Apparatus and method for determining carbon dioxide partial pressure values ​​on the blood side of an oxygenator

Abstract

1. A device 1 for determining a value of the partial pressure of CO2 on the blood side 2 of an oxygenator 4, comprising: an oxygenator 4 having a blood side 2, a gas side 6 and a semi-permeable membrane 8, said membrane 8 separating said blood side 2 from said gas side 6, said gas side 6 having an inlet 14 and an outlet 16, wherein during operation of said oxygenator 4 a gas flow enters said inlet 14 and flows to said outlet 16 at a flow rate; a first sensor 10 configured to measure the value of the partial pressure of CO2 on said gas side 6; and a control unit (12) configured to process the measured CO2 partial pressure values ​​on the gas side (6) and to determine a CO2 partial pressure value on the blood side (2) based on the measured CO2 partial pressure values ​​on the gas side (6), wherein the control unit (12) calculates a rate of change of the measured CO2 partial pressure values ​​on the gas side (6) during operation of the oxygenator (4), and determines the CO2 partial pressure value on the blood side (2) by estimating the CO2 partial pressure value on the blood side (2) from the CO2 partial pressure value on the gas side (6) measured when or after the calculated rate of change becomes equal to a predetermined rate of change value or falls within a predetermined rate of change range at a predetermined measurement distance.

Description

[Technical Field]

[0001] The present disclosure relates to devices and methods for determining carbon dioxide (CO2) partial pressure values ​​on the blood side of an oxygenator, extracorporeal membrane oxygenation systems including the devices, cardiopulmonary bypass including the devices, and the methods during extracorporeal membrane oxygenation therapy or cardiopulmonary bypass. [Background technology]

[0002] Oxygenators, particularly membrane oxygenators, are commonly known for their use in cardiopulmonary bypass (CPB) systems or extracorporeal membrane oxygenation (ECMO) systems. While CPB is a fairly short-term technique for taking over cardiac and pulmonary functions during cardiac surgery, such as coronary artery bypass surgery, ECMO is a simplified version that can be used for the long-term treatment and recovery of various cardiac and pulmonary dysfunctions. Both CPB and ECMO systems require an oxygenator to add oxygen (O) to the patient's blood and remove carbon dioxide (CO) from the blood to mimic or support the function of the patient's lungs, i.e., to allow the exchange of O and CO between the patient's blood and the gas phase inside the oxygenator, thereby maintaining blood O and CO levels within physiological ranges. In a membrane oxygenator, the exchange of O and CO is achieved through a semipermeable membrane that separates the blood side from the gas side inside the oxygenator, allowing O and CO diffusion across / through the membrane. Dissolved CO2 in blood, especially central arterial blood, plays an important role in regulating various physiological functions, such as respiratory rate and reflexes, as well as maintaining a normal blood pH of around 7.4. Therefore, it is essential to monitor and / or control the partial pressure of CO2 (pCO2) in the (central arterial) blood of patients undergoing treatment.

[0003] When a CPB system is used during surgery, the oxygenator is placed near the patient's heart and lungs. Therefore, the pCO2 at the blood side of the oxygenator at the oxygenator's blood side outlet corresponds to the patient's central arterial pCO2. The pCO2 value at the blood side of the oxygenator at the oxygenator's blood side outlet can be estimated from the pCO2 value at the gas side of the oxygenator at the oxygenator's gas side outlet, and this estimate is based on the characteristic map of the oxygenator type.

[0004] Several types of ECMO are known in the art. In the most common type of ECMO, blood is drained from a vein, oxygenated in an extracorporeal membrane oxygenator, and then returned to the patient's body either through an artery (veno-arterial ECMO) or a vein (veno-venous ECMO). Depending on the type of ECMO, the location of vascular access or cannulation varies. In non-centrally cannulated ECMO, central arterial pCO2 cannot be estimated from measurements on the gas side of the oxygenator. Therefore, during operation of such ECMO systems in the clinic, arterial pCO2 is typically monitored by intermittently sampling the patient's arterial blood and measuring the pCO2 of each sample.

[0005] However, the drawbacks of these methods are that the intermittent sampling is tedious and there is a delay in the measurement results, while the estimation of pCO2 on the blood side at the blood outlet of the oxygenator is inevitably accompanied by inaccuracies that may have adverse effects on the patient's health. Summary of the Invention

[0006] It is therefore an object of the presently disclosed technology to overcome or at least mitigate the shortcomings of the prior art, and in particular to provide an apparatus and method that allows for a quick, easy, and more reliable or accurate determination of the partial pressure of CO2 (pCO2) in a patient's blood.

[0007] This object is solved by an apparatus according to the independent apparatus claim and by a method according to the independent method claim. Preferred embodiments of the apparatus and the method are set out in the dependent claims.

[0008] According to the present disclosure, a patient's venous pCO2 as an indicator of the patient's overall condition can be monitored in addition to or instead of monitoring the central arterial pCO2 value, particularly during ECMO therapy. During oxygenator operation, the blood inlet is fluidly connected to the patient's venous system, and the blood outlet is fluidly connected to either the patient's venous or arterial system, depending on the type of treatment system. While the blood outlet of the oxygenator in CPB is typically fluidly connected to the patient's arterial system, the blood outlet in ECMO can be connected to either the patient's venous or arterial system, depending on the type of ECMO (veno-venous or veno-arterial). In either case, the pCO2 value determined according to the disclosed technology is the pCO2 value of the patient's blood at the blood inlet of the oxygenator. In all of the above cases, the pCO2 value at the blood inlet is the patient's venous pCO2.

[0009] In one aspect of the disclosed technology, a device for determining a CO2 partial pressure value (pCO2 value) of blood on a blood side of an oxygenator is provided, the device comprising: an oxygenator having a blood side, a gas side, and a semipermeable membrane, the membrane separating the blood side from the gas side, the blood side and the gas side each having an inlet and an outlet, wherein gas flows at a certain flow rate into the gas side inlet and out the gas side outlet during operation of the oxygenator; a first sensor configured to measure the pCO2 value of the gas on the gas side (at the gas side); and a control unit configured to process the measured pCO2 value on the gas side and determine the pCO2 value of the blood on the blood side (or at the blood side), particularly the pCO2 value of the blood at the blood side inlet or the blood side outlet, based on the measured pCO2 value on the gas side. To measure the pCO2 value on the gas side, the first sensor can be provided either on the gas side of the oxygenator or inside the gas side, i.e., at or upstream of the gas side outlet, or in a gas line or gas line connected to the gas side / oxygenator, i.e., directly downstream of the gas side outlet. The control unit calculates the rate of change or rate of change value of the pCO2 value measured in the gas on the gas side during operation of the oxygenator, i.e., while gas enters the gas side inlet and flows to the gas side outlet and while blood enters the blood side inlet and flows to the blood side outlet, and determines the pCO2 value of the blood on the blood side by estimating the pCO2 value of the blood on the blood side from the pCO2 value measured in the gas on the gas side when or after the calculated rate of change value equals a predetermined rate of change value or falls within a predetermined rate of change value at a predetermined (shortest) measurement distance.

[0010] By calculating the rate of change or rate of change value, it is possible to determine whether the diffusion equilibrium of CO2 between the gas side and the blood side has been reached, i.e., whether the rate of change or rate of change value is (approximately) zero.

[0011] The predetermined rate of change value would ideally be zero, but due to measurement inaccuracies and / or measurement tolerances, the predetermined rate of change value may be a small value. Instead of a predetermined individual value, it may be more useful to specify a range of predetermined rate of change values, where the predetermined rate of change range includes an acceptable value around the target value, e.g., zero, where the acceptable value depends on the particular measurement device.

[0012] Once equilibrium is reached, the pCO2 value measured on / in the gas on the gas side is equal to the pCO2 value of the blood on the blood side, at least at the measurement point, i.e., the location of the first sensor, i.e., the pCO2 value of the blood on the blood side can be equal to either a specific single pCO2 value measured on / in the gas on the gas side when or after the calculated rate of change is equal to a predetermined rate value at said predetermined measurement distance, or the average value of all pCO2 values ​​measured in the gas on the gas side when or after the calculated rate of change is equal to a predetermined rate value or falls within said predetermined rate range at said predetermined measurement distance, or the average value of multiple specific pCO2 values ​​measured in the gas on the gas side when or after the calculated rate of change is equal to a predetermined rate value or falls within said predetermined rate range at said predetermined measurement distance, or any other combination of the above.

[0013] In this way, convenient, accurate, and rapid determination of the pCO2 value of the blood on the blood side of the oxygenator, particularly at the inlet or outlet of the blood side of the oxygenator, can be achieved, which can be used as an indicator of the patient's overall condition, allowing for improved treatment and health. Furthermore, determining the pCO2 value on the blood side while the oxygenator is operating means, in particular, that the determination can be made during patient treatment. Furthermore, the above-mentioned device makes it possible to determine the pCO2 value on the blood side even when the gas exchange characteristics of the oxygenator are not precisely known.

[0014] In a preferred embodiment, the rate of change is a temporal rate of change, i.e., rate of change over time, and the predetermined measurement distance is a predetermined period of time, i.e., the control unit is able to determine the pCO2 value on the blood side by calculating the rate of change of the measured gas-side pCO2 values ​​over time, and when or after the calculated rate of change equals a predetermined rate value for a predetermined (shortest) period of time, by estimating the pCO2 value of the blood on the blood side from the gas-side pCO2 values ​​measured during or after said period of time.

[0015] The predetermined period is the period during which it can be assumed that no further changes in the measured pCO2 value on the gas side (beyond the measurement tolerance / predetermined rate of change value) will occur. The predetermined period depends, among other things, on the flow rate, the initial pCO2 value of the blood, the characteristics of the sensor and the membrane, and should be determined in advance for the device and operating conditions. A nondispersive infrared sensor (NDIR sensor) can be used as a sensor for measuring pCO2 in gas.

[0016] In another preferred embodiment, the device comprises a second sensor configured to measure a CO2 partial pressure value on the gas side (or at the gas side), wherein the rate of change is the rate of change with respect to position, in particular in the direction of gas flow, i.e. over the distance between the gas side inlet and the gas side outlet, wherein the predetermined measurement distance is a predetermined local measurement distance, and the first and second sensors are arranged at the predetermined local measurement distance. That is, the control unit is able to determine the pCO2 value on the blood side by calculating the rate of change of the measured pCO2 value on the gas side over the local distance and estimating the pCO2 value of blood on the blood side from the gas side pCO2 value measured at or after the calculated rate of change equals the predetermined rate of change value at the predetermined (shortest) local measurement distance.

[0017] The predetermined local measurement distance is a local measurement distance at which it can be assumed that no further changes in the measured pCO2 value on the gas side (beyond the measurement tolerance / predetermined rate of change value) will occur, i.e., a sufficient local distance between the first sensor and the second sensor.

[0018] The sufficient local distance depends, among other things, on the flow rate, the initial pCO2 value of the blood, the sensor and membrane properties, and should be predetermined for the device and operating conditions.

[0019] Preferably, the control unit is further configured to stop the gas flow into the inlet on the gas side, and the control unit stops the gas flow into the inlet on the gas side, preferably from the outlet on the gas side, e.g. by at least one valve at or upstream of the inlet on the gas side and / or at or downstream of the outlet on the gas side, before estimating the CO2 partial pressure value on the blood side, in particular before or during calculation of the rate of change of the measured CO2 partial pressure value on the gas side over time. Preferably, the blood flow rate is kept unchanged while the gas flow rate is stopped, more preferably the blood flow rate is maintained at a therapeutic flow rate.

[0020] When gas flow into the gas-side inlet is stopped, CO2 diffusing across / through the membrane from the blood side to the gas side accumulates on the gas side until diffusion equilibrium is reached, i.e., until the pCO2 value on the gas side equals the pCO2 value on the blood side. Because blood on the blood side continues to flow through the blood side of the oxygenator while gas is retained on the gas side, the pCO2 value on the gas side equals the pCO2 value of the blood at the blood-side inlet when diffusion equilibrium is reached. In other words, the pCO2 value on the gas side at which the CO2 diffusion gradient becomes zero / negligible over a period of time is the maximum pCO2 value of the blood on the blood side of the oxygenator, which is the pCO2 value of the (venous) blood at the blood-side inlet. This further means that CO2 diffusion equilibrium within the oxygenator is determined by the pCO2 value of the blood at the blood-side inlet, since the pCO2 value at the blood-side inlet is the maximum value within the oxygenator; therefore, the pCO2 value on the gas side adjusts to the pCO2 value of the blood at the blood-side inlet over a period of time.

