DE102023102145A1 - Blood treatment device for gas exchange - Google Patents

Abstract

The invention relates to a blood treatment device 100 for gas exchange via a gas exchange unit 300, which has two areas separated by a membrane, wherein blood flows through one area and flushing gas flows through the other area, and wherein the blood treatment device 100 comprises a pumping device for blood 101, sensors for measuring at least two treatment parameters, a device for changing at least one flushing gas parameter 404 and a control unit 500, which is 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 flushing gas parameter 404, and is configured such that it controls the device for changing at least one flushing gas parameter 404 depending on the at least two treatment parameters. The invention further relates to a method for controlling the device for changing at least one flushing gas parameter 404 and/or a mechanical ventilation unit 600 in the blood treatment device 100 according to the invention.

Description

Technical area

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.

background

The main task of the lungs is to supply the body with oxygen (O2) and to remove the carbon dioxide (CO2) produced by metabolism from the body. During inhalation, oxygen-containing air flows into the lungs. The oxygen diffuses through the lungs into the blood and circulates in 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. Through the respiratory movement and the circulating blood, a continuous exchange of O2 and CO2 takes place between the ambient air, the lungs and the blood.

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 body's supply of O2 and/or the removal of CO2 from it.

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).

In hypercapnic patients, such as those suffering from COPD, the removal of CO2 is particularly impaired. In order to effectively remove CO2 from the three compartments of the body - blood, tissue and bone - these patients usually receive mask ventilation with high gas pressure. However, since this treatment is very restrictive for the patient and is perceived as unpleasant, it is usually poorly tolerated.

Mechanical ventilation, which requires intubation to introduce gas into the lungs under high pressure, is avoided if possible in hypercapnic patients, since on the one hand the CO2 cannot be sufficiently removed in this way and on the other hand the ventilation is associated with considerable restrictions for the patient due to the required sedation as well as side effects and long-term effects, particularly for the lung tissue.

Another option for treating hypercapnic patients is the extracorporeal lung support (ECLS) procedure. In this procedure, blood is passed through a gas exchange device, such as a membrane oxygenator or a dialyzer, in an extracorporeal circuit. The gas exchange device takes over the gas exchange function of the lungs. The basic structure and functioning of a membrane oxygenator and a dialyzer are known from the state of the art. 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 of the purge gas mixture can vary.

The level of blood flow rate during ECLS treatment determines whether therapeutically relevant oxygen is predominantly supplied (extracorporeal membrane oxygenation, ECMO) and carbon dioxide is simultaneously removed, or whether carbon dioxide is predominantly 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), which can be less than 1.5 l/min or even less than 500 ml/min, so that treatment can be carried out with a smaller catheter for vascular access than with 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 with this treatment. Advantageously, the hypercapnic patient can be treated with ECCO2R treatment in a “minimally invasive” but still effective manner.

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

Therefore, most oxygenators are equipped with a heat exchanger, which can be heated by an external heating/cooling unit with tempered water, thus ensuring that the blood temperature remains largely constant during the treatment.

However, due to cost and space constraints, ECCO2R treatment devices are usually not equipped with a heat exchanger or an alternative solution for temperature control. Although the blood flow rate during ECCO2R treatment is lower than during ECMO treatment, a significant amount of heat loss occurs even at low blood flows.

In addition, the ratio of purge gas flow to blood flow is significantly higher in ECCO2R treatment at around 15:1 or 5:1 than in ECMO treatment, which is why heat loss is even greater in proportion. It is therefore necessary to actively influence or compensate for the heat loss of the blood during ECCO2R treatment.

During treatment, additional measures must therefore be taken, such as the use of heated blankets, to prevent the patient from cooling down. However, these measures are often perceived as disturbing by the patient, are also time-consuming and interrupt clinical operations.

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.

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

It is also conceivable that when using cold purge gas, a stronger heat exchange takes place 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 the purge gas is heated to blood temperature, no exchange of heat between the blood and the purge gas is to be expected 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 difference in vapor pressure as the driving force, 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 purge gas flows. The water vapor condenses on the other side of the membrane and is absorbed by the purge gas passing by. This process leads to heat loss through the creation of "evaporative cooling."

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

For example, the European patent EP 2 736 557 B1 , which deals with the electronically controlled mixing of various purge gas components, in addition to a heating element for heating the purge gas, also a unit for humidifying the purge gas in order to prevent the patient from cooling down.

