Method and apparatus for objectively measuring capillary refilling behavior

Abstract

To provide a method and device for objectively determining a resaturatioin behavior of a capillary vessel on a human body surface.SOLUTION: In a method and device for objectively determining a resaturatioin behavior of a capillary vessel on a human body surface, at least one detecting device having a light detecting device 1 is used in a skin surface region 2 having a predefined area size and outer contour to perform a spatial and spectrum resolution light detection. Then, on the skin surface region, a predefined constant pressure p is applied for a predefined period of time t1, and an action of this pressure terminates after termination of the time t1. During the period of time t2 in which at least one first threshold value of the measurement value simultaneously detected by the spatial resolution reaches the measurement value optically detected prior to a start of action of the pressure, the detecting device performs a spatial and spectrum resolution light detection and spatially and timely determines each of the resaturatioin behavior of a capillary vessel.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for objectively determining the capillary refill behavior on the surface of the human body.

Background Art

[0002] The present invention can be used for emergency medicine, intensive care, anesthesiology, and the treatment of outpatient and inpatient patients in the fields of pediatric and adult medicine. Although it is particularly considered for use in the above medical fields, it can also be widely used in nursing facilities for evaluating fluid balance.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Conventionally, an examiner presses a fingertip against the patient's nail or skin (for about 5 seconds). The time until capillary refill is restored is evaluated. The time until the pallor of the test area due to pressure disappears and returns to the original blood color is used as a reference point. This parameter is collected in a directional manner for evaluating the need for volume replacement and represents a rough parameter for evaluating microcirculation. In the conventionally used method, since the indentation depth and the pressure surface used vary, it is highly dependent on each examiner individually.

[0004] Therefore, an object of the present invention is to enable a standardized and user-independent examination of the microcirculation within a predefined skin surface area of a patient, that is, the initial shape situation, the quantitative change in the pallor situation related to the applied pressure, the inflow power (skin elasticity), and the inflow behavior.

Means for Solving the Problems

[0005] According to the present invention, this object is achieved by a method having the features described in claim 1. This method can be implemented using the apparatus described in claim 10. Advantageous embodiments and further developments of the present invention can be realized using the features of the dependent claims.

[0006] In the method according to the present invention, spatial and spectral resolved photodetection is performed on a skin surface region having a predetermined area size and outer contour using at least one detection device equipped with a photodetector. Then, a predetermined constant pressure is applied to the skin surface region for a predetermined time t1. The predetermined specific time t1 will be a value of 5 to 10 seconds. The constant pressure p can be selected from a pressure between 0.4 MPa and 2 MPa. For comparison, the predetermined time t1, the predetermined pressure p, and the predetermined size and outer contour of the skin surface region should always be the same in all patient examinations to ensure reproducibility and intercomparability.

[0007] The skin surface area is at least 100 mm 2 Preferably at least 150 mm 2 It will have an area of ​​.

[0008] After the end of this time t1, the effect of the pressure ceases, and the skin surface area is subsequently exposed to the normal atmospheric pressure.

[0009] After the effect of pressure application has ended, spatial and spectral resolved photodetection is performed by the detection device until a preset first threshold of simultaneously detected measurements, for example, at least 90%, preferably at least 95%, of the measurements detected by spatial resolution reaches the measurements that were optically detected before the start of the pressure effect, thereby spatially and spectrally determining the refilling behavior of each capillary at time t2.

[0010] The detected measurements can be compared with each other within the electronic evaluation unit. Furthermore, the time t2 until, for example, at least 90% of the measurements detected simultaneously by spatial resolution reach a preset first threshold, which was the measurement detected before the onset of pressure action, can be measured by the electronic evaluation unit. However, this is also possible if the measurements were detected by the detection device using temporal resolution.

[0011] Preferably, the intensity of electromagnetic radiation is detected by the detection unit at different locations distributed as uniformly as possible within the skin surface area. If the individual detectors of the detection device are configured to perform spatially resolved measurements, multiple intensities of individually selected wavelengths can be measured and considered in the evaluation of the determination of capillary refill behavior.

