Method, device and measuring system for providing a corrected physiological parameter

Abstract

The present invention relates to a method for providing a corrected physiological parameter, a corresponding device and a measuring system. The method comprises the following steps: irradiating a body portion of a patient with a first measurement radiation at a first wavelength, irradiating the body portion of the patient with a second measurement radiation at a second wavelength, with the first wavelength differing from the second wavelength, irradiating the body portion of the patient with a reference radiation at a third wavelength, with the third wavelength differing from the first wavelength and from the second wavelength and with the third wavelength being located in the blue or ultraviolet range, receiving measurement signals that correspond with radiation transmitted through the body portion or radiation reflected off the body portion and that correspond to the first wavelength, the second wavelength and the third wavelength, determining a physiological parameter on the basis of the measurement signals that correspond to the first wavelength and the second wavelength, determining a skin color correction factor on the basis of the measurement signals that correspond to the third wavelength and preferably the first wavelength and / or the second wavelength, determining a physiological parameter that is corrected on the basis of the skin color correction factor, and providing the corrected physiological parameter.

Description

[0001] Method, device and measuring system for providing a corrected physiological parameter

[0002] Description

[0003] The present invention relates to a method, a device and a measuring system for providing a corrected physiological parameter, for example a corrected oxygen saturation value.

[0004] Methods for determining physiological parameters using optical techniques are known. One example is pulse oximetry, which can be performed using a pulse oximeter and a corresponding measurement system.

[0005] Pulse oximetry is an optical measurement technique based on the discovery that oxygenated hemoglobin (oxygenated hemoglobin) exhibits different absorption behavior at predetermined wavelengths than non-oxygenated hemoglobin (deoxygenated hemoglobin). By irradiating a portion of a patient's body with two different wavelengths, the different absorption behaviors of oxygenated hemoglobin and deoxygenated hemoglobin can be determined and evaluated to calculate a corresponding oxygen saturation value. The oxygen saturation value indicates the proportion of hemoglobin in the blood that is oxygenated.

[0006] Since the absorption behavior described above is influenced by various factors, such as tissue types, it is common practice to measure the absorption behavior of oxygenated hemoglobin and deoxygenated hemoglobin relative to each other in order to improve the determination of the oxygen saturation value. The oxygen saturation value is usually determined by comparing the measurement signals with a reference curve or reference table, which is known in advance through calibration, i.e., by comparing it with calibration information.

[0007] To carry out the method described above, known pulse oximeters typically have two light-emitting diodes (LEDs) with different, predetermined wavelengths. Typically, a red LED with a wavelength in the range of 660 nm and an infrared LED with a wavelength in the range of 880 nm to 940 nm (905 nm to 920 nm) are provided. The known pulse oximeter typically has a photodiode as a radiation detector for receiving the radiation emitted by the LEDs. The LEDs and the photodiode are typically provided in a clip, which can be attached to the patient's body part and additionally reduces the incidence of stray light.

[0008] An example of a known method for determining the oxygen saturation value and a corresponding pulse oximeter are known, for example, from EP 1 237 465 A1.

[0009] It is known that the skin color of the patient's body part influences the determination of physiological parameters such as the oxygen saturation value described above.

[0010] However, at present, no method for providing a corrected physiological parameter and no corresponding device and measuring system are known with which it is possible to at least partially take this influence into account when determining the physiological parameter.

[0011] The present invention is therefore based on the object of providing a method for providing a corrected physiological parameter such as an oxygen saturation value, a corresponding device such as a pulse oximeter and a corresponding measuring system which can at least partially take into account the patient's skin colour when determining the physiological parameter.

[0012] This task is solved by the independent and subordinate claims.

[0013] The dependent claims, the description and the figures provide advantageous embodiments of the invention.

[0014] According to the invention, a method for providing a corrected physiological parameter is initially provided. The method comprises the following steps: irradiating a body portion of a patient with a first measurement radiation having a first wavelength; irradiating the body portion of the patient with a second measurement radiation having a second wavelength, wherein the first wavelength is different from the second wavelength; irradiating the body portion of the patient with a reference radiation having a third wavelength, wherein the third wavelength is different from the first wavelength and the second wavelength, and wherein the third wavelength lies in the blue or ultraviolet range; receiving measurement signals corresponding to the first wavelength, the second wavelength, and the third wavelength, which correspond to radiation transmitted through the body portion or reflected by the body portion.Determining a physiological parameter based on the measurement signals corresponding to the first wavelength and the second wavelength, determining a skin color correction factor based on the measurement signals corresponding to the third wavelength and preferably the first wavelength and / or preferably the second wavelength, determining a physiological parameter corrected based on the skin color correction factor, and providing the corrected physiological parameter.

