METHOD AND DEVICE FOR MEASURING A PATIENT'S BODY TEMPERATURE

Description

[0001] The present invention relates to a method and a device for detecting body temperature, preferably the core body temperature of a patient, wherein the patient has a fistula for draining blood into an extracorporeal circuit and / or for supplying blood from an extracorporeal circuit.

[0002] Patient monitoring is crucial during dialysis treatment to ensure a safe course of treatment and to enable rapid and targeted intervention should any adverse situations or conditions arise. One important patient parameter to monitor during treatment is the patient's body temperature.

[0003] Measuring a patient's body temperature allows for the detection of infections, for example, but is also of great importance for the patient's thermoregulation during dialysis treatment. Hemodialysis, in particular, poses a challenge for thermoregulation, as the temperature of the blood equalizes with the temperature of the dialysate during treatment.

[0004] Typically, the blood is returned to the patient at temperature equilibrium with the dialysate, with the heat transfer from the blood to the dialysate taking place in the dialyzer, which is part of the extracorporeal circuit of the dialysis machine.

[0005] Depending on the temperature of the dialysate, body temperature can rise or fall. Even slight changes in body temperature (especially core body temperature), for example in the range of 0.3–0.8 °C, trigger complex counter-regulatory mechanisms. These mechanisms serve to maintain a constant body temperature within a specific range. These counter-regulatory mechanisms, or changes in body temperature, affect either circulatory stability, for example through vasodilation or a drop in blood pressure when the blood becomes warm, or patient comfort, which can manifest as a feeling of cold, chills, etc., when the blood cools.

[0006] Against this background, it is important to keep the patient's body temperature constant or essentially constant during treatment, i.e., to keep the patient "isothermal". This can be achieved by monitoring the patient's blood temperature and adjusting the dialysate temperature accordingly.

[0007] Body temperature can be measured, for example, with a standard fever thermometer or with an ear or forehead thermometer.

[0008] A disadvantage of this measurement method is that, depending on the measurement site (oral, rectal, axillary, eardrum), the body temperature cannot be measured precisely, a relatively long measurement time is required, the measurement result is influenced by environmental conditions, and it can also be subject to artifacts. Furthermore, it is a disadvantage that manipulations of the patient are required, which may be perceived as uncomfortable or are generally impractical for the dialysis treatment process.

[0009] Another disadvantage of these known measurement methods is that they cannot be carried out continuously, but only at time intervals, meaning that only intermittent temperature measurement is possible.

[0010] Although continuous temperature measurement in the patient's esophagus is possible, this requires an invasive and therefore unpleasant procedure for the patient, in which a temperature sensor is inserted as a probe into the patient's esophagus and remains there for the duration of the measurement.

[0011] DE102014111403A1 discloses a method for monitoring the alignment and / or positioning of a blood tubing connected to an arterial and / or venous patient needle, or at least a section of the blood tubing, in an access area of ​​an extracorporeal blood circulation.

[0012] The aforementioned measurement methods are particularly disadvantageous for dialysis treatment because the measurements are subject to delays, meaning that changes in body temperature can only be reflected or recorded with a delay. This precludes or hinders a very rapid response by the device or staff to undesirable temperature changes in the patient.

[0013] Rapid blood temperature measurement is possible using an infrared sensor on the blood tubing of the extracorporeal circuit. However, this method is technically complex and expensive.

[0014] The present invention is based on the objective of overcoming the disadvantages of the prior art and, in particular, providing an improved method and an improved device for measuring body temperature, preferably core body temperature.

[0015] This problem is solved by a method having the features of claim 1 and a device having the features of claim 7.

[0016] The invention provides that, for the purpose of determining the patient's body temperature, a thermal image, hereinafter also simply referred to as a "thermal image," is taken of the fistula or a part of the fistula using an infrared camera. The present invention is thus based on the idea of ​​applying a thermal imaging measurement known from the prior art using an infrared camera to the surface of the fistula or the skin in the area of ​​the fistula. "Determining body temperature" does not necessarily mean that a temperature value, such as 37 °C, is measured. The term also includes the determination of a value representative of the temperature, such as the color of the thermal image in the area of ​​the fistula, etc.

[0017] From the thermal image of the fistula or the skin over the fistula obtained in this way, conclusions can be drawn about the patient's core body temperature, skin temperature, blood temperature or any other body temperature.

[0018] A fistula is generally understood to be a surgically created connection between an artery and a vein in the patient. It can be made of natural or artificial tissue.

[0019] The term "body temperature" is to be understood broadly and includes the temperature at any point in the body, such as on the skin surface, in the blood, etc.

[0020] Preferably, the term "body temperature" should be understood to mean "core body temperature".

