Blood treatment device for gas exchange

Abstract

The invention relates to a blood treatment device (100) for gas exchange via a gas exchange unit (300) which has two regions separated by a membrane, wherein blood flows through the one region and purge gas flows through the other region, and wherein the blood treatment device (100) comprises a pump apparatus for blood (101), sensors for measuring at least two treatment parameters, an apparatus for changing at least one purge gas parameter (404) and a control unit (500) which is connected to the pump apparatus for blood (101), the sensors for measuring at least two treatment parameters and the apparatus for changing at least one purge gas parameter (404), and is configured such that it controls the apparatus for changing at least one purge gas parameter (404) depending on the at least two treatment parameters. Furthermore, the invention relates to a method for controlling the apparatus for changing at least one purge gas parameter (404) and / or a mechanical respirator (600) in the blood treatment device (100) according to the invention.

Description

[0001] Blood treatment device for gas exchange

[0002] Technical area

[0003] The present invention relates to a blood treatment device for gas exchange via a gas exchange unit according to claim 1 and to a method for controlling the device for changing at least one purge gas parameter according to claim 12.

[0004] background

[0005] The lungs' primary function is to supply the body with oxygen (O2) and to remove carbon dioxide (CO2) produced by metabolism from the body. During inhalation, oxygen-rich air flows into the lungs. The oxygen diffuses through the lungs into the blood and circulates throughout the body to supply the organs. The CO2 produced by metabolism is transported by the blood to the lungs, where it is eliminated from the body through exhalation. Thus, a continuous exchange of O2 and CO2 takes place between the ambient air, the lungs, and the blood through respiratory movement and the circulating blood.

[0006] If the lungs are so damaged that they can no longer adequately perform their gas exchange function, medical measures are required to replace or support the supply of O2 to the body and / or the removal of CO2 from it.

[0007] Extracorporeal lung support has become increasingly important in recent years, not least due to the Covid19 pandemic, but also due to the ever-increasing importance of chronic obstructive pulmonary disease (COPD).

[0008] In hypercapnic patients, such as those suffering from COPD, the removal of CO2 is particularly impaired. To effectively remove CO2 from the body's three compartments: blood, tissue, and bone, these patients typically receive mask ventilation with high gas pressure. However, because this treatment is very restrictive and unpleasant for the patient, it is generally poorly tolerated.

[0009] Mechanical ventilation, which requires intubation to introduce gas into the lungs under high pressure, is avoided if possible in hypercapnic patients because, on the one hand, this method does not allow sufficient removal of CO2 and, on the other hand, ventilation is associated with considerable restrictions for the patient due to the necessary sedation as well as with side effects and late effects, particularly for the lung tissue.

[0010] Another option for treating hypercapnic patients is extracorporeal lung support (ECLS). This involves blood being pumped through a gas exchange device, such as a membrane oxygenator or dialyzer, in an extracorporeal circuit. The gas exchange device performs the gas exchange function of the lungs. The basic design and function of a membrane oxygenator and dialyzer are well known. Ambient air, pure oxygen, or a mixture of air with oxygen, nitrogen, and / or noble gases is used as the purge gas. The proportion of the individual gas components in the purge gas mixture can vary.

[0011] The blood flow rate during ECLS treatment determines whether, for therapeutic purposes, predominantly oxygen is supplied (extracorporeal membrane oxygenation, ECMO) and carbon dioxide is removed at the same time, or whether predominantly only carbon dioxide is removed (extracorporeal CO2 removal, ECCO2R). High blood flow rates of more than 1.5 l / min are usually required for ECMO. However, a low blood flow is sufficient for the removal of excess CO2 (ECCO2R). This can be less than 1.5 l / min or even less than 500 ml / min. This means that treatment can be carried out using a smaller catheter for vascular access than in ECMO, for example, as used for dialysis (e.g. Shaldon catheter, 11-13.5 Fr). The amount of anticoagulant used, such as heparin or citrate, is also lower in this treatment.Advantageously, the hypercapnic patient can be treated with ECCO2R treatment in a minimally invasive but still effective manner.

[0012] However, in all extracorporeal blood treatment systems, and especially in lung support procedures, heat loss from the blood inevitably occurs through heat radiation and conduction across the surface of the blood tubing system and the treatment unit housing, and especially through heat flow across the treatment unit's gas exchange membrane. This leads to an undesirable reduction in the patient's body temperature.