[0015] The invention is based on the finding that the skin color of the patient's body part is particularly characterized by melanin, and that melanin has an easily measurable absorption or transmission behavior in the blue or ultraviolet range. The degree of absorption or transmission, in turn, depends on the amount of melanin in the skin and thus makes it possible to determine a skin color correction factor that correlates with the skin color and can be used to correct (at least partially, preferably completely) the physiological parameter determined in the conventional way with regard to its distortion by the skin color. By taking into account at least the measurement signal corresponding to the third wavelength, which correlates with the degree of absorption or transmission.Transmittance and preferably further by taking into account the measurement signal corresponding to the first wavelength and / or the second wavelength, the skin color correction factor can be determined.

[0016] Preferably, the determined physiological parameter is an oxygen saturation value. The oxygen saturation value indicates the proportion of hemoglobin in the patient's blood that is loaded with oxygen in the area of ​​the body.

[0017] A body segment is defined as an area or section of a patient's body. A body segment is, for example, a finger, an arm, a forehead, an earlobe, a foot, or a leg.

[0018] A (first or second) measuring radiation and a reference radiation are understood to be electromagnetic radiation in the optical frequency range, i.e., light. The light can be in the visible range, the ultraviolet range, and / or the infrared range.

[0019] Measurement radiation in the visible range is defined as light with a wavelength of not less than 380 nm and not more than 780 nm. Reference radiation in the ultraviolet range is defined as light with a wavelength of not less than 200 nm and not more than 400 nm.

[0020] Measuring radiation in the infrared range is understood to mean light with a wavelength of not less than 760 nm and not more than 3000 nm, preferably a wavelength of 880 nm to 940 nm.

[0021] Reference radiation in the blue range is understood to mean light with a wavelength of not less than 380 nm and not more than 500 nm.

[0022] Measuring radiation in a red range is understood to mean light with a wavelength of not less than 650 nm and not more than 780 nm, preferably a wavelength of 660 nm.

[0023] In the case of measurement radiation with essentially discrete wavelengths, different wavelengths are understood to mean wavelengths that are not identical. In the case where the measurement radiation does not have essentially discrete wavelengths, but rather, for example, a spectral distribution, the wavelengths are different from each other if at least the respective parameters selected from the following: peak wavelength, center wavelength, and center wavelength of the measurement radiation are not identical to each other.

[0024] Measurement signals corresponding to the first wavelength, the second wavelength, and the third wavelength corresponding to radiation transmitted through the body section or reflected by the body section are understood to be measurement signals which indicate a parameter of the radiation transmitted through the body section or reflected by it, wherein at least one measurement signal is received which corresponds to the first wavelength, at least one measurement signal is received which corresponds to the second wavelength, and at least one measurement signal is received which corresponds to the third wavelength. A measurement signal corresponds to a wavelength if it is the result of the detection of radiation in the range of the emitted wavelength or if it can be assigned to radiation in the range of the emitted wavelength using signal processing methods.A measurement signal also corresponds to a wavelength if it is the result of the detection of radiation which lies in a range which takes into account an influence of the wavelength, for example a shift, by properties of the measuring section.

[0025] The measurement signals can indicate radiation intensity as parameters of the radiation, i.e., they can correlate with it directly or indirectly. For example, a photodiode provides an electrically measurable quantity, such as a current, which correlates with the radiation intensity.

[0026] A skin color correction factor is understood to be a value that corresponds to or indicates the skin color of the patient's body part and thus enables at least a partial, e.g. percentage, correction of the physiological parameter, such as the oxygen saturation value, with regard to its distortion by the skin color.

[0027] The step of "providing the corrected physiological parameter" may include making the corrected physiological parameter available via a data interface and / or outputting the corrected physiological parameter via a human-machine interface, such as a display. For example, the corrected oxygen saturation value may be displayed on a patient monitor or transmitted to a medical device.

[0028] The first wavelength is preferably in the red range. The second wavelength is preferably in the infrared range.