[0021] The thermal image is preferably acquired without contact, i.e., without touching the patient, so that the patient is not affected in any way. The acquisition is relatively simple and also accurate. The different colors or color depths represent the respective temperatures.

[0022] The measurement or recording can be performed without significant technical effort and is comfortable for the patient. Expensive or technically complex components are not required.

[0023] Thermal imaging can be performed continuously or at specific or irregular intervals, e.g., when special events occur that make checking body temperature seem necessary.

[0024] In a preferred embodiment of the invention, the temperature of the patient's skin can be measured using thermal imaging, i.e., a specific temperature value can be determined. However, the conversion of the thermal image to temperature values ​​is not a mandatory requirement of the invention. It is also conceivable, in principle, to compare the measured color in the area of ​​the fistula with a reference value or a reference color and, based on this, to determine whether the patient's temperature is within a target range or not.

[0025] Preferably, the recording or temperature measurement in the infrared spectral range (IR) is carried out using an array, i.e., a two-dimensional measurement field.

[0026] Preferably, the maximum temperature on the IR surface is determined. Because of the two-dimensional measurement and the determination of the maximum temperature, movements of the patient's arm are also recorded and therefore do not influence the measurement result.

[0027] It is advantageous that the surface temperature of the skin on the affected arm largely corresponds to the internal temperature of the fistula, so that the fistula temperature, and thus the blood temperature, can be inferred from the measured skin temperature. If necessary, the measurement of the internal fistula temperature at the beginning of treatment can be refined empirically or by comparison with the skin temperature.

[0028] The fistula internal temperature determined in this way can be equated with the core body temperature. Assuming a cardiac output of 5 l / min, the flow in the fistula is typically 1 l / min and therefore very high. This suggests that the fistula internal temperature is identical or nearly identical (± 5%) to the core body temperature. Therefore, an algorithm for determining the core body temperature is unnecessary.

[0029] Thermal imaging and / or the measurement of body temperature based on it can be performed before and / or after dialysis treatment.

[0030] As explained above, thermal imaging can be performed continuously or intermittently. This applies accordingly to the derivation of body temperature based on the thermal image.

[0031] It is also conceivable that an actual value from a thermal image or a quantity derived from it is compared with a target value or target value range, and that adjustments are made so that the actual value matches the target value or lies within the target value range. In this way, body temperature control is possible. This control of body temperature can be achieved, for example, by changing the flow rate and / or temperature of the dialysate flowing through the dialyzer on the dialysate side.

[0032] This regulation is preferably carried out by a control unit of the dialysis machine.

[0033] Other control variables are also conceivable and are included in the invention.

[0034] Within the scope of the invention, the controlled variable can be the temperature obtained from the thermal image or another parameter, for example the color of the thermal image.

[0035] In order to give the patient or medical staff an indication of the patient's temperature, it is conceivable that a deviation between the actual and target value or target value range is displayed numerically, for example, by providing a corresponding display device, e.g., on the dialysis machine.

[0036] The present invention further relates to a device in the form of a dialysis machine, such as a hemodialysis machine, a hemofiltration machine or a hemodiafiltration machine with an extracorporeal blood circuit in which a dialyzer is located which is perfused with the patient's blood during operation of the device, wherein the dialysis machine has a thermal imaging camera which is suitable and aligned to take a thermal image of the fistula or part of the fistula of the patient connected to the dialysis machine.

[0037] The thermal imaging camera can be located, for example, on the infusion pole of the dialysis machine and / or form an integral part of the dialysis machine.

[0038] The thermal imaging camera can be, for example, an infrared gun or another mobile device, which has the advantage that a doctor can go from one treatment location to the next and quickly and easily take thermal images.

[0039] According to the invention, the recording area of ​​the thermal imaging camera is variable, so that it can, for example, follow the movement of the patient's arm and thus also the movement of the fistula.

[0040] This tracking is automatic, meaning the dialysis machine follows the thermal imaging camera to a reference point. This reference point does not change its position relative to the fistula. The reference point is the warmest area of ​​the arm within the region captured by the thermal imaging camera.

[0041] The dialysis machine can have a controller that maintains the temperature in or around the fistula at a setpoint or within a setpoint range. This makes it possible, for example, to maintain the patient's core body temperature at a setpoint or within a setpoint range during dialysis treatment. This control is preferably performed automatically by the dialysis machine, so that no user intervention is necessary. Preferably, the dialyzer is perfused with dialysate on the dialysate side during operation, and the controller is designed such that the temperature and / or flow rate of the dialysate can be adjusted as control variables. By adjusting the temperature and / or flow rate of the dialysate, the temperature of the blood flowing through the dialyzer on the blood side can be kept constant, increased, or decreased.The dialyzer preferably comprises a membrane or a plurality of membranes, preferably hollow fiber membranes, which separate the blood side from the dialysate side and through which mass and heat transfer is possible.