[0013] Therefore, most oxygenators are equipped with a heat exchanger, which is supplied with tempered water, for example, from an external heating / cooling unit, thus ensuring that the blood temperature remains largely constant during treatment. However, devices for ECCO2R treatment are generally not equipped with a heat exchanger or an alternative temperature control solution due to cost and space constraints. Although the blood flow rate during ECCO2R treatment is lower than during ECMO treatment, a significant amount of heat loss still occurs even at low blood flows.

[0014] Furthermore, during ECCO2R treatment, the ratio of purge gas flow to blood flow is significantly higher at approximately 15:1 or 5:1, respectively, than during ECMO treatment, resulting in even greater heat loss. Therefore, there is a need to actively influence or compensate for blood heat loss during ECCO2R treatment.

[0015] During treatment, additional measures, such as the use of heated blankets, must therefore be taken to prevent the patient from becoming hypothermic. However, these measures are often perceived as disruptive by the patient, are time-consuming, and disrupt clinical operations.

[0016] Other factors that influence blood heat loss are known from the state of the art, such as the flow rate, temperature and humidity of the purge gas used during ECLS treatment.

[0017] Regarding the flow rate factor, it is obvious to the person skilled in the art that the heat loss increases with increasing purge gas flow.

[0018] It is also conceivable that when using cold purge gas there is a greater heat exchange between the warmer blood and the colder purge gas than when using a heated purge gas, because various heat transfer mechanisms ensure that there is always an exchange of heat between a cold and a warm medium. When a purge gas is heated to blood temperature, no exchange of heat is to be expected between the blood and the purge gas during treatment. It is also obvious that dry purge gas removes comparatively more heat from the blood than moist purge gas, because due to the vapor pressure difference as the driving force during gas exchange, water in the form of vapor passes from the area of ​​the gas exchanger through which blood flows, across the membrane to the area of ​​the gas exchanger through which the purge gas flows.The water vapor condenses on the other side of the membrane and is absorbed by the passing purge gas. This process leads to heat loss through the creation of "evaporative cooling."

[0019] The application of measures that influence the above-mentioned factors is already known from the state of the art.

[0020] For example, European patent EP 2 736 557 B1 , which deals with the electronically controlled mixing of various purge gas components, discloses not only a heating element for heating the purge gas but also a unit for humidifying the purge gas in order to prevent the patient from cooling down.

[0021] IIS patent US 3,927,981 describes a blood oxygenator for enriching O2 and removing CO2. To reduce gas and energy consumption, the purge gas is heated and humidified.

[0022] Overall, it can be stated that the heat loss occurring during ECLS treatment can be reduced by reducing the purge gas flow or by warming or humidifying the purge gas.

[0023] However, it has been shown that when applying the aforementioned measures, gas exchange itself becomes less effective, for example, because less CO2 is removed from the blood. As a result, either the treatment frequency or the treatment duration, or both, must be increased, which in turn leads to greater patient cooling.

[0024] The present invention is therefore based on the object of overcoming this disadvantage by proposing an improved blood treatment device which makes it possible to optimize the blood treatment in such a way that the patient suffers the smallest possible drop in temperature but receives the most effective treatment possible, regardless of whether O2 is supplied and / or CO2 is removed.

[0025] The object of the invention can be achieved by a blood treatment device having the features of claim 1 and by a method having the features of claim 12. The subclaims also contain advantageous embodiments of the invention.

[0026] Summary of the invention

[0027] The blood treatment device according to the invention for gas exchange via a gas exchange unit comprises a pumping device for blood, which conveys the blood along a blood line in the extracorporeal circuit, sensors for measuring at least two treatment parameters, and a device for changing at least one purge gas parameter.

[0028] The blood treatment device further comprises a control unit connected to the blood pumping device, the sensors for measuring at least two treatment parameters, and the device for changing at least one purge gas parameter. The control unit is configured to control the device for changing at least one purge gas parameter depending on the at least two treatment parameters. The control unit can serve as a pure control device or as a regulating device and can initiate the execution of all or substantially all method steps.

[0029] The term gas exchange includes the removal of CO2 from the extracorporeal blood circulation or the supply of CO2 to the extracorporeal blood circulation or both.

[0030] The gas exchange unit consists of a housing containing hollow fiber bundles. The hollow fiber bundles form a semipermeable membrane that separates the gas exchange unit into two compartments. Thus, the blood flows—usually in countercurrent—for example, within the hollow fibers, while the purge gas flows outside, or vice versa. The gas exchange unit can be a commercially available membrane oxygenator or dialyzer. The hollow fiber bundles of the gas exchange unit are preferably made of a hydrophilic, microporous hollow fiber, for example, polysulfone or polyethersulfone containing a proportion of polyvinylpyrrolidone (PVP). The hollow fiber can also be made of polymethylpentene (PMP) if the geometry allows for humidification without the membrane becoming clogged by an accumulation of tiny water droplets.