[0029] Preferably, determining the skin color correction factor comprises the steps of: receiving calibration information indicating a predetermined relationship between the measurement signals corresponding to the third wavelength and preferably the first wavelength and / or preferably the second wavelength and the skin color correction factor, and determining the skin color correction factor based on the calibration information.

[0030] In this way, a simple to implement and low computational effort option can be provided to determine the skin color correction factor from the corresponding or some or all measurement signal(s).

[0031] The calibration information can be obtained, for example, through clinical trials and provided as predetermined information for the procedure. The calibration information can be provided, for example, as a look-up table or as a calibration curve.

[0032] Preferably, the irradiation of the patient's body section with the first measuring radiation, with the second measuring radiation and with the reference radiation takes place at different times and preferably repeatedly.

[0033] This makes it possible to reduce cross-influence of the measurement radiation and improve the quality of the measurement signals. Furthermore, it is possible to reduce the number of radiation detectors and provide multiple measurement signals with one or more radiation detectors at different times.

[0034] According to the invention, a device for providing a corrected physiological parameter, in particular a pulse oximeter, is further provided. The device comprises a number of radiation sources for irradiating a body portion of a patient with a first measuring radiation having a first wavelength, with a second measuring radiation having a second wavelength, and with a reference radiation having a third wavelength. The first wavelength is different from the second wavelength, and the third wavelength is different from the first wavelength and the second wavelength, wherein the third wavelength lies in the blue or ultraviolet range.The device further comprises a radiation detector for providing measurement signals corresponding to radiation transmitted through the body portion or reflected from the body portion, corresponding to the first wavelength and corresponding to the second wavelength, and preferably corresponding to the third wavelength.

[0035] A radiation source is understood to be a source for the (first and / or second) measuring radiation and / or for the reference radiation.

[0036] For example, the radiation source can emit broadband to provide each of the measurement radiations and the reference radiation. Furthermore, for example, a first radiation source, a second radiation source, and a third radiation source can be provided, wherein the first radiation source can be configured to emit the first measurement radiation, wherein the second radiation source can be configured to emit the second measurement radiation, and wherein the third radiation source can be configured to emit the reference radiation.

[0037] Each of the plurality of radiation sources can be configured, for example, as a light-emitting diode (LED) or a laser diode. Preferably, the first radiation source, if present, is configured to emit measurement radiation in the red range. Preferably, the second radiation source, if present, is configured to emit measurement radiation in the infrared range. Preferably, the third radiation source, if present, is configured to emit the reference radiation at the third wavelength.

[0038] If the number of radiation sources is configured as only one radiation source, it is preferred that this is configured to emit white light.

[0039] A radiation detector is a component designed to measure electromagnetic radiation, specifically light. A radiation detector can be configured, for example, as a photoresistor, a photodiode, a phototransistor, a bolometer, a pyroelectric detector, a thermoelectric detector, and / or a thermal detector. Other examples of suitable radiation detector designs include detector arrays, line detectors, CCD sensors, and CMOS sensors.

[0040] A plurality of radiation detectors may also be provided, wherein each radiation detector may be assigned, in terms of radiation technology, to exactly one radiation source of the number of radiation sources or to several, for example all, of the number of radiation sources.

[0041] The radiation detector or the radiation detectors may have one or more optical elements for beam guidance, e.g. lenses or optical fibers.

[0042] By providing the measurement signals corresponding to the third wavelength through the second radiation detector, it is possible to adapt the detection properties of the first radiation detector and those of the second radiation detector to the respective wavelengths to be detected, thus improving the measurement signal quality. If scattered light can be detected alternatively or additionally, it is also possible to determine information about incident scattered light, which can be used to further improve the measurement performance.

[0043] The radiation detector or detectors can have one or more optical filters, designed as physical filters, such as filter disks, or designed as digital filters. An optical filter is understood to be a component that selects the incident radiation according to predetermined criteria. Such a filter can be designed, for example, as a bandpass filter or double bandpass filter and select the radiation according to one wavelength or one or more wavelength ranges. By means of an optical filter, it is also possible to reduce the influence of stray light on the measurement and to improve the signal quality of the measurement signals. All features, definitions, and advantageous effects disclosed in relation to the method according to the invention and its preferred embodiments are also deemed to be disclosed in connection with the device, and vice versa.

[0044] Preferably, the number of radiation sources is configured as a number of light-emitting diodes. Additionally or alternatively, it is preferred that the radiation detector is configured as a photodiode.

