Method and device for detecting the ultrafiltration coefficient of a dialyzer

Abstract

The application discloses a method and device for detecting an ultrafiltration coefficient of a dialyzer. The detection method comprises the following steps: under a preset blood pump flow rate, a transmembrane pressure is roughly adjusted, the ultrafiltration coefficient of the dialyzer under different transmembrane pressures is determined, and a plurality of groups of transmembrane pressure-ultrafiltration coefficient data are obtained; based on the plurality of groups of transmembrane pressure-ultrafiltration coefficient data, a fitting calculation formula is obtained according to a logarithmic function; and the ultrafiltration coefficient of a specific point value transmembrane pressure under the preset blood pump flow rate is determined according to the fitting calculation formula. The detection method of some examples of the application only needs to control the transmembrane pressure to be fixed in a certain range, does not need to be accurately constant at a specific numerical point, can quickly complete the constant and test of the transmembrane pressure, and then obtains the fitting curve of the ultrafiltration coefficient and the transmembrane pressure through corresponding data processing, so that the ultrafiltration coefficient data under different transmembrane pressures can be quickly obtained, and the performance comparison demand of different models and different manufacturers can be met.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of hemodialysis, and particularly relates to a method and device for detecting the ultrafiltration coefficient of a dialyzer. BACKGROUND

[0002] Hemodialysis is one of the ways of kidney replacement therapy for patients with acute and chronic renal failure. It achieves the purpose of removing metabolic waste, maintaining electrolyte and acid-base balance, and removing excess water in the body by inducing blood in the body to pass through a dialyzer composed of countless hollow fibers to exchange substances through diffusion, ultrafiltration, adsorption and convection principles. The dialyzer is a key part of hemodialysis, and its technical performance directly affects the quality of dialysis treatment.

[0003] The ultrafiltration coefficient is one of the important performance indicators of the dialyzer, mainly reflecting the water removal capacity of the dialyzer, and is also an important indicator for quality detection of the dialyzer. Wu Jingbiao (Wu Jingbiao, Tian Liyan, Chen Ying. Influence of transmembrane pressure on in vitro detection of ultrafiltration rate of hollow fiber dialyzer [J]. Clinical Medicine Engineering, 2010.) and others selected four specifications of hollow fiber dialyzers, measured the values of ultrafiltration rate in order of transmembrane pressure from small to large, and compared and analyzed. The results showed that with the increase of transmembrane pressure, the ultrafiltration rate of high-flux dialyzer (membrane area 2.1 m 2 ) decreased by 53.0 ml / mmHg / hr, that of high-flux dialyzer (membrane area 1.5 m 2 ) decreased by 40.2 ml / mmHg / hr, that of low-flux dialyzer (membrane area 2.1 m 2 ) decreased by 6.4 ml / mmHg / hr, and that of low-flux dialyzer (membrane area 1.3 m 2 ) decreased by 3.1 ml / mmHg / hr. Conclusion: The increase of transmembrane pressure will cause the in vitro detection results of ultrafiltration rate to decrease to different degrees. There is a complex relationship between transmembrane pressure and ultrafiltration coefficient. In order to more accurately evaluate the ultrafiltration coefficient, the standard (YY 0053-2016 "Hemodialysis and related treatment hemodialysis, hemodialysis filter, hemofilter and blood concentrator") requires that the test of the ultrafiltration coefficient needs to cover the range of transmembrane pressure and blood flow rate specified by the manufacturer, and the ultrafiltration coefficient needs to be determined at different blood flow rates and fixed transmembrane pressure at a specific point. However, the transmembrane pressure is currently controlled by manually adjusting the opening of the liquid pump or valve, and it is difficult to maintain the transmembrane pressure at the required fixed value. The transmembrane pressure is also stable after a certain period of operation, so it needs to be adjusted repeatedly to reach the required transmembrane pressure value, resulting in a tedious and time-consuming process for determining the ultrafiltration coefficient. At the same time, the test of transmembrane pressure uses a conventional pressure gauge, one end of which is connected to the external atmospheric environment, and the measured pressure is the pressure value of the measured point relative to the atmospheric pressure. In order to obtain the transmembrane pressure data, the blood inlet side PBI , blood outlet side P BO , and filtrate side P FI The pressure value of the filtrate side P is obtained by the calculation formula P = P0 + K * t, where P0 is the initial pressure value of the filtrate side P, K is the pressure gradient of the filtrate side P, and t is the time. The required transmembrane pressure is obtained by the calculation formula P = P0 + K * t, where P0 is the initial pressure value of the filtrate side P, K is the pressure gradient of the filtrate side P, and t is the time.