[0031] The term treatment parameters includes, for example, patient temperature, carbon dioxide partial pressure (pCO2), and blood flow rate. Patient temperature can be measured using a suitable sensor either in the blood line or directly on the patient, or it can be read into the clinical data system via a data interface. pCO2, which reflects the amount of CO2 dissolved in the arterial blood, can be measured using a suitable sensor, preferably downstream of the gas exchange unit in the purge gas, or in the blood, for example, using a blood gas analysis. Blood flow rate can be measured using a sensor integrated into the blood pumping device or using a flow sensor located in the arterial or venous line in the extracorporeal blood circuit.

[0032] Purge gas parameters include temperature, humidity, or the purge gas flow rate. These parameters can also be measured using suitable sensors located in the purge gas line, preferably upstream of the gas exchanger.

[0033] The device for changing at least one purge gas parameter can be a heating device for heating the purge gas, a humidifying device for humidifying the purge gas, or a pumping device that conveys the purge gas along the purge gas line. The pumping device can consist of one or more active elements for generating a flow, such as a pump. However, it can also be or be connected to a passive element by which the flow is fixed or adjustable, such as a throttle or a valve. In some embodiments, the control unit is connected to a user input module (user interface) for entering and / or storing at least one treatment target.The user can thus select an individual treatment goal and / or influence the treatment process by entering parameters, taking into account the contradictory goals of minimal heat loss and maximum CO2 removal.

[0034] The user input module can also be connected to a decision support system, which suggests appropriate parameters for the user to input. Alternatively or in support, parameters from a data storage system, for example, those from previous treatments, can be used.

[0035] Alternatively or additionally, the use of a script is conceivable, i.e. a source code that contains a list of commands and, based on the recorded values ​​for the patient temperature and the pCO2, automatically specifies a treatment mode with minimal heat loss and maximum CO2 removal.

[0036] In some embodiments, the blood treatment device is connected to the patient and the gas exchange unit via a tubing set. It can also be connected to at least one further blood treatment unit, with which the blood can be influenced in a shared extracorporeal blood circuit. The effect can be mechanical, chemical, physical, or other. Such combination therapy is used primarily when the treatment techniques exhibit advantageous synergies. The further blood treatment unit can, for example, be a dialyzer for renal replacement therapy, an adsorption cartridge for therapeutic apheresis, or even a diagnostic unit that can determine various blood parameters to detect pathological changes in the blood.In this way, ECMO or ECCO2R treatment can be combined simultaneously with dialysis and / or adsorption treatment, for example. The treatment units can be combined in any order, for example, in a serial arrangement.

[0037] In a further embodiment, the blood treatment device can comprise, in addition to the gas exchange unit, a mechanical ventilation unit that supports O2 and CO2 exchange. Mechanical ventilation can be provided either non-invasively via a mask or invasively via an endotracheal tube inserted through the nose or mouth, or via a tracheostomy cannula inserted into the trachea via a stoma. The control unit is configured to also control the mechanical ventilation unit depending on the at least two treatment parameters.

[0038] The method according to the invention can be carried out essentially or completely by the control unit; in particular, those steps which do not require or involve human intervention and / or provision can be carried out by the control unit.

[0039] In the method for controlling the device for changing at least one purge gas parameter and / or the mechanical ventilation unit, the treatment parameters, i.e., the patient temperature and / or the pCO2 and / or the blood flow rate, are first recorded by the sensors and transmitted to the control unit. One or more treatment parameters can be entered via the user interface or preset.

[0040] The control unit compares the recorded treatment parameters (actual values) with values ​​entered by the user and / or with preset values ​​(setpoints) and calculates manipulated variables for configuring the device to change at least one purge gas parameter.

[0041] Based on the calculated values, the control unit controls the heating, humidification, and / or pumping device so that the purge gas is heated and / or humidified and / or the purge gas flow rate is increased or decreased. It is also conceivable to calculate and / or balance the total amount of CO2 removed based on the measured pCO2. Assuming that the CO2 content at the purge gas inlet is equal to or nearly equal to zero, the CO2 content in percent is multiplied by the purge gas flow rate.