[0012] Furthermore, time measurement or consideration can be achieved by configuring the detection device to perform time-resolved detection of the measured values. However, time measurement or consideration in determining capillary refill behavior can also be achieved, for example, by an electronic evaluation unit using timing increments.

[0013] Pressure can be applied to a skin surface area mechanically, pneumatically, and / or hydraulically. For this purpose, pressure can be applied to a skin surface area by a mechanical device that has a stamp that acts temporarily on the skin surface area. Here, the stamp is advantageously optically transparent, through which detection can be performed. In this case, the detection device is positioned away from the skin surface, on the stamp side. The stamp will have a front surface that corresponds to the size and outer contour of the area of ​​the skin surface.

[0014] The stamp can be applied, for example, by at least one compression spring having linear spring characteristics in the direction of each skin surface region, with an applied pressure F1 such that a predetermined pressure p acts on the skin surface region.

[0015] However, pressure p can also be applied pneumatically and hydraulically. For this purpose, gases and / or liquids acting directly on the skin surface area or via a detection device can be used within the hollow space of a stamp or pressing element, in a correspondingly compressed state, inside the hollow space of the pressing element.

[0016] The stamp and / or detection device can be placed inside a hollow pressing element that can temporarily contact the skin surface while surrounding the skin surface area from the outside. However, it can also be a gas and / or liquid temporarily compressed to a predetermined pressure inside the hollow pressing element, which can be introduced for the action of pressure on the skin surface. The latter can be done by appropriate pressure adjustment and / or by a valve connected to a compressed gas line or compressed gas tank. The gas pressure and / or liquid pressure can then be held inside for a time t1. After the end of time t1, for example, the outlet valve can be opened so that the pressure acting on the surface of the skin surface area drops to the ambient pressure of the atmosphere, and then spatial and spectral resolution detection of the measurements is performed until at least the refilling behavior of each capillary is reached.

[0017] As the detection device, a combined device having detection and illumination components can be used. For example, this could be a bidirectional OLED microdisplay device known from German Patent No. 10 2006 030 541 B4. However, the detection device can also be a suitable array of optical detectors, particularly a hyperspectral imaging camera (HSI camera). For this purpose, it is advantageous to use an additional light source capable of illuminating at least the skin surface area.

[0018] At least 10 measurements / mm 2 These will be detected simultaneously and considered by the detector of the detection unit at each different location where the respective skin surface region or pressure p is evenly distributed across the skin surface region.

[0019] During spectral resolution detection, only the wavelengths of color on the human skin surface occurring before, during, and after the action of pressure and / or applied pressure can be considered, thereby reducing the spectral range to be evaluated. This can be achieved by appropriate optical filtering or by appropriate software selection in the evaluation of individual measurements detected by spatial resolution.

[0020] In a further development of the present invention, a hollow pressing element, whose surface in direct contact with the skin surface has predetermined dimensions and geometric shape, and which completely encloses the outer edge of the skin surface region within the region of the skin surface, can be pressed onto the skin surface with a predetermined pressing force F2 during the duration of the pressure application. Before the start of the pressing application, spatial and spectral resolved photodetection of an image is performed within the surface region in which the pressing element is in contact with the skin surface by the detection device or other detection device within this surface region. When the application of pressure to the skin surface region ends, the pressing element is removed from the skin surface or lifted from the skin surface, and spatial and spectral resolved photodetection of measurements is repeated in this surface region. Then, the measurements detected before and during the application of pressure are compared with the measurements detected starting from the end of the application of contact pressure.

[0021] The stamp or pressing element would preferably have a rotationally symmetrical cross-section, considering the circular skin surface area. Alternatively, an elliptical cross-section can be selected. While polygonal geometric shapes are certainly possible, they are not preferred.

