WO2007056995A1

WO2007056995A1 - Autoadaptive calibration

Info

Publication number: WO2007056995A1
Application number: PCT/DE2006/002013
Authority: WO
Inventors: Klaus Forstner
Original assignee: Weinmann Geräte für Medizin GmbH & Co. KG
Priority date: 2005-11-15
Filing date: 2006-11-14
Publication date: 2007-05-24
Also published as: DE112006002808A5; DE102006053975A1

Abstract

The invention relates to a method for the autoadaptive calibration of at least one extinction of at least one constituent of body tissue. The extinction is combined with at least one measuring value variable and/or at least one parameter of a measuring value variable and/or at least one constant. The result of the combination represents the quantity of the wanted constituent of body tissue at the time of measurement. The measurement is carried out using electromagnetic radiation whose source is disposed adjacent to the body tissue. The source generates radiation of various wavelengths and radiation penetrating the body tissue or reflected radiation is detected by a photoreceivers. The measurement signals of the photoreceiver are fed to an evaluation device which, in accordance with the number of wavelengths, determines at least one measuring value variable.

Description

Autoadaptive calibration

The invention relates to a method for calibration which adapts to individual measuring properties of patients, called "autoadaptive calibration". The method according to the invention serves to correct the results of the measurement of physiological variables. When measuring physiological quantities, the results can be influenced by physiological and / or external influences.

According to the invention, measured value variables are extracted from the results, which serve to determine correction factors. The results of the measurement of physiological quantities are linked by mathematical relationships with the correction factors in order to compensate the physiological and / or external influences individually and automatically.

The prior art methods have the disadvantage that a calibration according to the results of a collective of persons, which was selected in the development of the respective methods. As a result, when used for an individual patient, a relatively high degree of measurement inaccuracy may exist, since individual can not be taken into account in the general calibration of the patient in question.

It is therefore an object of the present invention to specify a method of the type mentioned in the introduction in such a way that it is possible to take into account the individual characteristics of the patient and / or all external factors acting on the determination of the target values and thus to provide increased measurement accuracy.

The calibration function G according to the invention is a mathematical relationship of measured value variables MV of the results of the measurement of physiological variables and a target value Z, which are obtained on a collective of test persons, in order to be applied to all subsequent patient measurements. Simplified, the relationship between Z and MV is as follows:

Z = G (MV)

The function G transfers the measured value variables MV into the desired target variable Z and is therefore called a calibration function.

If the functional relationship between the measured value variables MV and the target variable Z is constant, this is called a KONSTANT calibration. If the calibration function G itself depends on further parameters that are obtained from the measuring system in the course of the measurement, this is called ADAPTIVE calibration.

This is exemplified by a simple calibration function:

The calibration function is given with the large K ₀ and Ki as follows: Z = K ₀ + Ki ^• MV

If K ₀ and Ki are constant quantities that can be applied to all patient measurements, a constant calibration is available.

However, if K ₀ and / or Ki are dependent on further variables which originate from the measuring system, an adaptive calibration is present. With this calibration, individual properties of the measuring system are corrected, which would not be adequately described by MV alone.

In accordance with the present invention, adaptive type calibration functions are proposed for use in medicine. This can be a dynamic compensation of physiological and / or external parameter changes of the measurement, such as changes in sensor position, sensor compression of the tissue, patient movements, volume changes in the tissue and / or vessels involved, varying blood fillings or the influence of specific histoanatomy during the Carry out the measurement.

In the following, the relationships concerning the different types of calibration will be described in more detail.

In general, the determination of the target variable Z is carried out via the calibration function G, and this in turn depends on system parameters K and measured value variables MV.

It therefore applies:

Z = G (K, MV) System parameters K are coefficients of the calibration function which define the basic structure of this function, in which they describe the underlying physical and physiological conditions of the measurement.

Measurement variables MV are computational variables resulting from the measurement of physiological magnitudes P. The Meßswert- variables are with these physiological quantities P on the

V

Measured value - function H (P) connected.

So in total for any calibration functions:

Z = G (K, H (P)) with MV = H (P).

V V V

It should be noted that with respect to the determination of. Target variables can be any number of measured value variables, physiological base parameters and system parameters.

In the practical application of pulse spectroscopic measurements, the physiological parameters represent measurement results of the recorded patient plethysmograms, the measured value variables are generated by linking the plethysmogram values and the system parameters result from the place of application, the measurement methodology (transmission or reflection) as well as the electrophotographic and mechanical sensor construction.

a) constant calibration (K _v = constant)

Where: K _v ≠ f (P _v , MV _V ) = const.

With:

K _v : fixed, ie constant system parameters. P _v : physiological basic parameters MV _υ : measured value variables derived from the physiological basic parameters.

The principle of constant calibrations, which are very common in medicine and biology, is shown in FIG.

b) Adaptive calibration

In this case, the system parameters K _v become non-constants V _v , which are dependent on the measured value variables themselves. The principle of adaptive calibrations is shown in FIG.

