Apparatus and method for determining co2 partial pressure value on blood side of oxygenator

Abstract

An apparatus (1) for determining a CO2 partial pressure value of a blood side (2) of an oxygenator (4) comprises: the oxygenator (4) having a blood side (2), a gas side (6) and a semi-permeable membrane (8), wherein the membrane (8) separates the blood side (2) from the gas side (6), the gas side (6) has an inlet (14) and an outlet (16), and, during operation of the oxygenator (4), a gas flow flows into the inlet (14) to the outlet (16) at a flow rate; a first sensor (10) configured to measure CO2 partial pressure values of the gas side (6); a control unit (12) configured to process the measured CO2 partial pressure values of the gas side (6) and to determine a CO2 partial pressure value of the blood side (2) based on the measured CO2 partial pressure values of the gas side (6), wherein the control unit (12) determines the CO2 partial pressure value of the blood side (2) by calculating a rate of change of the measured CO2 partial pressure values of the gas side (6) during operation of the oxygenator (4), and, 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 interval, derives the CO2 partial pressure value of the blood side (2) from the CO2 partial pressure value of 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.

Description

Technical Field

[0001] This disclosure relates to an apparatus and method for determining the partial pressure of CO2 on the blood side of an oxygen concentrator, an extracorporeal membrane oxygen concentrator system including the apparatus, a cardiopulmonary bypass of the apparatus and method included in extracorporeal membrane oxygen concentrator therapy, or an extracorporeal bypass including the method. Background Technology

[0002] Oxygen concentrators, particularly membrane oxygen concentrators, are commonly known for use in extracorporeal circulation (CPB) systems or extracorporeal membrane oxygenation (ECMO) systems. CPB is a relatively short-term technology that replaces the function of the heart and lungs during cardiac surgery, such as coronary bypass surgery, while ECMO is a simplified version that can be used for longer-term treatment of a range of cardiac and pulmonary dysfunctions and for rehabilitation. Both CPB and ECMO systems require an oxygen concentrator to add oxygen (O2) to the patient's bloodstream and remove carbon dioxide (CO2) from the blood to mimic or assist the function of the patient's lungs, allowing the exchange of O2 and CO2 between the patient's blood and the gas phase inside the oxygen concentrator, maintaining O2 and CO2 levels in the blood within physiological ranges. In membrane oxygen concentrators, the exchange of O2 and CO2 is accomplished through a semi-permeable membrane that separates the blood side from the gas side inside the oxygen concentrator, while allowing O2 and CO2 to diffuse across / through the membrane. CO2 dissolved in the blood, especially in the central artery, plays a crucial role in regulating various physiological functions (such as respiratory rate and reflexes) and maintaining a normal blood pH of approximately 7.4. Therefore, during treatment, the partial pressure of CO2 (pCO2) in the patient's (central artery) blood must be monitored and / or controlled.

[0003] When using a CPB system during surgery, the oxygen concentrator is placed near the patient's heart and lungs. Therefore, the pCO2 on the blood side of the oxygen concentrator at the blood side outlet corresponds to the pCO2 in the patient's central artery. The pCO2 value on the blood side of the oxygen concentrator at the gas side outlet can be estimated based on the measured pCO2 value on the gas side outlet, where this estimation is based on a characteristic map of the oxygen concentrator type.

[0004] Several types of ECMO are known in this 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 artery (venous-arterial ECMO) or vein (venous-venous ECMO). The location of the vascular access or cannula varies depending on the type of ECMO. In ECMO without a central cannula, the pCO2 of the central artery cannot be derived from measurements on the oxygenator's gas side. Therefore, during the use of such ECMO systems in a clinic, arterial pCO2 is typically monitored by intermittently sampling the patient's arterial blood and measuring the pCO2 in each sample.

[0005] However, these methods have the drawbacks of being cumbersome due to intermittent sampling and causing delays in measurement results. Furthermore, the estimation of blood-side pCO2 at the blood-side outlet of the oxygen concentrator inevitably involves errors, which can negatively impact the patient's health. Summary of the Invention

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

[0007] This objective is achieved by the apparatus according to the independent device claim and the method according to the independent method claim. Preferred embodiments of the apparatus and method are specifically described in the dependent claims.

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

[0009] In one aspect of the present disclosure, an apparatus is provided for determining the partial pressure of CO2 (pCO2 value) of blood on the blood side of an oxygen concentrator. The apparatus includes: an oxygen concentrator having a blood side, a gas side, and a semi-permeable membrane, wherein the membrane separates the blood side from the gas side, and each of the blood side and the gas side has an inlet and an outlet, and during operation of the oxygen concentrator, gas flows at a certain flow rate from the inlet to the outlet of the gas side; a first sensor configured to measure the pCO2 value in the gas on the gas side (or on the gas side); and a control unit configured to process the pCO2 value measured on the gas side and determine, based on the pCO2 value measured on the gas side, the pCO2 value of blood on the blood side (or on the blood side), particularly the blood pCO2 value at the blood side inlet or outlet. To measure these pCO2 values ​​on the gas side, a first sensor can be directly installed on or inside the gas side of the oxygen concentrator, either at the gas side outlet or upstream of it, or on or inside the gas pipeline connected to the gas side / oxygen concentrator, downstream of the gas side outlet. During oxygen concentrator operation, when gas flows from the gas side inlet to the gas side outlet and blood flows from the blood side inlet to the blood side outlet, the control unit determines the pCO2 value of the blood on the blood side by calculating the rate of change or value of change of the pCO2 value measured in the gas on the gas side. Furthermore, when the calculated rate of change is equal to or falls within a predetermined range of a predetermined rate of change at a predetermined (minimum) measurement interval, the blood pCO2 value on the blood side is derived from the pCO2 value measured in the gas on the gas side (measured when the calculated rate of change is equal to or falls within the predetermined range of a predetermined rate of change at the predetermined (minimum) measurement interval).

[0010] By calculating the rate of change or the value of the rate of change, it can be determined whether the diffusion equilibrium of CO2 has been reached between the gas and blood sides, that is, whether the rate of change or the value of the rate of change is (nearly) zero.

[0011] Ideally, the predetermined rate of change value could be zero; however, due to measurement inaccuracies and / or measurement tolerances, it could also be an infinitesimally small value. It may be more beneficial to specify a range of predetermined rate of change values ​​rather than a single predetermined value, where the range includes tolerance values ​​near the target value, such as zero, where the tolerance values ​​depend on the specific measuring equipment.

[0012] When equilibrium is reached, at least at the measurement point, i.e., at the location of the first sensor, the pCO2 value measured in the gas on the gas side is equal to the pCO2 value in the blood on the blood side. This means that the pCO2 value in the blood on the blood side can be equivalent to a specific single pCO2 value, measured in the gas on the gas side when the calculated rate of change is equal to or after the predetermined measurement interval equals the predetermined rate of change value, or equivalent to the average of all pCO2 values, measured in the gas on the gas side when the calculated rate of change is equal to or after the predetermined measurement interval equals the predetermined rate of change value, or equivalent to the average of multiple specific pCO2 values, measured in the gas on the gas side when the calculated rate of change is equal to or after the predetermined measurement interval equals the predetermined rate of change value, or any other combination thereof.

[0013] In this way, it is possible to conveniently, accurately, and quickly determine the blood pCO2 value on the blood side of the oxygen concentrator, especially the blood pCO2 value at the inlet or outlet of the blood side. This value can be used as an indicator of the patient's overall condition, thereby improving the patient's treatment and health. Furthermore, determining the pCO2 value on the blood side during the operation of the oxygen concentrator means that this determination can be performed during the patient's treatment. Moreover, even without complete knowledge of the gas exchange characteristics of the oxygen concentrator, the above-mentioned device can determine the pCO2 value on the blood side.

[0014] In a preferred embodiment, the rate of change is a temporal change rate, i.e., the rate of change over time, and the predetermined measurement interval is a predetermined time period. This means that the control unit can determine the blood-side pCO2 value by calculating the rate of change of the measured gas-side pCO2 value over time, and derive the blood-side pCO2 value from the gas-side pCO2 value when or after the calculated rate of change equals the predetermined rate of change value and remains at a predetermined (minimum) time period, the gas-side pCO2 value being measured during or after the time period.

[0015] The predetermined time interval is a period of time after which it can be assumed that no further change (outside the measurement tolerance / predetermined rate of change) will occur in the pCO2 value measured on the gas side. The predetermined time interval depends particularly on the flow rate, the initial pCO2 value of the blood, the characteristics of the sensor and membrane, and is predetermined due to the apparatus and operating conditions. As the sensor for measuring pCO2 in the gas, a nondispersive infrared sensor (NDIR sensor) can be used.

[0016] In another preferred embodiment, the device includes a second sensor configured to measure the partial pressure of CO2 on the gas side (or on the gas side), wherein the rate of change is a rate of change with position, specifically with distance in the gas flow direction. That is, between the gas side inlet and outlet, and the predetermined measurement interval is a predetermined local measuring distance, with the first and second sensors positioned at this predetermined local measuring distance. This means that the control unit can determine the pCO2 value on the blood side by calculating the rate of change of the pCO2 value measured on the gas side over the local measuring distance, and derive the pCO2 value of the blood on the blood side from the pCO2 value on the gas side when or after the calculated rate of change equals a predetermined (minimum) local measuring distance.

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

[0018] The required spacing between regions depends in particular on the flow rate, the initial pCO2 value of the blood, the characteristics of the sensor and the membrane, and is predetermined due to the device and operating conditions.

[0019] Preferably, the control unit is further configured to stop the gas flow into the gas-side inlet, and the gas flow is stopped from exiting the gas-side outlet, for example, via at least one valve located at or upstream of the gas-side inlet and / or at or downstream of the gas-side outlet, before deriving the CO2 partial pressure value on the blood side, particularly before or during calculating the rate of change of the CO2 partial pressure value measured on the gas side over time. Preferably, the blood flow rate is kept constant while the gas flow rate is stopped, and more preferably, the blood flow rate is maintained at the therapeutic flow rate.

