20. This allows the pulse to be optimized over the determined possible pulse duration in order to achieve a desired or required pulsatile contribution, thereby increasing the ratio between the energy equivalent pressure 18 and the mean arterial pressure 16 to, for example, 1.1 or more. As a further pulsatile parameter, for example, a speed change per time unit can be selected, which increases the pulse amplitude during the determined and thus predefined pulse duration in such a way that the output has a predefined volume or flow per time unit of the pulse, which achieves a corresponding contribution to the mean arterial pressure.

[0114] The pulsatile parameter 20 is adjusted to the determined value 22 accordingly and continues to be set according to the ECG signal 14, resulting in an exact timing specification of the output pulse. For example, this allows diastolic pressure augmentation without increasing or as little as possible increasing the afterload, in particular because the pulse is output in such a way that it ends before the systolic phase of the cardiac cycle, so that the remaining pressure is very low.

[0115] Figure 2One example of an arterial pressure curve (P) and a corresponding flow curve (Q) over a predefined time period (t) is shown. For the time interval t1 to t2 (t2 > t1, i.e. t1 is in the past compared to t2), an integral of the pressure change, e.g. in mmHg and an integral of the flow change, e.g. in l / min, can be calculated, which is the basis for calculating the energy equivalent pressure, e.g. according to the following formula:

[0116]

[0117] where the blood flow (f) and the pressure (p) are considered over the time interval from t1 to t2.

[0118] Figure 2 It is also shown that the increase in pressure and flow can have a time delay. In other words, the flow change can occur delayed after the pressure change, thus potentially leading to a latency of the extracorporeal circulation support.

[0119] In order to provide pulsatile blood flow, it is provided that at least one pulse parameter is set in dependence of the ECG signal. This allows regular pulses and the respective pulses can be adapted to the physiological condition of the patient. Figure 3 One example of such a pulse parameter is schematically shown.

[0120] Thus, two pulses are shown at regular intervals over time (t), wherein the pulses are added to an optional base flow. The base flow can be achieved by adjusting the speed such that a blood flow of e.g. between about 2 l / min to 3 l / min is provided.

[0121] In the present example, the respective pulses are achieved by a speed change induced by the actuation of a motor in the blood pump and the pump drive. This induces a pulse amplitude 32, which induces a respective change in pressure (P) and thus flow (Q). The pulses are outputted over a predefined pulse duration 34, which corresponds to a determined possible pulse duration, such that the pulse duration 34 and the speed change per time unit lead to a maximum blood flow or maximum pulse amplitude 32. Once the pulse amplitude 32 has been achieved, the pump drive is no longer actuated such that the speed of the blood pump is reduced to the base flow after the predefined or set pulse duration 34. From the pulse and the base flow, an average flow 30 is obtained, which is indicated with a dashed line. Thus, the average flow 30 is greater than the base flow and provides an additional contribution to the cardiac output, which increases the mean arterial pressure of the patient and allows sufficient perfusion or oxygenation of the end organs.

[0122] In Figure 4A system 36 for extracorporeal circulation support is schematically shown in Fig. 1. The system 36 is connected to a patient 38 and allows for extracorporeal blood flow using a non-occlusive blood pump 40. Similarly, the blood pump 40 is connected to the patient 38 circuit via a venous patient access 42 and an arterial patient access 44 such that blood is drawn from the patient 38 via a suction line and returned to the patient 38 via a high pressure delivery line. The patient accesses 42, 44 are optionally formed as cannulae and inserted such that the venous blood collection site (cannula tip and cannula shaft) is located in the region of the right atrium, for example in the superior and / or inferior vena cava, and the arterial return occurs via the femoral patient access 44 located in the region of the femoral artery or the aorta in order to provide retrograde blood flow. Furthermore, an optional flow restrictor 46 can be provided downstream of the blood pump 40. Although Figure 4 Not shown in Fig. 1, but the system 36 can also comprise an oxygenator for oxygenation and / or CO2 reduction of the venous blood, which can for example be arranged downstream of the blood pump 40 in the flow direction.

[0123] The blood pump 40 is operated or regulated by a control unit 48. The control unit 48 can be formed as a console comprising a user interface 50 and a monitor 52 via which settings can be performed or information can be output. Thus, parameters of the system 36 can be changed and / or monitored by a user.