[0021] Furthermore, while gas flow is stopped, the pCO2 values ​​at the gas side inlet and gas side outlet adjust to the same value by diffusion. That is, the pCO2 equilibrium value can be measured on the gas side at any point between the gas side inlet and the gas side outlet (and also at a point downstream of the outlet if gas flow is stopped up to this point), and a single sensor is sufficient to determine the pCO2 value on the blood side when the gas is stopped until it reaches the pCO2 equilibrium value, as determined by calculating the rate of change of the pCO2 value measured on the gas side by the single sensor over time. After determining the blood pCO2 value on the blood side, the control unit can increase the gas flow rate back to the normal (therapeutic) flow rate to proceed or continue patient treatment.

[0022] Further preferably, the control unit is configured to adapt the rate of gas flow into the gas-side inlet, where the control unit gradually reduces the rate of gas flow into the gas-side inlet, i.e., continuously or at predetermined time intervals, until the calculated rate of change with respect to the position is equal to a predetermined rate of change value or falls within a predetermined rate of change range at a predetermined local measurement distance. Preferably, the blood flow rate is maintained unchanged while the gas flow rate is reduced, more preferably, the blood flow rate is maintained at a therapeutic flow rate. After determining the pCO2 value of blood on the blood side, the control unit can increase the gas flow rate back to a normal (therapeutic) flow rate in order to proceed or continue the patient's treatment.

[0023] When gas flow through the gas side is reduced, especially to a flow rate lower than the blood flow rate, gas on the gas side remains in the oxygenator longer than blood on the blood side, and CO2 diffusing from the blood side to the gas side accumulates either up to a pCO2 value (or CO2 concentration) where the CO2 diffusion gradient between the blood side and the gas side is zero / negligible, i.e., until CO2 diffusion equilibrium between the blood side and the gas side is reached, or up to a pCO2 value where the CO2 diffusion gradient is greater than zero / negligible, i.e., if CO2 diffusion equilibrium between the blood side and the gas side is not reached and the gas is not retained in the oxygenator long enough to reach the pCO2 equilibrium value, i.e., if the gas flow rate is too high and / or the membrane area / oxygenator length is too short. With the first and second sensors fixedly positioned at a predetermined local measurement distance, CO2 equilibrium is achieved only at a certain sufficiently low gas flow rate. Said sufficiently low gas flow rate is achieved / found by the control unit gradually decreasing the gas flow rate until the calculated rate of change between the pCO2 value measured by the first sensor and the pCO2 value measured by the second sensor becomes zero / insignificant. In other words, compared to the above case where the gas flow is stopped, i.e. the flow rate is decreased to zero, the waiting time until the calculated rate of change becomes zero / insignificant is substituted by gradually decreasing the gas flow rate until the rate of change becomes zero / insignificant.

[0024] More preferably, the control unit is configured to adapt the flow rate of the gas flow into the inlet, reducing the flow rate of the gas flow into the inlet to a predetermined reduced gas flow rate before estimating the CO2 partial pressure value on the blood side, in particular before or during calculation of the rate of change of the measured CO2 partial pressure value on the gas side. To calculate the rate of change, the CO2 partial pressure value on the gas side is measured at a certified point or in a certified part of the device, in particular on the gas side, where it has been (preliminarily) proven that the CO2 partial pressure on the gas side reaches a saturation value (at the maximum value, i.e., equilibrium value, on the gas side) at the predetermined reduced gas flow rate. In this embodiment, both the first and second sensors can be located in the certified part to calculate the rate of change with respect to position. Alternatively, only a single sensor can be provided in the certified part to calculate the rate of change over time.

[0025] As mentioned above, the gas flow rate and oxygenator length must be adapted to reach CO2 diffusion equilibrium within the gas side of the oxygenator; the higher the gas flow rate, the longer the oxygenator length. Therefore, before treatment, experimentally test how long the oxygenator is long enough to reach CO2 diffusion equilibrium at a given reduced flow rate. The downstream portion of sufficient length is the certified portion and can be the gas side only portion (including the gas side outlet) or at least the portion including the gas side outlet (and preferably a portion of the gas side upstream of the outlet) as well as a portion of the gas line downstream of the outlet.

[0026] In a preferred embodiment, the gas side of the oxygenator is formed by a plurality of hollow fibers through which gas flows from the inlet to the outlet. The first sensor is connected to the gas side via only a portion (or a subset) of the hollow fibers. That is, the sensor is not connected to all of the hollow fibers. In other words, the first sensor is connected to only a portion of the gas side. The portion of the hollow fibers to which the first sensor is connected may be limited to a small number of the fibers. Here, the first sensor can be connected to a portion of the hollow fibers at the downstream end of the portion of the hollow fibers or downstream of the downstream end of the portion of the hollow fibers. This allows the first sensor to measure the CO2 partial pressure value of only a portion of the hollow fibers, rather than all of the hollow fibers. Furthermore, the control unit can process the measured CO2 partial pressure value of the portion of the hollow fibers and determine the CO2 partial pressure value on the blood side based on the measured CO2 partial pressure value of the portion of the hollow fibers. The control unit can determine the CO2 partial pressure value on the blood side by calculating the rate of change of the measured CO2 partial pressure value of a portion of the hollow fiber during operation of the oxygenator, and estimating the CO2 partial pressure value on the blood side from the CO2 partial pressure value of the portion of the hollow fiber measured when, or after, the calculated rate of change equals a predetermined rate of change value or falls within a predetermined rate of change range at a predetermined measurement distance.

[0027] A valve can be provided downstream of the first sensor, the valve being configured to stop or reduce gas flow through the portion of the hollow fiber and the first sensor in a first state and to release or increase gas flow through the portion of the hollow fiber and the first sensor in a second state.

[0028] The control unit can be configured to stop the gas flow through the portion of the hollow fiber by the valve when the rate of change is a rate of change over time and the predetermined measurement distance is a predetermined period of time, where the control unit stops the gas flow through the portion of the hollow fiber before estimating the CO2 partial pressure value on the blood side, in particular before or during calculation of the rate of change of the measured CO2 partial pressure value of the portion of the hollow fiber.

[0029] Alternatively, if the rate of change is a rate of change over time and the predetermined measurement distance is a predetermined period of time, the control unit can be configured to reduce the flow rate of the gas flow through the portion of the hollow fiber by means of the valve to a predetermined reduced gas flow rate before estimating the CO2 partial pressure value on the blood side, in particular before or during calculation of the rate of change of the measured CO2 partial pressure value of the portion of the hollow fiber, where the location at which the CO2 partial pressure value of the portion of the hollow fiber is measured for calculating the rate of change is a certified location in the device for which it has been proven that the CO2 partial pressure of the portion of the hollow fiber reaches a saturation value at the predetermined reduced gas flow rate.

[0030] By connecting the first sensor to only a portion of the fibers making up the gas side, it is possible to determine the CO2 partial pressure value on the blood side without changing or interrupting gas flow throughout the gas side. This means that patient treatment can be maintained without interruption or substantial modification while the CO2 partial pressure value on the blood side is being determined. Because the fibers on the gas side to which the sensor is connected and through which gas flow is stopped or reduced for measurement purposes only make up a small portion of the gas side, gas flow through the majority of the remaining gas side (i.e., all fibers not connected to sensors and valves) is not impeded during the measurement of the CO2 partial pressure value, and patient treatment is not impaired.

[0031] Preferably, when the control unit gradually reduces the flow rate of the gas, the control unit is further configured to adapt the proportion of CO2 in (or of) the gas stream, and the control unit increases the proportion of CO2 in (or of) the gas stream up to a predetermined increased proportion of CO2, in particular when or while the control unit reduces the flow rate. After determining the pCO2 value of the blood on the blood side, the control unit can reduce the proportion of CO2 in the gas stream back to a normal (therapeutic) proportion of CO2 in the gas stream in order to proceed or continue treatment of the patient.

[0032] More preferably, in the above cases where either both sensors or a single sensor is provided in the certified section, the control unit is configured to adapt the CO2 proportion in the gas stream (or of the gas stream), and the control unit increases the CO2 proportion in the gas stream (or of the gas stream) by a predetermined CO2 increment rate before estimating the CO2 partial pressure value on the blood side, in particular before, during or after the control unit reduces the flow rate to a predetermined reduced flow rate, and for the certified point or certified section, it has been (previously) proven that the CO2 partial pressure on the gas side reaches a saturation value at a predetermined CO2 increment rate and at a predetermined reduced gas flow rate (at an internal maximum value on the gas side, i.e., at an equilibrium value). After determining the pCO2 value of blood on the blood side, the control unit can reduce the CO2 proportion in the gas stream back to a normal (therapeutic) CO2 proportion in the gas stream in order to proceed or continue the patient's treatment.

[0033] By increasing the proportion of CO2 in the gas stream, the difference between the pCO2 value of the blood on the blood side at the blood side inlet, which is the maximum pCO2 value in the oxygenator, and the pCO2 value of the gas on the gas side is reduced. In other words, the pCO2 gradient between the blood side and the gas side is reduced, and therefore the time / flow rate reduction required to reach (near) diffusion equilibrium is also reduced. As a result, the pCO2 value of the blood on the blood side at the blood side inlet can be determined more quickly.

[0034] The pCO value in a gas with a given CO2 increase rate should be just below the patient's venous pCO2 value, which is ideally about 46 mm / Hg. Therefore, the pCO2 value of a gas with a given CO2 increase rate should be less than 46 mm / Hg, and preferably less than 35 mm / Hg.

[0035] In another aspect of the disclosed technique, an apparatus is provided for determining a CO2 partial pressure value on a blood side of an oxygenator, the apparatus comprising: an oxygenator having a blood side, a gas side, and a semipermeable membrane, the membrane separating the blood side from the gas side, the gas side having an inlet and an outlet, wherein a gas flow enters the inlet and flows to the outlet at a flow rate during operation of the oxygenator; a first sensor configured to measure a CO2 partial pressure value on the gas side; and a device configured to control the flow rate of the gas flow into the inlet, process the measured CO2 partial pressure value on the gas side, and determine a CO2 partial pressure value on the blood side (or blood side) based on the measured CO2 partial pressure value on the gas side. and a control unit, which determines the CO2 partial pressure value on the blood side during operation of the oxygenator by stopping the gas flow into the inlet (and preferably from the outlet, e.g. by means of a valve), measuring at least one CO2 partial pressure value on the gas side when a certified period of time has elapsed after stopping the gas flow, and estimating the CO2 partial pressure value on the blood side from the at least one CO2 partial pressure value on the gas side measured when the certified period of time has elapsed, and for which it has been (previously) proven that the CO2 partial pressure on the gas side reaches a saturation value (at an internal maximum value on the gas side, i.e. at an equilibrium value).

[0036] In this way, convenient, accurate and rapid determination of the pCO2 value of the blood on the blood side of the oxygenator, in particular the pCO2 value of the blood at the inlet or outlet of the blood side of the oxygenator, can be achieved, which can be used as an indicator of the patient's overall condition, allowing for improved treatment and health of the patient.

[0037] In yet another aspect of the disclosed technique, an apparatus is provided for determining a CO2 partial pressure value on a blood side of an oxygenator, the apparatus comprising: an oxygenator having a blood side, a gas side, and a semipermeable membrane, the membrane separating the blood side from the gas side, the gas side having an inlet and an outlet, wherein during operation of the oxygenator, a gas flow enters the inlet and passes to the outlet at a rate, the gas side being formed by a plurality of hollow fibers through which the gas flows from the inlet to the outlet; and a first sensor connected to a portion of the plurality of hollow fibers on the gas side, preferably at a downstream end of the portion of the hollow fibers or downstream of the downstream end of the portion of the hollow fibers; a first sensor configured to measure a CO2 partial pressure value in the portion of the hollow fiber; a valve disposed downstream of the first sensor configured to stop or reduce gas flow through the portion of the hollow fiber in a first state and to release or increase gas flow through the portion of the hollow fiber in a second state; and a control unit configured to control the flow rate of the gas flow through the portion of the hollow fiber by the valve, process the measured CO2 partial pressure value in the portion of the hollow fiber, and determine a CO2 partial pressure value on the blood side based on the measured CO2 partial pressure value in the portion of the hollow fiber. wherein the control unit determines the CO2 partial pressure value on the blood side by stopping the gas flow through a portion of the hollow fiber by means of a valve during operation of the oxygenator, measuring at least one CO2 partial pressure value in the portion of the hollow fiber when a certified period of time has elapsed after stopping the gas flow, and estimating the CO2 partial pressure value on the blood side from the at least one CO2 partial pressure value in the portion of the hollow fiber measured when the certified period of time has elapsed, and it has been proven that for the certified period of time the CO2 partial pressure in the portion of the hollow fiber on the gas side has reached a saturation value.