[0004] CN216646192U discloses a dialyzer ultrafiltration coefficient testing device, which comprises a blood pump, a pressure controller, a filtrate pump and a plurality of pressure sensors arranged in a cabinet, and a clamping assembly for mounting the dialyzer to be tested on the cabinet. The pressure controller is used to adjust different transmembrane pressures to meet the testing requirements under different transmembrane pressures, and to avoid disassembly and assembly of the testing structure multiple times.

[0005] CN214224883U discloses a hollow fiber hemodialysis ultrafiltration coefficient detection device, which comprises a machine table, a panel fixed above the machine table, a rolling pump fixed on the machine table top, an electronic scale fixed at the bottom of the machine table, a first container placed on the electronic scale, a touch screen and a plurality of pipelines connected with the dialyzer installed on the panel, a plurality of pressure sensors arranged at the ports of the dialyzer, a signal input module, a processing module and an output module, wherein the signal input module receives signals from the electronic scale and the pressure sensors, the output module feeds back the data processed by the processing module to the touch screen, and a control device capable of providing stable transmembrane pressure values.

[0006] These improved devices still need multiple attempts to stabilize the transmembrane pressure, and the transmembrane pressure is still obtained by the traditional testing method, which has low testing efficiency and low testing precision. SUMMARY

[0007] The purpose of the present application is to overcome at least one deficiency of the prior art and provide a method and device for detecting the ultrafiltration coefficient of a dialyzer.

[0008] The technical solution adopted by the present application is as follows:

[0009] In a first aspect, the present application provides:

[0010] A method for detecting the ultrafiltration coefficient of a dialyzer, comprising the following steps:

[0011] At a predetermined blood pump flow rate, the transmembrane pressure is roughly adjusted, the ultrafiltration coefficient of the dialyzer under different transmembrane pressures is determined, and a plurality of sets of transmembrane pressure-ultrafiltration coefficient data are obtained;

[0012] Based on the plurality of sets of transmembrane pressure-ultrafiltration coefficient data, a fitting calculation formula is obtained according to a logarithmic function;

[0013] According to the fitting calculation formula, the ultrafiltration coefficient of the specific point value transmembrane pressure under the preset blood pump flow rate is determined.

[0014] In some examples of the detection method, the transmembrane pressure ranges of the multiple sets of transmembrane pressure-ultrafiltration coefficient data are [50-100) mmHg, [100-200) mmHg, [200-300) mmHg, [300-400) mmHg, and [400-500) mmHg.

[0015] In some examples of the detection method, the calculation formula of the transmembrane pressure is: transmembrane pressure In the formula, P1 is the test pressure between the blood inlet side and the filtrate side of the dialyzer, and P2 is the test pressure between the blood outlet side and the filtrate side of the dialyzer.

[0016] In some examples of the detection method, at least one transmembrane pressure value in different transmembrane pressure ranges is taken, and the ultrafiltration coefficient under the transmembrane pressure value is determined, and the fitting calculation formula is obtained based on the obtained multiple sets of transmembrane pressure-ultrafiltration coefficient data.

[0017] In some examples of the detection method, the preset blood pump flow rates are 200 mL / min, 300 mL / min, and 400 mL / min, respectively.

[0018] In some examples of the detection method, when the transmembrane pressure is adjusted, it is adjusted from low to high.

[0019] In some examples of the detection method, when the ultrafiltration coefficient is determined, anticoagulated bovine plasma is used as the fluid.

[0020] In some examples of the detection method, a standard curve is drawn with the transmembrane pressure TMP as the abscissa and the ultrafiltration coefficient KUF as the ordinate, a logarithmic function is selected for fitting, and the correlation coefficient R 2 should be ≥0.98, and if R 2 < 0.98, one or two data points deviating from the trend line of the regression equation can be discarded, and the fitting calculation formula is recalculated.