[0045] In this way, the device can be provided cost-effectively.

[0046] Preferably, the device further comprises a second radiation detector, in particular a second photodiode, for providing measurement signals corresponding to radiation transmitted through the body portion or reflected by the body portion, corresponding to the third wavelength and / or corresponding to a wavelength which lies in the range of scattered light.

[0047] According to the invention, a measuring system is further provided.

[0048] The measuring system comprises a previously described device and an evaluation unit. The evaluation unit is configured to receive the measurement signals, determine a physiological parameter based on the measurement signals corresponding to the first wavelength and the second wavelength, determine a skin color correction factor based on the measurement signals corresponding to the third wavelength and preferably corresponding to the first wavelength and / or preferably corresponding to the second wavelength, determine a corrected physiological parameter based on the skin color correction factor, and provide the corrected physiological parameter. The physiological parameter can be configured as an oxygen saturation value.

[0049] All features, definitions and advantageous effects disclosed in relation to the method and device according to the invention and their preferred embodiments are also deemed to be disclosed in connection with the measuring system and vice versa.

[0050] The evaluation unit can be present as a hardware and / or software component of the device, for example, the pulse oximeter, or can be configured as a separate hardware and / or software component, for example, as part of a patient monitor or a medical device that receives and processes the measurement signals accordingly. For this purpose, the device can have power and / or data interfaces for the power and / or data coupling of the device to external devices. The data interface can be wireless or wired.

[0051] These and other features and advantageous embodiments of the invention will become apparent from the following description of the figures. Here:

[0052] Fig. 1 is a flow chart of an embodiment of the method according to the invention,

[0053] Fig. 2 shows an embodiment of the invention for determining the skin color correction factor,

[0054] Fig. 3 shows an embodiment of calibration information for use with the method according to the invention,

[0055] Fig. 4 shows a schematically illustrated embodiment of a device according to the invention in side view, Fig. 5 shows a schematically illustrated embodiment of the device according to the invention according to Fig. 4 along section line VV and a measuring system with the device.

[0056] Fig. 1 shows a simplified flow chart of a method 100 according to the invention for providing a corrected physiological parameter, for example an oxygen saturation value, SpO2_corr.

[0057] The method 100 comprises, as shown, at least the steps V1, V2, ...

[0058] V8. Further steps, especially data processing, signal conditioning, etc., are of course possible.

[0059] Step V1 is the irradiation of a body section K of a patient with a first measuring radiation M1 having a first wavelength.

[0060] Step V2 involves irradiating the patient's body section K with a second measuring radiation M2 having a second wavelength. The first wavelength is different from the second wavelength.

[0061] Step V3 is the irradiation of the body portion K of the patient with a reference radiation R having a third wavelength, wherein the third wavelength is different from the first wavelength and from the second wavelength, and wherein the third wavelength lies in the blue or ultraviolet range.

[0062] Step V4 is the reception of measurement signals s1, s2, s3 corresponding to the first wavelength, the second wavelength and the third wavelength, which correspond to radiation transmitted through the body section K or reflected by the body section K.

[0063] Step V5 is the determination of a physiological parameter, for example, an oxygen saturation value, SpO2, based on the measurement signals s1, s2 corresponding to the first wavelength and the second wavelength. Corresponding methods for determining a physiological parameter, for example, an oxygen saturation value, SpO2, are known. In the case of determining the oxygen saturation value SpO2, these are essentially based on the formation of a modulation quotient from the absorption quotients of the oxygenated and deoxygenated hemoglobin. To form the modulation quotient, the respective quotient of the alternating component over the constant component at each wavelength is first formed in an intermediate step, and the modulation quotient is then formed from these.The modulation quotient can then be used, for example, by comparison with an empirically determined calibration curve to determine the current oxygen saturation value (SpO2). Other methods for determining the oxygen saturation value (SpO2) are also known.

[0064] Step V6 is the determination of a skin color correction factor corr based on the measurement signals s3 corresponding to the third wavelength and preferably the first wavelength s1 and / or preferably the second wavelength s2.

[0065] This determination can be done in different ways.

[0066] For example, using a physiological model of body segment K, the relationship between the correction factor corr and skin color with respect to some or all of the measurement signals s3, s2, s1 can be modeled. A look-up table can be generated from this and provided as predetermined information for the method. By carefully selecting the level of abstraction of the model, the accuracy of the model can be predetermined and the complexity of the predetermined information can be influenced.