[0038] Also in this way, convenient, accurate and rapid determination of blood pCO2 values ​​on the blood side of the oxygenator can be achieved, while at the same time not substantially interfering with patient treatment.

[0039] In yet another aspect of the disclosed technique, an apparatus is provided for determining a CO2 partial pressure value on a blood side of an oxygenator, the apparatus comprising: an oxygenator having a blood side, a gas side, and a semipermeable membrane, the membrane separating the blood side from the gas side, the gas side having an inlet and an outlet, wherein a gas flow enters the inlet and flows to the outlet at a rate during operation of the oxygenator; a first sensor configured to measure a CO2 partial pressure value on the gas side; and a control unit configured to control a flow rate of the gas flow into the inlet, process the measured CO2 partial pressure value on the gas side, and determine a CO2 partial pressure value on the blood side (or of the CO2 partial pressure value) based on the measured CO2 partial pressure value on the gas side, wherein the control unit controls the flow rate of the gas flow into the inlet on the gas side during operation of the oxygenator. determining the CO2 partial pressure value on the blood side by: reducing the flow rate of the device to a predetermined reduced gas flow rate; measuring at least one CO2 partial pressure value on the gas side of the device, in particular at a certified point or within a certified part of the gas side, when a certified period has elapsed after reducing the flow rate to the predetermined reduced flow rate; and estimating the CO2 partial pressure value on the blood side from the at least one CO2 partial pressure value on the gas side measured at the certified point or within the certified part when the certified period has elapsed, wherein it has been (previously) proven that for the certified period and at the certified point or for the certified part, the CO2 partial pressure on the gas side reaches a saturation value (at a maximum value inside the gas side, i.e. at an equilibrium value).

[0040] In this way, convenient, accurate and rapid determination of the pCO2 value of the blood on the blood side of the oxygenator, in particular the pCO2 value of the blood at the inlet or outlet of the blood side of the oxygenator, can be achieved, which can be used as an indicator of the patient's overall condition, allowing for improved treatment and health of the patient.

[0041] In yet another aspect of the disclosed technique, an apparatus is provided for determining a CO2 partial pressure value on a blood side of an oxygenator, the apparatus comprising: an oxygenator having a blood side, a gas side, and a semipermeable membrane, the membrane separating the blood side from the gas side, the gas side having an inlet and an outlet, wherein during operation of the oxygenator, a gas flow enters the inlet and flows to the outlet at a rate, the gas side being formed by a plurality of hollow fibers through which gas flows from the inlet to the outlet; and a first sensor connected to a portion of the plurality of hollow fibers on the gas side, preferably at a downstream end of the portion of the hollow fibers or downstream of the downstream end of the portion of the hollow fibers, wherein the first sensor is connected to the gas side. a first sensor configured to measure a CO2 partial pressure value in a portion of the hollow fiber on the blood side; a valve disposed downstream of the first sensor configured to stop or reduce gas flow through the portion of the hollow fiber in a first state and to release or increase gas flow through the portion of the hollow fiber in a second state; and a control unit configured to control the flow rate of the gas flow through the portion of the hollow fiber by the valve, process the measured CO2 partial pressure value in the portion of the hollow fiber, and determine a CO2 partial pressure value on the blood side based on the measured CO2 partial pressure value in the portion of the hollow fiber. wherein the control unit determines the CO2 partial pressure value on the blood side by reducing the flow rate of the gas flow through a portion of the hollow fiber by the valve to a predetermined reduced gas flow rate during operation of the oxygenator, measuring at least one CO2 partial pressure value of the portion of the hollow fiber at a certified location when a certified period of time has elapsed after reducing the flow rate to the predetermined reduced gas flow rate, and estimating the CO2 partial pressure value on the blood side from the at least one CO2 partial pressure value of the portion of the hollow fiber measured at the certified location when the certified period of time has elapsed, and it is proven that for the certified period of time and at the certified location, the CO2 partial pressure of the hollow fiber on the gas side reaches a saturation value.

[0042] Such a method still provides convenient, accurate and rapid determination of blood pCO2 values ​​on the blood side of the oxygenator, while substantially not interfering with patient treatment.

[0043] In all the above-mentioned devices, the control unit can determine the CO2 partial pressure value on the blood side at predetermined time intervals and / or when predetermined operating conditions occur, for example in the case of a medical abnormality or critical therapeutic value. In particular, the calculated rate of change and / or the measured pCO2 value on the gas side are constantly or intermittently monitored, and when the calculated rate of change and / or the measured pCO2 value on the gas side are below or above a predetermined limit value, the control unit determines the pCO2 value on the blood side.

[0044] Preferably, in all of the above-mentioned devices, the first sensor is located inside the oxygenator at the gas outlet or (immediately) downstream of the outlet. By locating the first sensor at the end of the oxygenator membrane (in the flow direction) or downstream of the end of the oxygenator membrane, i.e., by locating the first measurement point, the entire length of the oxygenator membrane is used to ensure that diffusion equilibrium is reached, and the dimensions of the oxygenator can be kept as small as possible.

[0045] More preferably, if the rate of change is measured over a local distance, at least one of the first and second sensors, preferably the first and second sensors, are located inside the oxygenator.

[0046] Optionally, a main gas line is provided downstream of the gas-side outlet, a branch line branches off from the main line, and one of the first sensor and the second sensor is located on or in the branch line. By locating the sensor on the branch line, problems with humidity during measurement of pCO2 values ​​can be solved or at least mitigated.

[0047] Preferably, in the above-described device having sensors connected to only a portion (or subset) of the plurality of hollow fibers constituting the gas side, the portion of the hollow fibers on the gas side to which the first sensor is connected can be positioned at the blood inlet in the direction of blood flow through the blood side. This allows for determining the venous pCO2 value. Alternatively, the portion of the hollow fibers on the gas side to which the first sensor is connected can be positioned at the blood outlet in the direction of blood flow through the blood side. This allows for determining the arterial pCO2 value. Two or more sensors can also be provided in the device, each connected to only a portion (or subset) of the plurality of hollow fibers at a different position in the direction of blood flow through the blood side to determine two or more different pCO2 values ​​on the blood side. For example, to determine both the venous pCO2 value and the arterial pCO2 value, a first sensor can be positioned at the blood inlet and a second sensor can be positioned at the blood outlet.

[0048] In a further preferred embodiment, the above-described device forms part of an extracorporeal membrane oxygenation system (veno-venous or veno-arterial ECMO system). In another preferred embodiment, the above-described device forms part of a cardiopulmonary bypass system.

[0049] According to one aspect of the disclosed technique, there is provided a method for determining a pCO value (of blood) on a blood side of an oxygenator of an apparatus, the oxygenator comprising a blood side, a gas side, and a semi-permeable membrane separating the blood side from the gas side, the blood side and the gas side each having an inlet and an outlet, and during operation of the oxygenator, a gas flow flows from the gas side inlet to the gas side outlet at a flow rate, the method comprising: - measuring the pCO2 value in the gas on the gas side (or at the gas side) by means of a first sensor of the device; - processing the measured pCO2-values ​​on the gas side and determining by a control unit of the device a pCO2-value on the blood side (or of the blood), in particular at the blood side inlet or at the blood side outlet, based on the pCO2-values ​​measured in the gas on the gas side, - the control unit, during operation of the oxygenator, performs the following further steps: - calculating a rate of change or a rate of change value of the pCO2-value measured in the gas on the gas side, and estimating a (blood) pCO2-value on the blood side from the pCO2-value measured in the gas on the gas side when or after the calculated rate of change or the calculated rate of change value equals or falls within a predetermined rate of change value at a predetermined measurement distance, The pCO2 value at the blood side (blood) is determined.

[0050] Preferably, the rate of change is a rate of change over time and the predetermined measurement distance is a predetermined period of time.

[0051] Preferably, the rate of change is a rate of change with respect to position, the predetermined measurement distance is a predetermined local measurement distance, and the gas-side CO2 partial pressure value is measured at the predetermined local measurement distance by a first sensor and a second sensor of the device, the second sensor being positioned at the predetermined local measurement distance from the first sensor.

[0052] Preferably, the control unit determines the CO2 partial pressure value on the blood side by the further step of stopping the gas flow into the gas side inlet before estimating the CO2 partial pressure value on the blood side, in particular before or during calculation of the rate of change of the measured CO2 partial pressure value on the gas side.

[0053] Preferably, the control unit determines the CO2 partial pressure value on the blood side by the further step of gradually reducing the flow rate of the gas flow into the gas side inlet until the rate of change with respect to position is equal to a predetermined rate of change value or falls within a predetermined rate of change range at a predetermined local measurement distance.

[0054] Preferably, the control unit determines the CO2 partial pressure value on the blood side by a further step of reducing the gas flow into the gas side inlet to a predetermined reduced gas flow rate before estimating the CO2 partial pressure value on the blood side, in particular before or during calculation of the rate of change of the measured CO2 partial pressure value on the gas side, in order to calculate the rate of change, the CO2 partial pressure value on the gas side is measured at a certified point or in a certified part of the device, in particular on the gas side, and for the certified point or certified part it has been proven that the CO2 partial pressure reaches a saturation value at a predetermined flow rate.

[0055] In a preferred embodiment, the gas side is formed by a plurality of hollow fibers through which gas flows from an inlet to an outlet, and the first sensor is connected to the gas side via only a portion of the hollow fibers on the gas side, preferably at a downstream end of the portion of the hollow fibers or downstream of the downstream end of the hollow fibers. Further, in the step of measuring the CO2 partial pressure value by the first sensor, the CO2 partial pressure value of the portion of the hollow fibers is measured, the measured CO2 partial pressure value is processed, and the CO2 partial pressure value on the blood side is determined based on the measured CO2 partial pressure value of the portion of the hollow fibers. Furthermore, in the step of calculating the rate of change of the measured CO2 partial pressure value on the gas side, the rate of change of the measured CO2 partial pressure value of a portion of the hollow fiber on the gas side is calculated, and in the step of estimating the CO2 partial pressure value on the blood side from the measured CO2 partial pressure value, the CO2 partial pressure value on the blood side is estimated from the CO2 partial pressure value of the portion of the hollow fiber measured when, or after, the calculated rate of change becomes equal to a predetermined rate of change value or falls within a predetermined rate of change range at a predetermined measurement distance.

[0056] A valve can be provided downstream of the first sensor, the valve being configured to stop or reduce gas flow through a portion of the hollow fiber on the gas side in a first state and to release or increase gas flow through the portion of the hollow fiber in a second state.

[0057] If the rate of change is a rate of change over time and the predetermined measurement distance is for a predetermined period of time, the control unit can determine the CO2 partial pressure value on the blood side by the further step of stopping the gas flow through the portion of the hollow fiber on the gas side by a valve before or during calculation of the rate of change of the measured CO2 partial pressure value of the portion of the hollow fiber before estimating the CO2 partial pressure value on the blood side.

[0058] Alternatively, if the rate of change is a rate of change over time and the predetermined measurement distance is a predetermined period of time, the control unit can determine the CO2 partial pressure value on the blood side by a further step of reducing the gas flow through the portion of the hollow fiber by means of a valve to a predetermined reduced gas flow rate before or during calculation of the rate of change of the measured CO2 partial pressure value of the portion of the hollow fiber before estimating the CO2 partial pressure value on the blood side, and in order to calculate the rate of change, the CO2 partial pressure value of the portion of the hollow fiber on the gas side is measured at a certified location within the device, and for that certified location it has been proven that the CO2 partial pressure of the portion of the hollow fiber reaches a saturation value at the predetermined reduced gas flow rate.