[0020] When the gas flow into the gas-side inlet stops, CO2 diffusing from the blood side through / through the membrane into the gas side will accumulate 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. Since blood continues to flow through the blood side of the oxygen concentrator while the gas remains 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 CO2 diffusion gradient will become zero / infinite within a certain time interval. The pCO2 value on the gas side is the maximum pCO2 value of the blood on the blood side of the oxygen concentrator, i.e., the pCO2 value of the blood at the blood-side inlet (venous). This further indicates that the CO2 diffusion equilibrium inside the oxygen concentrator will depend on the pCO2 value of the blood at the blood-side inlet, because the pCO2 value at the blood-side inlet is the maximum value inside the oxygen concentrator. Therefore, within a certain time interval, the pCO2 value on the gas side will adjust to the pCO2 value of the blood at the blood-side inlet.

[0021] Furthermore, upon cessation of gas flow, the pCO2 values ​​at both the gas-side inlet and outlet will be adjusted to the same value due to diffusion. This means that the pCO2 equilibrium value on the gas side can be measured at any point between the gas-side inlet and outlet (and even at a point downstream of the outlet if the gas flow is stopped at that point). When the gas stops until pCO2 equilibrium is reached, a single sensor is sufficient to determine the pCO2 value on the blood side. This determination is made by calculating the rate of change of the pCO2 value measured on the gas side over time. After determining the pCO2 value on the blood side, the control unit can increase the gas flow rate back to normal (therapeutic) flow rate to continue or resume the patient's treatment.

[0022] More preferably, the control unit is configured to adjust the flow rate of the gas flow into the inlet on the gas side, and the control unit gradually reduces the flow rate of the gas flow into the inlet on the gas side, i.e., continuously or at predetermined time intervals, until the calculated rate of change of position is equal to a predetermined rate of change value or falls within a predetermined rate of change range at a predetermined measurement interval. Preferably, the blood flow rate remains constant while the gas flow rate decreases, and more preferably, the blood flow rate is maintained at the therapeutic flow rate. After determining the pCO2 value of the blood on the blood side, the control unit can increase the gas flow rate back to the normal (therapeutic) flow rate to initiate or continue the patient's treatment.

[0023] When the gas flow rate on the gas side decreases, especially to a rate lower than the blood flow rate, the residence time of the gas on the gas side in the oxygen concentrator will be longer than that of the blood on the blood side. CO2 diffusing from the blood side to the gas side will accumulate on the gas side, reaching a pCO2 value (or CO2 concentration) at which the CO2 diffusion gradient between the blood and gas is zero / infinitesimal, meaning that CO2 diffusion between the blood and gas sides will reach equilibrium. Alternatively, a pCO2 value will be reached at which the CO2 diffusion gradient is greater than zero / infinitesimal, meaning that CO2 diffusion between the blood and gas sides has not reached equilibrium. This occurs when the residence time of the gas in the oxygen concentrator is insufficient to reach the pCO2 equilibrium value, i.e., when the gas flow rate is too high and / or the membrane area / oxygen concentrator length is too short. With the first and second sensors fixed at a predetermined measurement interval, CO2 equilibrium can only be achieved at a sufficiently low gas flow rate. The achievement or discovery of the sufficiently low gas flow rate is achieved by gradually reducing the gas flow rate by the control unit until the rate of change calculated between the pCO2 value measured by the first sensor and the pCO2 value measured by the second sensor is zero or infinitesimal. In other words, compared to the case where the gas stops flowing (i.e., the flow rate is reduced to zero), the waiting time until the calculated rate of change becomes zero or infinitesimal is replaced by a gas flow rate that is gradually reduced until the rate of change becomes zero or infinitesimal.

[0024] More preferably, the control unit is configured to adjust the gas flow rate at the inlet and reduce the gas flow rate at the inlet to a predetermined reduced gas flow rate before deriving the CO2 partial pressure value on the blood side, particularly before or during the calculation of the rate of change of the CO2 partial pressure values ​​measured on the gas side. For calculating the rate of change, the CO2 partial pressure values ​​on the gas side are measured within a verified point or validated section of the device, especially for the gas side, where it has been (previously) verified that the CO2 partial pressure on the gas side has reached a saturation value (the maximum value within the gas side, i.e., the equilibrium value) at the predetermined reduced gas flow rate. In this embodiment, both the first and second sensors can be positioned within the validated section to calculate the rate of change with position. Alternatively, only one sensor may be provided within the validated section to calculate the rate of change with time.

[0025] As mentioned above, the gas flow rate and the length of the oxygen concentrator must be matched to achieve CO2 diffusion equilibrium within the gas side of the oxygen concentrator, and the higher the gas flow rate, the longer the oxygen concentrator must be. Therefore, experimental tests must be conducted before treatment to determine that the length of the oxygen concentrator is sufficient to achieve CO2 diffusion equilibrium at a predetermined reduced flow rate. The sufficiently long downstream section is a validated section, which can be only a portion of the gas side (including the gas side outlet), or it can be at least a portion including the gas side outlet (and preferably a portion upstream of the gas side outlet) and a portion downstream of the gas line outlet.

[0026] In a preferred embodiment, the gas side of the oxygen concentrator is formed by multiple hollow fibers through which gas flows from the inlet to the outlet. A first sensor is connected to the gas side only through a portion (or a subset) of these hollow fibers; that is, the sensor is not connected to all hollow fibers. In other words, the first sensor is only connected to a portion of the gas side. The portion of the hollow fiber connected to the first sensor can be limited to a small number of fibers. Specifically, the first sensor may be connected to that portion of the hollow fiber downstream of that portion or downstream of the downstream end of that portion. Thus, the first sensor can measure the CO2 partial pressure of only a portion of the hollow fiber, not all of the hollow fibers. Furthermore, the control unit can process the measured CO2 partial pressure of the portion of the hollow fiber and determine the CO2 partial pressure of the blood side based on the measured CO2 partial pressure of the portion of the hollow fiber. The control unit can determine the partial pressure of CO2 on the blood side during the operation of the oxygen concentrator by calculating the rate of change of the measured partial pressure of CO2 in the hollow fiber section. Furthermore, when the calculated rate of change is equal to or falls within a predetermined range at a predetermined measurement interval, the partial pressure of CO2 on the blood side is derived from the partial pressure of CO2 in that hollow fiber section. The partial pressure of CO2 in that hollow fiber section is measured when or after the calculated rate of change is equal to or falls within a predetermined range at a predetermined measurement interval.

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

[0028] When the rate of change is the rate of change over time, and the predetermined measurement interval is a predetermined time period, the control unit is configured to stop the gas flow through that portion of the hollow fiber via a valve. Specifically, the control unit stops the gas flow through that portion of the hollow fiber before deriving the CO2 partial pressure value on the blood side, particularly before or during the calculation of the rate of change of those CO2 partial pressure values ​​measured in that portion of the hollow fiber.

[0029] Alternatively, when the rate of change is a rate of change over time and the predetermined measurement interval is a predetermined time period, the control unit can be configured to reduce the flow rate of the gas through that portion of the hollow fiber to a predetermined reduced gas flow rate via a valve before calculating the CO2 partial pressure value measured in that portion of the hollow fiber, particularly before or during the calculation of the rate of change of the CO2 partial pressure value measured in that portion of the hollow fiber. The location for measuring the CO2 partial pressure value of the hollow fiber portion is an empirically verified location within the device, for which it has been confirmed that the CO2 partial pressure of that portion of the hollow fiber reaches a saturation value at the predetermined reduced flow rate.

[0030] By connecting the first sensor to only a portion of the fibers constituting the gas side, the partial pressure of CO2 on the blood side can be determined without altering or interrupting the gas flow on the entire gas side. This means that while determining the partial pressure of CO2 on the blood side, patient treatment can be maintained without interference or substantial alteration. Because the fibers on the gas side—the fibers to which the sensor is connected, and through which airflow is stopped or reduced for measurement purposes—constitute only a small portion of the gas side, the gas flow through the remaining main portion of the gas side (i.e., all the fibers not connected to the sensor and valve) remains undisturbed during CO2 partial pressure measurement, and patient treatment is not compromised.

[0031] Preferably, as the control unit gradually reduces the gas flow rate, the control unit is also configured to adjust the CO2 ratio in the gas flow (or the gas stream), and the control unit increases the CO2 ratio in the gas flow (or the gas stream) to a predetermined CO2 increase ratio, particularly when or during the reduction of the flow rate. After determining the blood pCO2 value on the blood side, the control unit can reduce the CO2 ratio in the gas flow back to the normal (therapeutic) CO2 ratio in the gas flow to continue or sustain the patient's treatment.

[0032] More preferably, in the above-described case, two sensors or a single sensor are installed within the validated section, and the control unit is configured to adjust the CO2 ratio in the gas flow (or the gas stream). Specifically, before deriving the CO2 partial pressure value on the blood side, and particularly before, during, or after the control unit reduces the flow rate to a predetermined reduction, the control unit increases the CO2 ratio in the gas flow to a predetermined CO2 increase ratio. This is because, for the validated point or validated section, it has been (previously) confirmed that the CO2 partial pressure on the gas side reaches the saturation value (the maximum value on the gas side, i.e., the equilibrium value) at the predetermined reduced gas flow rate with the predetermined CO2 increase ratio. After determining the pCO2 value of the blood on the blood side, the control unit can reduce the CO2 ratio in the gas flow back to the normal (therapeutic) CO2 ratio in the gas flow to continue or sustain the patient's treatment.

[0033] By increasing the proportion of CO2 in the airflow, the difference between the pCO2 value of the blood at the blood-side inlet (which is the maximum pCO2 value within the oxygen concentrator) 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 reduction in the time interval / flow rate required to reach diffusion equilibrium (nearly) is also reduced. Therefore, the pCO2 value of the blood at the blood-side inlet can be determined more quickly.

[0034] The pCO2 value of the gas with a predetermined increase in CO2 should be just lower than the pCO2 value of the patient's vein, ideally around 46 mm / Hg. Therefore, the pCO2 value of the gas with a predetermined increase in CO2 should be lower than 46 mm / Hg, preferably lower than 35 mm / Hg.