In the US patent US$3,927,981 A blood oxygenator for enriching O2 and removing CO2 is described. To reduce gas and energy consumption, the purge gas is heated and humidified.

Overall, it can be stated that the heat loss resulting from ECLS treatment can be reduced by reducing the purge gas flow or by heating or humidifying the purge gas.

However, it has been shown that when the above measures are applied, the effectiveness of gas exchange itself decreases because, for example, less CO2 is removed from the blood. As a result, either the frequency or duration of treatment or both must be increased, which in turn leads to the patient cooling down more.

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 as little temperature drop as possible, but receives as effective treatment as possible, regardless of whether O2 is supplied and/or CO2 is removed.

The object according to 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 each contain advantageous embodiments of the invention.

Summary of the invention

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 flushing gas parameter.

The blood treatment device further comprises a control unit which is connected to the pumping device for blood, 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 such that it controls 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 essentially all method steps.

The term gas exchange includes the removal of CO2 from the extracorporeal bloodstream or the addition of O2 to the extracorporeal bloodstream, or both.

The gas exchange unit consists of a housing that contains hollow fiber bundles. The hollow fiber bundles form a semi-permeable membrane that separates the gas exchange unit into two areas. For example, the blood flows - usually in countercurrent - inside the hollow fibers, the flushing gas 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 preferably consist of a hydrophilic, microporous hollow fiber, for example of polysulfone or polyethersulfone, containing a proportion of polyvinylpyrrolidone (PVP). The hollow fiber can also consist of polymethylpentene (PMP) if the geometry allows humidification without the membrane becoming closed by an accumulation of tiny water droplets.

The term treatment parameters includes, for example, the patient temperature, the carbon dioxide partial pressure (pCO2) or the blood flow rate. The patient temperature can be measured using a suitable sensor either in the blood line or directly on the patient, or it can be read in via a data interface to the clinical data system. The 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 flushing gas, or in the blood, for example using a blood gas analysis. The blood flow rate can be measured using a sensor integrated in the blood pumping device or using a flow sensor located in the arterial or venous line in the extracorporeal blood circuit.

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

The device for changing at least one purge gas parameter can be a heating device for heating the purge gas or a humidification 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 goal. 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.

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

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

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

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

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.

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 can be preset.

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

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 flow rate of the purge gas is increased or decreased.

It is also conceivable to calculate and/or balance the total amount of CO2 removed based on the pCO2 measured. Assuming that the CO2 content at the purge gas inlet is equal to or almost equal to zero, the CO2 content in percent is multiplied by the purge gas flow rate.

• 1 zeigt ein Verfahrensbild der erfindungsgemäßen Blutbehandlungsvorrichtung in einer vereinfachten Darstellung
• 2 zeigt eine CO2-Entfernungskurve in Abhängigkeit des Spülgasflusses
• 3 zeigt den Kohlenstoffdioxidpartialdruck bei verschiedenen Konditionierungen des Spülgases über die Zeit
• 4 zeigt die erfindungsgemäße Behandlungsvorrichtung in einer schematischen Darstellung
• 5 zeigt die Bluttemperatur bei verschiedenen Konditionierungen des Spülgases

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:

• 1 shows a process diagram of the blood treatment device according to the invention in a simplified representation
• 2 shows a CO2 removal curve depending on the purge gas flow
• 3 shows the carbon dioxide partial pressure for different purge gas conditioning over time
• 4 shows the treatment device according to the invention in a schematic representation
• 5 shows the blood temperature under different purge gas conditioning conditions

1 shows a process diagram of the blood treatment device according to the invention in a simplified representation. The blood treatment device 100 is optionally connected to an extracorporeal blood circuit 200 in the form of a hose set, which leads in an arterial blood line 201 to a gas exchange unit 300 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 hose set can be designed as a disposable medical article, which is discarded after treatment.

The arterial and venous blood lines 201 and 202 optionally have an arterial clamp 203 and a venous clamp 204, by means of which the respective blood line can be closed.

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

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 S.r.l., Medolla (MO), Italy) or dialyzer. The gas exchange unit 300 is divided by hollow fiber bundles, which together form a semipermeable membrane, into an area through which blood flows and an area through which purge gas flows (not shown here). In the gas exchange unit 300, CO2 is removed from or O2 is supplied to the extracorporeal blood circuit 200, or both. The membrane can be coated with silicone or a silicone solution, with the blood side of the hollow fibers preferably being coated.

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

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.