[0059] More preferably, if the control unit changes the gas flow rate before estimating the CO2 partial pressure value on the blood side, i.e. stops the gas flow into the gas side inlet or reduces the flow rate of the gas flow into the gas side inlet (gradually or to a predetermined gas flow rate), the (current) pCO2 value in the gas on the gas side (or at the gas side) is measured before (just before / shortly before) the control unit changes the gas flow rate.

[0060] Preferably, the control unit determines the CO2 partial pressure value on the blood side by a further step of increasing the CO2 proportion in the gas flow to a predetermined CO2 proportion, in particular before stopping the gas flow or before, when or while reducing the flow rate.

[0061] Preferably, the control unit determines the CO2 partial pressure value on the blood side by a further step of increasing the proportion of CO2 in the gas flow to a predetermined CO2 increment rate before estimating the CO2 partial pressure value on the blood side, in particular before, during or after reducing the flow rate to a predetermined reduced flow rate, and certifies that for an authenticated point or authenticated portion, the CO2 partial pressure reaches a saturation value at a predetermined CO2 increment rate and at a predetermined flow rate.

[0062] In another aspect of the disclosed technique, there is provided a method for determining a CO2 partial pressure value on a blood side of an oxygenator of a device, the oxygenator comprising a blood side, a gas side, and a semi-permeable membrane separating the blood side from the gas side, the gas side having an inlet and an outlet, wherein during operation of the oxygenator, a gas flow enters the inlet and flows to the outlet at a certain flow rate, the method comprising the steps of measuring at least one CO2 partial pressure value on the gas side (or on the gas side) by a first sensor of the device; processing the at least one measured CO2 partial pressure value on the gas side; and determining, by a control unit of the device, a CO2 partial pressure value on the blood side (or on the blood side) based on the at least one measured CO2 partial pressure value on the gas side; and controlling the flow rate of the gas flow of the oxygenator, wherein the control unit determines the CO2 partial pressure value on the blood side by the further steps of stopping the gas flow into the gas side inlet (preferably from the gas side outlet, e.g. by a valve) during operation of the oxygenator, measuring at least one CO2 partial pressure value on the gas side when a certified period has elapsed after stopping the gas flow, and estimating the CO2 partial pressure value on the blood side from the at least one CO2 partial pressure value on the gas side measured when the certified period has elapsed, for which certified period it has been (previously) proven that the CO2 partial pressure on the gas side reaches a saturation value (at a maximum value inside the gas side, i.e. at an equilibrium value).

[0063] In yet another aspect of the disclosed technique, there is provided a method for determining a CO2 partial pressure value on a blood side of an oxygenator of a device, the method comprising: an oxygenator having a blood side, a gas side, and a semipermeable membrane separating the blood side from the gas side, the gas side having an inlet and an outlet, wherein during operation of the oxygenator, a gas flow enters the inlet and flows to the outlet at a rate, the gas side being formed by a plurality of hollow fibers through which gas flows from the inlet to the outlet; a first sensor connected to only a portion of the plurality of hollow fibers on the gas side, preferably at a downstream end of the portion of the hollow fibers or downstream of the downstream end of the hollow fibers, the first sensor configured to measure a CO2 partial pressure value of the portion of the hollow fibers on the gas side; and a valve downstream of the first sensor configured to, in a first state, stop or reduce gas flow through the portion of the hollow fibers and, in a second state, release or increase gas flow through the portion of the hollow fibers; the method comprising: controlling the gas flow through the portion of the hollow fibers by a control unit of the device; and measuring by a first sensor at least one CO2 partial pressure value in the portion of the hollow fibers on the gas side, and processing the at least one measured CO2 partial pressure value in the portion of the hollow fibers and determining by a control unit a CO2 partial pressure value on the blood side based on the at least one measured CO2 partial pressure value in the portion of the hollow fibers on the gas side, wherein the control unit determines the CO2 partial pressure value on the blood side by the further steps of stopping the gas flow through the portion of the hollow fibers by a valve during operation of the oxygenator, measuring the at least one CO2 partial pressure value in the portion of the hollow fibers when a certified period of time has elapsed after the gas flow has been stopped, and estimating the CO2 partial pressure value on the blood side from the at least one CO2 partial pressure value in the portion of the hollow fibers measured when the certified period of time has elapsed, and for which certified period of time it has been proven that the CO2 partial pressure in the portion of the hollow fibers on the gas side has reached a saturation value.

[0064] In yet another aspect of the disclosed technique, there is provided a method for determining a CO2 partial pressure value on a blood side of an oxygenator of a device, the oxygenator comprising a blood side, a gas side, and a semi-permeable membrane separating the blood side from the gas side, the gas side having an inlet and an outlet, wherein during operation of the oxygenator a gas flow enters the gas side inlet and flows to the gas side outlet at a flow rate, the method comprising: measuring at least one CO2 partial pressure value on the gas side (or on the gas side) by a first sensor of the device; processing the at least one measured CO2 partial pressure value on the gas side and determining, by a control unit of the device, a CO2 partial pressure value on the blood side (or on the blood side) based on the at least one measured CO2 partial pressure value on the gas side; and controlling, by the control unit, a flow rate of the gas flow into the inlet of the gas side, wherein the control unit controls operation of the oxygenator. In operation, the CO2 partial pressure value on the blood side is determined by the further steps of reducing the flow rate of the gas flow into the gas side inlet to a predetermined reduced gas flow rate, measuring at least one CO2 partial pressure value on the gas side when a certified period has elapsed after reducing the flow rate to the predetermined reduced gas flow rate and at a certified point or within a certified portion of the device, in particular on the gas side, and estimating the CO2 partial pressure value on the blood side from the at least one CO2 partial pressure value on the gas side measured at the certified point or within the certified portion when the certified period has elapsed, and for which certified period and at the certified point or certified portion it has been (preliminarily) proven that the CO2 partial pressure on the gas side reaches a saturation value (at a maximum value inside the gas side, i.e., at an equilibrium value).

[0065] In yet another aspect of the disclosed technique, there is provided a method for determining a CO2 partial pressure value on a blood side of an oxygenator of a device, the method comprising: an oxygenator having a blood side, a gas side, and a semipermeable membrane separating the blood side from the gas side, the gas side having an inlet and an outlet, wherein during operation of the oxygenator, a gas flow enters the inlet and flows to the outlet at a rate, the gas side being formed by a plurality of hollow fibers through which gas flows from the inlet to the outlet; a first sensor connected to only a portion of the plurality of hollow fibers on the gas side, preferably at a downstream end of the portion of the hollow fibers or downstream of the downstream end of the hollow fibers, the first sensor configured to measure a CO2 partial pressure value of the portion of the plurality of hollow fibers on the gas side; and a valve downstream of the first sensor configured to, in a first state, stop or reduce gas flow through the portion of the hollow fibers and to, in a second state, release or increase gas flow through the portion of the plurality of hollow fibers, the method comprising the steps of: controlling, by a control unit of the device, a flow rate of the gas flow through the portion of the hollow fibers; and processing the at least one measured CO2 partial pressure value in the portion of the hollow fibers and determining by the control unit a CO2 partial pressure value on the blood side based on the at least one measured CO2 partial pressure value in the portion of the hollow fibers, wherein the control unit determines the CO2 partial pressure value on the blood side by the further step of: reducing the flow rate of the gas stream through the portion of the hollow fibers to a predetermined reduced gas flow rate during operation of the oxygenator; measuring the at least one CO2 partial pressure value in the portion of the hollow fibers when a certified period of time has elapsed after reducing the flow rate to the predetermined reduced flow rate and at a certified location within the device; and estimating the CO2 partial pressure value on the blood side from the at least one CO2 partial pressure value in the portion of the hollow fibers measured at the certified location when the certified period of time has elapsed, and for which certified period of time and at which certified location it has been proven that the CO2 partial pressure in the portion of the hollow fibers on the gas side has reached a saturation value.

[0066] Preferably, in all the above-mentioned embodiments, the control unit determines the value of the CO2 partial pressure on the blood side at predetermined time intervals and / or when predetermined operating conditions occur.

[0067] In a preferred embodiment of this method, the first sensor is placed inside the oxygenator at or downstream of the gas side outlet.

[0068] In a further preferred embodiment of the method, a main gas line is provided downstream of the gas side outlet, a branch line branches off from the main line and the first sensor is arranged on / in the branch line.

[0069] Preferably, in the above-described method in which sensors are connected to only some of the hollow fibers constituting the gas side, the part of the hollow fiber on the gas side to which the first sensor is connected is positioned at the blood inlet in the direction of blood flow through the blood side. Alternatively, the part of the hollow fiber on the gas side to which the first sensor is connected is positioned at the blood outlet in the direction of blood flow through the blood side. Two or more sensors may also be provided, each connected to only some of the hollow fibers at a different position in the direction of blood flow through the blood side. For example, the first sensor is positioned at the blood inlet and the second sensor is positioned at the blood outlet.

[0070] The above-described method can be performed during extracorporeal membrane oxygenation therapy, preferably veno-venous extracorporeal membrane oxygenation therapy or veno-arterial extracorporeal membrane oxygenation therapy. Additionally, the above-described method can be performed during cardiopulmonary bypass therapy.

[0071] The above-mentioned apparatus is configured to carry out the above-mentioned method, and the above-mentioned method is designed to be carried out by the above-mentioned apparatus, and therefore the advantages and variations of the above-mentioned apparatus apply to the above-mentioned method.

[0072] The foregoing summary and the following detailed description of the preferred embodiments will be better understood when read in conjunction with the accompanying drawings. For purposes of explaining the present disclosure, reference is made to the drawings. However, the scope of the present disclosure is not limited to the specific embodiments disclosed in the drawings. [Brief explanation of the drawings]

[0073] [Figure 1] 1 is a schematic diagram of an apparatus for determining pCO2 values ​​on the blood side of an oxygenator according to a first embodiment of the disclosed technique. FIG. [Figure 2] FIG. 10 is a schematic diagram of an apparatus for determining pCO2 values ​​on the blood side of an oxygenator according to a second embodiment of the disclosed technology. [Figure 3] FIG. 10 is a schematic diagram of an apparatus for determining pCO2 values ​​on the blood side of an oxygenator according to a third embodiment of the disclosed technique. [Figure 4] FIG. 1 shows a schematic representation of pCO2 values ​​at measuring points on the gas side over time. [Figure 5] FIG. 10 is a schematic diagram of an apparatus for determining pCO2 values ​​on the blood side of an oxygenator according to a fourth embodiment of the disclosed technology. [Figure 6] FIG. 10 shows a schematic representation of gas-side pCO2 rate of change values ​​over time across the length of the oxygenator at two different flow rates. [Figure 7] FIG. 10 is a schematic diagram of an apparatus for determining pCO2 values ​​on the blood side of an oxygenator according to a fifth embodiment of the disclosed technology. DETAILED DESCRIPTION OF THE INVENTION

[0074] FIG. 1 shows a schematic diagram of an apparatus 1 for determining the pCO value of blood on the blood side 2 of an oxygenator 4 according to a first embodiment of the disclosed technique. The apparatus 1 comprises an oxygenator 4 having a blood side 2, a gas side 6, and a semipermeable membrane 8 separating the blood side 2 from the gas side 6. The apparatus 1 further comprises a sensor 10 configured to measure the pCO value of gas on the gas side 6, and a control unit 12 configured to control, inter alia, the gas flow rate and the CO percentage in the gas flow from a source (not shown), e.g., a medical gas outlet of a hospital, to the gas side 6 of the oxygenator 4, e.g., by controlling a valve unit (not shown) upstream of the oxygenator 4, and configured to receive and process the pCO value measured by the sensor 10. The gas side 6 of the oxygenator 4 has an inlet 14 and an outlet 16, and the blood side 2 has an inlet 18 and an outlet 20. A main line 22 for conducting gas is connected to the oxygenator 4 downstream of the outlet 16 of the gas side 6.