[0124] The control unit 48 is also coupled with an ECG device such that an ECG signal 54 can be received. The ECG device can for example be installed as an ECG card or ECG module in an interface of a sensor box such as the system 36, but can alternatively also be coupled to the system 36 via an interface as an external device. The ECG signal 54 is provided by sensors 56 attached to the patient 38, for example as a 4-pole surface ECG, and can be displayed in a single or multi-channel representation with derivative selection, for example Goldberger derivatives and / or limb derivatives.

[0125] The sensors 56, which are only schematically shown here, can also comprise a pressure sensor which can be arranged in another anatomical region of the patient, but in the present embodiment a pressure sensor is provided which measures the arterial pressure of the patient 38. For example, the pressure sensor can be coupled to an arterial cannula or inserted as a separate cannula into the radial artery. Thus, the pressure sensor outputs a pressure measurement 55 which is received by the control unit 48.

[0126] However, as mentioned above, the pressure measurement values can also be calculated, for example, or can be performed via an arterial cannula or a line or leg of a transfer line in order to detect the respective pressure values of the extracorporeal circulation support. Alternatively, more than one pressure sensor can be provided in the line set, wherein, preferably, one pressure sensor is arranged upstream of the blood pump 40, one pressure sensor is arranged downstream of the blood pump 40, and, if applicable, a further pressure sensor is arranged downstream of an optionally provided oxygenator.

[0127] The control unit 48 is configured to determine the mean arterial pressure of the patient 38 based on the received pressure measurement values 55, preferably continuously and in real time. The mean arterial pressure can be used as a reference value for the blood flow provided by the blood pump 40 in order to achieve sufficient perfusion of the end organs. However, too much blood flow can cause retrograde blood flow to close the aortic valve, increase the afterload in systole or prevent left ventricular ejection if delivered at the wrong time of the cardiac cycle. This increases the pressure in the left ventricle, which restricts coronary blood flow due to an increase in the wall tension of the left ventricle. At the same time, the pulmonary veins are backed up to the lungs, which can cause pulmonary edema and reduced lung function.

[0128] In order to further adjust the blood flow according to the patient 38, the control unit 48 is configured to receive a flow value of the extracorporeal circulation support from a flow sensor 58, wherein the flow sensor 58 is mounted on a tube arm of the arterial patient access 44. Thus, the flow sensor 58 provides feedback for the set speed at the blood pump 40. In addition, the flow value allows the control unit 48 to determine an energy equivalent pressure in addition to the mean arterial pressure, as described above. This allows the control unit 48 to determine a ratio between the current energy equivalent pressure and the current mean arterial pressure and to iteratively determine values of the pulse parameters required to raise the ratio above 1.0.

[0129] The heart rate determined from the ECG signal 54 and the resulting pulse duration are also taken into account, so that an overlap of the pulse with the intrinsic systole can be avoided. The control unit 48 also adjusts the at least one pulse parameter determined therefrom in accordance with the ECG signal 54, for example in accordance with the R wave determined from the ECG signal 54.

[0130] In Figure 5This pulsing is schematically shown in the normal frequency heart rate of a supported patient. The ECG signal 14 comprising the QRS complex is continuously received from the patient over time (t). Although basically every amplitude change in the ECG signal can be used as a trigger signal for the blood pump, in this embodiment the R-wave is used, which marks the systole of the cardiac ejection or cardiac cycle. This is also shown in the third or third line, which depicts the course of the arterial pressure of the patient over time (t). Thus, due to the ejection of the heart, a change in arterial pressure occurs immediately after the R-wave, which is marked by the first two dotted lines and can for example amount to 300 ms. After the initial pressure increase, the pressure decreases again until the aortic valve closes, which causes a slight increase in pressure and is marked by the dicrotic point (aortic valve closure). At this point, the diastole or filling phase of the heart starts.

[0131] As Figure 5 shown, in the case of no augmented pressure, the pressure further decreases, which is indicated by the arrow with reference numeral 60. In other words, no support or diastolic augmentation occurs for this heartbeat, i.e. no pulses of extracorporeal support occur, as shown in the course of the extracorporeal support flow (Q) in the second or second line. Thus, the filling of the heart is not supported, such that the arterial pressure of the patient decreases rapidly.

