DEVICE AND METHOD FOR DETERMINATION OF A CO2 PARTIAL PRESSURE VALUE ON A BLOOD SIDE OF AN OXYGENATOR

Abstract

Device for determination of a CO2 partial pressure value on a blood side of an oxygenator having an oxygenator with a blood side, a gas side and a semipermeable 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 oxygenator, a gas flow flows into the inlet to the outlet at a flow rate. The device also has a first sensor configured to measure CO2 partial pressure values of the gas side and a control unit configured to process the measured CO2 partial pressure values of the gas side and to determine a CO2 partial pressure value on the blood side based on the measured CO2 partial pressure values of the gas side. The control unit determines the CO2 partial pressure value on the blood side during operation of the oxygenator.

Claims

1. A Ddevice for determination of a CO.sub.2 partial pressure value on a blood side of an oxygenator, comprising: an oxygenator (with a blood side), a gas side and a semipermeable 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 oxygenator-(4), a gas flow flows into the inlet to the outlet at a flow rate; a first sensor configured to measure CO.sub.2 partial pressure values of the gas side; a control unit configured to process the measured CO.sub.2 partial pressure values of the gas side and to determine a CO.sub.2 partial pressure value on the blood side based on the measured CO.sub.2 partial pressure values of the gas side, and wherein the control unit determines the CO.sub.2 partial pressure value on the blood side during operation of the oxygenator by calculating a change rate of the measured CO.sub.2 partial pressure values of the gas side, and, when or after the calculated change rate equals a predetermined change rate value or falls within a predetermined change rate range at a predetermined measuring distance, deducing the CO.sub.2 partial pressure value on the blood side from the CO.sub.2 partial pressure values of the gas side which are measured when or after the calculated change rate either equals the predetermined change rate value or falls within the predetermined change rate range at the predetermined measuring distance.

2. The device according to claim 1, wherein the change rate is a change rate over time and the predetermined measuring distance is a predetermined period of time.

3. The device according to claim 1, wherein the device comprises a second sensor configured to measure CO.sub.2 partial pressure values of the gas side, and wherein the change rate is a change rate over location, the predetermined measuring distance is a predetermined local measuring distance and the first sensor and the second sensor are positioned at the predetermined local measuring distance.

4. The device according to claim 2, wherein the control unit is further configured to stop the gas flow into the inlet, and wherein the control unit stops the gas flow into the inlet before deducing the CO.sub.2 partial pressure value on the blood side, in particular before or during calculating the change rate of the measured CO.sub.2 partial pressure values of the gas side.

5. The device according to claim 3, wherein the control unit is further configured to adapt the flow rate of the gas flow into the inlet, and wherein the control unit gradually reduces the flow rate of the gas flow into the inlet until the change rate over location either equals the predetermined change rate value or falls within the predetermined change rate range at the predetermined local measuring distance.

6. The device according to claim 2, wherein the control unit is further configured to adapt the flow rate of the gas flow into the inlet, and wherein the control unit reduces the flow rate of the gas flow into the inlet to a predetermined reduced gas flow rate before deducing the CO.sub.2 partial pressure value on the blood side), in particular before or during calculating the change rate of the measured CO.sub.2 partial pressure values of the gas side, wherein, for calculating the change rate, the CO.sub.2 partial pressure values of the gas side are measured at a validated point or within a validated portion of the device, in particular of the gas side, for which validated point or validated portion it has been proven that the CO.sub.2 partial pressure of the gas side-(6) reaches a saturation value at the predetermined reduced gas flow rate.

7. The device according to claim 1, wherein: the gas side-(6) is formed by a plurality of hollow fibers through which the gas flows from the inlet to the outlet, and the first sensor is connected to the gas side via only a part of the plurality of hollow fibers of the gas side, at a downstream end of the part of the plurality of hollow fibers or downstream of the downstream end of the part of the plurality of hollow fibers; the first sensor is configured to measure CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side; the control unit is configured to process the measured CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side 6-and to determine a CO.sub.2 partial pressure value on the blood side based on the measured CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side; and the control unit determines the CO.sub.2 partial pressure value on the blood side during operation of the oxygenator-(4) by calculating a change rate of the measured CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side, and, when or after the calculated change rate either equals a predetermined change rate value or falls within a predetermined change rate range at a predetermined measuring distance, deducing the CO.sub.2 partial pressure value on the blood side from the CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side which are measured when or after the calculated change rate either equals the predetermined change rate value or falls within the predetermined change rate range at the predetermined measuring distance.

8. The device according to claim 7, wherein a valve is provided downstream of the first sensor), the valve being configured to either stop or reduce the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to a gas outlet in a first state and to either release or increase the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet in a second state.

9. The device according to claim 8, wherein: the change rate is a change rate over time and the predetermined measuring distance is a predetermined period of time; and the control unit is configured to stop the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet by means of the valve, wherein the control unit stops the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet before deducing the CO.sub.2 partial pressure value on the blood side, either before or during calculating the change rate of the measured CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side.

10. The device according to claim 8, wherein: the change rate is a change rate over time and the predetermined measuring distance is a predetermined period of time; and the control unit is configured to reduce the flow rate of the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet to a predetermined reduced gas flow rate by means of the valve before deducing the CO.sub.2 partial pressure value on the blood side either before or during calculating the change rate of the measured CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side-(6), wherein, for calculating the change rate, a position at which the CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side are measured is a validated position within the device for which it has been proven that the CO.sub.2 partial pressure of the part of the plurality of hollow fibers of the gas side reaches a saturation value at the predetermined reduced gas flow rate.