[0075] The oxygenator 4 in the above-described embodiment operates in a parallel flow mode. That is, gas entering the inlet 14 of the gas side 6 and blood entering the inlet 18 of the blood side 2 flow in the same direction along the membrane 8 to their respective outlets 16, 20. However, there may be other types of oxygenators with different modes of operation that can be used in accordance with the disclosed technology. In any case, during operation of the oxygenator 4, CO2 contained in / dissolved in the blood entering and flowing through the blood side 2 is extracted from the blood by diffusion across / through the membrane 8 and becomes part of the gas entering and flowing through the gas side 6. To enable the diffusion of CO2 from the blood side to the gas side, a CO2 diffusion gradient is required, meaning that the CO2 concentration or CO2 partial pressure (pCO2) in the gas is lower than in the blood. At the same time, O2 contained in the gas entering and passing through the gas side 6 is believed to diffuse across the membrane 8 into the blood entering and flowing through the blood side 2, which requires an O2 diffusion gradient. That is, the O2 concentration or O2 partial pressure (pO2) in the gas must be higher than in the blood, thus inducing an exchange of O2 and CO2 between the gas side and the blood side.

[0076] During operation of the device 1, the inlet 18 of the blood side 2 is connected to the patient's venous system. That is, since the oxygenator 4 is assumed to take over the function of the patient's lungs, the blood entering the blood side 2 at the inlet 18 of the blood side 2 has the highest concentration of CO or the highest pCO and the lowest concentration of O or the lowest pO in the patient's blood circulation, while the blood leaving the blood side 2 at the outlet 20 of the blood side 2 has the lowest concentration of CO or the lowest pCO and the highest concentration of O or the highest pO in the patient's blood circulation. The outlet 20 of the blood side 2 can be connected to the patient's venous or arterial system, depending on the type of treatment.

[0077] According to the disclosed technique, the pCO value of venous blood at inlet 18 of blood side 2 can be used as an indicator to determine the patient's overall CO status. To determine the pCO value at inlet 18 of blood side 2, gas flow is significantly reduced to a predetermined reduced gas flow rate or stopped completely, i.e., reduced to zero. At the same time, blood flow through blood side 2 is maintained, for example, at a normal therapeutic flow rate. CO dissolved in the blood travels through blood side 2, diffuses across membrane 8 into the gas, is retained on gas side 6 (for a long time compared to the normal therapeutic flow rate), and accumulates in the gas until the CO diffusion gradient becomes zero (or negligible). If the gas flow into the inlet 14 of the gas side 6 is completely stopped (e.g., by a valve at or upstream of the inlet 14 and / or at or downstream of the outlet 16), after a certain time the CO diffusion gradient will be zero due to diffusion within the gas side 6 across the entire gas side 6, i.e., across the entire length of the oxygenator 4, in other words, across the entire longitudinal section between the inlet 14 of the gas side 6 and the outlet 16 of the gas side 6. If the gas flow into the inlet 14 of the gas side 6 is reduced to a predetermined reduced gas flow rate, after a certain time the CO diffusion gradient will be zero only across a specific longitudinal section between the inlet 14 of the gas side 6 and the outlet 16 of the gas side, depending on the specific reduced gas flow rate. A section in which the diffusion gradient is reliably zero after a certain time at a predetermined reduced gas flow rate is a certified part of the gas side; that is, it has been experimentally proven for said section at said reduced flow rate that the diffusion gradient will be zero after a certain time. The certified section may extend beyond the outlet 16 on the gas side 6 into the connected main line 22, since the pCO2 value downstream of the outlet 16 is constant and has the same value as the outlet 16 on the gas side 6, but the outlet 16 itself must be within the certified section to ensure the oxygenator is long enough to reach CO2 diffusion equilibrium within the oxygenator 4.

[0078] Thus, to determine or measure that pCO2 equilibrium has been reached on the gas side, sensor 10 can be located at inlet 14, outlet 16, or anywhere between inlet 14 and outlet 16 when gas flow into inlet 14 is stopped, and sensor 10 can be located in an authenticated portion of the gas side when gas flow is reduced to a predetermined gas flow rate. Then, after gas flow is stopped or reduced by control unit 12, the pCO2 value at / on gas side 6 is measured by sensor 10, and control unit 12 receives and processes the pCO2 values ​​measured by sensor 10 and estimates the pCO2 value at inlet 18 of blood side 2 from the pCO2 values ​​measured by sensor 10 on gas side 6 by calculating the rate of change of the pCO2 values ​​measured by sensor 10 over time to determine whether diffusion equilibrium of CO2 across / through membrane 8 has been achieved. This equilibrium is achieved when the rate of change is (near) zero or insignificant (and remains unchanged for a predetermined period of time, after which it can be assumed that no further changes in the rate of change occur). That is, the pCO2 value measured on the gas side 6 when or after equilibrium is achieved corresponds to the pCO2 value of the blood at the inlet 18 of the blood side 2, and conversely, the pCO2 value of the blood at the inlet 18 of the blood side 2, i.e. the patient's venous blood, is identical to the pCO2 value measured by the sensor 10 on / at the gas side 6.

[0079] After equilibrium is achieved and the pCO2 value at the inlet 18 of the blood side 2 is determined, the flow rate of gas into the inlet 14 of the gas side 6 can be increased to the normal therapeutic gas flow rate to continue or proceed with normal oxygenator therapy. The above-described determination of the pCO2 value at the inlet 18 of the blood side 2 can be repeated as many times as necessary during the treatment of the patient, for example at regular intervals, to closely monitor the patient's condition.

[0080] To accelerate the CO2 diffusion equilibrium, the control unit 12 can increase the proportion of CO2 in the gas flowing into the inlet 14 of the gas side 6 by a predetermined CO2 increase percentage before or while calculation of the rate of change of pCO2 measured on the gas side 6 begins, or at least before estimation of the pCO2 value on the blood side 2 begins.

[0081] In a preferred embodiment, the percentage of CO2 in the gas stream is increased before the gas flow rate is reduced or stopped. In particular, after the percentage of CO2 in the gas stream is increased, the gas flow is reduced or stopped only after a specific period of time, which is the time it takes for the gas to flow from inlet 14 to outlet 16.

[0082] In a first form of the device 1 as shown in FIG. 1, the sensor 10 is located inside the oxygenator 4 on the gas side 6 , directly at the outlet 16 .

[0083] A second embodiment of the device 1 according to the disclosed technology is shown in Figure 2. The embodiment shown in Figure 2 corresponds to the above-described embodiment shown in Figure 1, with the difference that the sensor 10 is not provided inside the oxygenator 4, but in the main line 22 or downstream of the outlet 16 of the gas side 6 in the main line 22, which makes it easier to build and maintain the device 1. When gas flow into the inlet 14 of the gas side 6 is stopped and a valve is used, the valve downstream of the outlet 16 is located downstream of the sensor 10.

[0084] A third embodiment of the device 1 according to the disclosed technology is shown in Figure 3. The embodiment shown in Figure 3 corresponds to the above-described embodiment shown in Figure 2, with the difference that the sensor 10 is not provided in or on the main line 22, but in or on a branch line 24 branching off from the main line 22, which facilitates measuring pCO2 at high humidity levels. When gas flow into the inlet 14 of the gas side 6 is stopped and valves are used, two valves are positioned downstream of the outlet 16, one in the main line 22 at or downstream of the branch point and one in the branch line 24 downstream of the sensor 10.

[0085] FIG. 4 shows a schematic diagram of pCO2 values ​​measured by sensor 10 over time t after gas flow has been reduced to a predetermined reduced gas flow rate or stopped completely, with sensor 10 positioned within an authenticated portion of device 1 where gas flow is reduced. Gas flow is reduced or stopped at time t0. Until time t1, the measured pCO2 value remains constant. (When gas flow is stopped, the time interval between t0 and t1 may be nearly zero, depending on the location of sensor 10 and the diffusion rate within gas side 6.) At time t1, the pCO2 value rises to a maximum value reached at time t2. After time t2, the measured pCO2 value remains (nearly) constant, which is why the pCO2 value measured at time t3 is the same as the pCO2 value measured at time t2, i.e., why the calculated rate of change of pCO2 between time t2 and time t3 is zero / insignificant. The constant pCO2 value measured at or after time t2 is the pCO2 equilibrium value on the gas side and corresponds to the pCO2 value at the inlet 18 on the blood side 2, i.e. the pCO2 value of the patient's venous blood.

[0086] It should be noted that the measurement curves shown in Figure 4 are purely schematic in nature, and the slope and linear portion between times t0 and t3 may vary depending on the type of oxygenator and / or the flow rates of both blood and gas.

[0087] Depending on the type of oxygenator, particularly the type of membrane, as well as the blood and gas flow rates through the oxygenator 4, time t2, i.e., CO2 diffusion equilibrium, may be achieved in a shorter or longer time. As with the certified portion of the device 1, the certified period after gas flow is stopped or reduced can be determined by experimentation before therapeutic use of the oxygenator, the certified period being a period proven sufficient to reach pCO2 equilibrium on the gas side 6. If gas flow is stopped and a certified period has elapsed after gas flow has stopped, a single measurement of the pCO2 value on the gas side is sufficient to determine the pCO2 value on the blood side 2, since it is proven that pCO2 equilibrium is reached after the certified period. If gas flow is reduced to a predetermined reduced gas flow rate, the certified period is to be determined for the certified portion.

[0088] A fourth embodiment of the device 1 according to the disclosed technology is shown in FIG. 5. The embodiment shown in FIG. 5 corresponds to the above-described embodiment shown in FIG. 1, with the difference that in addition to the first sensor 10, a second sensor 11 is provided inside the gas side 6 of the oxygenator 4. The two sensors 10, 11 allow a position-related pCO2 change rate value to be determined, i.e., the local pCO2 change rate value between the second sensor 11 and the first sensor 10. To determine the pCO2 value on the blood side 2, the control unit 12 can gradually reduce the flow rate of gas into the inlet 14 of the oxygenator 4 until the local pCO2 change rate value between the second sensor 11 and the first sensor 10 is zero / insignificant. This mode of operation does not require knowledge of the authenticated part, as will become clearer in FIG. 6.

[0089] FIG. 6 is a diagram showing the dCO2 / dt value, which is the rate of change of gas-side pCO2 over time, across the length l of the oxygenator at two different flow rates, f1 and f2. The flow rate f1, shown as a solid line, is greater than the flow rate f2, shown as a dashed line. Generally, as the gas flow rate decreases to a reduced flow rate, the rate of change of pCO2 over time becomes zero / infinite. That is, the pCO2 equilibrium value is reached at or downstream of a specific longitudinal section of the oxygenator 4 (if the oxygenator 4 is long enough). However, this specific longitudinal section of the oxygenator 4 depends on the specific flow rate: it is shorter (in the flow direction) for lower flow rates and longer for higher flow rates. Thus, for flow rates f1 and f2, the longitudinal section l1 of the oxygenator 4 where the dCO2 / dt value becomes zero / infinite at the lower flow rate f2 is shorter than or upstream of the longitudinal section l2 where the dCO2 / dt value becomes zero / infinite at the higher flow rate f2. 5 and with two sensors 10, 11 fixedly positioned in / on the gas side 6 of the oxygenator 4, there is a specific gas flow rate at which the two sensors 10, 11 are positioned at or upstream of a specific longitudinal section of the oxygenator 4 at which the dCO2 / dt value is zero / negligible, and this specific flow rate can be found by gradually decreasing the gas flow rate until the local rate of change of pCO2 between the sensors 10, 11 is zero / negligible. As an example, when the first sensor 10 is positioned at the outlet 16 and the second sensor 11 is positioned at longitudinal section 11 and the control unit 12 starts to gradually decrease the gas flow rate at flow rate f1, the flow rate at which the local rate of change is zero is flow rate f2.

[0090] As an alternative to the device 1 shown in Figure 5, the first sensor 10 can be positioned downstream of the outlet 16, for example as shown in Figures 2 and 3, and the second sensor 11 can be positioned downstream of the inlet 14 and upstream of the outlet 16, or anywhere at the outlet 16. However, when the second sensor 11 is positioned closer to the outlet 16 (and further at least a predetermined local measurement distance from the outlet 16), the reduction in flow rate is accelerated until the rate of change is zero / infinite.

[0091] As an alternative mode of operation, the flow rate of gas into the inlet 14 can be reduced to a predetermined flow rate with both sensors 10, 11 located in an authenticated portion of the device 1, and the authenticated portion is authenticated for the predetermined flow rate. Thereafter, the flow need not be gradually reduced.