[0042] The present invention is explained below by way of example with reference to the accompanying drawings, in which identical reference numerals designate identical or similar components. The following applies:

[0043] Fig. 1 shows a process diagram of the blood treatment device according to the invention in a simplified representation

[0044] Fig. 2 shows a CO2 removal curve depending on the purge gas flow

[0045] Fig. 3 shows the carbon dioxide partial pressure for different purge gas conditioning over time

[0046] Fig. 4 shows the treatment device according to the invention in a schematic representation

[0047] Fig. 5 shows the blood temperature in different purge gas conditioning

[0048] Fig. 1 shows a simplified process diagram of the blood treatment device according to the invention. The blood treatment device 100 is optionally connected to an extracorporeal blood circuit 200 in the form of a tubing set, which leads to a gas exchange unit 300 in an arterial blood line 201 and away from it in a venous blood line 202. Both blood lines can be connected to the vascular system of a patient (not shown here). The small arrowheads indicate the direction of flow. For hygienic reasons, the tubing set can be designed as a disposable medical article that is discarded after treatment. The arterial and venous blood lines 201 and 202 optionally have an arterial clamp 203 and a venous clamp 204, with the aid of which the respective blood line can be closed.

[0049] The blood treatment device 100 comprises a blood pumping device 101, which conveys the blood along the arterial blood line 201 toward the gas exchange unit 300 and along the venous blood line 202 back to the patient. The blood pumping device 101 can be, for example, a diaphragm pump and preferably an occluding pump, such as a roller pump. During the return flow, the blood can flow through a venous blood chamber 205, which optionally has a venting device 206. The blood pumping device 101 can also be connected to a throttle or a valve for adjusting the flow.

[0050] The gas exchange unit 300 has a purge gas inlet 301 and a purge gas outlet 302. It can be designed as a gas exchanger, membrane oxygenator, CO2 remover (e.g., multiECCO2R from EUROSETS Srl, Medolla (MO), Italy), or dialyzer. The gas exchange unit 300 is separated by hollow fiber bundles, which together form a semipermeable membrane, into a region through which blood flows and a region through which purge gas flows (not shown here). In the gas exchange unit 300, CO2 is removed from the extracorporeal blood circuit 200, or O2 is supplied to it, or both, or both. The membrane can be coated with silicone or a silicone solution, with the blood side of the hollow fibers preferably being coated.

[0051] Downstream of the blood pumping device 101, but upstream of the gas exchange unit 300, an addition point 207 for a fluid, such as a substitution solution, medication, or an anticoagulant that inhibits blood clotting, can be provided. The anticoagulant is preferably a systemically acting anticoagulant such as heparin, but can also be a locally acting anticoagulant such as citrate.

[0052] Furthermore, pressure sensors can be provided in the extracorporeal circuit 200, for example, as indicated in the simplified illustration, an arterial pressure sensor PS1 which measures the pressure in the arterial blood line 201 upstream of the pumping device for blood 101, an arterial pressure sensor PS2 which measures the pressure in the arterial blood line 201 downstream of the pumping device for blood 101 and upstream of the gas exchange unit 300 and a venous pressure sensor PS3 which measures the pressure in the venous blood line 202 downstream of the gas exchange unit 300.

[0053] Also located in the venous blood line 202 downstream of the gas exchange unit 300 is a temperature sensor TS, which measures the blood temperature as a treatment parameter. Alternatively or additionally, a temperature sensor can also be provided directly on the patient, whereby the blood temperature can be determined based on the values ​​measured there.

[0054] In addition, at least one sensor for measuring the blood flow rate in the extracorporeal circuit can be provided in a blood line (201, 202) upstream and / or downstream of the gas exchanger 300 or integrated into the pumping device for blood (101) (not shown here).

[0055] In addition to the gas exchange unit 300, the blood treatment device 100 can also comprise one or more additional blood treatment units, such as a dialyzer, an adsorber cartridge, or a diagnostic unit (not shown here). In this way, multiple treatment techniques can be combined.

[0056] The gas exchange unit 300 is connected on the one hand to the purge gas circuit 400 via a purge gas inlet 301 and a purge gas outlet 302 and on the other hand to the extracorporeal blood circuit 200 via a blood inlet 303 and outlet 304.

[0057] The gas flows from a purge gas source 401 into the gas exchange unit 300 via a first line section for the purge gas supply 402 and out of the gas exchange unit 300 via a second line section for the purge gas supply 403.

[0058] The second line section for the purge gas supply 403 can have a sensor PS4 for measuring the carbon dioxide partial pressure (pCO2) and / or for measuring the oxygen partial pressure (pO2). Alternatively or additionally, such a sensor can also be provided in the venous blood line 202 downstream of the gas exchange unit 300 (not shown here). However, instead of using the sensor PS4, the pCO2 or pO2 can also be measured via a blood gas analysis, in which a blood sample is taken from the extracorporeal circuit 200 at a designated sampling point.