11. The device according to claim 4, wherein the control unit is further configured to adapt a proportion of CO.sub.2 in the gas flow, and wherein the control unit increases the proportion of CO.sub.2 in the gas flow up to a predetermined increased proportion of CO.sub.2, either before the control unit stops the gas flow or before, when or while the control unit reduces the flow rate.

12. The device according to claim 6, wherein the control unit is further configured to adapt a proportion of CO.sub.2 in the gas flow, and wherein the control unit increases the proportion of CO.sub.2 in the gas flow up to a predetermined increased proportion of CO.sub.2 before deducing the CO.sub.2 partial pressure value on the blood side, either before, when or after the control unit reduces the flow rate to the predetermined reduced flow rate, and wherein for the validated point or validated portion it has been proven that the CO.sub.2 partial pressure of the gas side reaches the saturation value at the predetermined reduced gas flow rate at the predetermined increased proportion of CO.sub.2.

13. A device for determination of a CO.sub.2 partial pressure value on a blood side of an oxygenator, comprising: an oxygenator-(4) with a blood side, a gas side and a semipermeable membrane, wherein the membrane separates the blood side from the gas side-(6), the gas side-(6) has an inlet and an outlet and, during operation of the oxygenator, a gas flow flows into the inlet to the outlet at a flow rate; a first sensor configured to measure CO2 partial pressure values of the gas side; a control unit configured to control the flow rate of the gas flow into the inlet and to process the measured CO2 partial pressure values of the gas side and to determine a CO2 partial pressure value on the blood side based on the measured CO2 partial pressure values of the gas side; and wherein the control unit determines the CO2 partial pressure value on the blood side during operation of the oxygenator by stopping the gas flow into the inlet, measuring at least one CO.sub.2 partial pressure value of the gas side when a validated period of time after stopping the gas flow has lapsed, and deducing the CO.sub.2 partial pressure value on the blood side from the at least one CO.sub.2 partial pressure value of the gas side which is measured when the validated period of time has lapsed, for which validated period of time it has been proven that the CO.sub.2 partial pressure of the gas side reaches a saturation value.

14. A device for determination of a CO2 partial pressure value on a blood side of an oxygenator, comprising: the oxygenator comprising a blood side, a gas side and a semipermeable membrane, wherein the membrane separates the blood side from the gas side, the gas side has an inlet and an outle, a gas flow flows into the inlet to the outlet at a flow rate during operation of the oxygenator, and the gas side is formed by a plurality of hollow fibers through which the gas flows from the inlet to the outlet; a first sensor which is connected to a part of the plurality of hollow fibers of the gas side, at a downstream end of the part of the plurality of hollow fibers or downstream of the downstream end of the part of the plurality hollow fibers, the first sensor being configured to measure CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side; a valve which is provided downstream of the first sensor, the valve being configured to stop or reduce the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet in a first state and to release or increase the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet in a second state; a control unit which is configured to control the flow rate of the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet by means of the valve, and to process the measured CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side and to determine a CO.sub.2 partial pressure value on the blood side based on the measured CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side; and wherein the control unit determines the CO.sub.2 partial pressure value on the blood side during operation of the oxygenator by stopping the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet by means of the valve, measuring at least one CO2 partial pressure value of the part of the plurality of hollow fibers of the gas side when a validated period of time after stopping the gas flow has lapsed, and deducing the CO.sub.2 partial pressure value on the blood side from the at least one CO.sub.2 partial pressure value of the part of the plurality of hollow fibers of the gas side which is measured when the validated period of time has lapsed, for which validated period of time it has been proven that the CO.sub.2 partial pressure of the part of the plurality of hollow fibers of the gas side reaches a saturation value.

15. A device for determination of a CO.sub.2 partial pressure value on a blood side of an oxygenator, comprising: an oxygenator-(4) with a blood side, a gas side and a semipermeable 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 oxygenator-(4), a gas flow flows into the inlet to the outlet at a flow rate; a first sensor configured to measure CO.sub.2 partial pressure values of the gas side; a control unit configured to control the flow rate of the gas flow into the inlet and to process the measured CO.sub.2 partial pressure values of the gas side and to determine a CO.sub.2 partial pressure value on the blood side based on the measured CO.sub.2 partial pressure values of the gas side; and wherein the control unit determines the CO.sub.2 partial pressure value on the blood side during operation of the oxygenator-(4) by reducing the flow rate of the gas flow into the inlet to a predetermined reduced gas flow rate, measuring at least one CO.sub.2 partial pressure value of the gas side when a validated period of time after reducing the flow rate to the predetermined reduced flow rate has lapsed and at a validated point or within a validated portion of the device, in particular of the gas side, and deducing the CO.sub.2 partial pressure value on the blood side from the at least one CO.sub.2 partial pressure value of the gas side which is measured at the validated point or within the validated portion when the validated period of time has lapsed, for which validated period of time and validated point or validated portion it has been proven that the CO.sub.2 partial pressure of the gas side reaches a saturation value.