[0092] A fifth embodiment of the device 1 according to the present disclosure is shown schematically in FIG. 7 . The gas side of the oxygenator 4 is shown to be comprised of a plurality of fibers 26. The fibers 26 are hollow fibers formed by semipermeable membranes. The gas side of the oxygenator is disposed inside the hollow fibers, and the blood side of the oxygenator 4 is disposed outside the hollow fibers and extends around the hollow fibers. During operation of the oxygenator 4, gas flow (indicated by arrow a) enters the oxygenator 4 at the gas inlet 14, flows through each of the fibers 26 toward the gas outlet 16, and exits the oxygenator 4 at the gas outlet 16. Blood flow (indicated by arrow b) enters the oxygenator 4 at the blood inlet 18 and flows between the fibers 26, so that blood flows around the fibers 26 toward the blood outlet 20 and exits the oxygenator 4 at the blood outlet 20.

[0093] The fifth embodiment differs from the previous embodiments in that the sensor 10 is connected to only a portion (or subset) of the multiple fibers 26 that make up the gas side, but not all of the fibers 26 that make up the gas side. The portion of the fibers 26 to which the sensor 10 is connected is shown as a selected fiber bundle 30. The sensor 10 is located downstream of the fiber bundle 30, and gas flow flows through the entire length (in the flow direction) of the fiber bundle 30 before entering the sensor 10 and eventually exiting the oxygenator 4 via the gas outlet 16. A shutoff or throttle valve 28 is located downstream of the sensor 10, so that gas flow through the fiber bundle 30 and the sensor 10 can be stopped or reduced. In this way, gas flow can be stopped or reduced within the fiber bundle 30 while proceeding unstopped or unreduced through the remaining fibers 26. In other words, gas flow only through the fiber bundle 30 can be stopped or reduced for measurement purposes by the valve 28, while gas flow through the remaining fibers 26 remains unimpeded.

[0094] The specific location of the fiber bundle 30 in the direction of blood flow, i.e., between the blood inlet 18 and the blood outlet 20, can be selected according to the purpose of the measurement. In the embodiment shown in FIG. 7, the fiber bundle 30 is positioned at or near the blood inlet 18 so that the venous pCO2 value on the blood side can be determined. In another embodiment (not shown), the fiber bundle 30 can be positioned at or near the blood outlet 20 so that the arterial pCO2 value on the blood side can be determined. It is also possible to provide at least two fiber bundles at different locations, each connected to a sensor and a valve in the manner described above, so that the pCO2 value on the blood side can be determined for at least two different locations. For example, one fiber bundle can be positioned at or near the blood inlet 18, and another fiber bundle can be positioned at or near the blood outlet 20, so that both the venous pCO2 and the arterial pCO2 on the blood side can be determined.

Claims

1. CO on the blood side (2) of the oxygenator (4) ２ A device (1) for determining a partial pressure value, comprising: an oxygenator (4) having a blood side (2), a gas side (6) and a semipermeable membrane (8), said membrane (8) separating said blood side (2) from said gas side (6), said gas side (6) having an inlet (14) and an outlet (16), wherein during operation of said oxygenator (4) a gas flow enters said inlet (14) and flows to said outlet (16) at a certain rate; - CO on the gas side (6) ２ a first sensor (10) configured to measure a partial pressure value; - the measured CO on the gas side (6) ２ The measured CO partial pressure value of the gas side (6) is processed. ２ Based on the partial pressure value, CO ２ a control unit (12) configured to determine the partial pressure value; The control unit (12) controls the measured CO 2 on the gas side (6) during operation of the oxygenator (4). ２ calculating a rate of change of the partial pressure value, and when or after said calculated rate of change equals a predetermined rate of change value or falls within a predetermined rate of change range at a predetermined measurement distance; the CO2 concentration on the gas side (6) measured when or after the calculated rate of change is equal to the predetermined rate of change value or when or after the calculated rate of change is within the predetermined rate of change range at the predetermined measurement distance. ２ From the partial pressure value, the CO ２ By estimating the partial pressure value, the CO ２ A device (1) for determining partial pressure values.

2. 2. The device (1) according to claim 1, characterized in that the rate of change is a rate of change over time and the predetermined measured distance is a predetermined period of time.

3. 2. The device (1) according to claim 1, wherein the device (1) is configured to: ２ The device (1) comprises a second sensor (11) configured to measure a partial pressure value, wherein the rate of change is a rate of change with respect to position, the predetermined measurement distance is a predetermined local measurement distance, and the first sensor (10) and the second sensor (11) are arranged at the predetermined local measurement distance.

4. 3. The device (1) according to claim 2, wherein the control unit (12) is further configured to stop the gas flow into the inlet (14), and the control unit (12) is configured to stop the CO 2 flow on the blood side (2). ２ Before estimating the partial pressure value, the measured CO ２ The apparatus (1) is characterized in that the gas flow into the inlet (14) is stopped before or during calculation of the rate of change of partial pressure value.

5. 4. The apparatus (1) of claim 3, wherein the control unit (12) is further configured to adapt the flow rate of the gas flow into the inlet (14), wherein the control unit (12) gradually reduces the flow rate of the gas flow into the inlet (14) until the rate of change with respect to position is equal to the predetermined rate of change value or falls within the predetermined rate of change range at the predetermined local measurement distance.

6. 4. The device (1) according to claim 2 or 3, wherein the control unit (12) is further configured to adapt the flow rate of the gas flow into the inlet (14), and the control unit (12) controls the CO 2 flow rate on the blood side (2). ２ Before estimating the partial pressure value, the measured CO ２ Before or during calculation of the rate of change of partial pressure value, the flow rate of the gas stream into the inlet (14) is reduced to a predetermined reduced gas flow rate, and the CO ２ The partial pressure value is measured at a certified point or in a certified part of the device (1), in particular on the gas side (6), and for that certified point or certified part, the CO partial pressure value of the gas side (6) is measured. ２ The device (1) is characterized in that the partial pressure is proven to reach a saturation value at said predetermined reduced gas flow rate.

7. 3. A device (1) according to claim 1 or 2, the gas side (6) is formed by a plurality of hollow fibers (26) through which the gas flows from the inlet (14) to the outlet (16), the first sensor (10) being connected to the gas side (6) via only a portion of the plurality of hollow fibers (26) of the gas side (6), preferably at the downstream end of said portion of the plurality of hollow fibers (26) or downstream of the downstream end of said portion of the plurality of hollow fibers (26); the first sensor (10) detects the CO ２ configured to measure a partial pressure value; - the control unit (12) determines the measured CO ２ and processing the measured CO partial pressure values ​​of the portion of the plurality of hollow fibers (26) on the gas side (6). ２ Based on the partial pressure value, CO ２ configured to determine a voltage division value; - the control unit (12) determines the measured CO2 of the portion of the plurality of hollow fibers (26) of the gas side (6) during operation of the oxygenator (4). ２ calculating a rate of change of partial pressure values, and detecting the CO partial pressure of the portion of the plurality of hollow fibers (26) on the gas side (6) measured when or after the calculated rate of change equals a predetermined rate of change value or falls within a predetermined rate of change range at a predetermined measurement distance; ２ From the partial pressure value, the CO ２ By estimating the partial pressure value, the CO ２ A device (1) for determining partial pressure values.

8. 8. The device (1) according to claim 7, wherein a valve (28) is provided downstream of the first sensor (10), the valve (28) being configured in a first state to stop or reduce the gas flow through the portion of the plurality of hollow fibers (26) on the gas side (6) and the first sensor (10) to the gas outlet (16), and in a second state to release or increase the gas flow through the portion of the plurality of hollow fibers (26) on the gas side (6) and the first sensor (10) to the gas outlet (16).

9. 9. A device (1) according to claim 8, - said rate of change is a rate of change over time and said predetermined measured distance is a predetermined period of time; the control unit (12) is configured to stop the gas flow through the part of the plurality of hollow fibers (26) on the gas side (6) and the first sensor (10) to the gas outlet (16) by means of the valve (28), and the control unit (12) is configured to stop the gas flow through the part of the plurality of hollow fibers (26) on the gas side (6) and the first sensor (10) to the gas outlet (16), ２ Before estimating the partial pressure value, the measured CO ２ and stopping the gas flow through the portion of the plurality of hollow fibers (26) on the gas side (6) and the first sensor (10) to the gas outlet (16) before or during calculation of the rate of change of partial pressure value.

10. 9. A device (1) according to claim 8, - said rate of change is a rate of change over time and said predetermined measured distance is a predetermined period of time; - the control unit (12) controls the CO ２ Before estimating the partial pressure value, the measured CO ２ The valve (28) is configured to reduce the flow rate of the gas stream through the portion of the plurality of hollow fibers (26) on the gas side (6) and the first sensor (10) to the gas outlet (16) to a predetermined reduced gas flow rate before or during calculation of the rate of change of partial pressure value, and to calculate the rate of change by measuring the CO partial pressure of the portion of the plurality of hollow fibers (26) on the gas side (6). ２ The location at which the partial pressure value is measured is a certified location in the device (1), and for that certified location, the CO partial pressure value of the part of the plurality of hollow fibers (26) on the gas side (6) is measured. ２ The device (1) is characterized in that the partial pressure is proven to reach a saturation value at said predetermined reduced gas flow rate.

11. 6. The apparatus (1) according to claim 4 or 5, wherein the control unit (12) controls the CO 2 in the gas stream. ２ and the control unit (12) is further configured to adapt the proportion of the CO in the gas flow, in particular before the control unit (12) stops the gas flow or before, when or while the control unit (12) reduces the flow rate. ２ The ratio of CO ２ The device (1) is characterized in that the increase in the

12. 7. The apparatus (1) according to claim 6, wherein the control unit (12) controls the CO 2 in the gas stream. ２ and the control unit (12) is further configured to adapt the ratio of the CO ２ the CO partial pressure in the gas stream before estimating the partial pressure value, in particular before, during or after the control unit (12) reduces the flow rate to the predetermined reduced flow rate. ２ The ratio of CO ２ and for the certified point or certified portion, the CO ２ The partial pressure of the predetermined CO ２ The device (1) is characterized in that it is proven that the saturation value is reached at the predetermined reduced gas flow rate with an increasing rate of .

13. CO on the blood side (2) of the oxygenator (4) ２ A device (1) for determining a partial pressure value, comprising: an oxygenator (4) having a blood side (2), a gas side (6) and a semipermeable membrane (8), said membrane (8) separating said blood side (2) from said gas side (6), said gas side (6) having an inlet (14) and an outlet (16), wherein during operation of said oxygenator (4) a gas flow enters said inlet (14) and flows to said outlet (16) at a certain rate; - CO on the gas side (6) ２ a first sensor (10) configured to measure a partial pressure value; - controlling the flow rate of the gas stream into the inlet (14) and measuring the CO ２ The measured CO partial pressure value of the gas side (6) is processed. ２ Based on the partial pressure value, CO ２ a control unit (12) configured to determine the partial pressure value; The control unit (12) is adapted to stop the gas flow into the inlet (14) during operation of the oxygenator (4) and to detect at least one CO 2 concentration in the gas side (6) after a certified period of time has elapsed after stopping the gas flow. ２ measuring a partial pressure value of the at least one CO 2 gas on the gas side (6) measured when the certified period has elapsed; ２ The CO partial pressure value on the blood side (2) ２ By estimating the partial pressure value, the CO ２ The partial pressure value of the CO on the gas side (6) is determined for the certified period. ２ The device (1) is characterized in that the partial pressure is proven to reach a saturation value.