[0035] In another aspect of this disclosure, an apparatus is provided for determining the partial pressure of CO2 on the blood side of an oxygen concentrator. The apparatus includes: an oxygen concentrator having a blood side, a gas side, and a semi-permeable membrane, wherein the membrane separates the blood side from the gas side; the gas side has an inlet and an outlet; and during operation of the oxygen concentrator, a gas flow enters from the inlet to the outlet at a certain flow rate; a first sensor is configured to measure the partial pressure of CO2 on the gas side; and a control unit is configured to control the flow rate of the gas flow into the inlet, process the CO2 partial pressure measured on the gas side, and determine the partial pressure on the blood side (or the gas side) based on the CO2 partial pressure measured on the gas side. The CO2 partial pressure value is determined by the control unit during oxygen generator operation by stopping the gas flow into the inlet (preferably outside the outlet, e.g., through a valve), measuring at least one CO2 partial pressure value on the gas side after an empirical time interval following the cessation of the gas flow, and deriving the CO2 partial pressure value on the blood side from the at least one CO2 partial pressure value on the gas side, which is measured after an empirical time interval has elapsed, wherein the CO2 partial pressure on the gas side has been (pre-)confirmed to have reached a saturation value (the maximum value within the gas side, i.e., at the equilibrium value) for the empirical time interval.

[0036] In the same way, the pCO2 value of the blood on the blood side of the oxygen concentrator can be determined conveniently, accurately and quickly (especially the pCO2 value of the blood at the inlet or outlet of the blood side of the oxygen concentrator). This value can be used as an indicator of the patient's overall condition, thereby improving the patient's treatment and health.

[0037] In another aspect of this disclosure, an apparatus for determining the partial pressure of CO2 on the blood side of an oxygen concentrator is provided, comprising: an oxygen concentrator containing a blood side, a gas side, and a semi-permeable membrane, wherein the membrane separates the blood side from the gas side, the gas side has an inlet and an outlet, during operation of the oxygen concentrator, a gas flow flows from the inlet to the outlet at a certain flow rate, and the gas side is formed of multiple hollow fibers, through which gas flows from the inlet to the outlet; a first sensor is connected to a portion of the multiple hollow fibers on the gas side, preferably connected to a downstream end of that portion of the multiple hollow fibers or the downstream end of that portion of the multiple hollow fibers. Downstream of the gas-side component, a first sensor is configured to measure the partial pressure of CO2 in that portion of a plurality of hollow fibers on the gas side; a valve is located downstream of the first sensor and is configured to stop or reduce the gas flow through that portion of the hollow fibers in a first state, and to release or increase the gas flow through that portion of the hollow fibers in a second state; a control unit is configured to control the gas flow through that portion of the hollow fibers via the valve, process the partial pressure of CO2 measured in that portion of the hollow fibers, and determine the partial pressure of CO2 on the blood side based on the partial pressure of CO2 measured in that portion of the hollow fibers. The control unit determines the partial pressure of CO2 on the blood side during oxygen generator operation by stopping the gas flow into the hollow fiber portion by a valve, measuring at least one partial pressure of CO2 in the hollow fiber portion after a verified time interval following the gas flow cessation, and deriving the partial pressure of CO2 on the blood side from the at least one partial pressure of CO2 in the hollow fiber portion, wherein the at least one partial pressure of CO2 in the hollow fiber portion is measured after a verified time interval has elapsed, and the verified time interval has confirmed that the partial pressure of CO2 in the hollow fiber portion on the gas side has reached a saturation value.

[0038] In the same way, the CO2 value of the blood can be conveniently, accurately, and quickly determined on the blood side of the oxygen concentrator without significantly interfering with the patient's treatment.

[0039] In another aspect of this disclosure, an apparatus is provided for determining the partial pressure of CO2 on the blood side of an oxygen concentrator. The apparatus includes: an oxygen concentrator having a blood side, a gas side, and a semi-permeable membrane, wherein the membrane separates the blood side from the gas side, the gas side has an inlet and an outlet, and during operation of the oxygen concentrator, a gas flow enters from the inlet to the outlet at a certain flow rate; a first sensor is configured to measure the partial pressure of CO2 on the gas side; a control unit is configured to control the flow rate of the gas flow entering the inlet, process the CO2 partial pressure values ​​measured on the gas side, and determine a partial pressure of CO2 on the blood side based on the CO2 partial pressure values ​​measured on the gas side, wherein the control unit determines the CO2 partial pressure of the blood side during operation of the oxygen concentrator by reducing the flow rate of the gas flow entering the gas side inlet to a predetermined reduced gas flow rate. The flow rate is reduced to the predetermined reduced gas flow rate. At least one CO2 partial pressure value on the gas side is measured after a verified time interval has elapsed and at a verified point or a verified section of the device, particularly on the gas side. The CO2 partial pressure value on the blood side is derived from the at least one CO2 partial pressure value on the gas side. The at least one CO2 partial pressure value on the gas side is measured at the verified point or within the verified section after the verified time interval has elapsed, wherein the CO2 partial pressure on the gas side has been (pre-) verified to have reached a saturation value (the maximum value on the gas side, i.e., the equilibrium value) for the verified time interval and the verified point or verified section.

[0040] In the same way, the pCO2 value of the blood on the blood side of the oxygen concentrator (especially the pCO2 value of the blood at the inlet or outlet of the blood side of the oxygen concentrator) can be conveniently, accurately and quickly determined. This value can be used as an indicator of the patient's overall condition, thereby improving the patient's treatment and health.

[0041] In another aspect of this disclosure, an apparatus is provided for determining the partial pressure of CO2 on the blood side of an oxygen concentrator, comprising: the oxygen concentrator including a blood side, a gas side, and a semi-permeable membrane, wherein the membrane separates the blood side from the gas side, the gas side has an inlet and an outlet, and during operation of the oxygen concentrator, a gas flow flows from the inlet to the outlet at a certain flow rate, and the gas side is formed of multiple hollow fibers, through which gas flows from the inlet to the outlet; a first sensor connected to a portion of the multiple hollow fibers on the gas side, preferably downstream of that portion of the hollow fibers or downstream of the downstream end of that portion of the hollow fibers. A first sensor is configured to measure the partial pressure of CO2 in a portion of the hollow fiber on the gas side; a valve is located downstream of the first sensor and is configured to stop or reduce the gas flow through the portion of the hollow fiber in a first state, and to release or increase the gas flow through the portion of the hollow fiber in a second state; a control unit is configured to control the gas flow through the portion of the hollow fiber via the valve, process the partial pressures of CO2 measured in the portions of the plurality of hollow fibers on the gas side, and determine a partial pressure of CO2 on the blood side based on the partial pressures of CO2 measured in the portions of the hollow fibers. The control unit determines the partial pressure of CO2 on the blood side during oxygen generator operation by reducing the flow rate of the gas through the hollow fiber portion to a predetermined reduced gas flow rate via a valve, measuring at least one partial pressure of CO2 on the hollow fiber portion at a verified location after a verified time interval has elapsed following the reduction of the flow rate to the predetermined reduced gas flow rate, and deriving the partial pressure of CO2 on the blood side from the at least one partial pressure of CO2 on the hollow fiber portion. The at least one partial pressure of CO2 on the hollow fiber portion is measured at a verified location after the verified time interval has elapsed, wherein the CO2 partial pressure on the gas side of the hollow fiber has been confirmed to have reached a saturation value for the verified time interval and the verified location.

[0042] In the same way, the pCO2 value of the blood can be conveniently, accurately, and quickly determined on the blood side of the oxygen concentrator without significantly interfering with the patient's treatment.

[0043] In all the aforementioned devices, the control unit can determine the partial pressure of CO2 on the blood side at predetermined time intervals and / or when predetermined operating conditions occur, such as in cases of medical anomalies or extreme treatment values. Specifically, the control unit determines the pCO2 value on the blood side when the calculated rate of change and / or the measured pCO2 value on the gas side is monitored constantly or intermittently and the calculated rate of change and / or the measured pCO2 value on the gas side is below or exceeds a predetermined limit value.

[0044] Preferably, in all the above-described devices, the first sensor is positioned at or (immediately) downstream of the outlet on the gas side inside the oxygen concentrator. Positioning the first sensor at the end of the oxygen concentrator membrane (viewed in the flow direction) or downstream of the end of the oxygen concentrator membrane, i.e., positioning the first measurement point, ensures that the overall length of the oxygen concentrator membrane is used to achieve diffusion equilibrium, which keeps the size of the oxygen concentrator as small as possible.

[0045] More preferably, when it is necessary to measure the rate of change over the area spacing, at least one of the first sensor and the second sensor, preferably the first sensor and the second sensor, is located inside the oxygen generator.

[0046] Optionally, the main gas line is positioned downstream of the gas outlet on the gas side, and a branch line branches off from the main line, with one of the first and second sensors located on or at the branch line. Positioning the sensors on the branch line can resolve or at least mitigate the humidity issue during pCO2 measurement.

[0047] Preferably, in the aforementioned device comprising a sensor connected only to a portion (or subset) of the plurality of hollow fibers constituting the gas side, the portion of the hollow fiber on the gas side connected to the first sensor is located at the blood inlet in the flow direction of blood across the blood side. This allows the pCO2 value of the vein to be determined. Alternatively, this portion of the hollow fiber on the gas side to which the first sensor is connected may be located at the blood outlet in the flow direction of blood across the blood side. This allows the pCO2 value of the artery to be determined. The device may also provide two or more sensors, each connected only to a portion (or subset) of the plurality of hollow fibers, located at different positions along the direction of blood flow across the blood side, to determine two or more different pCO2 values ​​on the blood side. For example, the first sensor is located at the blood inlet, and the second sensor is located at the blood outlet, to determine both the venous and arterial pCO2 values.

[0048] In another preferred embodiment, the device forms part of an extracorporeal membrane oxygenation system (venous-venous or venous-arterial ECMO system). In another preferred embodiment, the device forms part of an extracorporeal circulation system.