[0022] The detection device can be arranged inside a pressing element with a hollow interior. In this process, the outer contour of the detection device will correspond in shape and dimensions to the inner contour of the pressing element. In this regard, the detection device can be arranged away from the skin surface area. However, the detection device can also be pneumatically pressed directly onto the skin surface by a stamp or simply by compressed gas during the time t1 for which the pressure p should be effective. It will then be supported playfully and optionally guided longitudinally to avoid rotation. For example, it will be supported in a longitudinal groove.

[0023] The device can be temporarily fixed in a predetermined manner to the body part of the person on which each skin surface area is located. For this, for example, an extension belt or a fixture option adapted to the shape in the corresponding body part can be used. In this regard, each body part can be at least partially gripped, for example, by a fastener to which the device is fixed.

[0024] Also, advantageously, it is possible to perform a two-dimensional or three-dimensional spatial decomposition detection of the topology of the skin surface area by the detection device before and after the start and end of the action of the pressure. In that case, it is possible to evaluate the temporal recovery behavior by comparing the measured values detected before and after the action of the pressure.

[0025] Similarly, the two-dimensional or three-dimensional spatial decomposition detection of the topology of the skin surface area can be performed by the detection device or another detection device before the start and after the end of the action of the pressing force by the pressing element, and then the temporal recovery behavior can be evaluated by comparing the measured values detected before and after the action of the pressing force.

[0026] For this purpose, a contact film sensitive to pressure measurement can be used, which can be adhered and fixed to the stamp, whereby the stamp can detect area and time until the recovery of contact, preferably after it has returned to its starting position.

[0027] Alternatively, in an external cylinder, for example a stamp with a hollow interior, an optical device can be used. For this purpose, the optical device can emit appropriate electromagnetic radiation inside each skin surface area at the edge facing the direction of the skin surface. The electromagnetic radiation reflected and / or scattered by the surface of the skin surface area can be detected by a detection device suitable for spatial and spectral decomposition detection on the opposite side of the arrangement side of the external cylinder or stamp. It is conceivable that small bulges are formed towards the inside in the indentation on the skin surface of the external cylinder or stamp, which can be detected as a deficiency of the measurement signal on the opposite side. After the action of skin compression and pressure is completed, an optical signal can be detected, and this optical signal can be interrupted again after reaching the starting state. Or it cannot be interrupted (if the skin surface remains partially concave).

[0028] Also, in the evaluation of capillary refill behavior, after the action of pressure is completed, the change in spatially and spectrally decomposed measurement values occurring from the outer edge of the skin surface area towards the center of the area or in the opposite direction can be measured.

[0029] The measurement values that can be detected by a detection device configured for spatial and spectral decomposition detection can be processed, for example, by an appropriate evaluation algorithm that can be stored in an electronic evaluation unit. In this regard, the following criteria can be considered to determine the spatial decomposition dynamics of the recovery of the starting state in each skin surface area: - Determination of the changes occurring from the periphery to the center or from the center to the periphery, - Simultaneous detection and evaluation of the entire area of the measurement values detected across the entire skin surface area, - The evaluation area can be configured into individual corresponding sectors, and spot-shaped detection and evaluation can be performed to analyze the spatially decomposed intensity (signal intensity) of each detected during a specific predetermined inspection time.

[0030] As pressure is applied to the skin surface, the detection device can determine the time until 90% of the individual measurements simultaneously detected by the device in the wavelength range of 570-650 nm fall below a second threshold, for example, less than 5%. In this way, the pallor time can be determined sequentially.

[0031] In substantial aspects of the present invention, capillary refill behavior can be detected using a standard method, minimizing the factors for parameter determination by each examiner. Therefore, comparative testing is objective, more reliable in interpretation, and more quantitative. The present invention is further advantageously configured to enable the complex determination of, in addition to the main parameter (capillary refill time), pallor time, capillary refill force, color ratio analysis, indentation depth determination, and recovery behavior / elasticity of the tested area.

[0032] A certain indentation depth in a skin surface area can be achieved by indentation into the skin and tissue using a stamp with a contact surface to the skin surface, or a standard pressure applicator such as compressed gas and / or compressed liquid acting on each skin surface area at a predetermined pressure.