[0059] The purge gas circuit 400 can consist of a hose set which can be designed as a disposable medical item for hygienic reasons.

[0060] The purge gas circuit 400 further comprises a device for changing at least one purge gas parameter 404. This device includes a purge gas pump 405 or, alternatively, a throttle-based flow regulator, for example, which conveys the purge gas from the purge gas source 401, which produces or provides fresh purge gas consisting of room air, oxygen, or a mixture of oxygen and other gases, such as noble gases or nitrogen, along the first purge gas line section 402 via the purge gas inlet 301 into the gas exchange unit 300 and out again along the second purge gas line section 403 via the purge gas outlet 302. The purge gas source 401 can provide the purge gas in a container, such as a gas cylinder, or can be connected to a gas line from which purge gas is continuously supplied.When using room air, the purge gas source 401 may include or be connected to a particle filter to provide purge gas that is as free as possible from harmful particles, such as dust.

[0061] The device for changing at least one purge gas parameter 404 optionally further includes a heating device 406 for heating the purge gas (for example ProLUNG Meter from ESTOR, which heats the purge gas and simultaneously controls the purge gas flow) and optionally a humidification device 407 (for example Bennet Cascade Humidifier from Robin Medical Ltd. or respiratory gas humidifier and heater Aircon from WILAmed) for humidifying the purge gas.

[0062] The purge gas circuit 400 may, preferably upstream of the gas exchange unit 300, comprise sensors for detecting purge gas parameters, such as the purge gas temperature, purge gas humidity and purge gas flow rate (not shown here).

[0063] The blood treatment device 100 further comprises a control unit 500 configured to regulate or control the device for changing at least one purge gas parameter 404. For this purpose, it can be in wired or wireless signal communication with each of the aforementioned components, in particular with the blood pumping device 101, the temperature sensor TS, the sensor PS1 and / or PS2 for measuring pCO2 and / or pO2, the purge gas source 401, and with the individual components of the device for changing at least one purge gas parameter 404.

[0064] The control unit 500 is configured to operate the purge gas pump 405 with electrical power to regulate the flow rate of the purge gas. The control unit 500 is further configured to operate the heating device 406 and humidification device 407 with electrical power to regulate the temperature and humidity of the purge gas.

[0065] By means of the device electronics, the performance of the purge gas pump 405, the heating device 406 or the humidification device 407 can be controlled, regulated, stored and / or displayed depending on one or more values ​​detected by the sensor(s).

[0066] The method according to the invention can thus be carried out essentially or completely by the control unit 500; in particular, those steps which do not require or involve human intervention and / or provision can be carried out by the control unit.

[0067] In a further embodiment, the blood treatment device 100 can additionally comprise a mechanical ventilation unit 600, with which CO2 and O2 exchange can also be performed. Mechanical ventilation can be performed either non-invasively using a helmet or mask 601 or invasively using an endotracheal tube 602 inserted through the nose or mouth, or via a tracheostomy cannula inserted into the trachea via a stoma (shown only schematically in Fig. 1). The control unit 500 is also connected to the mechanical ventilation unit 600 and configured to control it taking into account the treatment parameters and sensor measurements.

[0068] In the method for controlling the device for changing at least one purge gas parameter 404 and / or the mechanical ventilation unit 600, at least values ​​for the treatment parameters, such as the patient temperature and / or the pCO2 and / or the flow rate, are first detected by the sensors (actual values) and transmitted to the control unit 500.

[0069] The control unit 500 compares the recorded values ​​with the values ​​entered by the user and / or with preset values ​​(setpoints) and calculates manipulated variables for the device for changing at least one purge gas parameter.

[0070] Based on the calculated manipulated variables, the control unit 500 controls the purge gas pump 405 and / or the heating device 406 and / or the humidification device 407 such that the flow rate of the purge gas is increased or decreased and / or the purge gas is heated and / or humidified. The purge gas pump 405, the heating device 406, and the humidification device 407 can be activated or deactivated independently of one another.

[0071] In the following, the method according to the invention will be explained in more detail using exemplary embodiments.

[0072] As stated initially, the flow rate, temperature, and humidity of the purge gas used during ECLS treatment are factors that influence both the CO2 removal rate and the heat loss from the blood.

[0073] For example, a high purge gas flow rate results in high CO2 removal. However, as the purge gas flow rate increases, so does heat loss, even increasing proportionally. It is therefore desirable to control the treatment parameters in such a way that they are adapted to the patient's condition and treatment status and optimally adjusted for the treatment goal.