In the venous blood line 202 downstream of the gas exchange unit 300 there is also a temperature sensor TS that measures the temperature of the blood as a treatment parameter. Alternatively or additionally, a temperature sensor can also be provided directly on the patient, whereby the temperature of the blood can be determined on the basis of the values measured there.

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).

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

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.

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.

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 measurement of the pCO2 or pO2 can also be carried out via a blood gas analysis in which a blood sample is taken from the extracorporeal circuit 200 at a sampling point provided for this purpose.

The purge gas circuit 400 can consist of a hose set, which can be designed as a medical disposable article for hygienic reasons.

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

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

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

The blood treatment device 100 further comprises a control unit 500 which is configured to regulate or control the device for changing at least one purge gas parameter 404. For this purpose, it can be in a wired or wireless signal connection with each of the previously mentioned components, in particular with the pump device for blood 101, the temperature sensor TS, the sensor PS 1 and/or PS2 for measuring the 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.

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

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).

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.

In a further embodiment, the blood treatment device 100 can additionally comprise a mechanical ventilation unit 600, with which a CO2 and O2 exchange can also be carried out. Mechanical ventilation can be carried out either non-invasively by means of a helmet or a mask 601 or invasively by means of an endotracheal tube 602, which is inserted through the nose or mouth, or via a tracheostomy tube, which is inserted into the trachea via a stoma (in 1 shown only schematically). 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 readings.

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 recorded by the sensors (actual values) and transmitted to the control unit 500.

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

Based on the calculated control 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.

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

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.

For example, a high purge gas flow rate results in a high removal of CO2. However, as the purge gas flow rate increases, the heat loss also increases, and even increases 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 are optimally adjusted for the treatment goal.

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

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, the setting with a purge gas flow to blood flow ratio of 15:1 is optimal.

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.

With 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, the CO2 removal is reduced by only 10%. If the purge gas flow is further reduced, the curve becomes steeper, which means that the CO2 removal rate decreases more. For the treatment goal of minimal heat loss, a setting with a purge gas flow to blood flow ratio of 5:1 is therefore optimal.

As already described above, the purge gas temperature and humidity also influence the amount of heat lost by the patient.

3 shows, by way of example, the reduction of the carbon dioxide partial pressure ΔpCO2 in mmHg between the blood inlet 303 and the blood outlet 304 of the gas exchanger 300 with different conditioning of the purge gas over time in seconds.

From the figure it can be seen that cold and dry purge gas (shown as a dotted line in the figure) has the highest CO2 removal rate in comparison.

However, cold and dry purge gas also causes the highest heat loss. By warming and humidifying the purge gas, the heat loss is reduced, while at the same time the CO2 removal rate is reduced.

However, the CO2 removal rate does not decrease proportionally: by heating the purge gas (in the shown as a dashed line) it decreases in the example shown by about 10%, by heating and moistening (in the shown as a solid line) it drops by a maximum of another 10%. Knowing these facts, an optimal setting for the treatment goal can be found for the patient's condition and treatment status.

In a further embodiment, a calculation and/or accounting of the total amount of CO2 removed may be performed based on the detected pCO2.

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).

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

In a further embodiment, the total CO2 removal rate can be calculated by the control device via an electronic interface when mechanical ventilation is taking place at the same time. The calculation is carried out by adding the removal rate of the natural lung from the ventilator and the removal rate of the membrane lung.

By means of an additional CO2 sensor at the outlet of the non-invasive (mask) ventilation unit, together with the purge gas flow rate O(CO2 content in the purge gas multiplied by the flow rate of the purge gas), it is possible to create an overall balance for removed CO2 analogous to a mechanical ventilation device. both determined removal rates (natural lung and membrane lung) are added.

4 shows the blood treatment device 100 according to the invention in a schematic representation.

Regarding the individual components 1 is also valid for 2 . In the following, therefore, only the additions in 2 compared to the representation in 1 received.

This shows 2 the control unit 500 already mentioned above, which is connected to an extracorporeal blood treatment device 200, a gas exchange unit 300, a device for changing the flushing gas parameters 404 and a gas source 401. The blood treatment device 200 can be connected to a patient P via a vascular access.

2 further shows that the control unit 500 is connected to a hardware and software unit 700, which includes further components. The data exchange between the individual components of the hardware and software unit 700 takes place via corresponding interfaces.

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

The user interface 701 can be designed, for example, as a graphical user interface. The user can select or change a treatment goal using a keyboard, a mouse or a touch screen.