[0033] Therefore, a specified pressure p acts on the skin surface on a specified surface in a standard manner. The continuous pallor phenomenon can be detected by a suitable measuring instrument. Here, the pressure is maintained for a specified time t1.

[0034] The termination of the pressure application effect on the tissue can be detected by an appropriate measuring instrument and output or evaluated as a quantitative parameter.

[0035] This allows for the presence of pressure or force sensors configured to continuously measure pressure or force acting on the skin surface region, thereby enabling monitoring within each skin surface region and allowing the detected measurements to be considered during the evaluation of capillary refill behavior.

[0036] The primary parameter is the time-dependent replenishment of blood flow, which in one aspect corresponds to the capillary refill time and thus approaches the comparability of conventional clinical applications. An essential aspect here is the development of the possibility of detecting specific two-dimensional (i.e., image) or three-dimensional location and region of intermittent inflow and decompression behavior between measurement steps with respect to the resumption of skin circulation. This allows for an additional time-dependent vector evaluation of inflow force, as well as one-dimensional / scalar characteristics. This makes it possible to derive new evaluation criteria, for example, from skin fading cluster morphology, compared to the prior art. The photodetector would preferably be configured to measure skin fading as a detector that performs spatial and spectral resolution detection and is capable of measuring dynamic changes.

[0037] This is, for example, a) Determining the change time elapsed until the end of the pressure effect or the release of the pressure is reached. b) Determination of the change pattern (e.g., change in blood color from the periphery to the center after the end of the pressure action on the skin surface area). c) The indentation depth and the recovery time (elasticity) of the compressed skin surface area under a given standard pressure can be further determined and optionally evaluated.

[0038] A hollow cylinder or hollow body with an opening, capable of being pressed against the skin surface, can be used separately as a pressing element, and its opening preferably borders a circular skin surface area. Thus, the central contact surface can be used once as an additional and regional expansion of the hollow cylinder or hollow body during pressure release. Therefore, the common pressure acting on the skin surface area and the contact surface of the pressing element used for evaluation can occur from the center to the periphery, in common or irregular pressure release.

[0039] As previously stated, the method according to the present invention can be carried out, for example, using a bidirectional OLED microdisplay device known from German Patent No. 10 2006 030 541 B4 as a suitable detection device. For this purpose, in certain modifications, optical imaging 1:1 can be achieved without additional optical elements by using a configuration with an extremely thin transparent encapsulation (barrier and mechanical / chemical / biological protection) between the OLED illumination layer and the layer (≤50 μm) formed by the detector.

[0040] In a detector array, particularly when using a bidirectional microdisplay, it is possible to continuously detect which / how many of the individual detection elements are in contact with a skin surface area using individual detection elements. This can be achieved both while pressure is being applied to each skin surface area and while the pressure is being gradually or abruptly terminated.

[0041] Alternatively, additional imaging microoptics can be incorporated into the thicker, transparent encapsulation of these microdisplays. Using the encapsulation of bidirectional OLED microdisplay components, geometrically detailed imaging of the contact surface can be achieved in direct physical contact with each surface of the patient being evaluated (in this case, the skin surface area), in terms of its optical properties (e.g., reflection and absorption) and the resulting contrast and / or color range. [Brief explanation of the drawing]

[0042] The present invention will be described in more detail below, using the example provided. These are shown below. [Figure 1] The principle of this invention is generally represented in a schematic manner. [Figure 2] A schematic diagram showing an example of the apparatus according to the present invention. [Modes for carrying out the invention]

[0043] Figure 1 shows a portion of a human patient's body surface where a circular skin surface area 2 is temporarily pressed by a predetermined pressure p during the examination. The skin surface area 2 has a defined specific area size and geometric shape and is imaged on the photodetector of the detection device 1. The detection device here is configured to spatially and spectrally resolve and measure the intensity at different locations within the skin surface area 2.

[0044] The measured values ​​are detected by individual detectors of the detection device 1 before the pressure p acts on the skin surface area 2, and can be stored in the electronic evaluation unit 5.