[0021] In some examples of the detection method, the fitting calculation formula is in the form of y=-a*lnx+b, where y is the ultrafiltration coefficient, with the unit of mL / mmHg·h, x is the transmembrane pressure, with the unit of mmHg, and a and b are constants.

[0022] The above technical features can be combined arbitrarily without conflict.

[0023] In a second aspect of the present application, there is provided:

[0024] A detection device for implementing the detection method of the first aspect of the present application comprises:

[0025] The cabinet body is provided with a mounting cavity;

[0026] The blood pump, the pressure controller and the filtrate pump are arranged in the mounting cavity of the cabinet body.

[0027] The clamp is arranged on the surface of the cabinet body and is used for clamping the dialyzer to be measured.

[0028] The pressure sensor is arranged between the blood inlet side and the filtrate side and between the blood outlet side and the filtrate side.

[0029] The data storage module is used for recording a plurality of groups of transmembrane pressure-ultrafiltration coefficient data under a preset blood pump flow rate.

[0030] The data processing module is used for calculating a fitting calculation formula based on the recorded plurality of groups of transmembrane pressure-ultrafiltration coefficient data and determining the ultrafiltration coefficient of the transmembrane pressure at a specific point under the preset blood pump flow rate according to the fitting calculation formula.

[0031] In some examples of the detection device, the controller and the control panel are further connected with the blood pump, the pressure controller and the filtrate pump and are used for adjusting the test of the transmembrane pressure.

[0032] In some examples of the detection device, the test liquid storage device is further included.

[0033] The detection device has the following beneficial effects:

[0034] The detection method of some examples of the present application only needs to control the transmembrane pressure to be fixed in a certain range, does not need to be accurately constant at a specific numerical point, can quickly complete the constant and test of the transmembrane pressure, and then obtains the fitting curve of the ultrafiltration coefficient and the transmembrane pressure through corresponding data processing, so that the ultrafiltration coefficient under different transmembrane pressures can be quickly obtained and the performance comparison demand of different models and different manufacturers can be met.

[0035] In the detection method of some examples of the present application, the pressure sensor is connected between the blood inlet side and the filtrate side and between the blood outlet side and the filtrate side of the dialyzer to be measured, so that the pressure difference between the inside and outside of the membrane, i.e., the transmembrane pressure value, can be directly obtained, the instantaneous test is convenient, and the test precision is high. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 FIG. 1 is a structural schematic diagram of a detection device according to some examples of the present application.

[0037] Figure 2 FIG. 2 is a KUF-TMP fitting curve under a blood pump flow rate of 200 ml / min.

[0038] Figure 3 FIG. 3 is a KUF-TMP fitting curve under a blood pump flow rate of 300 ml / min.

[0039] Figure 4 is the KUF-TMP fitting curve at 400 ml / min blood pump flow rate. DETAILED DESCRIPTION

[0040] The first aspect of the present application provides:

[0041] A method for detecting the ultrafiltration coefficient of a dialyzer, comprising the following steps:

[0042] At a preset blood pump flow rate, the transmembrane pressure is roughly adjusted, the ultrafiltration coefficient of the dialyzer at different transmembrane pressures is determined, and a plurality of sets of transmembrane pressure-ultrafiltration coefficient data are obtained;

[0043] Based on the plurality of sets of transmembrane pressure-ultrafiltration coefficient data, a fitting calculation formula is obtained according to a logarithmic function;

[0044] According to the fitting calculation formula, the ultrafiltration coefficient of the transmembrane pressure at a specific point value at the preset blood pump flow rate is determined.

[0045] When adjusting the transmembrane pressure, it is not necessary to accurately adjust the transmembrane pressure, but only to determine the ultrafiltration coefficient at a certain pressure, which greatly reduces the time consumed by accurately adjusting the transmembrane pressure. The ultrafiltration coefficient can be determined after the transmembrane pressure is stable.

[0046] In order to be consistent with the current standard, in some examples of the detection method, the transmembrane pressure range for determining the plurality of sets of transmembrane pressure-ultrafiltration coefficient data is [50-100) mmHg, [100-200) mmHg, [200-300) mmHg, [300-400) mmHg and [400-500) mmHg. The required transmembrane pressure range can also be selected as needed.