[0049] According to one aspect of the present disclosure, a method is provided for determining the pCO2 value of the blood side (of blood) of an oxygen concentrator of an apparatus. The oxygen concentrator includes a blood side, a gas side, and a semi-permeable membrane separating the blood side and the gas side, wherein the blood side and the gas side each have an inlet and an outlet, and during operation of the oxygen concentrator, a gas flow enters from the inlet of the gas side to the outlet of the gas side at a certain flow rate. The method includes the following steps:

[0050] —The pCO2 value on the gas side (or on the gas side) is measured by the first sensor of the device;

[0051] —The control unit of the device processes the pCO2 values ​​measured on the gas side, and determines the pCO2 partial pressure value on the blood side (or the blood itself), specifically at the blood inlet or blood outlet.

[0052] —The control unit determines the pCO2 value of the blood during oxygen concentrator operation through more steps:

[0053] — Calculate the rate of change or rate of change value of the pCO2 values ​​measured in the gas on the gas side, and derive the pCO2 values ​​of the blood side (blood) from these pCO2 values ​​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 a predetermined measurement interval.

[0054] Preferably, the rate of change is the rate of change over time, and the predetermined measurement interval is a predetermined time segment.

[0055] Preferably, the rate of change is the rate of change with position, and the predetermined measurement interval is the predetermined area measurement interval, wherein the CO2 partial pressure value on the gas side is measured at the predetermined area measurement interval by the first sensor and the second sensor of the device, and the second sensor is located at a position at a predetermined area measurement interval away from the first sensor.

[0056] Preferably, the control unit determines the partial pressure of CO2 on the blood side by a further step, which is to stop the gas flow into the gas-side inlet before deriving the partial pressure of CO2 on the blood side, particularly before or during the calculation of the rate of change of the CO2 partial pressure measured on the gas side.

[0057] Preferably, the control unit determines the partial pressure of CO2 on the blood side by a further step, which is to gradually reduce the flow rate of the gas flow into the inlet on the gas side until the rate of change with position is equal to a predetermined rate of change value or falls within a predetermined rate of change range at a predetermined measurement interval.

[0058] Preferably, the control unit determines the partial pressure of CO2 on the blood side by a further step, which is to reduce the gas flow into the inlet to a predetermined reduced gas flow rate before deriving the partial pressure of CO2 on the blood side, particularly before or during the calculation of the rate of change of the CO2 partial pressure values ​​measured on the gas side, wherein, in order to calculate the rate of change, the CO2 partial pressure values ​​on the gas side are measured at empirical points or verified sections of the device, particularly on the gas side, wherein it has been confirmed at the empirical points or verified sections that the CO2 partial pressure on the gas side has reached a saturation value at the predetermined flow rate.

[0059] In a preferred embodiment, the gas side is formed by multiple hollow fibers, with gas flowing from an inlet to an outlet. A first sensor is connected to the gas side only through a portion of the hollow fibers on the gas side, preferably downstream of that portion or downstream of that downstream end of the hollow fiber. Furthermore, in the step of measuring the CO2 partial pressure value via the first sensor, the CO2 partial pressure value of the hollow fiber portion is measured. In the step of processing the measured CO2 partial pressure value and determining the CO2 partial pressure value of the blood side based on the measured CO2 partial pressure value, the CO2 partial pressure value measured by the hollow fiber portion on the gas side is processed, and based on… The partial pressure of CO2 on the blood side is determined by the CO2 partial pressure value measured at this portion of the hollow fiber. Furthermore, in the step of calculating the rate of change of the CO2 partial pressure value measured on the gas side, the rate of change of the CO2 partial pressure value measured at this portion of the hollow fiber on the gas side is calculated. In the step of deriving 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 derived from the CO2 partial pressure value of this portion of the hollow fiber. The CO2 partial pressure value of the hollow fiber portion is measured when or after the calculated rate of change is equal to a predetermined rate of change value or falls within a predetermined rate of change range at a predetermined measurement interval.

[0060] A valve may be located downstream of the first sensor, and the valve is configured to stop or reduce the gas flow through the portion of the hollow fiber on the gas side in a first state, and to release or increase the gas flow through the portion of the hollow fiber on the gas side in a second state.

[0061] When the rate of change is the rate of change over time and the predetermined measurement interval is a predetermined time interval, the control unit can determine the partial pressure of CO2 on the blood side by a further step, which is to stop the gas flow through the hollow fiber section by a valve before deriving the partial pressure of CO2 on the blood side, especially before or during the calculation of the rate of change of the partial pressure of CO2 measured by the hollow fiber section on the gas side.

[0062] Alternatively, when the rate of change is a rate of change over time and the predetermined measurement interval is a predetermined time period, the control unit can determine the partial pressure of CO2 on the blood side through a further step. This further step involves reducing the gas flow through the portion of the hollow fiber to a predetermined reduced gas flow rate via a valve before deriving the partial pressure of CO2 on the blood side, particularly before or during the calculation of the rate of change of the CO2 partial pressure values ​​measured in the portion of the hollow fiber. In order to calculate the rate of change, the partial pressure values ​​of CO2 in the portion of the hollow fiber are measured at a verified location in the device, wherein the CO2 partial pressure in the portion of the hollow fiber has been confirmed to have reached a saturation value at the predetermined reduced gas flow rate at the verified location.

[0063] More preferably, in the case where the control unit changes the gas flow rate before deriving the partial pressure of CO2 on the blood side, that is, stops the gas from entering the inlet on the gas side or reduces the flow rate of the gas into the inlet on the gas side (gradually or until a predetermined gas flow rate), the (current) pCO2 value in the gas on the gas side (or on the gas side) is measured before the control unit changes the gas flow rate.

[0064] Preferably, the control unit further determines the partial pressure of CO2 on the blood side by increasing the proportion of CO2 in the gas flow to a predetermined increase proportion, particularly before, during, or after stopping the gas flow or reducing the flow rate.

[0065] Preferably, the control unit determines the partial pressure of CO2 on the blood side through a further step, which is to increase the proportion of CO2 in the gas flow to a predetermined increase proportion before deriving the partial pressure of CO2 on the blood side, particularly before, during, or after reducing the flow rate to a predetermined decrease proportion, and wherein for the verified point or the verified portion, it has been confirmed that the partial pressure of CO2 on the gas side has reached a saturation value at a predetermined increase proportion of CO2 and a predetermined decrease in gas flow rate.

[0066] In another aspect of this disclosure, a method is provided for determining the partial pressure of CO2 on the blood side of an oxygen concentrator of an apparatus. The oxygen concentrator includes a blood side, a gas side, and a semi-permeable membrane separating the blood side and the gas side. The gas side has an inlet and an outlet, and during operation of the oxygen concentrator, a gas flow enters from the inlet to the outlet at a certain flow rate. The method includes the steps of: measuring at least one partial pressure of CO2 on the gas side (or on the gas side) using a first sensor of the apparatus; processing the at least one partial pressure of CO2 measured on the gas side using a control unit of the apparatus, and determining the partial pressure of CO2 on the blood side (or on the blood side) based on the at least one partial pressure of CO2 measured on the gas side; and controlling the gas flow into the gas side using the control unit. The inlet flow rate, wherein the control unit determines the CO2 partial pressure value on the blood side through further steps during oxygen generator operation, the further steps being to stop the gas flow into the gas side inlet (and preferably outside the gas side outlet, for example, by a valve), to measure at least one CO2 partial pressure value on the gas side after an empirical time interval following the cessation of the gas flow, and to derive the CO2 partial pressure value on the blood side from the at least one CO2 partial pressure value on the gas side, the at least one CO2 partial pressure value on the gas side being measured after the empirical time interval has elapsed, wherein the CO2 partial pressure on the gas side has been (pre-)confirmed to have reached a saturation value (the maximum value within the gas side, i.e., the equilibrium value) for the empirical time interval.

[0067] In another aspect of this disclosure, a method is provided for determining the partial pressure of CO2 on the blood side of an oxygen concentrator of an apparatus. The apparatus includes: an oxygen concentrator comprising a blood side, a gas side, and a semi-permeable membrane separating the blood side and the gas side, wherein the gas side has an inlet and an outlet, and during operation of the oxygen concentrator, a gas flow flows into the inlet and outlet at a certain flow rate, and the gas side is formed of multiple hollow fibers, through which gas flows from the inlet to the outlet; a first sensor connected only to a portion of the multiple hollow fibers on the gas side, preferably downstream of that portion of the hollow fibers or downstream of the downstream end of that portion of the hollow fibers, the first sensor being configured to measure the partial pressure of CO2 on that portion of the hollow fibers on the gas side; and a valve disposed downstream of the first sensor, the valve being configured to stop or reduce the gas flow through that portion of the hollow fibers in a first state, and to release or increase the gas flow through that portion of the hollow fibers in a second state, wherein the method includes the step of: controlling the gas flow through the hollow fibers via a control unit of the apparatus. The flow rate of this portion of the hollow fiber; the measurement of at least one CO2 partial pressure value of this portion of the hollow fiber by a first sensor of the device; the processing of the at least one CO2 partial pressure value measured by the at least one CO2 partial pressure value of this portion of the hollow fiber by a control unit of the device, and the determination of a CO2 partial pressure value on the blood side based on the at least one CO2 partial pressure value measured by this portion of the hollow fiber on the gas side, wherein the control unit measures the CO2 partial pressure value on the blood side during oxygen generator operation through further steps, the further steps being: stopping the gas flow through this portion of the hollow fiber by a valve, measuring at least one CO2 partial pressure value of this portion of the hollow fiber after a verified time interval has elapsed following the cessation of the gas flow, and deriving the CO2 partial pressure value on the blood side from the at least one CO2 partial pressure value of this portion of the hollow fiber, the at least one CO2 partial pressure value of this portion of the hollow fiber being measured after the verified time interval has elapsed, wherein the CO2 partial pressure of the hollow fiber on the gas side has been confirmed to have reached a saturation value for the verified time interval.