The following applies:

Z = G (Kv (MV _v, Pv), MVV (Pv))

in which:

Kv = f (MV _V (Pv), Pv)

With:

K _v = f (MVv (Pv) / Pv) ••• variable variable K _υ which depends on the measured value variables MV _V and on the parameters P _v that determine the measured value variables.

MVv (Pv) ... Measured value variables dependent on the parameters P _v

Pv ... Physiological basis - parameters The adaptive calibration can be homogeneous or inhomogeneous:

If the parameters P _x which are also included in the function MV _V (P _V ) of the measured variable itself are used for adaptive calibration, this is called homogeneous adaptation. If, however, parameters P _x are used which are not included in the calculation of the measured value variables MV, then this is called inhomogeneous calibration.

For clarification, the parameters P ₁ ... P _x would be included in the MV (P _v ). Then there is a homogeneous adaptation if the ad- ditional size K is also given by all or a subset of the elements Pi ... P _x , ie, it holds for all P _v :

P _v . e (P ₁ ... P _x }.

Then:

£ = / [MF _1. (P, ... PJ..M ^ (P ₁ ... PJ; P ₁ ... PJ

However, if there is an adaptation with additional parameters that are NOT included in the measured value variables MVi - MV _x , then parameters P _y occur. This is the inhomogeneous adaptive calibration and applies to these:

It then follows for the variable K in the adaptive calibration:

K = f [MV _x (P _v. P _x ) .MV _x (P _λ ... P _x ) -P _v. P _x , P _y - \ The results of the measurement of physiological quantities are linked by mathematical relationships with the determinants K in order to compensate the physiological and / or external influences individually and automatically.

If this adaptation of the calibration to individual system properties is performed only once, namely initially for the measurement, this is called initial adaptive calibration.

However, if this adaptation is performed automatically in the course of the measurement, it is referred to as automatic adaptive calibration or "auto-adaptive calibration" for short, and even shorter to A ² C.

Auto-adaptive calibration has the advantage that it automatically corrects all system changes during a measurement by continually adjusting the calibration to them.

The inventive method can be applied according to an embodiment in the non-invasive and continuous measurement of the absolute hemoglobin concentration in the blood. For this purpose, electromagnetic radiation at different radiation frequencies is passed through a vessel and / or tissue containing the blood, and at least a portion of the radiation emerging from the vessel and / or tissue is detected by sensors and sent to an evaluation.

The invention can furthermore be embodied in a device for measuring further constituents in the blood, which has at least one emission source for generating electromagnetic radiation and for detecting a transmission component or reflection component of the radiation, which sensor is connected to an evaluation device. Among other things, the determination of the concentration of hemoglobin is clinically significant. Previous methods are associated with a blood sample and subsequent laboratory tests.

The total concentration of hemoglobin (cHb) is composed of the functional Hb components, namely the oxyhemoglobin (HbO ₂ ) and the deoxygenated hemoglobin (HbDe), as well as the dyshemoglobins (HbDys). HbDe and HbO ₂ are used for oxygen transport.

The dysfunctional hemoglobin derivatives such as carboxyhemoglobin (COHb), methemoglobin (MetHb) and sulfhemoglobin (HbSuIf) are not able to reversibly store oxygen. If these derivatives increase in blood, they can significantly reduce the transport capacity of hemoglobin for O ₂ and thus lead to hypoxemia.

After the release of Hb, which takes place during degradation, disintegration of the red blood cells, its degradation into bile pigments (porphyrin derivative), iron and the like occurs. Globin.

The exact determination of the concentrations of the hemoglobin fractions or the total Hb concentration was so far only invasive, .d.h by the investigation of a blood sample on the patient possible.

In one exemplary embodiment, at least one source of electromagnetic radiation and, in a specific arrangement, at least one photoreceiver are arranged in relation to the biological tissue to be examined. The sources of electromagnetic radiation may include different wavelengths and are passed through the tissue. Subsequently, measuring signals are then fed to the photoreceiver of an evaluation device. The evaluation device determines at least one measured value variable MV depending on the number of wavelengths. The measured value variable consists of at least two physiological parameters Parameters P, wherein at least one parameter P represents a variable size of the vessel and / or tissue at the time of beam passage. At least one measured value variable MV is linked to at least one parameter and at least one determination constant K. The result of the linkage represents the target variable Z, namely the concentration c of at least one constituent of the body tissue at the time of the beam passage.

A portion of the electromagnetic waves that has passed through the tissue is detected by a receiving system. The receiving system has a spectral bandwidth which makes it possible to detect a wide range of wavelengths which preferably strike the receiving system repetitively at a time interval of less than 0.5 sec. The detected electromagnetic waves are subsequently processed by signal conditioning. Their amplitude is weighted depending on the emitted wavelength. This can e.g. be realized by activated filter functions and / or reinforcing elements.

A particularly simple metrological structure can be achieved by using electromagnetic radiation in the ultraviolet, visible and infrared frequency ranges.