[0132] After the heart rate has been determined or detected and the respective delay between the R-wave and the aortic valve closure, the control unit outputs a signal to the pump driver or the motor of the blood pump in order to set the pulsing parameters of the blood pump accordingly. The R-wave is used as a trigger signal and for determining the pulsing parameters 20, and the respective pulsing parameters 20 are set or adjusted after the respective delay 22, as schematically shown in the fourth or fourth line. Thus, pulses are provided in the extracorporeal support, which are timely synchronized in such a way that they cause a respective pulsatile blood flow during the diastole, as shown in the second line. This causes an increase in pressure during the diastole, which includes a factor of 2 for the mean arterial pressure, while the diastolic pressure has a factor of 1, thus the contribution to the mean arterial pressure increase is doubled. The increased pressure 62 thus achieved ideally starts after the dicrotic point, such that the diastolic augmentation is without overlap with the systole.

[0133] However, with increasing heart rate, the support pulses can overlap with the systole of the patient pulses, or the augmented diastole can interfere with the increasing phase of the left ventricular ejection, i.e. the systole, as Figure 6is schematically shown. With an increasing heart rate, the distance between the respective R-waves is shortened, thus also the distance between the kick and the subsequent R-wave, so that the diastolic phase is also shortened. With a constant pulse duration, the enhanced pressure 62 provided by the respective pulse can overlap or interfere with the subsequent systolic phase, indicated by the pulse superposition 64. This leads to an increased afterload, and either the support frequency needs to be adjusted or the respective pulse parameters are adjusted in view of maintaining sufficient or physiological EEP.

[0134] Although an adjustment of the pulse rate can be necessary, for example, in tachycardia, the pulse parameters at an increased heart rate are preferably adapted to the physiological condition of the patient, as schematically shown in Figure 7A and 7B .

[0135] Thus, as shown in Figure 7A , at a normal frequency heart rate, the pulses can be distributed over a longer diastolic phase, so that a respective longer pulse duration 34 of, for example, about 200 ms can be set. At the same time, the speed variation per time unit can lie within a respective range, for example, between 2500 rpm and 4500 rpm, so that the pulse amplitude 32 also lies within this respective range. The pulse duration 34 can also be divided symmetrically into equal systolic phase pulse phases 66 and diastolic phase pulse phases 68 of about 100 ms each, so that a uniform pulse is output.

[0136] However, if the heart rate increases, the pulse parameters can be modified, as shown in Figure 7B . Thus, for example, the pulse duration 34 can be shortened to about 120 ms. However, in order to contribute sufficiently to the mean arterial pressure, a speed variation of between 3000 rpm and 5000 rpm can also be selected as long as the EEP is within the physiological range, in order to increase the pulse amplitude 32 and the blood flow during the pulse accordingly.

[0137] This prevents, for example, even at a heart rate of 90 to 130 beats per minute, a flow collision between the pump outlet and the beginning of the systole or heart ejection, and the afterload is accordingly optimized. Furthermore, the pulses can be divided asymmetrically, wherein the systole can comprise about 50% to about 90% (not shown).

[0138] A higher heart rate can be further adapted by changing the support ratio to 1 :2 and 1 :3 depending on the heart rate to maintain a respective mean flow.

[0139] Thus, adapting the pulse parameters to the physiological condition of the patient has the advantage that the afterload is not increased even at higher heart rates and sufficient mean arterial pressure and sufficient perfusion of the coronary arteries can be achieved. The pulse parameters are also chosen to achieve a pulse contribution to the mean arterial pressure and an EEP of the physiological pulse quality such that improved perfusion and end-organ protection due to pulsatile blood flow is achieved.

[0140] The reduction of the afterload can also be further improved by a corresponding pulse setting, as Figure 8 is schematically shown. The trigger signal and the control signal are not shown in this description to improve the display. However, the control unit can set the pulse parameters similar to the embodiment depicted in Figure 5 such that the R-wave of the QRS-complex from the ECG signal 14 according to Figure 8 is also used as a trigger signal and the pulse is output at the re-pulse point such that a diastolic augmentation is achieved.