16. A device for determination of a CO.sub.2 partial pressure value on a blood side of an oxygenator, comprising: the oxygenator comprising a blood side, a gas side and a semipermeable membrane, wherein the membrane separates the blood side from the gas side, the gas side has an inlet and an outlet, a gas flow flows into the inlet to the outlet at a flow rate during operation of the oxygenator, and the gas side is formed by a plurality of hollow fibers through which the gas flows from the inlet to the outlet; a first sensor which is connected to a part of the plurality of hollow fibers of the gas side, at a downstream end of the part of the plurality of hollow fibers or downstream of the downstream end of the part of the plurality of hollow fibers, the first sensor being configured to measure CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side; a valve which is provided downstream of the first sensor, the valve being configured to stop or reduce the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet in a first state and to release or increase the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet in a second state; a control unit which is configured to control the flow rate of the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet by means of the valve, and to process the measured CO2 partial pressure values of the part of the plurality of hollow fibers of the gas side-(6) and to determine a CO2 partial pressure value on the blood side based on the measured CO2 partial pressure values of the part of the plurality of hollow fibers of the gas side; and wherein the control unit determines the CO.sub.2 partial pressure value on the blood side during operation of the oxygenator by reducing the flow rate of the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet by means of the valve to a predetermined reduced gas flow rate, measuring at least one CO.sub.2 partial pressure value of the part of the plurality of hollow fibers of the gas side when a validated period of time after reducing the flow rate to the predetermined reduced flow rate has lapsed and at a validated position, and deducing the CO.sub.2 partial pressure value on the blood side from the at least one CO.sub.2 partial pressure value of the part of the plurality of hollow fibers of the gas side which is measured at the validated position when the validated period of time has lapsed, for which validated period of time and validated position it has been proven that the CO.sub.2 partial pressure of the plurality of hollow fibers of the gas side reaches a saturation value.

17. A device according to claim 16, wherein the control unit determines the CO.sub.2 partial pressure value on the blood side at predetermined time intervals and/or when a predetermined operating condition occurs.

18. A device according to claim 17, wherein the first sensor is positioned inside the oxygenator at the outlet of the gas side or downstream of the outlet.

19. A device according to claim 3, wherein at least one of the first sensor and the second sensor, or both the first sensor and the second sensor, is/are positioned inside the oxygenator.

20. A device according to claim 3, wherein a main gas line is provided downstream of the outlet at the gas side and a branch line branches off from the main line, and wherein one of the first sensor and the second sensor is positioned on the branch line.

21. A device according to claim 7, wherein the part of the plurality of hollow fibers of the gas side, to which the first sensor is connected, is located, in a flow direction of the blood flow through the blood side, at a blood inlet.

22. A device according to claim 7, wherein the part of the plurality of hollow fibers of the gas side, to which the first sensor is connected, is located, in a flow direction of the blood flow through the blood side), at a blood outlet.

23-26. (canceled)

27. A method for determining a CO.sub.2 partial pressure value on a blood side of an oxygenator of a device, the oxygenator comprising the blood side, a gas side and a semipermeable membrane which separates the blood side from the gas side, wherein the gas side has an inlet and an outlet and, during operation of the oxygenator, a gas flow flows into the inlet to the outlet at a flow rate, the method comprising: measuring CO.sub.2 partial pressure values of the gas side-(6) by a first sensor of the device; processing the measured CO.sub.2 partial pressure values of the gas side and determining a CO.sub.2 partial pressure value on the blood side based on the measured CO.sub.2 partial pressure values of the gas side-(6) by a control unit of the device; wherein the control unit determines the CO.sub.2 partial pressure value on the blood side during operation of the oxygenator by the further steps of: calculating a change rate of the measured CO.sub.2 partial pressure values of the gas side, and, when or after the calculated change rate equals a predetermined change rate value or falls within a predetermined change rate range at a predetermined measuring distance: and deducing the CO.sub.2 partial pressure value on the blood side from the CO.sub.2 partial pressure values of the gas side which are measured when or after the calculated change rate equals the predetermined change rate value or falls within the predetermined change rate range at the predetermined measuring distance.

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

29. The Mmethod according to claim 27, wherein the change rate is a change rate over location and the predetermined measuring distance is a predetermined local measuring distance, and wherein the CO.sub.2 partial pressure values of the gas side are measured at the predetermined local measuring distance by the first sensor and a second sensor of the device, said second sensor being positioned at the predetermined local measuring distance from the first sensor.

30. The Mmethod according to claim 28, wherein the control unit determines the CO.sub.2 partial pressure value on the blood side by the further step of stopping the gas flow into the inlet before deducing the CO.sub.2 partial pressure value on the blood side, in particular before or during calculating the change rate of the measured CO.sub.2 partial pressure values of the gas side.

31. The method according to claim 29, wherein the control unit determines the CO.sub.2 partial pressure value on the blood side by the further step of gradually reducing the flow rate of the gas flow into the inlet until the change rate over location either equals the predetermined change rate value or falls within a predetermined change rate range at the predetermined local measuring distance.

32. The Mmethod according to claim 28, wherein the control unit determines the CO.sub.2 partial pressure value on the blood side by the further step of reducing the gas flow into the inlet to a predetermined reduced gas flow rate before deducing the CO.sub.2 partial pressure value on the blood side, before or during calculating the change rate of the measured CO.sub.2 partial pressure values of the gas side, wherein, for calculating the change rate, the CO.sub.2 partial pressure values of the gas side are measured at a validated point or within a validated portion of the device, in particular of the gas side, for which validated point or validated portion it has been proven that the CO.sub.2 partial pressure of the gas side reaches a saturation value at the predetermined flow rate.

33. The Mmethod according to claim 27, wherein: the gas side is formed by a plurality of hollow fibers through which the gas flows from the inlet to the outlet, and the first sensor is connected to the gas side via only a part of the plurality of hollow fibers of the gas side, at a downstream end of the part of the plurality of hollow fibers or downstream of the downstream end of the part of the plurality of hollow fibers; in the step of measuring CO.sub.2 partial pressure values by the first sensor, the CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side are measured; in the step of processing the measured CO.sub.2 partial pressure values and determining a CO.sub.2 partial pressure value on the blood side based on the measured CO.sub.2 partial pressure values by a control unit, the measured CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side are processed and the CO.sub.2 partial pressure value on the blood side is determined based on the measured CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side; in the step of calculating a change rate of the measured CO.sub.2 partial pressure values of the gas side, a change rate of the measured CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side is calculated; and in the step of deducing the CO.sub.2 partial pressure value on the blood side from the measured CO.sub.2 partial pressure values, the CO.sub.2 partial pressure value on the blood side is deduced from the CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side which are measured when or after the calculated change rate either equals the predetermined change rate value or falls within the predetermined change rate range at the predetermined measuring distance.