[0074] Fig. 2 shows an example of a CO2 removal curve (carbon dioxide transfer rate, CTR) as a function of the purge gas flow, i.e., the removal of CO2 from the blood, at a constant blood flow rate and varying purge gas flow rates, determined in a laboratory test setup. Such CO2 removal curves are typical for specific gas exchange units.

[0075] The CO2 removal rate is greatest at a purge gas flow to blood flow ratio of 15:1, for example, a blood flow of 0.5 l / min and a maximum purge gas flow of 7.5 l / min. For the treatment goal of maximum CO2 removal, a purge gas flow to blood flow ratio of 15:1 is optimal.

[0076] If the purge gas flow rate is reduced and thus the ratio of purge gas flow to blood flow is changed, the heat loss is reduced, but also the amount of CO2 removed.

[0077] At a purge gas flow to blood flow ratio of 5:1, for example, a blood flow of 0.5 l / min and a purge gas flow of 2.5 l / min, CO2 removal decreases by only 10%. With a further reduction in purge gas flow, the curve becomes steeper, meaning the CO2 removal rate decreases more sharply. Therefore, for the treatment goal of minimal heat loss, a purge gas flow to blood flow ratio of 5:1 is optimal.

[0078] As already described above, the purge gas temperature and humidity also influence the amount of heat loss experienced by the patient. Figure 3 shows, as an example, the reduction in the carbon dioxide partial pressure ApCO2 in mmHg between the blood inlet 303 and the blood outlet 304 of the gas exchanger 300 for various purge gas conditioning conditions over time in seconds.

[0079] The figure shows that cold and dry purge gas (shown as a dotted line in the figure) has the highest CO2 removal rate in comparison.

[0080] However, cold and dry purge gas also causes the highest heat loss. Heating and humidifying the purge gas reduces heat loss, while simultaneously lowering the CO2 removal rate.

[0081] However, the CO2 removal rate does not decrease proportionally: heating the purge gas (shown as a dashed line in Figure X) reduces it by approximately 10% in the example shown; heating and humidifying it (shown as a solid line in Figure X) reduces it by a further 10% at most. Knowing these factors, an optimal setting for the treatment goal can be found based on the patient's condition and treatment status.

[0082] In a further embodiment, the total amount of CO2 removed may be calculated and / or accounted for based on the detected pCO2.

[0083] The calculation can be done, for example, by multiplying the CO2 concentration in the outflowing purge gas (e.g. in %) by the purge gas flow rate (ml / min).

[0084] Commercially available pCO2 sensors also take the humidity of the measured air into account. This assumes that the CO2 concentration of the purge gas is zero, or at least known and close to zero, as is the case with air.

[0085] In another embodiment, the total CO2 removal rate can be calculated by the control device via an electronic interface during simultaneous mechanical ventilation. The calculation is performed by adding the removal rate of the natural lung from the ventilator and the removal rate of the membrane lung. Using an additional CO2 sensor at the outlet of the non-invasive (mask) ventilation unit, together with the purge gas flow rate (CO2 content in the purge gas multiplied by the purge gas flow rate), it is possible to create a total balance for removed CO2, analogous to a mechanical ventilation device. The two determined removal rates (natural lung and membrane lung) are added together.

[0086] Fig. 4 shows the blood treatment device 100 according to the invention in a schematic representation.

[0087] What is stated with regard to the individual components in Fig. 1 also applies to Fig. 2. In the following, therefore, only the additions in Fig. 2 compared to the representation in Fig. 1 will be discussed.

[0088] Thus, Fig. 2 shows the aforementioned control unit 500, which is connected to an extracorporeal blood treatment device 200, a gas exchange unit 300, a device for changing the purge gas parameters 404, and a gas source 401. The blood treatment device 200 can be connected to a patient P via a vascular access.

[0089] Fig. 2 further shows that the control unit 500 is connected to a hardware and software unit 700, which includes additional components. Data exchange between the individual components of the hardware and software unit 700 takes place via corresponding interfaces.

[0090] The hardware and software unit 700 can, for example, have a user interface 701.

[0091] The user interface 701 can be designed, for example, as a graphical user interface. The user can select or change a treatment target using a keyboard, a mouse, or a touchscreen. According to the invention, the treatment target is selected based on the opposing goals of maximizing CO2 removal and minimizing heat loss with different purge gas parameter settings.