[0045] Next, the skin surface area 2 is subjected to a predetermined constant pressure p. This is done over a predefined time t1 of 5 seconds.

[0046] At the end of this time t1, the pressure application is terminated, and then ambient atmospheric pressure acts on the entire skin surface. The bodily fluids that were previously moved away from skin surface 2 return, and the pallor phenomenon on the skin surface region 2, which was caused by the action of pressure, gradually reverses again.

[0047] In this regard, the measured values ​​are still detected by detection device 1 in spatial and spectral resolution and compared to the initial measured values. This step measures the time it takes for at least 90% of the measured values ​​detected simultaneously by spatial resolution to reach the optically detected measured values ​​before the onset of pressure action. This time corresponds to the capillary refill time.

[0048] The pallor time can also be measured, as already described in the general part of the specification. Additionally, after the termination of the pressure action, changes in spatially and spectrally resolved measurements occurring from the outer edge of skin surface region 2 toward the center of the region can be measured.

[0049] A similar procedure can be performed using the apparatus shown as an example in Figure 2.

[0050] Here, there exists a hollow pressing element 4 with a circular wall whose inner diameter corresponds to the outer diameter of the skin surface area 2.

[0051] A cylindrical stamp 3 is placed within a pressing element 4 that is pressed against the skin surface with a constant force F2, and is pressed against the skin surface within the skin surface area 2 with a constant pressure F1. Within the skin surface area 2, a constant pressure p is applied so as to be in the range of 0.2 MPa to 2 MPa over time t1.

[0052] The detection device 1 is positioned inside the pressing element 4 above the stamp 3. The stamp 3 is guided into the pressing element 4 and pressed against the surface of the skin surface area 2 with a constant pressure F1, and a constant pressure p acts over time t1.

[0053] Stamp 3 can be formed from an optically transparent polymer such as PMMA.

[0054] The determination of the capillary refilling behavior can be carried out in a manner similar to the example in Figure 1, or as described in the general part of the specification.

[0055] Alternatively, instead of the stamp 3, compressed gas can be temporarily applied at a constant pressure p within the hollow space on the skin surface area 2 of the pressing element 4 over time t1, thereby pressing into the skin surface and moving bodily fluids from there. In principle, this does not change the measurement and evaluation in any way. In this case, the pressing element is a hollow body having an opening configured complementary to the outer contour of the skin surface area 2.

[0056] When the pressure effect is achieved by compressed gas, the gas can act directly on the skin surface. The detection device 1 is positioned at a distance from the skin surface.

[0057] However, it is also possible to place the detection device 1 inside the pressing element 4 and press it directly against the skin surface within the skin surface area 2 using compressed gas, thereby obtaining the effect of pressure from the detection device 1. After reducing the internal pressure in the hollow space of the pressing element 4 to ambient atmospheric pressure, the detection device 1 can be gently placed on the skin surface, and the measurement value can be detected at this position within the skin surface area 2.

Claims

1. A method for operating an apparatus for objectively measuring the behavior of capillary refilling, In a surface region (2) having a predetermined area size and outer contour and exhibiting capillary refilling behavior, spatial and spectral resolved photodetection is performed by at least one detection device (1) having a photodetector, thereby obtaining a measurement value based on the atmospheric pressure of the environment before the start of the additional pressure action, and then, A predetermined additional pressure p is applied to the surface region (2) at a constant rate over a predetermined time t1. The pressure application is terminated after the time t1 has elapsed. The detection device (1) repeatedly performs spatial and spectral decomposed light detection, and during the time t2 until at least 90% of the measured values ​​simultaneously detected by spatial decomposition reach the measured values ​​based on the atmospheric pressure of the atmospheric environment before the start of the additional pressure action, the refilling behavior of each capillary is determined spatially and spectrally. Before the start of the pressing action by the pressing element (4) or the internally hollow pressing element (4) having a hollow interior, and after the end of the pressing action, the detection device (1) performs two-dimensional or three-dimensional spatial resolution detection of the topology of the surface region (2). The temporal recovery behavior is evaluated by comparing the measured values ​​detected before and after the application of pressure on the surface region (2) in contact with the pressing element (4) or the internal hollow pressing element (4) by the electronic evaluation unit (5). method.