14. CO on the blood side (2) of the oxygenator (4) ２ A device (1) for determining a partial pressure value, comprising: the oxygenator (4) having a blood side (2), a gas side (6) and a semipermeable membrane (8), said membrane (8) separating said blood side (2) from said gas side (6), said gas side (6) having an inlet (14) and an outlet (16), wherein during operation of said oxygenator (4), a gas flow enters said inlet (14) and flows to said outlet (16) at a certain rate, said gas side (6) being formed by a plurality of hollow fibers (26) through which said gas flows from said inlet (14) to said outlet (16); a first sensor (10) connected to a portion of the plurality of hollow fibers (26) on the gas side (6), preferably at the downstream end of the portion of the plurality of hollow fibers (26) or downstream of the downstream end of the portion of the plurality of hollow fibers (26), which detects the CO ２ a first sensor (10) configured to measure a partial pressure value; a valve (28) downstream of said first sensor (10), configured in a first state to stop or reduce the gas flow through said portion of said plurality of hollow fibers (26) of said gas side (6) and said first sensor (10) to said gas outlet (16), and in a second state to release or increase the gas flow through said portion of said plurality of hollow fibers (26) of said gas side (6) and said first sensor (10) to said gas outlet (16); - by means of said valve (28), controlling the flow rate of said gas stream through said portion of said plurality of hollow fibers (26) of said gas side (6) and said first sensor (10) to said gas outlet (16), and said measured CO ２ and processing the measured CO partial pressure values ​​of the portion of the plurality of hollow fibers (26) on the gas side (6). ２ Based on the partial pressure value, CO ２ a control unit (12) configured to determine the partial pressure value; The control unit (12) is configured to stop the flow of gas through the portion of the plurality of hollow fibers (26) of the gas side (6) and the first sensor (10) to the gas outlet (16) by the valve (28) during operation of the oxygenator (4), and to detect CO2 levels in at least one of the portion of the plurality of hollow fibers (26) of the gas side (6) when a certified period of time has elapsed after stopping the gas flow. ２ measuring a partial pressure value of the at least one CO 2 of the portion of the plurality of hollow fibers (26) on the gas side (6) measured when the certified period has elapsed; ２ From the partial pressure value, the CO ２ and estimating the partial pressure value of the CO on the blood side (2). ２ determining a partial pressure value of the CO 2 in the portion of the plurality of hollow fibers (26) on the gas side (6) for the certified period; ２ The device (1) is characterized in that the partial pressure is proven to reach a saturation value.

15. CO on the blood side (2) of the oxygenator (4) ２ A device (1) for determining a partial pressure value, comprising: an oxygenator (4) having a blood side (2), a gas side (6) and a semipermeable membrane (8), said membrane (8) separating said blood side (2) from said gas side (6), said gas side (6) having an inlet (14) and an outlet (16), wherein during operation of said oxygenator (4) a gas flow enters said inlet (14) and flows to said outlet (16) at a certain rate; - CO on the gas side (6) ２ a first sensor (10) configured to measure a partial pressure value; - controlling the flow rate of the gas stream into the inlet (14) and measuring the CO ２ The measured CO partial pressure value of the gas side (6) is processed. ２ Based on the partial pressure value, CO ２ a control unit (12) configured to determine the partial pressure value; The control unit (12) is adapted to, during operation of the oxygenator (4), reduce the flow rate of the gas flow into the inlet (14) to a predetermined reduced gas flow rate, and, upon expiration of a certified time period after reducing the flow rate to the predetermined reduced gas flow rate, to detect at least one CO 2 concentration of the gas side (6) of the device (1), in particular at a certified point on or within a certified part of the gas side (6). ２ measuring a partial pressure value of the at least one CO 2 on the gas side (6) measured at the certified point or within the certified portion when the certified period has elapsed; ２ From the partial pressure value, the CO ２ and estimating the partial pressure value of the CO on the blood side (2). ２ The partial pressure value of the CO 2 on the gas side (6) is determined for the certified period and at the certified point or part. ２ The device (1) is characterized in that the partial pressure is proven to reach a saturation value.

16. CO on the blood side (2) of the oxygenator (4) ２ A device (1) for determining a partial pressure value, comprising: the oxygenator (4) having a blood side (2), a gas side (6) and a semipermeable membrane (8), said membrane (8) separating said blood side (2) from said gas side (6), said gas side (6) having an inlet (14) and an outlet (16), wherein during operation of said oxygenator (4), a gas flow enters said inlet (14) and flows to said outlet (16) at a certain rate, said gas side (6) being formed by a plurality of hollow fibers (26) through which said gas flows from said inlet (14) to said outlet (16); a first sensor (10) connected to a portion of the plurality of hollow fibers (26) on the gas side (6), preferably at the downstream end of the portion of the plurality of hollow fibers (26) or downstream of the downstream end of the portion of the plurality of hollow fibers (26), which detects the CO ２ a first sensor (10) configured to measure a partial pressure value; a valve (28) downstream of said first sensor (10), configured in a first state to stop or reduce the gas flow through said portion of said plurality of hollow fibers (26) of said gas side (6) and said first sensor (10) to said gas outlet (16), and in a second state to release or increase the gas flow through said portion of said plurality of hollow fibers (26) of said gas side (6) and said first sensor (10) to said gas outlet (16); - by means of said valve (28), controlling the flow rate of said gas stream through said portion of said plurality of hollow fibers (26) of said gas side (6) and said first sensor (10) to said gas outlet (16), and said measured CO ２ and processing the measured CO partial pressure values ​​of the portion of the plurality of hollow fibers (26) on the gas side (6). ２ Based on the partial pressure value, CO ２ a control unit (12) configured to determine the partial pressure value; The control unit (12) controls, during operation of the oxygenator (4), the valve (28) to reduce the flow rate of the gas flow through the portion of the plurality of hollow fibers (26) on the gas side (6) and the first sensor (10) to the gas outlet (16) to a predetermined reduced gas flow rate, and to measure, at a certified location, at least one CO 2 concentration of the portion of the plurality of hollow fibers (26) on the gas side (6) when a certified time period has elapsed after reducing the flow rate to the predetermined reduced flow rate. ２ measuring a partial pressure value of the at least one CO 2 partial pressure of the portion of the plurality of hollow fibers (26) on the gas side (6) measured at the certified location when the certified time period has elapsed; ２ The CO partial pressure value on the blood side (2) ２ and estimating the partial pressure value of the CO on the blood side (2). ２ determining a partial pressure value of the CO 2 of the plurality of hollow fibers (26) on the gas side (6) for the certified period and the certified location; ２ The device (1) is characterized in that the partial pressure is proven to reach a saturation value.

17. The device (1) according to any one of claims 1 to 16, wherein the control unit (12) controls the CO 2 concentration on the blood side (2) at predetermined time intervals and / or when predetermined operating conditions occur. ２ A device (1) for determining partial pressure values.

18. 18. The device (1) according to any one of claims 1 to 17, characterized in that the first sensor (10) is arranged inside the oxygenator (4) at the outlet (16) of the gas side (6) or downstream of the outlet (16).

19. 18. The device (1) according to any one of claims 3, 5, 6, 11, 12 and 17, characterized in that at least one of the first sensor (10) and the second sensor (11), preferably the first sensor (10) and the second sensor (11), is arranged inside the oxygenator (4).

20. 20. The device (1) according to any one of claims 1 to 6, 11 to 13, 15, and 17 to 19, characterized in that a main gas line (22) is provided downstream of the outlet (16) on the gas side (6), a branch line (24) branches off from the main line (22), and one of the first sensor (10) and the second sensor (11) is arranged on the branch line (24).

21. 19. The device (1) according to any one of claims 7 to 10, 14, 16 to 18, characterized in that the part of the plurality of hollow fibers (26) on the gas side (6) to which the first sensor (10) is connected is arranged at the blood inlet (18) in the direction of blood flow through the blood side (2).

22. 19. The device (1) according to any one of claims 7 to 10, 14, and 16 to 18, characterized in that the part of the plurality of hollow fibers (26) on the gas side (6) to which the first sensor (10) is connected is arranged at the blood outlet (20) in the direction of blood flow through the blood side (2).

23. An extracorporeal membrane oxygenation system, characterized in that it comprises a device (1) according to any one of claims 1 to 22.

24. 24. The extracorporeal membrane oxygenation system of claim 23, which is a veno-venous extracorporeal membrane oxygenation system.

25. 24. The extracorporeal membrane oxygenation system according to claim 23, which is a veno-arterial extracorporeal membrane oxygenation system.

26. A cardiopulmonary bypass system, characterized in that it comprises a device (1) according to any one of claims 1 to 22.

27. CO on the blood side (2) of the oxygenator (4) of the device (1) ２ A method for determining partial pressure values, comprising: the oxygenator (4) comprising the blood side (2), a gas side (6), and a semi-permeable membrane (8) separating the blood side (2) from the gas side (6), the gas side (6) having an inlet (14) and an outlet (16), wherein during operation of the oxygenator (4), a gas flow passes from the inlet (14) to the outlet (16) at a flow rate; the method comprising: - by a first sensor (10) of the device (1), the CO ２ measuring a partial pressure value; - the measured CO on the gas side (6) ２ The measured CO partial pressure values ​​on the gas side (6) are processed by the control unit (12) of the device (1). ２ Based on the partial pressure value, CO ２ determining a partial pressure value; The control unit (12) performs the following further steps during operation of the oxygenator (4): - the measured CO on the gas side (6) ２ calculating a rate of change of the partial pressure value; when or after the calculated rate of change equals a predetermined rate of change value or falls within a predetermined rate of change range at a predetermined measurement distance; the CO2 on the gas side (6) measured when or after the calculated rate of change is equal to the predetermined rate of change value or falls within the predetermined rate of change range at the predetermined measurement distance. ２ The CO partial pressure value on the blood side (2) ２ estimating a partial pressure value; The CO ２ determining a partial pressure value;

28. 28. The method of claim 27, wherein the rate of change is a rate of change over time and the predetermined measured distance is a predetermined period of time.

29. 28. The method according to claim 27, wherein the rate of change is a rate of change with respect to position, the predetermined measurement distance is a predetermined local measurement distance, and the CO ２ The method is characterized in that partial pressure values ​​are measured at the predetermined local measurement distance by the first sensor (10) and a second sensor (11) of the device (1), and the second sensor (11) is positioned at the predetermined local measurement distance from the first sensor (10).

30. 29. The method of claim 28, wherein the control unit (12) - the CO on the blood side (2) ２ Before estimating the partial pressure value, the measured CO ２ The CO partial pressure at the blood side (2) can be reduced by the further step of stopping the gas flow into the inlet (14) before or during the calculation of the rate of change of the partial pressure value. ２ determining a partial pressure value;

31. 30. The method of claim 29, wherein the control unit (12) - the CO2 concentration on the blood side (2) is reduced by a further step of gradually reducing the flow rate of the gas flow into the inlet (14) until the rate of change with respect to the position is equal to the predetermined rate of change value or falls within a predetermined rate of change range at the predetermined local measurement distance. ２ determining a partial pressure value;

32. 30. The method according to claim 28 or 29, wherein the control unit (12) - the CO on the blood side (2) ２ Before estimating the partial pressure value, the measured CO ２ The CO partial pressure at the blood side (2) is reduced by a further step of reducing the gas flow into the inlet (14) to a predetermined reduced gas flow rate before or during the calculation of the rate of change of partial pressure value. ２ The CO partial pressure on the gas side (6) is determined to calculate the rate of change. ２ The partial pressure value is measured at a certified point or in a certified part of the device (1), in particular on the gas side (6), and for that certified point or certified part, the CO partial pressure value of the gas side (6) is measured. ２ demonstrating that the partial pressure reaches a saturation value at said predetermined flow rate.

33. 29. The method of claim 27 or 28, the gas side (6) is formed by a plurality of hollow fibers (26) through which the gas flows from the inlet (14) to the outlet (16), the first sensor (10) being connected to the gas side (6) via only a portion of the plurality of hollow fibers (26) of the gas side (6), preferably at the downstream end of the portion of the plurality of hollow fibers (26) or downstream of the downstream end of the plurality of hollow fibers (26); - CO by said first sensor (10) ２ In the step of measuring the partial pressure value, the CO ２ The partial pressure value is measured, - the measured CO ２ The measured CO partial pressure value is processed and controlled by a control unit (12). ２ Based on the partial pressure value, CO ２ In the step of determining partial pressure values, the measured CO ２ The partial pressure value is processed and the CO ２ The measured CO partial pressure value of the portion of the plurality of hollow fibers (26) on the gas side (6) ２ It is determined based on the partial pressure value. - the measured CO on the gas side (6) ２ In the step of calculating the rate of change of partial pressure values, the measured CO ２ The rate of change of the partial pressure value is calculated, - the measured CO ２ The CO partial pressure value on the blood side (2) ２ In the step of estimating the partial pressure value, the CO ２ The partial pressure value of the CO 2 of the portion of the plurality of hollow fibers (26) on the gas side (6) measured when or after the calculated rate of change equals the predetermined rate of change value or falls within the predetermined rate of change range at the predetermined measurement distance. ２ The method is characterized in that the partial pressure is estimated from the partial pressure value.