34. The method according to claim 33, wherein a valve is provided downstream of the first sensor, the valve being configured to stop or reduce the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to a gas outlet in a first state and to release or increase the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet in a second state.

35. The method according to claim 34, wherein: the change rate is a change rate over time and the predetermined measuring distance is a predetermined period of time; and the control unit determines the CO.sub.2 partial pressure value on the blood side by the further step of stopping the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet by the valve before deducing the CO.sub.2 partial pressure value on the blood side, in particular before or during calculating the change rate of the measured CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side.

36. The method according to claim 34, wherein: the change rate is a change rate over time and the predetermined measuring distance is a predetermined period of time; and the control unit determines the CO.sub.2 partial pressure value on the blood side by the further step of reducing the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet to a predetermined reduced gas flow rate by valve before deducing the CO.sub.2 partial pressure value on the blood side, before or during calculating the change rate of the measured CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side, wherein, for calculating the change rate, the CO.sub.2 partial pressure values of the part of plurality of the hollow fibers of the gas side-(6) are measured at a validated position within the device for which it has been proven that the CO.sub.2 partial pressure of the part of the plurality of hollow fibers of the gas side reaches a saturation value at the predetermined reduced gas flow rate.

37. The Mmethod according to claim 30, wherein the control unit determines the CO.sub.2 partial pressure value on the blood side by the further step of increasing a proportion of CO.sub.2 in the gas flow up to a predetermined increased proportion of COthat there has not been any working of these inventions in India. The client has not yet determined if there is commercial viability for these inventions in India. The client may undertake investigations in the future to determine if there might be the potential for commercial activity, but the client has not yet undertaken any such investigations at present, before stopping the gas flow or before, when or while reducing the flow rate.

38. The method according to claim 32, wherein the control unit determines the CO.sub.2 partial pressure value on the blood side by the further step of increasing a proportion of CO.sub.2 in the gas flow up to a predetermined increased proportion of CO.sub.2 before deducing the CO.sub.2 partial pressure value on the blood side, before, when or after reducing the flow rate to the predetermined reduced flow rate, and wherein for the validated point or validated portion it has been proven that the CO.sub.2 partial pressure of the gas side reaches the saturation value at the predetermined reduced gas flow rate at the predetermined increased proportion of CO.sub.2.

39. A method for determining a CO.sub.2 partial pressure value on a blood side of an oxygenator of a device, the oxygenator comprising the blood side, a gas side and a semipermeable membrane which separates the blood side from the gas side, wherein the gas side has an inlet and an outlet and, during operation of the oxygenator, a gas flow flows into the inlet to the outlet at a flow rate, the method comprising: measuring at least one CO.sub.2 partial pressure value of the gas side by a first sensor of the device; processing the at least one measured CO.sub.2 partial pressure value of the gas side and determining a CO.sub.2 partial pressure value on the blood side based on the at least one measured CO.sub.2 partial pressure values of the gas side by a control unit of the device; controlling the flow rate of the gas flow into the inlet by the control unit wherein the control unit determines the CO.sub.2 partial pressure value on the blood side during operation of the oxygenator by the further steps of: stopping the gas flow into the inlet; measuring the at least one CO.sub.2 partial pressure value of the gas side when a validated period of time after stopping the gas flow has lapsed; and deducing the CO.sub.2 partial pressure value on the blood side from the at least one CO.sub.2 partial pressure value of the gas side which is measured when the validated period of time has lapsed, for which validated period of time it has been proven that the CO.sub.2 partial pressure of the gas side reaches a saturation value.

40. A method for determining a CO.sub.2 partial pressure value on a blood side of an oxygenator of a device, the device comprising: the oxygenator comprising the blood side, a gas side and a semipermeable membrane which separates the blood side from the gas side, wherein the gas side has an inlet and an outlet, a gas flow flows into the inlet to the outlet at a flow rate during operation of the oxygenator, and the gas side is formed by a plurality of hollow fibers through which the gas flows from the inlet to the outlet; a first sensor which is connected to a part of the plurality of hollow fibers of the gas side, at a downstream end of the part of the plurality of hollow fibers or downstream of the downstream end of the plurality of hollow fibers, the first sensor being configured to measure CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side; and a valve which is provided downstream of the first sensor, the valve being configured to stop or reduce the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet in a first state and to release or increase the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet in a second state, wherein the method comprises: controlling the flow rate of the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet by a control unit of the device; measuring at least one CO.sub.2 partial pressure value of the part of the plurality of hollow fibers of the gas side by the first sensor of the device; processing the at least one measured CO.sub.2 partial pressure value of the part of the plurality of hollow fibers of the gas side and determining a CO.sub.2 partial pressure value on the blood side based on the at least one measured CO.sub.2 partial pressure value of the part of the plurality of hollow fibers of the gas side by the control unit of the device, wherein the control unit determines the CO.sub.2 partial pressure value on the blood side during operation of the oxygenator by the further steps of: stopping the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet by the valve; measuring the at least one CO.sub.2 partial pressure value of the part of the plurality of hollow fibers of the gas side when a validated period of time after stopping the gas flow has lapsed; and deducing the CO.sub.2 partial pressure value on the blood side from the at least one CO.sub.2 partial pressure value of the part of the plurality of hollow fibers of the gas side which is measured when the validated period of time has lapsed, for which validated period of time it has been proven that the CO.sub.2 partial pressure of the part of the hollow fibers of the gas side reaches a saturation value.