[0042] It should be noted here that the terms "ein" and "eine" do not necessarily refer to exactly one of the elements, although this is a possible interpretation, but can also denote a plurality of elements. Likewise, the use of the plural also includes the presence of the element in question in the singular, and conversely, the singular also includes several of the elements in question.

[0043] Further details and advantages of the invention will be explained in more detail with reference to an exemplary embodiment shown in the drawing.

[0044] They show: Figure 1: a thermal image of two forearms, with a fistula located in the arm shown on the right, and Figure 2: a thermal image of the Figure 1 The arm shown on the right has a temperature reading in the fistula.

[0045] Out of Figure 1 A thermal image of a patient's two forearms is visible, with the different colors or shades of gray representing different temperatures. To the right of Figure 1 A temperature scale is provided, which allows for the assignment of colors or shades of gray to temperature values.

[0046] Out of Figure 1 It is evident that the arm shown on the right has the highest temperature in the area marked with the cross, where the fistula is located.

[0047] This is also evident from the enlarged representation according to Figure 2. This results in an actual temperature of 37.4 °C for the fistula and thus ultimately also for the blood flowing through the fistula and therefore also for the core body temperature.

[0048] This value is within a target range, so no measures need to be taken to change the temperature.

[0049] If the blood temperature in the fistula is too low, it can be increased, for example, by warming the dialysate flowing through the dialyzer of the extracorporeal circuit. Conversely, if the measured temperature is too high, the blood temperature can be reduced by lowering the dialysate temperature.

[0050] The present invention makes it relatively easy to draw conclusions about a patient's core temperature. Based on this, it is possible to regulate this temperature within a target range to ensure that the patient is not endangered during dialysis treatment and feels comfortable during the procedure. Complex or even invasive devices for measuring body temperature are not required.

Claims

1. Method for detecting the body temperature of a patient by means of a dialysis machine according to one of claims 7 to 11, wherein the patient has a fistula for removing blood into an extracorporeal circuit and / or for supplying blood from an extracorporeal circuit, wherein, for the purpose of detecting the body temperature of the patient by means of an infrared camera, a thermal image of the fistula or of a part of the fistula is produced, the region of maximum temperature is identified, and a change in the position of this region is taken into account during the acquisition and / or evaluation of the thermal image, wherein an imaging region of the infrared camera is tracked to follow the region of maximum temperature, wherein the body temperature is measured before or after a dialysis treatment.

2. Method according to claim 1, characterized in that, by means of the thermal image, the temperature of the patient's skin is detected and / or that, from this detected temperature value of the skin, the blood temperature in the fistula and / or the core body temperature is inferred.

3. Method according to one of the preceding claims, characterized in that the thermal image is recorded continuously or intermittently.

4. Method according to one of the preceding claims, characterized in that the measurement of the body temperature based on the thermal image is carried out continuously or intermittently.

5. Method according to one of the preceding claims, characterized in that the thermal image is recorded in a two-dimensional array.

6. Method according to one of the preceding claims, characterized in that the thermal image is recorded by an infrared gun or by another mobile device.

7. Dialysis machine having an extracorporeal blood circuit, in which a dialyzer is located, through which, during operation of the machine, blood of a patient having a fistula flows, wherein the dialysis machine comprises a thermal imaging camera which is suitable and oriented to produce a thermal image of the fistula or of a part of the fistula of the patient, wherein the dialysis machine is furthermore designed to identify the region of maximum temperature and to take into account a change in the position of this region during the acquisition and / or evaluation of the thermal image and to track an imaging region of the infrared camera to follow the region of maximum temperature as a reference point.

8. Dialysis machine according to claim 7, characterized in that the thermal imaging camera is located on the infusion pole of the dialysis machine and / or forms an integral component of the dialysis machine and / or that the imaging region of the thermal imaging camera is variable.

9. Dialysis machine according to claim 7 or 8, characterized in that the dialysis machine has determination means by means of which a temperature value can be determined from the thermal image.

10. Dialysis machine according to one of claims 7 to 9, characterized in that the dialysis machine has a controller by means of which the temperature of the skin above the fistula or the temperature in the fistula or in the region of the fistula can be maintained at a setpoint value or within a setpoint range.

11. Dialysis machine according to claim 10, characterized in that, during operation of the machine, the dialyzer is flowed through on the dialysate side by dialysate and that the controller is designed such that, for the purpose of control, the temperature and / or the flow rate of the dialysate can be varied by the controller as manipulated variables.