[0068] In another aspect of this disclosure, a method is provided for determining the partial pressure of CO2 on the blood side of an oxygen concentrator of an apparatus. The oxygen concentrator includes a blood side, a gas side, and a semi-permeable membrane separating the blood side and the gas side. The gas side has an inlet and an outlet. During operation of the oxygen concentrator, a gas flow enters from the inlet to the outlet at a certain flow rate. The method includes the steps of: measuring at least one partial pressure of CO2 on the gas side (or on the gas side) using a first sensor of the apparatus; processing the at least one partial pressure of CO2 measured on the gas side using a control unit of the apparatus; determining the partial pressure of CO2 on the blood side (or on the blood side) based on the at least one partial pressure of CO2 measured on the gas side; and controlling the flow rate of the gas flow into the gas side inlet using the control unit. The control unit further steps during operation of the oxygen concentrator. The further steps of measuring the partial pressure of CO2 on the blood side include reducing the flow rate of the gas entering the gas side inlet to a predetermined reduced flow rate, measuring at least one partial pressure of CO2 on the gas side, particularly on the gas side, after an empirical time period has elapsed following the reduction to the predetermined reduced flow rate, and within an empirical point or validated section of the device, and deriving the partial pressure of CO2 on the blood side from the at least one partial pressure of CO2 on the gas side, wherein the at least one partial pressure of CO2 on the gas side is measured at the validated point or validated section after the empirical time period has elapsed, wherein the partial pressure of CO2 on the gas side has been (pre-)confirmed to have reached a saturation value (the maximum value, the most balanced value, within the gas side) for the validated time period and the validated point or validated section.

[0069] In another aspect of this disclosure, a method is provided for determining the partial pressure of CO2 on the blood side of an oxygen concentrator of an apparatus. The apparatus includes: an oxygen concentrator comprising a blood side, a gas side, and a semi-permeable membrane separating the blood side and the gas side, wherein the gas side has an inlet and an outlet, and during operation of the oxygen concentrator, a gas flow flows into the inlet and outlet at a certain flow rate, and the gas side is formed by multiple hollow fibers, through which gas flows from the inlet to the outlet; a first sensor connected only to a portion of the multiple hollow fibers on the gas side, preferably downstream of that portion of the hollow fibers or downstream of the downstream end of that portion of the hollow fibers, the first sensor being configured to measure the partial pressure of CO2 on that portion of the multiple hollow fibers on the gas side; and a valve disposed downstream of the first sensor, wherein the valve is configured to stop or reduce the gas flow through that portion of the hollow fibers in a first state, and to release or increase the gas flow through that portion of the hollow fibers in a second state, wherein the method includes the steps of: controlling the flow rate of the gas flow through that portion of the hollow fibers by a control unit of the apparatus; and controlling the flow rate of the gas flow through the hollow fibers by the first sensor. The device measures at least one CO2 partial pressure value of this portion of the hollow fiber; the control unit of the device processes the at least one CO2 partial pressure value measured by this portion of the hollow fiber, and determines the CO2 partial pressure value on the blood side based on the at least one CO2 partial pressure value measured by this portion of the hollow fiber, wherein the control unit determines the CO2 partial pressure value on the blood side through additional steps during oxygen generator operation, the additional steps being: reducing the gas flow rate through this portion of the hollow fiber to a predetermined reduced gas flow rate, and further reducing the flow rate to the predetermined... After a validated time interval following a reduction in flow rate and at a validated location within the device, the partial pressure of at least one CO2 in that portion of the hollow fiber is measured, and the partial pressure of CO2 on the blood side is derived from the partial pressure of at least one CO2 in that portion of the hollow fiber, which is measured at the validated location after the validated time interval, wherein the partial pressure of CO2 in that portion of the hollow fiber has been confirmed to have reached a saturation value for the validated time interval and the validated location.

[0070] Preferably, in all the above aspects, the control unit determines the CO2 partial pressure value on the blood side at a predetermined time interval and / or when a predetermined operating condition occurs.

[0071] In a preferred embodiment of the method, the first sensor is located inside the oxygen generator at the outlet on the gas side or downstream of the outlet.

[0072] In another preferred embodiment of the method, the main gas line is located downstream of the outlet on the gas side, and a branch line branches off from the main line, with the first sensor positioned on / at the branch line.

[0073] Preferably, in the above method, the sensor is connected only to a portion of the multiple hollow fibers constituting the gas side, and this portion of the hollow fiber on the gas side to which the first sensor is connected is located at the blood inlet in the direction of blood flow across the blood side. Alternatively, this portion of the hollow fiber on the gas side to which the first sensor is connected may be located at the blood outlet in the direction of blood flow across the blood side. Two or more sensors may also be provided at different locations along the direction of blood flow across the blood side, each sensor being connected only to a portion of the multiple hollow fibers. For example, the first sensor is located at the blood inlet, and the second sensor is located at the blood outlet.

[0074] The above methods can be performed during extracorporeal membrane oxygenation (ECMO) therapy, preferably during venous-venous or venous-arterial ECMO therapy. Alternatively, the above methods can be performed during extracorporeal circulation therapy.

[0075] The aforementioned apparatus is configured to perform the aforementioned method, and the aforementioned method is designed to be performed by the aforementioned apparatus. The advantages and variations of the aforementioned apparatus are accordingly applicable to the aforementioned method. Attached Figure Description

[0076] The foregoing summary and the following detailed description of preferred embodiments will be better understood when read in conjunction with the accompanying drawings. Reference is made to the drawings for the purposes of this disclosure. However, the scope of this disclosure is not limited to the specific embodiments disclosed in the drawings. In the figures:

[0077] Figure 1 This diagram illustrates a device according to a first embodiment of the present invention for determining the pCO2 value on the blood side of an oxygen concentrator.

[0078] Figure 2 A schematic diagram of a device for determining the pCO2 value on the blood side of an oxygen concentrator, according to a second embodiment of the present invention, is shown.

[0079] Figure 3 This diagram illustrates a device according to a third embodiment of the present invention for determining the pCO2 value on the blood side of an oxygen concentrator.

[0080] Figure 4 This diagram illustrates the change of pCO2 values ​​over time at a measurement point on the gas side.

[0081] Figure 5 This diagram illustrates a device according to a fourth embodiment of the present invention for determining the pCO2 value on the blood side of an oxygen concentrator.

[0082] Figure 6 The figure shows the rate of change of gas-side pCO2 over time as the length of the oxygen generator varies, at two different flow rates.

[0083] Figure 7This diagram illustrates a device according to a fifth embodiment of the present invention for determining the pCO2 value on the blood side of an oxygen concentrator. Detailed Implementation

[0084] Figure 1 A schematic diagram of an apparatus 1 for determining the pCO2 value of blood on the blood side 2 of an oxygen concentrator 4, according to a first embodiment of the present disclosure, is shown. The apparatus 1 includes an oxygen concentrator 4 having a blood side 2, a gas side 6, and a semi-permeable membrane 8 separating the blood side 2 from the gas side 6. The apparatus 1 also includes a sensor 10 configured to measure the pCO2 value of gas on the gas side 6, and a control unit 12 configured to control, in particular, the gas flow rate of gas entering the gas side 6 of the oxygen concentrator 4 from a source (not shown), such as a medical gas outlet in a hospital, and to control the proportion of CO2 in the gas flow, for example, controlled by a valve unit (not shown) upstream of the oxygen concentrator 4. The control unit 12 is configured to receive and process the pCO2 value measured by the sensor 10. The gas side 6 of the oxygen concentrator 4 has an inlet 14 and an outlet 16, while the blood side 2 has an inlet 18 and an outlet 20. Downstream of the outlet 16 of the gas side 6, a main line 22 for supplying gas is connected to the oxygen concentrator 4.

[0085] The oxygen concentrator 4 in the above embodiment operates in cocurrent mode, that is, the gas flowing into the inlet 14 of the gas side 6 and the blood flowing into the inlet 18 of the blood side 2 flow along the membrane 8 in the same direction to their respective outlets 16, 20. However, other types of oxygen concentrators with different operating modes can be used according to the currently disclosed technology. In any case, during the operation of the oxygen concentrator 4, CO2 contained / dissolved in the blood flowing into and passing through the blood side 2 will be extracted from the blood by diffusion across / through the membrane 8 and enter the gas flowing into and passing through the gas side 6. For CO2 to diffuse from the blood side to the gas side, a CO2 diffusion gradient is required, which means that the CO2 concentration or partial pressure (pCO2) in the gas needs to be lower than the CO2 concentration or partial pressure (pCO2) in the blood. Simultaneously, the O2 contained in the gas flowing into and passing through the gas side 6 should diffuse across the membrane 8 and into the blood flowing into and passing through the blood side 2. This requires an O2 diffusion gradient, meaning that the O2 concentration or partial pressure (pO2) in the gas must be higher than the O2 concentration or partial pressure (pO2) in the blood. This induces the exchange of O2 and CO2 between the gas side and the blood side.

[0086] During operation of device 1, the inlet 18 of blood side 2 is connected to the patient's venous system. This means that, since the oxygen concentrator 4 should be used to perform the function of the patient's lungs, the blood flowing into blood side 2 through inlet 18 has the highest CO2 concentration or highest pCO2 and the lowest O2 concentration or lowest pO2 in the patient's blood circulation, while the blood flowing out of blood side 2 through outlet 20 has the lowest CO2 concentration or lowest pCO2 and the highest O2 concentration or highest pO2 in the patient's blood circulation. Depending on the type of treatment, outlet 20 of blood side 2 can be connected to the patient's venous or arterial system.