[0141] In the second line or second row of Figure 8 schematically shown, for example, the arterial pressure (P) measured on the arterial arm of the tubing set, both without augmentation 76 and with augmentation 78, wherein in the third line schematically shown is the change in flow curve or flow (Q) in the extracorporeal circulation support during the augmentation 78. Thus, without augmentation 76, the arterial pressure decreases rapidly, similar to the pressure 60 without augmentation in Figure 5 When the pulse is output, the pressure increases with the augmentation 78 and the pressure decreases more slowly, similar to the augmented pressure 62 in Figure 5 . However, the pressure drop can also look different such that the shape of the pressure curve is only to be understood as a schematic example and can look different in each patient, for example, depending on patient-related factors such as vessel elasticity, degree of calcification, heart strength, viscosity, etc.

[0142] The corresponding flow (Q) in the extracorporeal circulation support is added to the basic flow 72 and causes a maximum flow value due to the pulse, which is predefined by the change in speed per unit of time and the pulse duration, resulting in a diastolic augmentation 70 compared to the basic flow 72.

[0143] To reduce the afterload, the speed after the diastolic pump phase (cardiac systole) is further set to be lower than the corresponding value of the basic flow 72 such that a minimum flow 74 is obtained below the basic flow 72 and the pressure of the systole of the heart is also reduced accordingly, which is also a result of the pressure decrease during the systole in the augmentation curve 78. This continues to provide pulsatile blood flow with the required mean flow 30 and the basic flow 72 while further reducing the afterload. As shown, this can be related to the next cardiac ejection, but also to the penultimate cardiac ejection with a 1 :2 support ratio.

[0144] Although this is not shown in Figure 8 may be provided in such a way that a negative blood flow is provided. For example, such a negative blood flow can be provided by a four-quadrant control, as described above. Such a four-quadrant control not only allows a reduction (braking) of the speed or impeller, but also allows the reversal of the direction of rotation by a reversal of the current direction, so that the impeller can be rotated in the opposite direction. Thus, such a negative blood flow at the end of the pulse and during the systole leads to a suction effect, which further reduces the afterload of the stressed and supported heart, which promotes the ejection of the heart.

[0145] All individual features depicted in the exemplary embodiments can be combined and / or exchanged, where applicable, without departing from the scope of the invention.

[0146] List of reference signs

[0147] 10 flow value

[0148] 12 arterial pressure measurement

[0149] 14 ECG signal

[0150] 16 determining mean arterial pressure

[0151] 18 determining energy equivalent pressure

[0152] 20 determining blood pump pulse parameters

[0153] 22 adjusting pulse parameters

[0154] 24 interface

[0155] 26 control unit stage

[0156] 28 blood pump stage

[0157] 30 mean flow

[0158] 32 pulse amplitude

[0159] 34 pulse duration

[0160] 36 extracorporeal support system

[0161] 38 patient

[0162] 40 blood pump

[0163] 42 venous patient access

[0164] 44 arterial patient access

[0165] 46 optional flow restrictor

[0166] 48 control unit

[0167] 50 user interface

[0168] 52 monitor

[0169] 54 ECG signal

[0170] 56 sensor

[0171] 58 flow sensor

[0172] 60 non-augmented pressure

[0173] 62 augmented pressure

[0174] 64 pulse overlap

[0175] 66 systolic pulse phase or pump duration

[0176] 68 diastolic pulse phase or pump duration

[0177] 70 diastolic augmentation

[0178] 72 basal flow

[0179] 74 minimum flow

[0180] 76 pressure without augmentation

[0181] 78 pressure with augmentation

Claims

1. Control unit (48) for a non-occlusive blood pump (40) for extracorporeal circulation support, configured for - receiving a flow value (10) for extracorporeal circulation support; - receiving a measurement of arterial pressure (12) and an ECG signal (14) of a supported patient (38) over a predetermined time period; - determining a mean arterial pressure for extracorporeal circulation support or a mean arterial pressure of a supported patient (16) from the measurement of arterial pressure (12) and determining an energy equivalent pressure (18) from the flow value (10) and the arterial pressure; and - determining a required value of at least one pulse parameter (20) of the blood pump (40) from the mean arterial pressure (16), the energy equivalent pressure (18) and the ECG signal (14) in order to achieve a ratio of the energy equivalent pressure (18) to the mean arterial pressure (16) greater than 1.0, wherein the control unit (48) being further configured to adjust (22) the pulse parameter (20) in dependence on the ECG signal (14).