[0067] Another possibility is to obtain empirical calibration information, e.g., through clinical tests, and use this as predetermined information to determine the skin color correction factor corr. Another possibility is to derive empirical calculation rules from empirically obtained data that allow the assignment of some or all of the measurement signals s3, s2, s1 to the corresponding skin color correction factor corr.

[0068] Step V7 is the determination of a physiological parameter corrected based on the skin color correction factor corr, for example an oxygen saturation value SpO2_corr.

[0069] For this purpose, step V7 may, for example, comprise forming a quotient of the measurement signals corresponding to the third wavelength s3 and the measurement signals corresponding to the first wavelength s1. Another possibility is to form a quotient of the measurement signals corresponding to the third wavelength s3 and the measurement signals corresponding to the second wavelength s2.

[0070] Another possibility is to divide the measurement signals into DC components and AC components before forming the quotient and to also form a quotient for these, which are then used to form the first quotient, ie according to the following formula:

[0071] AC3

[0072] 0 =

[0073] V DC3AC l / 2 '

[0074] DC l / 2 where Q denotes the quotient of the measurement signals corresponding to the third wavelength s3 and the measurement signals corresponding to the first wavelength s1 or the quotient of the measurement signals corresponding to the third wavelength s3 and the measurement signals corresponding to the second wavelength s2, AC3 denotes the alternating component of the measurement signal corresponding to the third wavelength s3, DC3 denotes the direct component of the measurement signal corresponding to the third wavelength s3, AC1 / 2 denotes the alternating component of the measurement signal corresponding to the first s1 or second wavelength s2 and DC1 / 2 denotes the direct component of the measurement signal corresponding to the first s1 or second wavelength s2.

[0075] From the quotient thus determined and a predetermined, for example empirically determined, relationship between the quotient and the skin color correction factor corr, the currently available skin color correction factor corr can then be determined.

[0076] A simple way to correct the physiological parameter, for example oxygen saturation, SpO2, using the skin color correction factor corr determined in this way or otherwise, is to make a correction according to the following formula:

[0077] SpO2_corr = SpO2 + corr • SpO2 .

[0078] Step V8 of the method is the provision of the corrected physiological parameter, for example the oxygen saturation value SpO2_corr, preferably comprising the output of the corrected physiological parameter, for example the oxygen saturation value SpO2_corr.

[0079] Fig. 2 shows that step V6 of the method shown in Fig. 1 can comprise steps V61 and V62.

[0080] Step V61 is the reception of calibration information I which indicates a predetermined relationship between the measurement signals corresponding to the third wavelength s3 and preferably the first wavelength s1 and / or preferably the second wavelength s2 and the skin color correction factor corr.

[0081] Step V62 is the determination of the skin color correction factor corr based on the calibration information I. An example of calibration information I that can be used in the method 100 according to Fig. 2 is shown in Fig. 3.

[0082] The calibration information I can thus be designed, for example, as a calibration curve which provides a predetermined relationship between the skin colour correction factor corr and at least the measurement signal s3 corresponding to the third wavelength.

[0083] Fig. 3 illustrates by way of example that it is possible to form the relationship between a quotient of the measurement signal s3 corresponding to the third wavelength and the measurement signal s1 corresponding to the first wavelength using the correction factor corr. Instead of this quotient, the previously described quotient, referred to above as Q, can also be used and provided in correlation with the correction factor corr as calibration information I. It is not necessary to form a quotient; any other type of assignment of at least the measurement signal s3 corresponding to the third wavelength to the correction factor corr is possible.

[0084] The qualitative course of the curve shown in Fig. 3 is merely schematic and may differ from the actual course. A curve representation of the calibration information I is not required.

[0085] In the illustrated method 100 according to Fig.1 and 2, it is possible for the irradiation of the body section K with the first measuring radiation V1, with the second measuring radiation V2 and with the reference radiation V3 to be carried out at different times (i.e. not overlapping or partially overlapping, but not identically) and preferably repeatedly.