[0092] Based on user B's specification of a treatment goal, the control unit 500 executes predetermined processes individually or in combination. For example, an input on the user interface 701 by the user can trigger a change in the purge gas temperature, the purge gas humidity, and the purge gas flow rate, individually or in combination.

[0093] In this way, the blood treatment device 100 can be adjusted to the respective treatment target depending on the user's target specification via a control of the device for changing at least one purge gas parameter 404 by the control unit 500 based on the input treatment target and depending on the at least two treatment parameters pCO2 and / or blood temperature and / or blood flow rate.

[0094] Alternatively or additionally, the target setting can also be automated by a script 704 or by the automated execution of various predefined steps.

[0095] Alternatively or additionally, the target specification can also originate from a data-based decision support system 702, which considers data from at least one data source 703, such as a clinical data system, and proposes this to user B for selection for the target specification. The data can be, for example, a physiological parameter or a target value for purge gas or treatment parameters.

[0096] After confirmation or modification of this target, the data is transmitted to the control unit 500. The latter triggers a different combination of the purge gas flow rate and / or purge gas temperature and / or purge gas humidity.

[0097] At least 3 3Combinations are conceivable, and using individual gradations of heating, humidification, and flow rate, even significantly more. Some combinations may be more common, but others less common. For example, due to the higher complexity, humidification is generally only carried out in combination with heating of the purge gas. Conversely, while heating the purge gas can contribute to a reduction in temperature loss even without humidification, due to the enthalpy of gases, simply heating a gas only leads to a slight increase in its specific heat content. Additional humidification increases the enthalpy dramatically.

[0098] For example, when an initially dry purge gas is heated from 20°C (10% relative humidity) to 37°C (5% relative humidity), the specific heat content increases from 23.8 kJ per kg of dry air to 42.2 kJ per kg of dry air. If the purge gas is humidified simultaneously with the heating, the specific heat content increases to 142.8 kJ per kg of dry air.

[0099] This makes it clear that the greater part of the heating is caused by humidification of the purge gas before the gas exchanger, because the latter significantly reduces the vapor pressure difference across the membrane as the driving force for the transfer of water vapor, which reduces the amount of water evaporating at the membrane and thus the heat loss (evaporative cooling).

[0100] Fig. 5 shows exemplary measured values ​​for the blood temperature in °Celsius at the blood inlet 303 and outlet 304 at different purge gas temperatures and humidity over the duration of the treatment, given in hours.

[0101] The black, bold line represents the blood temperature over a certain period of time without treatment. It remains relatively constant at 36.5°C.

[0102] The gray, solid line shows the blood temperature over a certain period of time during extracorporeal treatment without the use of a purge gas. A heat loss of approximately 0.5°C can be seen, which occurs through heat radiation and conduction across the surface of the extracorporeal blood tubing system. The gray, dashed line shows the blood temperature over a certain period of time during ECLS using a purge gas at room temperature, i.e. without additional heating and humidification. It can be seen that the blood temperature is at a comparatively lower level of around 35.7°C at the start of treatment and continues to fall during the treatment until it settles at 35.5.

[0103] The black dashed line shows the blood temperature over a certain period of time during ECLS using purge gas, which is only warmed but not humidified. It can be seen that the blood temperature is at a very low level of 35.4°C at the beginning of the treatment, then rises and settles at a constant temperature of 35.5°C.

[0104] The thin black line shows the blood temperature over a certain period of time during ECLS using warmed and humidified purge gas. At the beginning of the treatment, the temperature is 36°C, which is slightly lower, but does not decrease further.

[0105] In summary, it can be seen that warm and humidified purge gas causes a similarly low temperature reduction as when purge gas is switched off. The influence of purge gas on the temperature in terms of a reduction can thus be reduced to almost zero by heating and humidifying.

[0106] Overall, it can be said that controlling the purge gas humidity is particularly relevant for reducing heat loss.

[0107] It is conceivable that the user changes the target during the course of treatment. For example, it may be useful to achieve a rapid reduction in blood pCO2 for a certain period of time at the start of treatment. As the treatment progresses, the focus is then on avoiding heat loss for a longer period of time. Intermediate goals are also conceivable. The user can enter the changed target via the user interface. A script with proven sequences of treatment steps, e.g. rapid initial reduction in the patient's pCO2 followed by moderate CO2 removal with simultaneous compensation for heat loss by heating and humidifying the purge gas, can be used to control the device. In treatment situations in which humidification and heating are not available, a reduction in the purge gas flow can be used instead.