41. A Mmethod for determining a CO.sub.2 partial pressure value on a blood side of an oxygenator of a device, the oxygenator comprising the blood side, a gas side and a semipermeable membrane which separates the blood side from the gas side, wherein the gas side has an inlet and an outlet and, during operation of the oxygenator, a gas flow flows into the inlet to the outlet at a flow rate, the method comprising: measuring at least one CO.sub.2 partial pressure value of the gas side by a first sensor of the device; processing the at least one measured CO.sub.2 partial pressure value of the gas side and determining a CO.sub.2 partial pressure value on the blood side based on the at least one measured CO.sub.2 partial pressure values of the gas side by a control unit of the device; controlling the flow rate of the gas flow into the inlet by the control unit, wherein the control unit determines the CO.sub.2 partial pressure value on the blood side during operation of the oxygenator by the further steps of: reducing the flow rate of the gas flow into the inlet to a predetermined reduced gas flow rate; measuring the at least one CO.sub.2 partial pressure value of the gas side when a validated period of time after reducing the flow rate to the predetermined reduced flow rate has lapsed and at a validated point or within a validated portion of the device, in particular of the gas side ; and deducing the CO.sub.2 partial pressure value on the blood side from the at least one CO.sub.2 partial pressure value of the gas side which is measured at the validated point or within the validated portion when the validated period of time has lapsed, for which validated period of time and validated point or validated portion it has been proven that the CO.sub.2 partial pressure of the gas side reaches a saturation value.

42. A method for determining a CO.sub.2 partial pressure value on a blood side of an oxygenator-(4) of a device, the device comprising: the oxygenator comprising the blood side, a gas side and a semipermeable membrane which separates the blood side from the gas side, wherein the gas side has an inlet and an outlet, a gas flow flows into the inlet to the outlet at a flow rate during operation of the oxygenator, and the gas side is formed by a plurality of hollow fibers through which the gas flows from the inlet to the outlet; a first sensor which is connected to a part of the plurality of hollow fibers of the gas side, at a downstream end of the part of the plurality of hollow fibers or downstream of the downstream end of the part of the plurality of hollow fibers, the first sensor being configured to measure CO.sub.2 partial pressure values of the part of the plurality of hollow fibers of the gas side; and a valve which is provided downstream of the first sensor, the valve being configured to stop or reduce the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet in a first state and to release or increase the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet in a second state; wherein the method comprises: controlling the flow rate of the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet by a control unit of the device; measuring at least one CO.sub.2 partial pressure value of the part of the plurality of hollow fibers of the gas side by the first sensor of the device; processing the at least one measured CO.sub.2 partial pressure value of the part of the plurality of hollow fibers of the gas side and determining a CO.sub.2 partial pressure value on the blood side based on the at least one measured CO.sub.2 partial pressure value of the part of the plurality of hollow fibers of the gas side by the control unit of the device ; wherein the control unit determines the CO.sub.2 partial pressure value on the blood side during operation of the oxygenator by the further steps of: reducing the flow rate of the gas flow through the part of the plurality of hollow fibers of the gas side and the first sensor to the gas outlet to a predetermined reduced gas flow rate; measuring the at least one CO.sub.2 partial pressure value of the part of the plurality of hollow fibers of the gas side when a validated period of time after reducing the flow rate to the predetermined reduced flow rate has lapsed and at a validated position within the device; and deducing the CO.sub.2 partial pressure value on the blood side from the at least one CO.sub.2 partial pressure value of the part of the plurality of hollow fibers of the gas side which is measured at the validated position when the validated period of time has lapsed, for which validated period of time and validated position it has been proven that the CO.sub.2 partial pressure of the part of the plurality of hollow fibers of the gas side reaches a saturation value.

43. The method according to claim 42, wherein the control unit determines the CO.sub.2 partial pressure value on the blood side at predetermined time intervals and/or when a predetermined operating condition occurs.

44. The method according to claim 43, wherein the part of the plurality of hollow fibers of the gas side, to which the first sensor is connected, is located, in a flow direction of the blood flow through the blood side, at a blood inlet.

45. The method according to claim 43, wherein the part of the plurality of hollow fibers of the gas side, to which the first sensor is connected, is located, in a flow direction of the blood flow through the blood side, at a blood outlet.

46-50. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0076] The foregoing summary, as well as the following detailed description of preferred embodiments, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, reference is made to the drawings. The scope of the disclosure is not limited, however, to the specific embodiments disclosed in the drawings. In the drawings:

[0077] FIG. 1 shows a schematic view of a device for determination of a pCO2 value on a blood side of an oxygenator according to a first embodiment of the presently disclosed technology;

[0078] FIG. 2 shows a schematic view of a device for determination of a pCO2 value on a blood side of an oxygenator according to a second embodiment of the presently disclosed technology;

[0079] FIG. 3 shows a schematic view of a device for determination of a pCO2 value on a blood side of an oxygenator according to a third embodiment of the presently disclosed technology;

[0080] FIG. 4 shows a diagram schematically illustrating the pCO2 value at a measuring point on the gas side over time;

[0081] FIG. 5 shows shows a schematic view of a device for determination of a pCO2 value on a blood side of an oxygenator according to a fourth embodiment of the presently disclosed technology;

[0082] FIG. 6 shows a diagram schematically illustrating the value of the change rate over time of pCO2 of the gas side over the length of the oxygenator at two different flow rates.