[0087] To determine the patient's overall CO2 status, according to the present disclosure, the pCO2 value of venous blood at inlet 18 of blood side 2 can be used as an indicator. To determine the pCO2 value at inlet 18 of blood side 2, the gas flow is significantly reduced to a predetermined reduced gas flow rate or completely stopped, i.e., reduced to zero. Simultaneously, the blood flow through blood side 2 is maintained at, for example, a normal therapeutic flow rate. CO2 dissolved in the blood continues to flow through blood side 2, now diffusing into the gas through membrane 8. CO2 is retained on gas side 6 (for a longer time compared to the normal therapeutic flow rate) and accumulates in the gas until the carbon dioxide diffusion gradient becomes zero (or infinitesimally small). In the case of completely stopping the gas flow into inlet 16 of gas side 6 (e.g., by a valve at or upstream of inlet 14 and / or at or downstream of outlet 16), after a certain period of time, due to diffusion within gas side 6, the CO2 diffusion gradient becomes zero throughout gas side 6, i.e., along the entire length of the oxygen concentrator 4, in other words, across the entire longitudinal section between inlet 14 and outlet 16 of gas side 6. When the gas flow into the inlet 16 of gas side 6 is reduced to a predetermined reduced gas flow rate, after a certain period of time, depending on this specific reduced gas flow rate, the CO2 diffusion gradient becomes zero only on a specific longitudinal section between the inlet 14 and the outlet 16 of gas side 6. This portion, where the diffusion gradient reliably becomes zero after a certain period of time at the predetermined reduced gas flow rate, is the empirically validated portion of the gas side. This indicates that prior to treatment, this portion has been experimentally verified at the reduced flow rate, and that the diffusion gradient will become zero after a certain period of time. Since the pCO2 value downstream of outlet 16 is constant and the same as the value at outlet 16 of gas side 6, the validated portion can extend beyond outlet 16 of gas side 6 into the connecting main line 22, and outlet 16 itself must be located within this validated portion to ensure that the length of the oxygen concentrator is sufficient to achieve CO2 diffusion equilibrium within the oxygen concentrator 4.

[0088] Therefore, in order to determine or measure whether pCO2 balance has been achieved on the gas side, when the gas flow into inlet 14 is stopped, the sensor 10 can be positioned at inlet 14, outlet 16, or any position between inlet 14 and outlet 16, and when the gas flow is reduced to a predetermined gas flow rate, the sensor 10 can be positioned within the empirical section on the gas side. Then, after the gas flow is stopped or reduced by the control unit 12, the pCO2 value on the gas side 6 is measured by the sensor 10, and the control unit 12 receives and processes the pCO2 value measured by the sensor 10, and derives the pCO2 value of the blood side 2 inlet 18 from the pCO2 value measured by the sensor 12 on the gas side 6 by calculating the rate of change of the pCO2 value measured by the sensor 10 over time, in order to determine whether the CO2 diffusion across / through the membrane 8 has reached equilibrium. When the rate of change is (approximately) zero or infinitesimal (and there is no change after a predetermined time interval, it can be considered that the rate of change has not changed further), equilibrium is achieved. This means that at or after the time equilibrium is reached, the pCO2 value measured on the gas side 6 corresponds to the pCO2 value of the blood at the inlet 18 on the blood side 2, and on the other hand, the pCO2 value of the blood (i.e., the patient's venous blood) at the inlet 18 on the blood side 2 is the same as the pCO2 value measured by the sensor 10 on the gas side 6.

[0089] After equilibrium is reached and the pCO2 value at inlet 18 on the blood side 2 is determined, the flow rate of gas entering inlet 14 on the gas side 6 can be increased to the normal therapeutic gas flow rate to allow for continued or ongoing normal oxygenation therapy. During patient treatment, the determination of the pCO2 value at inlet 18 on the blood side 2 can be repeated as needed, for example at regular intervals, to closely monitor the patient's condition.

[0090] To accelerate CO2 diffusion equilibrium, the control unit 12 may increase the proportion of CO2 in the gas flowing into the inlet 14 of the gas side 6 to a predetermined CO2 increase proportion before or during the calculation of the rate of change of pCO2, with the pCO2 value measured on the gas side 6 being at least before the pCO2 value on the blood side 2 is calculated.

[0091] In a preferred embodiment, the proportion of CO2 in the gas flow is increased before the gas flow rate is reduced or stopped. Specifically, after increasing the proportion of CO2 in the gas flow, the gas flow is reduced or stopped only after a specific time interval, which is the time it takes for the gas to flow from inlet 14 to outlet 16.

[0092] In such Figure 1 In the device 1 of the first embodiment shown, the sensor 10 is directly installed on the outlet 16 on the gas side 6 inside the oxygen generator 4.

[0093] Figure 2 The apparatus 1 according to a second embodiment of the present disclosure is shown in the figure. Figure 2 The illustrated embodiments and Figure 1 Corresponding to the above embodiment, the difference is that the sensor 10 is not located inside the oxygen generator 4, but rather on the main line 22 or downstream of the outlet 16 of the gas side 6 within the main line. This facilitates the construction and maintenance of the device 1. When the 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.

[0094] Figure 3 The apparatus 1 according to a third embodiment of the present disclosure is shown in the figure. Figure 3 The illustrated embodiments and Figure 2 Corresponding to the above embodiment shown, the difference is that the sensor 10 is not located in or above the main line 22, but in or above the branch line 24 branching off from the main line 22. This can help measure pCO2 at high humidity levels. In the case of stopping the gas flow into the inlet 14 of the gas side 6 and using valves, two valves are located downstream of the outlet 16, one at or downstream of the branch point of the main line 22, and the other downstream of the sensor 10 at the branch line 24.

[0095] Figure 4 A graph schematically illustrates the pCO2 values ​​measured by sensor 10 at time t after the gas flow rate decreases to a predetermined reduction or stops completely, where sensor 10 is located within the empirical section of device 1 in the case of reduced gas flow. The gas flow rate decreases or stops at time t0. Before time t1, the measured pCO2 value remains constant. (In the case of stopped airflow, the time interval between t0 and t1 can be approximated as zero, depending on the position of sensor 10 and the diffusion rate within gas side 6.) At time t1, the pCO2 value rises to its maximum value reached at time t2. After time t2, the measured pCO2 value remains (approximately) constant, which is why the pCO2 value measured at time t3 is the same as the pCO2 value measured at time t2, i.e., the rate of change of pCO2 calculated between time t2 and time t3 is zero / infinitesimal. The constant pCO2 value measured at and after time t2 is the pCO2 equilibrium value on the gas side, which corresponds to the pCO2 value at inlet 18 on the blood side 2, i.e., the pCO2 value of the patient's venous blood.

[0096] It is important to note that Figure 4 The measurement curves shown are only illustrative, and the slope and linear portion between times t0 and t3 can vary depending on the type of oxygen concentrator and / or the flow rates of both blood and gas.

[0097] Depending on the type of oxygen concentrator, especially the membrane type, and the flow rates of blood and gas through oxygen concentrator 4, time t2, i.e., CO2 diffusion equilibrium, is reached within a shorter or longer time interval. Similar to the empirical section of device 1, a validated time interval after the airflow stops or decreases can be experimentally determined before using the oxygen concentrator for treatment. This validated time interval is a time interval proven sufficient to reach pCO2 equilibrium on the gas side 6. If the gas flow is stopped and the empirical time interval after the stoppage has elapsed, a single measurement of the pCO2 value on the gas side 6 is sufficient to determine the pCO2 value on the blood side 2, as it has been confirmed that pCO2 equilibrium is reached after the validated time interval, thus eliminating the need to calculate the rate of change. If the gas flow is reduced to a predetermined reduced gas flow rate, then the validated time interval is determined for this validated section.

[0098] Figure 5 The apparatus 1 according to the fourth embodiment of the present disclosure is shown in the figure. Figure 5 The illustrated embodiments and Figure 1 Corresponding to the above embodiment, the difference lies in that, in addition to the first sensor 10, the second sensor 11 is disposed inside the gas side 6 of the oxygen concentrator 4. Using the two sensors 10 and 11, the rate of change of pCO2 with position can be determined, that is, the rate of change of pCO2 over the region 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 gas flow rate into the inlet 14 of the oxygen concentrator 4 until the rate of change of pCO2 over the region between the second sensor 11 and the first sensor 10 is zero / infinite. With this operating mode, it is not necessary to know the verified part from... Figure 6 You can see it more clearly.

[0099] Figure 6 A graph schematically illustrates the dCO2 / dt values ​​along the length l of the oxygen concentrator at two different flow rates f1 and f2. This dCO2 / dt value represents the rate of change of pCO2 over time on the gas side. The solid line represents a flow rate f1 higher than the dashed line represents a flow rate f2. Typically, as the gas flow rate decreases to a decreasing velocity, the rate of change of pCO2 over time becomes zero / infinite; that is, at a specific longitudinal section of the oxygen concentrator 4, or downstream of it, the pCO2 equilibrium value will be reached (if the oxygen concentrator 4 is long enough). However, this specific longitudinal section of the oxygen concentrator 4 depends on the specific flow rate and is shorter (in the flow direction) for lower flow rates and longer for higher flow rates. Therefore, with respect to flow rates f1 and f2, the longitudinal section l1 of the oxygen concentrator 4 where the dCO2 / dt value becomes zero / infinite at the lower flow rate f2 is smaller than the longitudinal section l2 where the dCO2 / dt value becomes zero / infinite at the higher flow rate f2, or upstream of the longitudinal section l2. Figure 5The described operating mode involves two sensors 10 and 11 fixedly positioned within / at the gas side 6 of the oxygen concentrator 4. A specific gas flow rate exists, causing the two sensors 10 and 11 to be positioned at or downstream of a specific longitudinal section of the oxygen concentrator 4. The dCO2 / dt value becomes zero / infinitely small, and this specific flow rate can be found by gradually decreasing the gas flow rate until the rate of change of pCO2 between sensors 10 and 11 is zero / infinitely small. As an example, when the first sensor 10 is located at outlet 16 and the second sensor 11 is located at longitudinal section l1, and the control unit 12 begins to gradually decrease the gas flow rate at a flow rate f1, the flow rate at which the rate of change of pCO2 becomes zero is flow rate f2.