2. The predetermined additional pressure p is applied to the surface region (2) at a constant rate mechanically and / or pneumatically and / or hydraulically. The method according to claim 1.

3. As the detection device (1), a combined device having a detection and illumination configuration is used. The method according to claim 1 or 2.

4. The internal hollow pressing element (4), which completely encloses the outer edge of the surface region (2) within the area of ​​the surface region (2) and whose surface in direct contact with the surface region (2) has a predetermined size and geometric shape, is pressed onto the surface region (2) with a predetermined pressing force F2 during the time t1. Before the start of the pressurizing action on the surface region (2) where the internal hollow pressing element (4) comes into contact with the surface region (2), spatial and spectral resolved light detection of the image is performed on the surface region (2) by the detection device (1). At the end of the pressure application to the surface region (2), the internal hollow pressing element (4) is removed, and spatial and spectral resolved photodetection of the measured values ​​is repeatedly performed on the surface region (2), and the measured values ​​detected before the start of the pressure application are compared with the measured values ​​detected after the removal of the internal hollow pressing element (4). The method according to any one of claims 1 to 3.

5. In spectral resolution detection, only the wavelengths of the color of the surface region (2) that occur before, during, and after the pressure action and / or the applied pressure action are considered. The method according to any one of claims 1 to 4.

6. After the pressure application has ended, the changes in spatially and spectrally resolved measurements occurring from the outer edge of the surface region (2) toward the center of the region or in the opposite direction are measured. The method according to any one of claims 1 to 5.

7. Upon commencement of the pressure application to the surface region (2), the time until the minimum number of individual measurements simultaneously detected by the detection device (1) in the wavelength range of 570 to 650 nm falls below the second threshold is detected, and the pallor time is determined accordingly. The method according to any one of claims 1 to 6.

8. A device exists on the surface region (2) that applies a predetermined additional pressure p at a constant rate for a predetermined time t1. The surface region (2), which can be monitored by a detection device (1) configured for spatial and spectral resolved photodetection, is arranged such that spatial and spectral resolved photodetection of the measured values ​​is achieved in the main surface region (2) before, during, and after the pressure application. The detection device (1) is connected to an electronic evaluation unit (5), or the electronic evaluation unit (5) is incorporated into the detection device (1) and is configured to compare measured values ​​detected before, during, and after the pressure action, and to measure the time it takes for the minimum configurable amount of the measured value detected by spatial resolution to reach the measured value that was optically detected before the start of the pressure action. An apparatus for carrying out the method described in any one of claims 1 to 7.

9. The predetermined additional pressure p acting constantly on the surface region (2) can be applied to the surface region (2) by a mechanical device having a pressing element (4) that acts temporarily on the surface region (2), or by gas and / or liquid acting directly on the surface region (2) in a correspondingly compressed state, via the internal hollow pressing element (4), or via the detection device (1) on the surface region (2), in a hydraulic and / or pneumatic manner. The apparatus according to claim 8.

10. A stamp (3) and / or the detection device (1) are arranged inside the internal hollow pressing element (4) so ​​as to be able to temporarily contact the surface region (2) while surrounding it from the outside. or A gas and / or liquid that is temporarily compressed by the predetermined additional pressure p acting at a constant rate on the surface region (2) inside the internal hollow pressing element (4) can be introduced for the pressure action on the surface region (2). The apparatus according to claim 9.

11. A pressure or force sensor is provided which is configured to continuously measure the pressure acting on the surface region (2) or the force acting on the surface region (2). The apparatus according to any one of claims 8 to 10.

12. The photodetector provided in the detection device (1) is selected from a bidirectional display device and a hyperspectral imaging camera (HSI camera). The apparatus according to any one of claims 8 to 11.

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