SYSTEM, COMPUTER SYSTEM AND COMPUTER PROGRAM FOR DETERMINING A CARDIOVASCULAR PARAMETER

Abstract

The system interacts with an apparatus for extracorporeal blood treatment, which is connected to the venous vascular system of the a patient via an inflow line and an outflow line. Temperature influencing means for causing an initial local temperature deviation T.sub.1 in the vicinity of a first point of the vascular system, as a result of which a traveling temperature change is introduced into the blood flow of the patient, a first temperature sensor for measuring the local temperature of the blood at a second point of the vascular system downstream of the first point, and a second temperature sensor for measuring the local temperature of the blood in the inflow line are provided. A computer system records the local blood temperature measured at the second point and at the inflow line, in each case as a function of time, and ascertains and evaluates a first and second thermodilution curve (TDK.sub.1, TDK.sub.2). A temperature deviation TEKBV, which is to be allocated to the extracorporeal blood treatment apparatus, is determined from the second thermodilution curve, and T.sub.1 and TEKBV are correlated to one another for the purposes of determining the cardiovascular parameter.

Claims

1. System for determining a cardiovascular parameter of a patient, configured to interact with an apparatus for extracorporeal blood treatment connected to a venous vascular system of the patient via an inflow line and an outflow line, wherein the extracorporeal blood treatment apparatus comprises at least one pump arranged between the inflow line and the outflow line for moving the blood of the patient within the extracorporeal blood treatment apparatus, the system comprising: a. a temperature influencing means for causing an initial local temperature deviation T.sub.1 in the vicinity of a first point of the venous vascular system of the patient, so that a traveling temperature change is introduced in the blood flow of the patient; b. a first temperature sensor for measuring a local temperature of the blood of the patient at a second point of the venous vascular system of the patient downstream of the first point; c. a second temperature sensor for measuring a local temperature of the blood of the patient in the inflow line of the extracorporeal blood treatment apparatus, and d. a computer system connected to the first temperature sensor and the second temperature sensor and configured to record the local temperature of the blood of the patient, at the second point of the venous vascular system of the patient and the local temperature of the blood of the patient in the inflow line of the extracorporeal blood treatment apparatus as a function of time, and to determine and evaluate a first and a second thermodilution curve (TDK.sub.1, TDK.sub.2), and wherein the computer system is further configured to determine, from the second thermodilution curve, a temperature deviation T.sub.EKBV which is to be allocated to the extracorporeal blood treatment apparatus, and to correlate T.sub.1 and T.sub.EKBV to determine the cardiovascular parameter.

2. Apparatus according to claim 1, wherein the first point of the venous vascular system of the patient is located upstream of the inflow line of the extracorporeal blood treatment apparatus.

3. Apparatus according to one of claim 1, wherein the extracorporeal blood treatment apparatus is a blood treatment apparatus with a pump providing a flow rate of >100 mL/min.

4. Apparatus according to claim 3, wherein the computer system is configured to determine, from the relation of T.sub.EKBV and T.sub.1, a proportion A.sub.reEKBV of a traveling temperature change recirculating through the extracorporeal blood treatment apparatus.

5. Apparatus according to claim 1, wherein the temperature influencing means comprise an injection means for injecting a liquid, a temperature of the liquid differing from the temperature of the blood of the patient.

6. Apparatus according to claim 1, wherein the first thermodilution curve is determined by means of transpulmonary thermodilution.

7. Apparatus according to claim 1, wherein the cardiovascular parameter is cardiac output (CO), extra vascular lung water (EVLW), or global end-diastolic volume (GEDV).

8. Apparatus according to claim 6, wherein the computer system is configured to correlate T.sub.1 and T.sub.EKBV and the area under the first thermodilution curve for calculating cardiac output.

9. Apparatus according to claim 4, wherein the computer system is also configured to interact with the pump of the extracorporeal blood treatment apparatus such that when determining the cardiovascular parameter A.sub.EKBV<30%.