According to the invention, the treatment objective is selected with regard to the contradictory objectives of maximizing CO2 removal and minimizing heat loss at different settings of the purge gas parameters.

Based on the user B's specification for a treatment goal, the control unit 500 carries out predetermined processes individually or in combination. An input on the user interface 701 by the user can, for example, trigger a change in the purge gas temperature, the purge gas humidity and the purge gas flow rate individually or in combination.

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 entered treatment target and depending on the at least two treatment parameters pCO2 and/or blood temperature and/or blood flow rate.

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

Alternatively or additionally, the target specification can also originate from a data-based decision support system 702, which takes into account data from at least one data source 703, such as a clinical data system, and suggests these 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.

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.

At least ³ combinations are conceivable, and even more using individual gradations of heating, humidification and flow rate.

Some combinations may be more common, but others are less common. For example, due to the higher effort involved, humidification is usually only carried out in combination with heating of the purge gas. Conversely, heating the purge gas can help reduce temperature loss even without humidification, but according to the enthalpy of gases, simply heating a gas only leads to a small increase in the specific heat content. Additional humidification increases the enthalpy dramatically.

For example, when an initially dry purge gas is heated from 20° Celsius (10% relative humidity) to 37° Celsius (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 at the same time as it is heated, the specific heat content increases to 142.8 kJ per kg of dry air.

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 The amount of water evaporating and thus the heat loss (evaporative cooling) is reduced.

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.

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

The blood temperature is shown as a gray, continuous line over a certain period of time during an extracorporeal treatment without the use of a purge gas. A heat loss of about 0.5°C can be seen, which is caused by 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 flushing gas at room temperature, i.e. without additional heating and humidification. It can be seen that the blood temperature at the beginning of the treatment is at a comparatively lower level of around 35.7°C and continues to fall during the treatment until it levels off at 35.5.

The black dashed line shows the blood temperature over a certain period of time during ECLS using purge gas, which is only heated 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 level of 35.5°C.

The blood temperature over a certain period of time during ECLS using warmed and humidified purge gas is shown as a thin black line. At the beginning of the treatment, the temperature is 36°C and is therefore slightly lower, but does not fall any further.

In summary, it can be seen that warm and humidified purge gas causes a similarly small reduction in temperature as purge gas that is switched off. The influence that the use of purge gas has on the temperature in terms of a reduction can therefore be reduced to almost zero by heating and humidifying.

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

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 the pCO2 in the blood for a certain period of time at the beginning of the treatment. As the treatment progresses, the focus is then on avoiding heat loss for a longer period of time. Intermediate targets 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 lowering of the patient's pCO2 and subsequent moderate CO2 removal while simultaneously compensating 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, lowering the purge gas flow can also be used instead.

List of reference symbols

100

Blood treatment device

101

Pumping device for blood

200

extracorporeal blood circulation

201

arterial blood flow

202

venous blood supply

203

arterial clamp

204

venous clamp

205

venous blood chamber

206

Ventilation device

207

Addition point for a fluid

300

Gas exchange unit

301

Purge gas inlet

302

Purge gas outlet

303

Blood intake

304

Blood outlet

400

Purge gas circuit

401

Purge gas source

402

first line section for purge gas supply

403

second pipe section for purge gas removal

404

Device for changing at least one purge gas parameter

405

Purge gas pump

406

Heating device

407

Humidification device

500

Control unit

600

mechanical ventilation unit

601

mask

602

Tube

700

Hardware and software unit

701

user interface

702

Decision support system

703

Data Source

704

Script

B

user

P

patient

PS1, PS2

arterial pressure sensor

PS3

venous pressure sensor

PS4

Sensor for measuring pCO2

TS

Temperature sensor

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• EP 2736557 B1 [0019]
• US3927981 [0020]

Claims (13)

Blood treatment device (100) for gas exchange via a gas exchange unit (300) which has two areas separated by a membrane, one area being flowed through by blood and the other area 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. 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). 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. Blood treatment device (100) according to one of the preceding claims, characterized in that the at least two treatment parameters are the patient temperature and/or the carbon dioxide partial pressure and/or the blood flow rate. 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). 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. 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) comprises - 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. 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 goal. 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). 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. 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. 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 the Claims 1 until 11 , characterized by the following steps: - detecting at least two treatment parameters by means of sensors, - comparing the detected treatment parameters with the treatment parameters entered and/or preset by the user - calculating manipulated variables on the basis of the comparison - controlling 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. Procedure 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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