[0047] In some examples of the detection method, at least one transmembrane pressure value in a different transmembrane pressure range is taken and the ultrafiltration coefficient at the transmembrane pressure value is determined, and a fitting calculation formula is obtained based on the obtained plurality of sets of transmembrane pressure-ultrafiltration coefficient data. By selecting more values, deviations can be better excluded, and a more accurate fitting calculation formula and a more accurate detection result are expected to be obtained.

[0048] In some examples of the detection method, the calculation formula of the transmembrane pressure is: In the formula, P1 is the test pressure between the blood inlet side and the filtrate side of the dialyzer, and P2 is the test pressure between the blood outlet side and the filtrate side of the dialyzer. In this way, the instantaneous value of the transmembrane pressure can be obtained in real time, which is more conducive to obtaining accurate detection results.

[0049] In order to be consistent with the current standard, in some examples of the detection method, the preset blood pump flow rate is 200 mL / min, 300 mL / min and 400 mL / min respectively. Of course, other flow rates can also be determined according to the needs of the user to determine the ultrafiltration coefficient under other flow rates.

[0050] In some examples of the detection method, the transmembrane pressure is adjusted from low to high. This is convenient for operation and is consistent with the current standard, and is conducive to obtaining more accurate detection results.

[0051] In order to be consistent with the current standard, in some examples of the detection method, when determining the ultrafiltration coefficient, anticoagulated bovine plasma is used as the fluid.

[0052] In some examples of the detection method, a standard curve is drawn with the transmembrane pressure TMP as the abscissa and the ultrafiltration coefficient KUF as the ordinate, a logarithmic function is selected for fitting, and the correlation coefficient R 2 should be greater than or equal to 0.98, and if R 2 < 0.98, one or two data points deviating from the trend line of the regression equation can be discarded, and the fitting calculation formula is recalculated.

[0053] In some examples of the detection method, the fitting calculation formula is of the form y = -a x ln x + b, where y is the ultrafiltration coefficient, the unit is mL / mmHg h; x is the transmembrane pressure, the unit is mmHg, and a and b are constants.

[0054] The second aspect of the present application provides:

[0055] Referring to Figure 1 , the detection device for implementing the detection method of the first aspect of the present application comprises:

[0056] The cabinet body is provided with a mounting cavity;

[0057] The blood pump 5, the pressure controller 1, the filtrate pump 3, and the blood filter or blood concentrator 2 are arranged in the mounting cavity of the cabinet body;

[0058] The clamp is arranged on the surface of the cabinet body and is used for clamping the dialyzer or hemodialysis filter to be detected.

[0059] The pressure sensors 6 and 7 are arranged between the blood outlet side and the filtrate side, and between the blood inlet side and the filtrate side, respectively.

[0060] The data storage module is used for recording a plurality of groups of transmembrane pressure-ultrafiltration coefficient data under the preset blood pump flow rate.

[0061] A data processing module, which is configured to calculate a fitting calculation formula based on a plurality of sets of transmembrane pressure-ultrafiltration coefficient data, and determine an ultrafiltration coefficient of a specific point value of transmembrane pressure at a preset blood pump flow rate according to the fitting calculation formula.

[0062] In some examples of the detection device, a three-way valve is arranged on the filtrate side and connected with the blood inlet side and the blood outlet side pressure sensors respectively; the pressure sensors are directly connected with the blood inlet side and the filtrate side, and the blood outlet side and the filtrate side, and the pressure values are the pressure differences between the inside and outside of the membrane, i.e. the transmembrane pressure, and the test precision is high.

[0063] In some examples of the detection device, a controller and a control panel are further included, which are connected with the blood pump 5, the pressure controller 1 and the filtrate pump 3, and used for adjusting the test of the transmembrane pressure.

[0064] In some examples of the detection device, a test liquid storage device 4 is further included.

[0065] The technical solutions of the present application are further illustrated below in combination with experiments.

[0066] S1, calibrate the blood pump flow rate and the filtrate pump flow rate, take the sample to be tested, and preflush the blood chamber with 500 mL of physiological saline at a flow rate of 80-100 mL / min and exhaust the air. According to the blood pump flow rate, the filtrate pump flow rate and the transmembrane pressure, the blood pump flow rate is adjusted to 200 mL / min, 300 mL / min and 400 mL / min respectively, and the transmembrane pressure is adjusted to 50-100 mmHg, 100-200 mmHg, 200-300 mmHg, 300-400 mmHg and 400-500 mmHg respectively. Figure 1 Assemble the test circuit, and keep the arterial and venous jugs at the same level, and the dialysate chamber should not be filled with dialysate.