10. Apparatus according to claim 1, wherein the first point of the venous vascular system of a patient, in the vicinity of which point the temperature influencing means cause an initial local temperature deviation, and the outflow line of the extracorporeal blood treatment apparatus are located cranially with respect to a plane in which the heart valves of the patient are located.

11. Computer system configured to interact with an apparatus for extracorporeal blood treatment, the apparatus connected to a venous vascular system of a patient via an inflow line and an outflow line, the computer system comprising: a first connecting means for connecting the computer system to a temperature influencing means; a second connecting means for connecting the computer system to a first temperature sensor; a third connecting means for connecting the computer system to a second temperature sensor; and, an access means for accessing executable commands in order to cause the computer system a. to control the temperature influencing means to cause an initial local temperature deviation T.sub.1 in the vicinity of a first point of the venous vascular system of the patient, thereby introducing a traveling temperature change in the blood flow of the patient; b. to record a local temperature of the blood of the patient measured at a second point of the venous vascular system of the patient downstream of the first point by means of the first temperature sensor, as a function of time, in order to determine a first thermodilution curve (TDK.sub.1; c. to record a local temperature of the blood of the patient measured in the inflow line of the extracorporeal blood treatment apparatus, as a function of time, in order to determine a second thermodilution curve (TDK.sub.2); d. to determine from the second thermodilution curve a temperature deviation T.sub.EKBV which is to be allocated to the extracorporeal blood treatment apparatus, and to correlate T.sub.1 and T.sub.EKBv to determine a cardiovascular parameter.

12. Non transitory computer-readable storage medium with computer-readable instructions stored thereon for determining a cardiovascular parameter of a patient by means of thermodilution measurements in a system configured to interact with an apparatus for extracorporeal blood treatment, the apparatus connected to the venous vascular system of the patient, the computer-readable instructions being executable by a computer system to cause the computer system: a. to control a temperature influencing means connected to the computer system to cause an initial local temperature deviation T.sub.1 in the vicinity of a first point of the venous vascular system of the patient, so that a traveling temperature change is introduced in the blood flow of the patient; b. to measure a local temperature of the blood of the patient measured at a second point in the venous vascular system of the patient downstream of the first point by means of a first temperature sensor, recorded as a function of time, in order to determine a first thermodilution curve TDK.sub.1; c. to record a local temperature of the blood of the patient measured in the inflow line of the extracorporeal blood treatment apparatus by means of a second temperature sensor, as a function of time, in order to determine a second thermodilution curve TDK.sub.2; d. to determine from the second thermodilution curve T.sub.EKBV a temperature deviation which is to be allocated to the extracorporeal blood treatment apparatus, and to correlate T.sub.1 and T.sub.EKBV to determine the cardiovascular parameter.

Description

BRIEF DESCRIPTION OF THE FIGURE

[0021] FIG. 1 shows a schematic overview of the measuring arrangement of the present disclosure in a preferred embodiment and the vascular system of a patient.

DESCRIPTION OF NON-LIMITING EMBODIMENTS OF THE DISCLOSURE

[0022] FIG. 1 shows a schematic overview of an aspect of the disclosed measuring arrangement and the vascular system of a patient, wherein the apparatus for extracorporeal blood treatment (10) is connected to the venous vascular system of the patient via an inflow line (11; “drainage”) and an outflow line (12). The extracorporeal blood treatment apparatus can be, for example, an apparatus for extracorporeal membrane oxygenation (vvECMO, as shown in FIG. 1) or an apparatus for liver dialysis. The inflow line (11) is introduced, for example, via the femoral vein and comes to rest in the inferior vena cava (V. cava inferior) below the convergence of the hepatic vein. The outflow line (12) is introduced, for example, via the jugular vein and comes to rest in the superior vena cava (V. cava superior) immediately in front of the right atrium. In the case of ECMO, low-oxygen, venous blood is supplied to the blood treatment apparatus via the inflow line (11), while the oxygenated blood reaches the right atrium via the outflow line (12). The inventive system can also be used in situations in which a vaECMO is used, in which the deoxygenated blood is conducted via the femoral vein to the ECMO and the oxygenated blood is returned to the vascular system of the patient via the femoral artery. In this arrangement, the ECMO takes over the entire pumping output.