[0086] 4 and 5 show embodiments of a device 200 according to the invention for providing a corrected physiological parameter, for example, configured as a pulse oximeter 200. Fig. 5 is a sectional view of the device 200 according to Fig. 4 along section line VV. The device 200, for example the pulse oximeter 200, comprises, as shown, a number of radiation sources 10, 20, 30 for irradiating a body portion K (in Fig.4, 5 (illustrated as a finger by way of example) of a patient with a first measuring radiation M1 having a first wavelength, with a second measuring radiation M2 having a second wavelength, wherein the first wavelength is different from the second wavelength, and with a reference radiation R having a third wavelength, wherein the third wavelength is different from the first wavelength and the second wavelength, and wherein the third wavelength lies in the blue or ultraviolet range, and a radiation detector 40.

[0087] The device 200, for example, the pulse oximeter 200, can otherwise be configured in any desired manner. In Figs. 4 and 5, the device 200, for example, the pulse oximeter 200, is embodied, for example, in a clamp arrangement with a first clamping element 51 and a second clamping element 52, which are pivotally connected via a joint 53 to clamp the body portion K, here the finger, between them.

[0088] The number of radiation sources 10, 20, 30 can, for example, comprise a first radiation source 10, a second radiation source 20, and a third radiation source 30. The number of radiation sources 10, 20, 30 can, for example, be accommodated in the first clamping element 51 of the device 200, for example, the pulse oximeter 200, and there emit the respective radiation, namely the first measuring radiation M1, the second measuring radiation M2, and the reference radiation R' and / or R" - shown in Fig. 5 with schematic center axes of the respective beams.

[0089] Depending on whether the device 200, for example the pulse oximeter 200, is designed to be transmissive or reflective, the radiation detector 40 is arranged on the same side as the number of radiation sources 10, 20, 30 or - as shown - on the opposite side, which provides measurement signals corresponding to the radiation transmitted through the body section K or reflected by the body section K, corresponding to the first wavelength s1 and corresponding to the second wavelength s2 and preferably corresponding to the third wavelength s3.

[0090] The first radiation source 10 and / or the second radiation source 20 and / or the third radiation source 30, if present as shown, can each be configured as a light-emitting diode. Configuring some or all of the aforementioned radiation sources 10, 20, 30 as individual or joint laser diodes is also possible.

[0091] In an example not shown, the number of radiation sources 10, 20, 30 can also be designed as only one common radiation source, which is configured to emit broadband radiation comprising at least the first measuring radiation, the second measuring radiation and the reference radiation.

[0092] The radiation detector 40 can be designed as a photodiode.

[0093] As shown in Fig. 5, the device 200, for example the pulse oximeter 200, can optionally have a second radiation detector 50, in particular a second photodiode, in one embodiment. The second radiation detector 50 can, in addition to the radiation detector 40 or alternatively to the radiation detector 40, provide measurement signals corresponding to the third wavelength s3 and / or a wavelength in the range of scattered light with radiation transmitted through the body portion K or reflected by the body portion K. Corresponding reference radiation R", which is emitted in the direction of the second radiation detector 50, is indicated by a schematic center axis of the corresponding beam in Fig. 5.

[0094] Fig. 5 also shows a schematic representation of a measuring system 300 according to the invention.

[0095] The measuring system 300 comprises, in addition to the device 200 described above, an evaluation unit 60, for example a control unit of the device 200 or an external control and / or computing unit, which is configured to: receive the measurement signals s1, s2, s3, determine a physiological parameter, for example an oxygen saturation value SpO2, based on the measurement signals corresponding to the first wavelength s1 and the second wavelength s2, determine a skin color correction factor corr based on the measurement signals corresponding to the third wavelength s3 and preferably corresponding to the first wavelength s1 and / or preferably corresponding to the second wavelength s2, determine a corrected physiological parameter, for example a corrected oxygen saturation value SpO2_corr, based on the skin color correction factor corr, and tofor example, to provide the corrected oxygen saturation value SpO2_corr.

[0096] Not shown is that the evaluation unit 60 can be connected in terms of data technology to a human-machine interface, such as a display, in order to output the corrected physiological parameter, for example the corrected oxygen saturation value SpO2_corr.

[0097] All features mentioned herein may be combined with each other as desired, provided that this does not affect alternatives or is contradictory.