[0100] As Figure 5 As an alternative to the device 1 shown, the first sensor 10 can be located downstream of the outlet 16, for example, as shown in the diagram. Figure 2 and 3 As shown, the second sensor 11 can be located anywhere downstream of the inlet 14 and at the outlet 16 or upstream of it. However, when the second sensor 11 is positioned close to the outlet 16 (at least a predetermined measurement distance from the outlet 16), it will accelerate the reduction of the flow rate until the rate of change becomes zero / infinite.

[0101] As an alternative operating mode, the gas flow rate in inlet 14 can be reduced to a predetermined flow rate, and both sensors 10 and 11 are located within the verification section of device 1, wherein the verification section is verified for the predetermined flow rate. This eliminates the need for gradually reducing the flow rate.

[0102] Figure 7 The diagram schematically illustrates a device 1 according to a fifth embodiment of the present disclosure. It schematically shows that the gas side of the oxygen concentrator 4 is composed of multiple fibers 26. The fibers 26 are hollow fibers formed from semi-permeable membranes. The gas side of the oxygen concentrator is located inside the hollow fibers, while the blood side of the oxygen concentrator 4 is located outside the hollow fibers and extends around them. During operation of the oxygen concentrator 4, a gas flow (indicated by arrow a) enters the oxygen concentrator 4 at a gas inlet 14 and flows through each fiber 26 to a gas outlet 16, exiting the oxygen concentrator 4 at the gas outlet 16. A blood flow (indicated by arrow b) enters the oxygen concentrator 4 at a blood inlet 18 and flows between the fibers 26, causing the blood flow to surround the fibers 26, towards a blood outlet 20, and exiting the oxygen concentrator 4 at the blood outlet 20.

[0103] The fifth embodiment differs from the previous embodiments in that the sensor 10 is connected only to a portion (or a subset) of the multiple fibers 26 constituting the gas side, and not to all of the fibers 26 constituting the gas side. The portion of the fibers 26 connected to the sensor 10 is described as a selected fiber bundle 30. The sensor 10 is positioned downstream of the fiber bundle 30 such that the gas flow passes through the entire length (in the flow direction) of the fiber bundle 30 before entering the sensor 10 and ultimately leaving the oxygen generator 4 through the gas outlet 16. A shut-off valve or throttling valve 28 is provided downstream of the sensor 10, allowing the gas flow through the fiber bundle 30 and the sensor 10 to be stopped or reduced. In this way, the gas flow can be stopped or reduced in the fiber bundle 30, while the gas flow continues to pass through the remaining fibers 26 without stopping or reducing. In other words, for measurement purposes, the gas flow through only the fiber bundle 30 can be stopped or reduced by the valve 28, while keeping the gas flow through the remaining fibers 26 undisturbed.

[0104] The specific location of the fiber bundle 30 in the blood flow direction, that is, the specific location of the fiber bundle 30 between the blood inlet 18 and the blood outlet 20, can be selected according to the measurement purpose. Figure 7 In the illustrated embodiment, fiber bundle 30 is located at or near blood inlet 18, thereby enabling the determination of the venous pCO2 value on the blood side. In another embodiment (not shown), fiber bundle 30 may be located at or near blood outlet 20, thereby enabling the determination of the arterial pCO2 value on the blood side. At least two fiber bundles may also be provided at different locations, each connected to the sensor and valve in the manner described above, thereby enabling the determination of the blood side pCO2 value at at least two different locations. For example, one fiber bundle may be located at or near blood inlet 18, while another fiber bundle may be located at or near blood outlet 20, thereby enabling the determination of both venous and arterial pCO2 on the blood side.

Claims

1. An apparatus (1) for determining a CO2 partial pressure value of a blood side of an oxygenator (4), comprising: - an oxygenator (4) having a 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), and, during operation of the oxygenator (4), a gas flow flowing into the inlet (14) to the outlet (16) at a flow rate; - a first sensor (10) configured to measure a CO2 partial pressure value of the gas side (6); - a control unit (12) configured to process the measured CO2 partial pressure value of the gas side (6) and to determine a CO2 partial pressure value of the blood side (2) based on the measured CO2 partial pressure value of the gas side (6), wherein the control unit (12) determines the CO2 partial pressure value of the blood side (2) by calculating a rate of change of the measured CO2 partial pressure value of the gas side (6) during operation of the oxygenator (4), and, 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 interval, the CO2 partial pressure value of the blood side (2) is derived from the CO2 partial pressure value of 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, wherein the rate of change value or the rate of change range is predetermined such that an equilibrium of diffusion of CO2 between the blood side (2) and the gas side (6) is indicated.

2. The apparatus (1) of claim 1, wherein the rate of change is a rate of change over time and the predetermined measurement interval is a predetermined time section.

3. The apparatus (1) of claim 1, wherein the apparatus (1) comprises a second sensor (11) configured to measure a CO2 partial pressure value of the gas side (6), and wherein the rate of change is a rate of change over position, the predetermined measurement interval is a predetermined zone measurement interval, and the first sensor (10) and the second sensor (11) are positioned at the predetermined zone measurement interval.

4. The apparatus (1) of claim 2, wherein the control unit (12) is further configured to stop the gas flow into the inlet (14), and wherein the control unit (12) stops the gas flow into the inlet (14) before deriving the CO2 partial pressure value of the blood side (2).

5. The apparatus (1) of claim 3, wherein the control unit (12) is further configured to adjust the flow rate of the gas flow into the inlet (14), and wherein the control unit (12) gradually reduces the flow rate of the gas flow into the inlet (14) until the rate of change over position equals the predetermined rate of change value or falls within the predetermined rate of change range at the predetermined zone measurement interval.

6. The apparatus (1) according to claim 2 or 3, wherein the control unit (12) is further configured to adjust a flow rate of the gas stream entering the inlet (14), and wherein the control unit (12) reduces the flow rate of the gas stream entering the inlet (14) to a predetermined reduced gas flow rate before deriving the CO2 partial pressure value of the blood side (2).

7. The apparatus (1) according to claim 1 or 2, wherein: - 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), and the first sensor (10) is connected to the gas side (6) only through a portion of the plurality of hollow fibers (26) of the gas side (6); - the first sensor (10) is configured to measure a CO2 partial pressure value of the portion of the plurality of hollow fibers (26) of the gas side (6); - the control unit (12) is configured to process the measured CO2 partial pressure value of the portion of the plurality of hollow fibers (26) of the gas side (6) and to determine the CO2 partial pressure value of the blood side (2) based on the measured CO2 partial pressure value of the portion of the plurality of hollow fibers (26) of the gas side (6); and - the control unit (12) determines the CO2 partial pressure value of the blood side (2) by calculating a rate of change of the measured CO2 partial pressure value of the portion of the plurality of hollow fibers (26) of the gas side (6) during operation of the oxygen generator (4), and derives the CO2 partial pressure value of the blood side (2) from the CO2 partial pressure value of the portion of the plurality of hollow fibers (26) of the gas side (6) measured at or after the predetermined measurement interval at which the calculated rate of change equals a predetermined rate of change value or falls within a predetermined rate of change range.

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

9. The apparatus (1) according to claim 8, wherein: - the rate of change is a rate of change over time, and the predetermined measurement interval is a predetermined time section; and - the predetermined rate of change value is a predetermined rate of change value over time, and the predetermined rate of change range is a predetermined rate of change range over time. - the control unit (12) is configured to stop 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 outlet (16) by the valve (28), wherein the control unit (12) stops 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 outlet (16) before deriving the CO2 partial pressure value of the blood side (2).

10. The apparatus (1) according to claim 8, wherein: - the rate of change is a rate of change over time and the predetermined measurement interval is a predetermined time interval; and - the control unit (12) is configured to reduce the flow rate of 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 outlet (16) to a predetermined reduced gas flow rate by the valve (28) before deriving the CO2 partial pressure value of the blood side (2).

11. The apparatus (1) according to claim 4 or 5, wherein the control unit (12) is further configured to adjust the CO2 proportion in the gas flow, and wherein the control unit (12) increases the CO2 proportion in the gas flow to a predetermined CO2 increased proportion.

12. The apparatus (1) as defined in claim 6, wherein the control unit (12) is further configured to adjust the proportion of CO2 in the gas flow, and wherein the control unit (12) increases the proportion of CO2 in the gas flow to a predetermined CO2 increase proportion before deriving the CO2 partial pressure value of the blood side (2), and wherein, The CO2 partial pressure value of the gas side (6) is measured in a validated point or a validated part in the apparatus (1), and it has been validated for the validated point or the validated part that the CO2 partial pressure value of the gas side (6) reaches a saturation value at the predetermined reduced gas flow rate at the predetermined CO2 increased proportion.

13. An apparatus (1) for determining a CO2 partial pressure value of a 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), wherein the semi-permeable membrane (8) separates the blood side (2) from the gas side (6), the gas side (6) has an inlet (14) and an outlet (16), and, during operation of the oxygenator (4), a gas flow flows at a flow rate into the inlet (14) to the outlet (16); - a first sensor (10) configured to measure a CO2 partial pressure value of the gas side (6); - a control unit (12) configured to control the flow rate of the gas flow into the inlet (14) and to process the measured CO2 partial pressure value of the gas side (6) and to determine a CO2 partial pressure value of the blood side (2) based on the measured CO2 partial pressure value of the gas side (6), wherein the control unit (12) determines the CO2 partial pressure value of the blood side (2) during operation of the oxygenator (4), stops the gas flow into the inlet (14), measures at least one CO2 partial pressure value of the gas side (6) after the gas flow has been stopped after a verified time section has elapsed, and derives the CO2 partial pressure value of the blood side (2) from the at least one CO2 partial pressure value of the gas side (6) measured after the verified time section has elapsed, wherein the CO2 partial pressure value of the gas side (6) has been verified to have reached a saturation value for the verified time section.