[0083] FIG. 7 shows a schematic view of a device for determination of a pCO2 value on a blood side of an oxygenator according to a fifth embodiment of the presently disclosed technology.

DETAILED DESCRIPTION

[0084] FIG. 1 shows a schematic view of a device 1 for determination of a pCO2 value of blood on a blood side 2 of an oxygenator 4 according to a first embodiment of the presently disclosed technology. The device 1 comprises an oxygenator 4 with a blood side 2, a gas side 6 and a semipermeable membrane 8 which separates the blood side 2 from the gas side 6. The device 1 further comprises a sensor 10 configured for measuring a pCO2 value of gas on the gas side 6 and a control unit 12 configured for, inter alia, controlling a gas flow rate of gas from a source (not shown), e.g. the medical gas outlet in the hospital, into the gas side 6 of the oxygenator 4, a proportion of CO2 in the gas flow, e.g. by controlling a valve unit (not shown) upstream of the oxygenator 4, and for receiving and processing the pCO2 values measured by the sensor 10. The gas side 6 of the oxygenator 4 has an inlet 14 and an outlet 16, and the blood side 2 has an inlet 18 and an outlet 20. A main line 22 for conducting gas is connected to oxygenator 4 downstream of the outlet 16 of the gas side 6.

[0085] The oxygenator 4 of the embodiment described above is operated in a cocurrent mode, i.e. gas flowing into the inlet 14 of the gas side 6 and blood flowing into the inlet 18 of the blood side 2 are flowing in the same direction along the membrane 8 to their respective outlets 16, 20. However, there can be other types of oxygenators with a different mode of operation that can be used according to the presently disclosed technology. In any case, during operation of the oxygenator 4, CO2 contained/solved in the blood which flows into and through the blood side 2 is to be extracted from the blood by diffusion across/through the membrane 8 and into the gas which flows into and through the gas side 6. To enable the diffusion of CO2 from the blood side to the gas side, a CO2 diffusion gradient is required which means that the CO2 concentration or the CO2 partial pressure (pCO2) in the gas needs to be lower than in the blood. At the same time, O2 contained in the gas flowing into and through the gas side 6 is supposed to diffuse across the membrane 8 and into the blood flowing into and through the blood side 2, which requires an O2 diffusion gradient, i.e. the O2 concentration or the O2 partial pressure (pO2) in the gas needs to be higher than in the blood. This way, an exchange of O2 and CO2 between the gas side and the blood side is induced.

[0086] During operation of the device 1, the inlet 18 of the blood side 2 is connected to the patient’s venous system. This means, since the oxygenator 4 is supposed to take over the function of the patient’s lungs, blood flowing into the blood side 2 at the inlet 18 of the blood side 2 has the highest concentration of CO2 or the highest pCO2 in the patient’s blood circulation and the lowest concentration of O2 or the lowest pO2 in the patient’s blood circulation, while blood flowing out of the blood side 2 at the outlet 20 of the blood side 2 has the lowest concentration of CO2 or the lowest pCO2 in the patient’s blood circulation and the highest concentration of O2 or the highest pO2 in the patient’s blood circulation. The outlet 20 of the blood side 2 can be connected to the patient’s venous or arterial system, depending on the type of treatment.

[0087] To determine the patient’s CO2 overall condition, according to the presently disclosed technology, the pCO2 value of the venous blood at the inlet 18 of the blood side 2 can be used as an indicator. To determine said pCO2 value at the inlet 18 of the blood side 2, the gas flow is significantly reduced to a predetermined reduced gas flow rate or completely stopped, i.e. reduced to zero. At the same time, the blood flow through the blood side 2 is maintained, e.g. at the normal therapy flow rate. The CO2 dissolved in the blood, which proceeds flowing through the blood side 2, now diffuses across the membrane 8 into the gas, which is held on the gas side 6 (for a longer time compared to normal therapy flow rate), and accumulates in the gas until the CO2 diffusion gradient becomes zero (or infinitesimal). In the case where the gas flow into the inlet 16 of the gas side 6 is completely stopped (e.g. by valves at or upstream of the inlet 14 and/or at or downstream of the outlet 16), after a certain time, the CO2 diffusion gradient becomes zero in the entire gas side 6, i.e. over the entire length of the oxygenator 4 or, in other words, over the entire longitudinal section between the inlet 14 of the gas side 6 and the outlet 16 of the gas side, due to diffusion inside the gas side 6. In the case where the gas flow into the inlet 16 of the gas side 6 is reduced to the predetermined reduced gas flow rate, after a certain time, the CO2 diffusion gradient becomes zero only over a certain longitudinal section between the inlet 14 of the gas side 6 and the outlet 16 of the gas side depending on the particular reduced gas flow rate. The section over which the diffusion gradient will become reliably zero after a certain time at the predetermined reduced gas flow rate, is the validated portion of the gas side. This means that, prior to therapy, it has been experimentally proven for said section at said reduced flow rate that the diffusion gradient would become zero after a certain time. The validated portion can extend beyond the outlet 16 of the gas side 6 into the connected main line 22, since the pCO2 value downstream of the outlet 16 is constant and has the same value as at the outlet 16 of the gas side 6, while the outlet 16 itself must be within the validated portion to ensure sufficient length of the oxygenator to reach the CO2 diffusion equilibrium inside the oxygenator 4.