[0098] List of reference symbols

[0099] 10 first radiation source

[0100] 20 second radiation source

[0101] 30 third radiation source

[0102] 40 Radiation detector

[0103] 50 second radiation detector

[0104] 51 first clamping element

[0105] 52 second clamping element

[0106] 53 joint

[0107] 60 evaluation unit

[0108] 100 procedures

[0109] 200 pulse oximeters, device

[0110] 300 Measuring system corr, corrl Correction factor

[0111] I Calibration information

[0112] K Body section

[0113] M1 first measuring radiation

[0114] M2 second measuring radiation

[0115] R, R', R” Reference radiation s1, s2, s3 Measurement signals

[0116] SpO2 physiological parameter, oxygen saturation value

[0117] SpO2_corr corrected physiological parameter, corrected

[0118] Oxygen saturation value

[0119] V1, V2, ... process steps

Claims

Patent claims 1. Method (100) for providing a corrected physiological parameter (SpO2_corr), comprising the steps (V1, V2, ...): (V1) Irradiating a body section (K) of a patient with a first measuring radiation (M1) having a first wavelength, (V2) Irradiating the patient's body section (K) with a second measuring radiation (M2) having a second wavelength, wherein the first wavelength is different from the second wavelength, (V3) Irradiating the patient's body section (K) with a reference radiation (R) having a third wavelength, wherein the third wavelength is different from the first wavelength and the second wavelength, and wherein the third wavelength is in the blue or ultraviolet range, (V4) receiving measurement signals (s1, s2, s3) corresponding to the first wavelength, the second wavelength and the third wavelength, which correspond to radiation transmitted through the body section (K) or reflected by the body section (K), (V5) Determining a physiological parameter (SpO2) based on the measurement signals (s1, s2) corresponding to the first wavelength and the second wavelength, (V6) Determining a skin color correction factor (corr) based on the measurement signals (s3, s1, s2) corresponding to the third wavelength and preferably the first wavelength and / or preferably the second wavelength, (V7) Determining a physiological parameter (SpO2_corr) corrected based on the skin color correction factor (corr), and (V8) Providing the corrected physiological parameter (SpO2_corr).

2. The method (100) according to claim 1, wherein determining the skin color correction factor (V6) comprises: (V61) receiving calibration information (I) which indicates a predetermined relationship between the measurement signals (s1, s2, s3) corresponding to the third wavelength and preferably the first wavelength and / or preferably the second wavelength and the skin colour correction factor (corr), and (V62) Determine the skin color correction factor (corr) using the calibration information (I).

3. Method (100) according to claim 1 or 2, wherein the irradiation of the body portion (K) of the patient with the first measuring radiation (V1), with the second measuring radiation (V2) and with the reference radiation (V3) is carried out with a time offset and preferably repeatedly.

4. A device (200) for providing a corrected physiological parameter (200), comprising: - a number of radiation sources (10, 20, 30) for irradiating a Body section (K) of a patient with: a first measuring radiation (M1) with a first wavelength, a second measuring radiation (M2) with a second wavelength, and with a reference radiation (R) with a third wavelength, wherein the first wavelength is different from the second wavelength, wherein the third wavelength is different from the first wavelength and from the second wavelength, and wherein the third wavelength is in the blue or ultraviolet range, and - a radiation detector (40) for providing radiation emitted by the Body section (K) transmitted or reflected by the body section (K) corresponding measurement signals (s1, s2, s3) according to the first wavelength and according to the second wavelength and preferably according to the third wavelength.

5. Device (200) according to claim 4, wherein the number of radiation sources (10, 20, 30) is designed as a number of light-emitting diodes, and / or wherein the radiation detector (40) is designed as a photodiode.

6. Device (200) according to claim 4 or 5, further comprising a second radiation detector (50), in particular a second photodiode, for providing measurement signals (s3) corresponding to radiation transmitted through the body portion (K) or reflected by the body portion (K) according to the third wavelength and / or according to a wavelength which lies in the range of scattered light.

7. Measuring system (300), comprising: - a device (200) according to one of claims 4 to 6, and - an evaluation unit (60) which is set up: - to receive the measuring signals (s1, s2, s3), - a physiological parameter (SpO2) based on the measuring signals (s1, s2) corresponding to the first wavelength and the second wavelength, - a skin color correction factor (corr) based on the measuring signals (s1, s2, s3) corresponding to the third wavelength and preferably corresponding to the first wavelength and / or preferably corresponding to the second wavelength, - to determine a corrected physiological parameter (SpO2_corr) based on the skin colour correction factor (corr), and - provide the corrected physiological parameter (SpO2_corr).

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