34. 34. The method of claim 33, wherein a valve (28) is provided downstream of the first sensor (10), the valve (28) being configured to, in a first state, stop or reduce the gas flow through the portion of the plurality of hollow fibers (26) on the gas side (6) and the first sensor (10) to the gas outlet (16), and to release or increase the gas flow through the portion of the plurality of hollow fibers (26) on the gas side (6) and the first sensor (10) to the gas outlet (16) in a second state.

35. 35. The method of claim 34, - said rate of change is a rate of change over time and said predetermined measured distance is a predetermined period of time; - the control unit (12) controls the CO ２ Before estimating the partial pressure value, the measured CO ２ The CO partial pressure at the blood side (2) is calculated by the further step of stopping the gas flow through the portion of the plurality of hollow fibers (26) on the gas side (6) and the first sensor (10) to the gas outlet (16) by the valve (28) before or during the calculation of the rate of change of partial pressure value. ２ determining a partial pressure value;

36. 35. The method of claim 34, - said rate of change is a rate of change over time and said predetermined measured distance is a predetermined period of time; - the control unit (12) controls the CO ２ Before estimating the partial pressure value, the measured CO ２ The CO partial pressure value is calculated by the further step of reducing the gas flow through the portion of the plurality of hollow fibers (26) on the gas side (6) and the first sensor (10) to the gas outlet (16) by the valve (28) to a predetermined reduced gas flow rate before or during the calculation of the rate of change of partial pressure value. ２ The CO partial pressure of the portion of the plurality of hollow fibers (26) on the gas side (6) is determined to calculate the rate of change. ２ A partial pressure value is measured at a certified location in the device (1), and for that certified location, the CO partial pressure value of the portion of the plurality of hollow fibers (26) on the gas side (6) is ２ The method is characterized in that the partial pressure is proven to reach a saturation value at said predetermined reduced gas flow rate.

37. 32. The method according to claim 30 or 31, wherein the control unit (12) - in particular before stopping the gas flow or before, when or during the reduction of the flow rate, ２ The ratio of CO ２ to an increasing rate of ２ determining a partial pressure value;

38. 33. The method of claim 32, wherein the control unit (12) - the CO on the blood side (2) ２ The CO partial pressure in the gas stream may be estimated before, during, or after the flow rate is reduced to a predetermined reduced flow rate. ２ The ratio of CO ２ to an increasing rate of ２ The partial pressure value of the CO 2 on the gas side (6) is determined for the certified point or certified portion. ２ The partial pressure of the predetermined CO ２ and demonstrating that said saturation value is reached at said predetermined reduced flow rate at an increasing rate of

39. CO on the blood side (2) of the oxygenator (4) of the device (1) ２ A method for determining partial pressure values, comprising: the oxygenator (4) comprising the blood side (2), a gas side (6), and a semi-permeable membrane (8) separating the blood side (2) from the gas side (6), the gas side (6) having an inlet (14) and an outlet (16), wherein during operation of the oxygenator (4), a gas flow enters the inlet (14) and flows to the outlet (16) at a flow rate, the method comprising: - by a first sensor (10) of said device (1), at least one CO ２ measuring a partial pressure value; - said at least one measured CO on said gas side (6) ２ The partial pressure values ​​are processed and the at least one measured CO 2 on the gas side (6) is calculated by a control unit (12) of the device (1). ２ Based on the partial pressure value, CO ２ determining a partial pressure value; - controlling the flow rate of the gas stream into the inlet (14) by the control unit (12), The control unit (12) controls the oxygenator (4) during operation. - the further step of stopping said gas flow into said inlet (14); - the at least one CO2 gas on the gas side (6) when a certified period of time has elapsed after stopping the gas flow ２ the further step of measuring the partial pressure value; - the at least one CO on the gas side (6) measured when the certified period has elapsed ２ From the partial pressure value, the CO ２ and a further step of estimating the partial pressure value of the CO 2 on the blood side (2). ２ The partial pressure value of the CO on the gas side (6) is determined for the certified period. ２ A method characterized in that the partial pressure is proven to reach a saturation value.

40. CO on the blood side (2) of the oxygenator (4) of the device (1) ２ A method for determining a partial pressure value, comprising the steps of: the oxygenator comprising the blood side (2), a gas side (6) and a semipermeable membrane (8) separating the blood side (2) from the gas side (6), the gas side (6) having an inlet (14) and an outlet (16), wherein during operation of the oxygenator (4), a gas flow enters the inlet (14) and flows to the outlet (16) at a certain rate, the gas side (6) being formed by a plurality of hollow fibres (26) through which the gas flows from the inlet (14) to the outlet (16); a first sensor (10) connected to a portion of the plurality of hollow fibers (26) on the gas side (6), preferably at the downstream end of the portion of the plurality of hollow fibers (26) or downstream of the downstream end of the plurality of hollow fibers (26), which detects the CO ２ a first sensor (10) configured to measure a partial pressure value; a valve (28) downstream of the first sensor (10), configured in a first state to stop or reduce the gas flow through the portion of the plurality of hollow fibers (26) of the gas side (6) and the first sensor (10) to the gas outlet (16), and in a second state to release or increase the gas flow through the portion of the plurality of hollow fibers (26) of the gas side (6) and the first sensor (10) to the gas outlet (16), The method comprises: - controlling, by a control unit (12) of the device (1), the flow rate of the gas stream through the portion of the plurality of hollow fibers (26) of the gas side (6) and through the first sensor (10) to the gas outlet (16); - by the first sensor (10) of the device (1), detecting the CO of at least one of the part of the plurality of hollow fibers (26) of the gas side (6). ２ measuring a partial pressure value; the at least one measured CO of the portion of the plurality of hollow fibers (26) of the gas side (6); ２ and processing the partial pressure values ​​of the at least one measured CO 2 of the part of the plurality of hollow fibers of the gas side of the device by the control unit of the device. ２ Based on the partial pressure value, CO ２ determining a partial pressure value; The control unit (12) controls the oxygenator (4) during operation. a further step of stopping the gas flow through the part of the plurality of hollow fibers (26) of the gas side (6) and the first sensor (10) to the gas outlet (16) by means of the valve (28); - when a certified period of time has elapsed after the gas flow has stopped, the at least one CO ２ the further step of measuring the partial pressure value; the at least one CO of the portion of the plurality of hollow fibers (26) of the gas side (6) measured when the certified period has elapsed; ２ From the partial pressure value, the CO ２ and a further step of estimating the partial pressure value of the CO 2 on the blood side (2). ２ The partial pressure value of the CO in the portion of the hollow fibers (26) on the gas side (6) is determined for the certified period. ２ A method characterized in that the partial pressure is proven to reach a saturation value.

41. CO on the blood side (2) of the oxygenator (4) of the device (1) ２ A method for determining partial pressure values, comprising: the oxygenator (4) comprising the blood side (2), a gas side (6), and a semi-permeable membrane (8) separating the blood side (2) from the gas side (6), the gas side (6) having an inlet (14) and an outlet (16), wherein during operation of the oxygenator (4), a gas flow enters the inlet (14) and flows to the outlet (16) at a flow rate, the method comprising: - by a first sensor (10) of said device (1), at least one CO ２ measuring a partial pressure value; - said at least one measured CO on said gas side (6) ２ The partial pressure values ​​are processed and the at least one measured CO 2 on the gas side (6) is calculated by a control unit (12) of the device (1). ２ Based on the partial pressure value, CO ２ determining a partial pressure value; - controlling the flow rate of the gas stream into the inlet (14) by the control unit (12), The control unit (12) controls the oxygenator (4) during operation. - a further step of reducing the flow rate of the gas stream into the inlet (14) to a predetermined reduced gas flow rate; - after a certified period of time has elapsed after reducing the flow rate to the predetermined reduced gas flow rate, and at a certified point or in a certified part of the device (1), in particular on the gas side (6), of the at least one CO ２ the further step of measuring the partial pressure value; - when the certified period has elapsed, the at least one CO2 of the gas side (6) measured at the certified point or within the certified section ２ From the partial pressure value, the CO ２ and a further step of estimating the partial pressure value of the CO 2 on the blood side (2). ２ The partial pressure value of the CO 2 on the gas side (6) is determined for the certified period and at the certified point or part. ２ A method characterized in that the partial pressure is proven to reach a saturation value.

42. CO on the blood side (2) of the oxygenator (4) of the device (1) ２ 1. A method for determining a partial pressure value, the apparatus comprising: the oxygenator comprising the blood side (2), a gas side (6) and a semipermeable membrane (8) separating the blood side (2) from the gas side (6), the gas side (6) having an inlet (14) and an outlet (16), wherein during operation of the oxygenator (4), a gas flow enters the inlet (14) and flows to the outlet (16) at a certain rate, the gas side (6) being formed by a plurality of hollow fibres (26) through which the gas flows from the inlet (14) to the outlet (16); a first sensor (10) connected to a portion of the plurality of hollow fibers (26) on the gas side (6), preferably at the downstream end of the portion of the hollow fibers (26) or downstream of the downstream end of the portion of the plurality of hollow fibers (26), which detects the CO ２ a first sensor (10) configured to measure a partial pressure value; a valve (28) downstream of the first sensor (10), configured in a first state to stop or reduce the gas flow through the portion of the plurality of hollow fibers (26) of the gas side (6) and the first sensor (10) to the gas outlet (16), and in a second state to release or increase the gas flow through the portion of the plurality of hollow fibers (26) of the gas side (6) and the first sensor (10) to the gas outlet (16), The method comprises: - controlling, by a control unit (12) of the device (1), the flow rate of the gas stream through the portion of the plurality of hollow fibers (26) of the gas side (6) and through the first sensor (10) to the gas outlet (16); - by the first sensor (10) of the device (1), detecting the CO of at least one of the part of the plurality of hollow fibers (26) of the gas side (6). ２ measuring a partial pressure value; - the at least one measured CO of the portion of the plurality of hollow fibers (26) of the gas side (6). ２ and processing the partial pressure values ​​of the at least one measured CO 2 of the part of the plurality of hollow fibers of the gas side of the device by the control unit of the device. ２ Based on the partial pressure value, CO ２ determining a partial pressure value; The control unit (12) controls the oxygenator (4) during operation. the further step of reducing the flow rate of the gas stream through the portion of the plurality of hollow fibers (26) on the gas side (6) and the first sensor (10) to the gas outlet (16) to a predetermined reduced gas flow rate; - after a certified time period has elapsed after reducing the flow rate to the predetermined reduced gas flow rate, and at a certified location within the device (1), ２ the further step of measuring the partial pressure value; - when the certified period has elapsed, the at least one CO2 of the portion of the plurality of hollow fibers (26) of the gas side (6) measured at the certified location ２ From the partial pressure value, the CO ２ and a further step of estimating the partial pressure value of the CO 2 on the blood side (2). ２ determining a partial pressure value of the CO 2 of the portion of the plurality of hollow fibers (26) on the gas side (6) for the certified period and the certified location; ２ A method characterized in that the partial pressure is proven to reach a saturation value.

43. 43. The method according to any one of claims 27 to 42, wherein the control unit (12) monitors the CO2 concentration on the blood side (2) at predetermined time intervals and / or when predetermined operating conditions occur. ２ determining a partial pressure value;

44. 44. The method according to any one of claims 33 to 36, 40, 42 and 43, characterized in that the part of the plurality of hollow fibers (26) on the gas side (6) to which the first sensor (10) is connected is arranged at the blood inlet (18) in the direction of blood flow through the blood side (2).

45. 44. The method according to any one of claims 33 to 36, 40, 42 and 43, characterized in that the part of the plurality of hollow fibers (26) on the gas side (6) to which the first sensor (10) is connected is arranged at the blood outlet (20) in the direction of blood flow through the blood side (2).

46. The method according to any one of claims 27 to 45, in extracorporeal membrane oxygenation therapy.

47. 47. The method of claim 46, wherein the extracorporeal membrane oxygenation therapy is veno-venous extracorporeal membrane oxygenation therapy.

48. 47. The method of claim 46, wherein the extracorporeal membrane oxygenation therapy is veno-arterial extracorporeal membrane oxygenation therapy.

49. The method according to any one of claims 27 to 45 in cardiopulmonary bypass therapy.

50. An apparatus (1) according to any one of claims 1 to 26, characterized in that the apparatus (1) is configured to carry out a method according to any one of claims 27 to 49.

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