[0088] Therefore, in order to determine or to measure that the pCO2 equilibrium on the gas side is reached, in the case where the gas flow into the inlet 14 is stopped, the sensor 10 can be positioned at the inlet 14, at the outlet 16 or anywhere between the inlet 14 and the outlet 16, and in the case where the gas flow is reduced to the predetermined gas flow rate, the sensor 10 can be positioned within the validated portion of the gas side. Then, after the gas flow has been stopped or reduced by the control unit 12, the pCO2 value on/of the gas side 6 is measured by the sensor 10 and the control unit 12 receives and processes the pCO2 values measured by the sensor 10 and deduces the pCO2 value on the inlet 18 of the blood side 2 from the pCO2 values measured by the sensor 12 on the gas side 6 by calculating a change rate of the pCO2 values measured by the sensor 10 over time in order to determine if the diffusion equilibrium of CO2 across/through the membrane 8 has been reached. The equilibrium is reached when the change rate is (approximately) zero or infinitesimal (and does not change for a predetermined period of time after which it can be assumed that no further change in the change rate occurs), this means the pCO2 value measured on the gas side 6 when or after the equilibrium is reached corresponds to the pCO2 value of blood at the inlet 18 of the blood side 2 and, the other way round, the pCO2 value of blood at the inlet 18 of the blood side 2, i.e. of the patient’s venous blood, is identical to the pCO2 value measured by the sensor 10 of/on the gas side 6.

[0089] After the equilibrium is reached and after the pCO2 value at the inlet 18 of the blood side 2 is determined, the flow rate of gas into the inlet 14 of the gas side 6 can be increased to the normal therapy gas flow rate in order to continue or proceed with the normal oxygenation treatment. The above described determination of the pCO2 value at the inlet 18 of the blood side 2 can be repeated as often as necessary during the patient’s treatment, e.g. at regular intervals, for close monitoring of the patient’s condition.

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

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

[0092] In the first embodiment of the device 1 as shown in FIG. 1, the sensor 10 is provided inside the oxygenator 4 on the gas side 6 directly at the outlet 16.

[0093] A second embodiment of the device 1 according to the presently disclosed technology is shown in FIG. 2. The embodiment shown in FIG. 2 corresponds to the above-described embodiment shown in FIG. 1 with the difference that the sensor 10 is not provided inside the oxygenator 4, but downstream of the outlet 16 of the gas side 6 in or at the main line 22, which facilitates the construction and the maintenance of the device 1. In the case where the gas flow into the inlet 14 of the gas side 6 is stopped and valves are used, the valve downstream of the outlet 16 is positioned downstream of the sensor 10.

[0094] A third embodiment of the device 1 according to the presently disclosed technology is shown in FIG. 3. The embodiment shown in FIG. 3 corresponds to the above-described embodiment shown in FIG. 2 with the difference that the sensor 10 is not provided in or on the main line 22, but in or on a branch line 24 that branches off from the main line 22, which can facilitate the measurement of pCO2 at high humidity levels. In the case where the gas flow into the inlet 14 of the gas side 6 is stopped and valves are used, two valves are positioned downstream of the outlet 16, one being at or downstream of the branch point at the main line 22 and one being downstream of the sensor 10 at the branch line 24.

[0095] FIG. 4 shows a diagram that schematically illustrates the pCO2 value measured by the sensor 10 over time t, after the gas flow rate is reduced to a predetermined reduced gas flow rate or completely stopped, wherein in the case where the gas flow is reduced, the sensor 10 is positioned within the validated portion of the device 1. The gas flow rate is reduced or stopped at time t0. Until time t1, the measured pCO2 value remains constant. (In the case where the gas flow is stopped, the time interval between t0 and t1 can be approximately zero, depending on the position of the sensor 10 and the diffusion rate inside the gas side 6.) At time t1, the pCO2 value rises up to a maximum that is reached at time t2. After time t2, the measured pCO2 value remains (approximately) constant, which is why at time t3 the measured pCO2 value is the same as the pCO2 value measured at time t2, i.e. the calculated pCO2 change rate value 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 the inlet 18 of the blood side 2, i.e. the pCO2 value of the patient’s venous blood.

[0096] It is noted that the measurement curve shown in FIG. 4 is of a purely schematic nature and the slopes and the linear sections between the times t0 and t3 can vary depending on the type of oxygenator, and/or the flow rates of both blood and gas.

[0097] Depending on the oxygenator type, in particular the membrane type, and the flow rates of blood and gas through the oxygenator 4, time t2, i.e. the CO2 diffusion equilibrium, is reached in a shorter or longer period of time. Similar to the validated portion of the device 1, a validated period of time after the gas flow is stopped or reduced can be determined by experiment prior to therapy use of the oxygenator, wherein the validated period of time is the period of time that is proven sufficient to reach the pCO2 equilibrium on the gas side 6. If the gas flow is stopped and the validated period of time after the gas flow has been stopped has lapsed, a single measurement of the pCO2 value of the gas side is sufficient for the determination of the pCO2 value on the blood side 2, since it has been proven that after the validated period of time the pCO2 equilibrium is reached and therefore, a change rate does not have to be calculated. If the gas flow is reduced to the predetermined reduced gas flow rate, the validated period of time is to be determined for the validated portion.

[0098] A fourth embodiment of the device 1 according to the presently disclosed technology is shown in FIG. 5. The embodiment shown in FIG. 5 corresponds to the above-described embodiment shown in FIG. 1 with the difference that in addition to the first sensor 10, a second sensor 11 is provided inside the gas side 6 of the oxygenator 4. By means of the two sensors 10, 11, a pCO2 change rate value over location can be determined, i.e. the local change rate value of pCO2 between the second sensor 11 and the first sensor 10. To determine the pCO2 value on the blood side 2, the control unit 12 can gradually reduce the flow rate of gas into the inlet 14 of the oxygenator 4, until the local change rate value of pCO2 between the second sensor 11 and the first sensor 10 is zero / infinitesimal. By this mode of operation, a validated portion does not have to be known, as becomes clearer in view of FIG. 6.