2. The control unit (48) according to claim 1, wherein the at least one pulse parameter (20) being selected from a pulse amplitude (32), a pump speed, a pulse duration (34), a systolic pump duration (66), a diastolic pump duration (68), a drive wheel deceleration, a drive wheel acceleration and / or a mean pump flow.

3. The control unit (48) according to claim 1 or 2, wherein the control unit (48) being further configured to determine the required value of the pulse parameter (20) in dependence on a given or predetermined mean arterial pressure (16) and / or a given or predetermined energy equivalent pressure (18).

4. The control unit (48) according to claim 1 or 2, wherein the control unit (48) being further configured to determine the flow value (10) based on an input speed of the blood pump (40) or automatically based on a received flow measurement.

5. The control unit (48) according to claim 1 or 2, wherein the flow value (10) comprising a patient-specific mean flow (30), wherein the control unit (48) is further configured to adjust (22) the mean flow (30) by adjusting (22) the pulse parameter (20) based on a received flow measurement and a mean arterial pressure (16).

6. The control unit (48) according to claim 1 or 2, wherein the control unit (48) being further configured to determine a heart rate from the ECG signal (14) and to adjust (22) the pulse parameter (20) in dependence on the heart rate.

7. The control unit (48) according to claim 1 or 2, wherein the control unit (48) being further configured to determine an amplitude variation from the ECG signal (14) and to adjust (22) the pulse parameter (20) at a predetermined point in time after the amplitude variation.

8. The control unit (48) according to claim 7, wherein the control unit (48) being configured to determine an R-wave from the ECG signal (14) and to adjust the pulse parameter (20) at a predetermined point in time after the R-wave.

9. The control unit (48) according to any one of claims 1, 2, 8, wherein, the control unit (48) being further configured to receive a measurement of aortic pressure of a supported patient (38) over a predetermined time period and to adjust (22) the pulse parameter (20) at a predetermined aortic pressure and a change in aortic pressure.

10. The control unit (48) according to claim 9, wherein The control unit (48) is further configured to determine a diastolic phase and a systolic phase of the heart of the supported patient (38) from the ECG signal (14) and / or the aortic pressure and to adjust (22) at least the pulse duration (34) such that it ends before the systolic phase.

11. A system (36) for extracorporeal circulation support of a patient (38), comprising: - a venous patient access (42) and an arterial patient access (44), - a non-occlusive blood pump (40) fluidically connected to the venous patient access (42) and the arterial patient access (44) and configured to provide a blood flow from the venous patient access (42) to the arterial patient access (44), - an interface (24) for receiving a measurement of an arterial pressure (12) and an ECG signal of the patient (38), and - a control unit (48) according to any one of the preceding claims 1 to 10.

12. The system (36) of claim 11, wherein, The system further comprises a membrane oxygenator and / or a membrane fan.

13. The system (36) of claim 12, wherein, The system further comprises the membrane oxygenator being a membrane oxygenator extracorporeally arranged.

14. The system (36) according to any one of claims 11-13, wherein, The system further comprises an ECG device communicatively connected to the interface (24).

15. The system (36) according to any one of claims 11-13, wherein, The non-occlusive blood pump (40) and / or the control unit (48) are configured to be extracorporeally arranged.

16. The system (36) according to any one of claims 11-13, wherein, The system further comprises at least one cannula for inserting the arterial patient access (44) into the patient (38) and one cannula for inserting the venous patient access (42) into the patient (38).

17. The system (36) of claim 16, wherein, The cannula for inserting the arterial patient access (44) forms a cannula for inserting into an aortic region or into a femoral artery, and / or the cannula for inserting the venous patient access (42) forms a cannula for inserting into a right atrium or into a vena cava. The cannula for inserting the arterial patient access (44) forms a cannula for inserting into an aortic region or into a femoral artery, and / or the cannula for inserting the venous patient access (42) forms a cannula for inserting into a right atrium or into a vena cava.

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