[0067] S2, take 1.5-3 L of anticoagulated bovine blood plasma with a total protein concentration of 60 g / L±5 g / L, and place the bovine blood plasma solution in a water bath before the test, and control the temperature at 37℃±1℃. The blood chamber absorbs the bovine blood plasma solution, and the physiological saline in the pipeline and the hemodialysis filter is discharged, and then the blood pump flow rate is adjusted to 200 mL / min, 300 mL / min and 400 mL / min respectively, and the closed loop circulation (the liquid at the filtrate outlet is also circulated), and the transmembrane pressure is monitored, and the transmembrane pressure is adjusted to 50-100 mmHg, 100-200 mmHg, 200-300 mmHg, 300-400 mmHg and 400-500 mmHg respectively by adjusting the filtrate pump or the pressure control device, and each value is stabilized, and when the transmembrane pressure is stabilized, the pressure value is recorded within 30 s, the transmembrane pressure is calculated, the filtrate is collected by a measuring cylinder, the volume V is measured, and the ultrafiltration coefficient is calculated according to the formula.

[0068] Note: When adjusting the transmembrane pressure, first use the filtrate pump to gradually increase the transmembrane pressure. When the transmembrane pressure reaches 300 mmHg or above, or when a large number of bubbles are generated at the outlet of the sample filtrate, begin using the pressure control device to adjust the required transmembrane pressure. During the test, the arteriovenous reservoir and the filtrate reservoir should be kept at the same level, and the filtrate reservoir should be at least 1 / 2 full of liquid. There should be no large number of bubbles at the outlet of the product filtrate during the measurement.

[0069] The ultrafiltration coefficients were measured in order of increasing transmembrane pressure.

[0070] S3. After the sample is tested, drain the anticoagulated bovine plasma from the sample and fill the sample with physiological saline for further processing.

[0071] Note: Formula for calculating transmembrane pressure:

[0072]

[0073] 3. Result Calculation

[0074]

[0075] Where: KUF—ultrafiltration coefficient of hemodialysis filter, in mL / mmHg·h;

[0076] TMP – Transmembrane pressure of a hemodialysis filter, measured in mmHg;

[0077] P1—Pressure between the blood inlet side and the filtrate side of the sample to be tested, in mmHg;

[0078] P2—Pressure between the blood outlet side and the filtrate side of the sample to be tested, in mmHg;

[0079] V – Volume of anticoagulated bovine plasma filtrate, in mL.

[0080] Plot a standard curve with transmembrane pressure (TMP) on the x-axis and ultrafiltration coefficient (KUF) on the y-axis. Choose a logarithmic function; the correlation coefficient R² should be ≥ 0.98. If R² < 0.98, discard one or two data points that deviate from the regression equation trend line and recalculate the standard curve equation. Substitute transmembrane pressures of 50 mmHg, 100 mmHg, 200 mmHg, 300 mmHg, and 500 mmHg into the standard curve equation to calculate the corresponding ultrafiltration coefficient (KUF).

[0081] Test Result Analysis:

[0082] (1) Based on the test data, the algebraic fitting formula of ultrafiltration coefficient-transmembrane pressure under different blood pump flow rates was obtained, and the results are shown in Table 1.

[0083] Table 1. Ultrafiltration coefficient-transmembrane pressure and fitting calculation formula at different flow rates

[0084]

[0085]

[0086] Figure 2 This is the KUF-TMP fitting curve at a blood pump flow rate of 200 ml / min. Figure 3 This is the KUF-TMP fitting curve at a blood pump flow rate of 300 ml / min. Figure 4 This is the KUF-TMP fitting curve at a blood pump flow rate of 400 ml / min. From Figures 2 to 4 It can be seen that there is a good linear relationship.

[0087] The ultrafiltration coefficients at fixed transmembrane pressures under different flow rates were obtained based on the algebraic fitting formula, and compared with the actual measured data (ultrafiltration coefficients measured at fixed transmembrane pressures of 50 mmHg, 100 mmHg, 200 mmHg, 300 mmHg and 500 mmHg) and the data specified in the product standard. The results are shown in Table 2.