[0108] List of reference symbols

[0109] 100 blood treatment devices

[0110] 101 Blood pumping device

[0111] 200 extracorporeal blood circulation

[0112] 201 arterial blood line

[0113] 202 venous blood line

[0114] 203 arterial clamp

[0115] 204 venous clamp

[0116] 205 venous blood chamber

[0117] 206 Ventilation device

[0118] 207 Addition point for a fluid

[0119] 300 gas exchange units

[0120] 301 Purge gas inlet

[0121] 302 Purge gas outlet

[0122] 303 Blood inlet

[0123] 304 Blood outlet

[0124] 400 purge gas circuit

[0125] 401 Purge gas source

[0126] 402 first line section for purge gas supply

[0127] 403 second pipe section for purge gas discharge

[0128] 404 Device for changing at least one purge gas parameter

[0129] 405 Purge gas pump 06 Heating device 07 Humidification device 00 Control unit 00 Mechanical ventilation unit 01 Mask 02 Tube

[0130] 700 hardware and software units

[0131] 701 User Interface

[0132] 702 Decision support system

[0133] 703 Data source

[0134] 704 Script

[0135] B User

[0136] P Patient

[0137] PS1, PS2 arterial pressure sensor

[0138] PS3 venous pressure sensor

[0139] PS4 sensor for measuring pCO2

[0140] TS temperature sensor

Claims

Patent claims 1. A blood treatment device (100) for gas exchange via a gas exchange unit (300) having two regions separated by a membrane, one region being flowed through by blood and the other region being flowed through by purge gas, comprising: - a pumping device for blood (101 ), - Sensors for measuring at least two treatment parameters - a device for changing at least one purge gas parameter (404) and a control unit (500) connected to the pumping device for blood (101), the sensors for measuring at least two treatment parameters and the device for changing at least one purge gas parameter (404), characterized in that the control unit (500) is configured such that it controls the device for changing at least one purge gas parameter (404) depending on the at least two treatment parameters.

2. Blood treatment device (100) according to claim 1, characterized in that the gas exchange is a removal of carbon dioxide from the extracorporeal blood circuit (200).

3. Blood treatment device (100) according to claim 1 or 2, characterized in that the gas exchange unit (300) is a membrane oxygenator or a dialyzer.

4. Blood treatment device (100) according to one of the preceding claims, characterized in that at least two treatment parameters are patient temperature and / or carbon dioxide partial pressure and / or blood flow rate.

5. Blood treatment device (100) according to one of the preceding claims, characterized in that the patient temperature is a treatment parameter measured in the extracorporeal blood circuit (200) or on the patient's body and that the carbon dioxide partial pressure is a treatment parameter measured in the purge gas or in the extracorporeal blood circuit (200).

6. Blood treatment device (100) according to one of the preceding claims, characterized in that at least one purge gas parameter is the temperature and / or the humidity and / or the flow rate of the purge gas.

7. Blood treatment device (100) according to one of the preceding claims, characterized in that the device for changing at least one purge gas parameter (404) - a purge gas pump or a flow regulator (405) for conveying the purge gas and / or - a heating device (406) for heating the purge gas and / or - a humidification device (407) for humidifying the purge gas.

8. Blood treatment device (100) according to one of the preceding claims, characterized in that the control unit (500) is connected to a user interface (701) for the input of at least one treatment target.

9. Blood treatment device (100) according to one of the preceding claims, characterized in that the control unit (500) is connected to a decision support system (702).

10. Blood treatment device (100) according to one of the preceding claims, characterized in that it is connected via a hose system to the patient and the gas exchange unit (300) or to the patient and the gas exchange unit (300) and at least one further blood treatment unit, such as a dialyzer or an adsorber cartridge.

11. Blood treatment device (100) according to one of the preceding claims, characterized in that the blood treatment device (100) further comprises a mechanical ventilation unit (600) and that the control unit (500) is configured such that it controls the device for changing at least one purge gas parameter (404) and / or the mechanical ventilation unit (600) depending on the at least two treatment parameters.

12. A method for controlling and / or regulating the device for changing at least one purge gas parameter (404) and / or the mechanical ventilation unit (600) in a blood treatment device (100) according to one of claims 1 to 11, characterized by the following steps: - Recording of at least two treatment parameters using sensors, - Comparison of the recorded treatment parameters with the treatment parameters entered and / or preset by the user - Calculation of control variables based on the adjustment - Control of the purge gas pump (405), and / or the heating device (406) and / or the humidification device (407) on the basis of the calculated manipulated variables.

13. Method according to claim 12, characterized in that a calculation and / or balancing of the total amount of carbon dioxide removed by the device is carried out on the basis of the value for the carbon dioxide partial pressure and the purge gas flow.

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