14. An apparatus (1) for determining a CO2 partial pressure value of a blood side (2) of an oxygenator (4), comprising: - the oxygenator (4) having a 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), during operation of the oxygenator (4) a gas flow flowing into the inlet (14) to the outlet (16) at a flow rate, and the gas side (6) being formed by a plurality of hollow fibers (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) of the gas side (6), the first sensor (10) being configured to measure a CO2 partial pressure value of the portion of the plurality of hollow fibers (26) of the gas side (6); - a valve (28) arranged downstream of the first sensor (10), the valve (28) being configured 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 outlet (16) in a first state, and 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 outlet (16) in a second state; - a control unit (12) configured to control 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 outlet (16) by means of the valve (28), and to process the measured CO2 partial pressure value of the portion of the plurality of hollow fibers (26) of the gas side (6) and to determine a CO2 partial pressure value of the blood side (2) based on the measured CO2 partial pressure value of the portion of the plurality of hollow fibers (26) of the gas side (6), wherein the control unit (12) determines the CO2 partial pressure value of the blood side (2) during operation of the oxygenator (4) by stopping the gas flow into the part of the plurality of hollow fibers (26) of the gas side (6) with the valve (28), measuring at least one CO2 partial pressure value of the part of the plurality of hollow fibers (26) of the gas side (6) after a verified time period has elapsed after stopping the gas flow with the first sensor (10) to the outlet (16), and deriving the CO2 partial pressure value of the blood side (2) from the at least one CO2 partial pressure value of the part of the plurality of hollow fibers (26) of the gas side (6), which is measured after the verified time period has elapsed, wherein for the verified time period it has been verified that the CO2 partial pressure value of the part of the plurality of hollow fibers (26) of the gas side (6) has reached a saturation value.

15. An apparatus (1) for determining a CO2 partial pressure value of a blood side (2) of an oxygenator (4), comprising: - an oxygenator (4) having a blood side (2), a gas side (6) and a semipermeable membrane (8), wherein the semipermeable membrane (8) separates the blood side (2) from the gas side (6), the gas side (6) having an inlet (14) and an outlet (16), during operation of the oxygenator (4) a gas flow flowing into the inlet (14) to the outlet (16) at a flow rate; - a first sensor (10) configured to measure a CO2 partial pressure value of the gas side (6); - a control unit (12) configured to control the flow rate of the gas flow into the inlet (14) and to process the measured CO2 partial pressure value of the gas side (6) and to determine a CO2 partial pressure value of the blood side (2) based on the measured CO2 partial pressure value of the gas side (6), wherein the control unit (12) determines the CO2 partial pressure value of the blood side (2) during operation of the oxygenator (4) by reducing the flow rate of the gas flow into the inlet (14) to a predetermined reduced gas flow rate, measuring at least one CO2 partial pressure value of the gas side (6) after a verified time period has elapsed after reducing the flow rate to the predetermined reduced gas flow rate and within a verified point or a verified part of the apparatus (1), and deriving the CO2 partial pressure value of the blood side (2) from the at least one CO2 partial pressure value of the gas side (6), which is measured within the verified point or the verified part when the verified time period has elapsed, wherein for the verified time period and the verified point or the verified part it has been verified that the CO2 partial pressure value of the gas side (6) has reached a saturation value.

16. An apparatus (1) for determining a CO2 partial pressure value of a blood side (2) of an oxygenator (4), comprising: - the oxygenator (4) comprising a 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) and, during operation of the oxygenator (4), a gas flow flowing at a flow rate from the inlet (14) to the outlet (16), the gas side (6) being formed by a plurality of hollow fibers (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) of the gas side (6), the first sensor (10) being configured to measure a CO2 partial pressure value of the portion of the plurality of hollow fibers (26) of the gas side (6); - a valve (28) arranged downstream of the first sensor (10), the valve (28) being configured 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 outlet (16) in a first state and 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 outlet (16) in a second state; - a control unit (12) configured to control the flow rate of 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 outlet (16) by the valve (28) and to process the measured CO2 partial pressure value of the portion of the plurality of hollow fibers (26) of the gas side (6) and to determine a CO2 partial pressure value of the blood side (2) based on the measured CO2 partial pressure value of the portion of the plurality of hollow fibers (26) of the gas side (6), wherein the control unit (12) determines the CO2 partial pressure value of the blood side (2) during operation of the oxygen generator (4) by reducing the flow rate of 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 outlet (16) with the valve (28) to a predetermined reduced gas flow rate, after the reduced flow rate has been reduced to the predetermined reduced gas flow rate and after a verified time period has elapsed and at least one CO2 partial pressure value of the portion of the plurality of hollow fibers (26) of the gas side (6) is measured at a verified location, the at least one CO2 partial pressure value of the portion of the plurality of hollow fibers (26) of the gas side (6) being measured at the verified location when the verified time period has elapsed, wherein for the verified time period and verified location it has been verified that the CO2 partial pressure value of the plurality of hollow fibers (26) of the gas side (6) has reached a saturation value.

17. The device (1) according to any one of claims 1 to 5 and 13 to 16, wherein the control unit (12) determines the CO2 partial pressure value of the blood side (2) at predetermined time intervals and / or when predetermined operating conditions occur.

18. The device (1) according to any one of claims 1 to 5 and 13 to 16, wherein the first sensor (10) is positioned at or downstream of the outlet (16) of the gas side (6) within the oxygen generator (4).

19. The device (1) according to claim 3 or 5, wherein at least one of the first sensor (10) and the second sensor (11) is positioned within the oxygen generator (4).

20. The device (1) according to claim 3 or 5, wherein a main line (22) is provided downstream of the outlet (16) of the gas side (6) and a branch line (24) branches off from the main line (22), and wherein one of the first sensor (10) and the second sensor (11) is positioned on the branch line (24).

21. The device (1) according to claim 14 or 16, wherein the portion of the plurality of hollow fibers (26) of the gas side (6) to which the first sensor (10) is connected is located upstream of the blood inlet (18) in the direction of flow of the blood through the blood side (2).

22. The device (1) according to claim 14 or 16, wherein the portion of the plurality of hollow fibers (26) of the gas side (6) to which the first sensor (10) is connected is located downstream of the blood outlet (20) in the direction of flow of the blood through the blood side (2).

23. The device (1) according to claim 4, wherein the control unit (12) stops the gas flow into the inlet (14) before or during the calculation of the rate of change of the measured CO2 partial pressure value of the gas side (6).

24. The apparatus (1) as claimed in claim 6, wherein said control unit (12) reduces the flow rate of the gas stream entering into said inlet (14) to a predetermined reduced gas flow rate, before or during the calculation of the rate of change of the measured CO2 partial pressure value of the gas side (6), wherein, For calculating the rate of change, the CO2 partial pressure value of the gas side (6) is measured at a proven point or a proven portion in the device (1), for which it has been proven that the CO2 partial pressure value of the gas side (6) reaches a saturation value at the predetermined reduced gas flow rate.

25. The device (1) according to claim 24, wherein the proven point is a proven point of the gas side (6) or the proven portion is a proven portion of the gas side (6), for which it has been proven that the CO2 partial pressure value of the gas side (6) reaches a saturation value at the predetermined reduced gas flow rate.

26. The device (1) according to claim 7, wherein the first sensor (10) is connected to the gas side (6) only through the portion of the plurality of hollow fibers (26) of the gas side (6) at or downstream of a downstream end of the portion of the plurality of hollow fibers (26).

27. The device (1) according to claim 9, wherein the control unit (12) stops the gas flow to the outlet (16) through the portion of the plurality of hollow fibers (26) of the gas side (6) and the first sensor (10) before or during calculating the rate of change of the measured CO2 partial pressure value of the portion of the plurality of hollow fibers (26) of the gas side (6).

28. The apparatus (1) according to claim 10, wherein the control unit (12) is configured to reduce, by means of the valve (28), the flow rate of 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 outlet (16) to a predetermined reduced gas flow rate, before or during the calculation of the rate of change of the measured CO2 partial pressure values of the portion of the plurality of hollow fibers (26) of the gas side (6), wherein, For calculating the rate of change, the CO2 partial pressure value of the portion of the plurality of hollow fibers (26) of the gas side (6) is measured at a proven location in the device (1), for which it has been proven that the CO2 partial pressure value of the portion of the plurality of hollow fibers (26) of the gas side (6) reaches a saturation value at the predetermined reduced gas flow rate.

29. The device (1) according to claim 11, wherein the control unit (12) increases the proportion of CO2 in the gas flow to a predetermined CO2 increase proportion before, while or after the control unit (12) stops the gas flow or reduces the flow rate.

30. The device (1) according to claim 12, wherein the control unit (12) increases the proportion of CO2 in the gas flow to a predetermined CO2 increase proportion before, while or after the control unit (12) reduces the flow rate to the predetermined reduced flow rate.

31. The device (1) according to claim 14, wherein the first sensor (10) is connected to the portion of the plurality of hollow fibers (26) of the gas side (6) at or downstream of a downstream end of the portion of the plurality of hollow fibers (26).

32. The device (1) according to claim 15, wherein the proven point is a proven point of the gas side (6) or the proven portion is a proven portion of the gas side (6).

33. The device (1) of claim 16, wherein the first sensor (10) is connected to a portion of the plurality of hollow fibers (26) of the gas side (6) at or downstream of a downstream end of the portion of the plurality of hollow fibers (26).

34. The device (1) of claim 19, wherein the first sensor (10) and the second sensor (11) are positioned within the oxygenator (4).

35. The device (1) of claim 7, wherein the portion of the plurality of hollow fibers (26) of the gas side (6) to which the first sensor (10) is connected is located upstream of a blood inlet (18) in a direction of blood flow through the blood side (2).

36. The device (1) of claim 7, wherein the portion of the plurality of hollow fibers (26) of the gas side (6) to which the first sensor (10) is connected is located downstream of a blood outlet (20) in a direction of blood flow through the blood side (2).

37. An extracorporeal membrane oxygenation system comprising the device (1) of any one of claims 1 to 36.

38. The extracorporeal membrane oxygenation system of claim 37, wherein the extracorporeal membrane oxygenation system is a venovenous extracorporeal membrane oxygenation system.

39. The extracorporeal membrane oxygenation system of claim 37, wherein the extracorporeal membrane oxygenation system is a venoarterial extracorporeal membrane oxygenation system.

40. An extracorporeal circulation system comprising the device (1) of any one of claims 1 to 36.

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