[0088] Table 2. Comparison of calculated and measured ultrafiltration coefficients (mL / mmHg·h) at different flow rates and transmembrane pressures.

[0089]

[0090] As can be seen from Table 2, the ultrafiltration coefficient data calculated based on the algebraic fitting formula is basically consistent with the ultrafiltration coefficient data measured after the actual constant transmembrane pressure, and both are within the range required by the product standard.

[0091] The above is a further detailed description of the present invention and should not be considered as a limitation on the specific implementation of the present invention. For those skilled in the art, simple deductions or substitutions without departing from the concept of the present invention are all within the protection scope of the present invention.

Claims

1. A method for detecting the ultrafiltration coefficient of a dialyzer, comprising the following steps: coarse adjustment of the transmembrane pressure at a preset blood pump flow rate, determination of the ultrafiltration coefficient of the dialyzer at different transmembrane pressures, and obtaining a plurality of sets of transmembrane pressure-ultrafiltration coefficient data, wherein the transmembrane pressure ranges from 50 to 100 mmHg, from 100 to 200 mmHg, from 200 to 300 mmHg, from 300 to 400 mmHg, and from 400 to 500 mmHg during determination of the plurality of sets of transmembrane pressure-ultrafiltration coefficient data; At least one transmembrane pressure value in different transmembrane pressure ranges is taken and the ultrafiltration coefficient at the transmembrane pressure value is determined, based on the plurality of sets of transmembrane pressure-ultrafiltration coefficient data, a fitting calculation formula is obtained according to a logarithmic function, and the calculation formula of the transmembrane pressure is: transmembrane pressure , wherein P1 is the test pressure between the blood inlet side and the filtrate side of the dialyzer, and P2 is the test pressure between the blood outlet side and the filtrate side of the dialyzer. determination of the ultrafiltration coefficient of the dialyzer at a specific point value of the transmembrane pressure at the preset blood pump flow rate according to a fitting calculation formula.

2. The detection method according to claim 1, characterized in that, The preset blood pump flow rate is 200 mL / min, 300 mL / min, and 400 mL / min, respectively.

3. The method of claim 1, wherein, During adjustment of the transmembrane pressure, the adjustment is from low to high; and / or during determination of the ultrafiltration coefficient, anticoagulated bovine plasma is used as the fluid.

4. The assay of any one of claims 1 to 3, characterized in that, A standard curve was plotted with trans-membrane pressure (TMP) as the abscissa and ultrafiltration coefficient (KUF) as the ordinate. A logarithmic function was selected to fit the data, and the correlation coefficient (R 2 should be > 0.98, and if R 2 < 0.98, one or two data points deviating from the trend line of the regression equation were discarded, and the fitting calculation formula was recalculated.

5. The assay of any one of claims 1 to 3, wherein, The fitting calculation formula is of the form y = -a × lnx + b, wherein y is the ultrafiltration coefficient, with the unit of mL / mmHg·h, x is the transmembrane pressure, with the unit of mmHg, and a and b are constants. 6.A device for detecting the ultrafiltration coefficient of a dialyzer according to any one of claims 1 to 5, comprising: a cabinet, wherein the cabinet is provided with a mounting cavity; a blood pump, a pressure controller, and a filtrate pump, which are arranged in the mounting cavity of the cabinet; a clamp, which is arranged on the surface of the cabinet and is used for clamping the dialyzer to be detected; characterized in that the device further comprises a pressure sensor, which is arranged between the blood inlet side and the filtrate side, and between the blood outlet side and the filtrate side; a data storage module and a data processing module, wherein: the data storage module is used for recording a plurality of sets of transmembrane pressure-ultrafiltration coefficient data at a preset blood pump flow rate; the data processing module is used for calculating a fitting calculation formula based on the recorded plurality of sets of transmembrane pressure-ultrafiltration coefficient data, and determining the ultrafiltration coefficient of the dialyzer at a specific point value of the transmembrane pressure at the preset blood pump flow rate according to the fitting calculation formula.

7. The detection device of claim 6, wherein, The device further comprises a controller and a control panel, which are connected to the blood pump, the pressure controller, and the filtrate pump, and are used for testing the adjustment of the transmembrane pressure.

8. The detection device according to claim 6 or 7, characterized in that The device further comprises a test liquid storage device.

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