[0099] FIG. 6 shows a diagram schematically illustrating the dCO2/dt value, which is the change rate value over time of pCO2 of the gas side, over the length l of the oxygenator at two different flow rates f1 and f2. Flow rate f1, shown with the solid line, is higher than flow rate f2, shown with the dashed line. Generally, when the flow rate of gas is reduced to a reduced flow rate, the change rate of pCO2 over time will become zero / infinitesimal, i.e. the pCO2 equilibrium value will be reached, at or downstream of a certain longitudinal section of the oxygenator 4 (provided the oxygenator 4 is sufficiently long). However, said certain longitudinal section of the oxygenator 4 depends on the particular flow rate and is shorter (seen in flow direction) for a lower flow rate and longer for a higher flow rate. Therefore, with regard to the flow rates f1 and f2, the longitudinal section 11 of the oxygenator 4 at which the dCO2/dt value becomes zero / infinitesimal at the lower flow rate f2, is shorter than or upstream of the longitudinal section 12 at which the dCO2/dt value becomes zero / infinitesimal at the higher flow rate f2. With regard to the operating mode as described along with FIG. 5 and the two sensors 10, 11 being fixedly positioned inside/at the gas side 6 of the oxygenator 4, there is a certain gas flow rate at which the two sensors 10, 11 are positioned at or downstream of the certain longitudinal section of the oxygenator 4 at which the dCO2/dt value becomes zero / infinitesimal, and this certain flow rate can be found by gradually reducing the gas flow rate until the local change rate value of pCO2 between the sensors 10, 11 is zero / infinitesimal. As an example, when the first sensor 10 is positioned at the outlet 16 and the second sensor 11 is positioned at the longitudinal section 11, and the control unit 12 starts gradually reducing the gas flow rate at the flow rate f1, the flow rate at which the local change rate becomes zero is the flow rate f2.

[0100] As an alternative to the device 1 as shown in FIG. 5, the first sensor 10 can be positioned downstream of the outlet 16, e.g. as shown in FIGS. 2 and 3, and the second sensor 11 can be positioned anywhere downstream of the inlet 14 and upstream of or at the outlet 16. However, reducing the flow rate until the change rate becomes zero/infinitesimal will be accelerated when the second sensor 11 is positioned close to the outlet 16 (and yet at least at the predetermined local measuring distance from the outlet 16).

[0101] As an alternative mode of operation, the flow rate of gas into the inlet 14 can be reduced to a predetermined flow rate with the two sensors 10, 11 being both positioned within the validated portion of the device 1, wherein the validated portion is validated for the predetermined flow rate. Gradually reducing the flow is then not necessary.

[0102] A fifth embodiment of the device 1 according to the presently disclosed technology is schematically shown in FIG. 7. It is schematically indicated that the gas side of the oxygenator 4 is constituted by a plurality of fibers 26. The fibers 26 are hollow fibers formed by the semipermeable membrane. The gas side of the oxygenator is located inside the hollow fibers, while the blood side of the oxygenator 4 is located outside the hollow fibers and extends around the hollow fibers. During operation of the oxygenator 4, the gas flow (indicated by arrows a) enters the oxygenator 4 at the gas inlet 14 and flows through each of the fibers 26 towards the gas outlet 16 and exits the oxygenator 4 at the gas outlet 16. The blood flow (indicated by arrows b) enters the oxygenator 4 at the blood inlet 18 and flows between the fibers 26, so that the blood flow flows around the fibers 26, towards the blood outlet 20 and exits the oxygenator 4 at the blood outlet 20.

[0103] The fifth embodiment differs from the afore-described embodiments in that the sensor 10 is connected to only a part (or subset) of the plurality of fibers 26 constituting the gas side, but not to all of the fibers 26 constituting the gas side. The part of the fibers 26, to which the sensor 10 is connected, is illustrated as a selected fiber bundle 30. The sensor 10 is provided at the downstream side of the fiber bundle 30 such that the gas flow flows through the entire length (in flow direction) of the fiber bundle 30 before flowing into the sensor 10 and finally leaving the oxygenator 4 via the gas outlet 16. A shut-off or throttle valve 28 is provided downstream of the sensor 10 such that the gas flow through the fiber bundle 30 and the sensor 10 can be stopped or reduced. In this way, the gas flow can be stopped or reduced in the fiber bundle 30, while the gas flow proceeds flowing through the remaining fibers 26 without being stopped or reduced. In other words, the gas flow through only the fiber bundle 30 can be stopped or reduced for measuring purposes by the valve 28, while leaving the gas flow through the remaining fibers 26 undisturbed.

[0104] The specific position of the fiber bundle 30 in the direction of the blood flow, i.e. the specific position of the fiber bundle 30 between the blood inlet 18 and the blood outlet 20, can be selected in accordance with the measuring purposes. In the embodiment shown in FIG. 7, the fiber bundle 30 is located at or near the blood inlet 18 so that the venous pCO2 value of the blood side can be determined. In another embodiment (not shown), the fiber bundle 30 can be located at or near the blood outlet 20 so that the arterial pCO2 value of the blood side can be determined. It is also possible to provide at least two fiber bundles at different positions, each of which connected to a sensor and a valve in the above-described manner, so that a pCO2 value of the blood side can be determined for at least two different positions. For example, one fiber bundle can be located at or near the blood inlet 18 and another fiber bundle can be located at or near the blood outlet 20 so that both the venous pCO2 and the arterial pCO2of the blood side can be determined.