[0023] The cardiovascular parameter is determined by means of thermodilution; several cardiovascular parameters can also be determined and/or calculated by means of thermodilution. The disclosed temperature influencing means (20) are preferably an injection device by means of which a cooled liquid is injected as a bolus into the vascular system of the patient. In principle, the temperature change can be generated at any point in the central venous vascular system of the patient. The outflow line of the ECMO (via which oxygenated blood is supplied to the vascular system of the patient) and the first point (31) are preferably cranial with respect to the plane of the heart valve. As shown in FIG. 1, it is particularly preferred to perform a bolus injection for the thermodilution measurement at a first point (31), e.g., the jugular vein, upstream of the inflow line (11) of the ECMO. A traveling temperature change generated in the jugular vein travels via the right heart and pulmonary circulation into the left heart and from there via the aorta into the systemic circulation. The initial temperature deviation T.sub.1 generated by the bolus injection is calculated or measured, e.g., using a corresponding algorithm. The temperature influencing means can preferably detect the temperature, time, and possibly also duration of the bolus injection, for example by means of a temperature sensor which is arranged within or in the immediate vicinity of the temperature influencing means. The temperature influencing means can preferably supply the measurement results to a computer system (40) which is connected to the disclosed system via connecting means. The first temperature sensor (21) for measuring the local temperature of the blood of the patient is arranged at a second point (32) of the vascular system of the patient, downstream of the first point (31), in this case e.g., in the femoral artery. A further temperature sensor (22) is arranged in the inflow line (11) of the extracorporeal blood treatment apparatus. Depending on the flow rate of the extracorporeal blood treatment apparatus, e.g., at a high flow rate >500 mL/min, or depending on the pointal relationship between the injection site/inflow to the line, a part of the injected temperature bolus branches off into the extracorporeal circuit. This part of the injected temperature bolus is recorded by the second temperature sensor (22). The computer system (40) connected to the first (21) and second temperature sensor (22) via connecting means records the detected temperature as a function of time and correspondingly determines a first and a second thermodilution curve (TDK.sub.1, TDK.sub.2). The technical program device for carrying out evaluation steps of a thermodilution is known per se from the prior art (e.g., from German laid-open specification DE 4 214 402 A1). The computer system is furthermore configured to determine from the second thermodilution curve TDK.sub.2 a temperature deviation T.sub.EKBV which is to be allocated to the extracorporeal blood treatment apparatus, and T.sub.1 and T.sub.EKBV for determining the cardiovascular parameter. The system of the present disclosure advantageously enables an indicator loss, possibly caused by the extracorporeal circuit, to be detected and subsequently corrected so that errors in the determination of cardiovascular parameters, such as, e.g., the CO, during an extracorporeal blood treatment, e.g., during ECMO treatment, can be minimized and thus the accuracy and reliability of the determination is increased. The system of the present disclosure can be used independently of the arrangement/flow direction of the specific extracorporeal blood treatment apparatus and is therefore versatile. The patient is better integrated into the extracorporeal blood treatment apparatus and the configuration of the latter is optimally adjusted to the cardiovascular condition of the patient.

[0024] In a further embodiment of the system of the present disclosure, the first point of the vascular system of the patient, in the vicinity of which point the temperature influencing means cause the initial local temperature deviation T.sub.1, can be located in the vicinity of a first point of the vascular system of the patient upstream of the inflow line (11) of the extracorporeal blood treatment apparatus. The term “upstream” refers to the direction of flow in the inflow line of the blood treatment apparatus. For example, the inflow line of the blood treatment apparatus can be located in the inferior vena cava, while the temperature deviation is caused in the jugular vein. The arrangement leads to the least possible interference by the system of the present disclosure in the extracorporeal blood treatment apparatus, so that, e.g., the number of measurement cycles required is advantageously kept low.