Advantageously, the source emits electromagnetic radiation of at least two wavelengths selected from a range of substantially 300 nm to 1800 nm. Preferably, however, not exclusively selected from the following wavelengths:

400nm ± 25%, 460nm ± 25%, 480nm ± 25%, 520nm ± 25%, 550nm ± 25%, 560nm + 25%, 606nm ± 25%, 616nm ± 25%, 624nm ± 25%, 630 nm ± 25%, 650 nm ± 25%, 660 nm ±, 705 nm ± 25%, 710 nm ± 25%, 720 nm ± 10%, 805 nm ± 25%, 810 nm ± 25%, 880 nm ± 25%, 905 nm ± 25%, 910nm ± 25%, 950nm ± 25%, 980nm ± 25%, 1050nm ± 25%, 1200nm ± 25%, 1310nm ± 25%, 1380nm ± 25%, 1450nm ± 25%, 1550 nm] ± 25%, 1600 nm ± 25%, 1800 nm ± 25%.

The method of pulse spectroscopy can be used for the measurement. This determines the absolute or relative concentration of certain substances by measuring pulsatile perfusion curves at different wavelengths with reference to known absorption spectra of biological substances.

By calculating at least two detected electromagnetic wavelengths, an analyzer determines from these signals at least one measured value variable (MV).

Depending on the number N of. investigated wavelengths different numbers of MV can be formed.

It applies to the maximum number of measured value variables MV from the number of the measuring wavelengths, if in each case a pair of measuring wavelengths is used for measuring value variable formation:

Number MV = - N- (N-V) N = number of wavelengths

Generally, however, each measured value variable MV _AB can be made up of M _A parameters P _A and M ₈ parameters P ₈ .

It then applies to MV _AB :

MV _AB = f (PAI .-. PAMA; PBI .-. PBMB)

Preferably, M _A = 1 and M ₁₃ = I parameters are used. It _. Then there is a pair A, B of parameters for which the above-mentioned maximum number of measured value variables applies. A typical, but not exclusive, application example is that the concentration of total hemoglobin (c _Hb ) is determined. The concentration of oxyhemoglobin (HbO ₂ ) and / or deoxygenated hemoglobin (HbDe) and / or carboxyhemoglobin (HbCO) and / or methemoglobin (HbMet) and / or sulfhemoglobin (HbSuIf) can also be determined.

Furthermore, it is also possible to determine the concentration of those substances which can intentionally and / or unintentionally bind with hemoglobin. According to the invention, any substance concentration which results from the addition and / or binding of a substance X to Hb (called HbX) can be determined.

It is also possible that further transport proteins both natively (in naturally occurring form) and in iatrogenic binding after pharmacological doping spectroscopically by the resulting characteristic course of the spectral characteristics (eg but not exclusively: absorption, reflection, transmission & extinction) be determinable by means of a determination using an adaptive calibration.

It is also specifically contemplated that concentrations of non-hemoglobin-associated components will be determined. This applies to both native and iatrogenically applied blood substances. An application example is that both derivatives of bilirubin and the total concentration of bilirubin is determined. It is also possible that a concentration of myoglobin and troponin is determined. The invention also contemplates the determination of the concentration of glucose and / or insulin.

In addition, it is intended to determine the concentrations of iatrogenically applied dyes and their kinetics. The concentration of total hemoglobin is composed of the proportions of the hemoglobin fractions.

cHb = CHbDe + CHbO ₂ + cHbDys cHbDys = cHbCO + cHbMet + CHbSuIf

Where: cHbDe: concentration of deoxygenated hemoglobin cHbCO: concentration of the carboxylated hemoglobin cHbMet: concentration of methemoglobin cHbSulf: concentration of SuIf - hemoglobin

CHbO ₂ : the concentration of oxygenated hemoglobin

A determination of the cHb can thus be carried out as follows, but here, but not necessarily, saSulf = cHbSulf / cHb is not taken into account:

1 = cHbDe + cHbOl + cHbCO + cHbMet cHb cHb cHb cHb

1 = SaDe + SaO ₂ + SaCO + SaMet

saDe: Hematuration of hemoglobin sa02: Oxygen saturation of hemoglobin saCO: Carbon monoxide saturation of hemoglobin saMet: Methemoglobin saturation

The passage of light through a vessel or tissue is given as follows: see Fig. 6

Iout (t) = I _1n ^• e ^" ° ^• e ^{" p (t)}

ε are the molar extinction coefficients underlying the respective substances, c the respective concentrations, d _k is the total thickness of the constant tissue. dA (t) is the pulse-cyclic time-dependent thickness of the pulsating blood vessels. If two times t _x and t _{2 are} considered, the weakening fraction of the constant tissue is eliminated:

In this case, after logarithmation on both sides:

π is a wavelength-dependent variable, which depends on the extinction coefficients of the substances of the pulsating blood space as well as their Hb saturations as well as on the extinction of water and the relative concentration c _H 2o / c _H b. Where:

The relationship

Δ /

4, (A)

is then termed "partial pulse modulation PPM" when ΔI corresponds to a portion of the maximum systolic-diastolic plethysmographic pulse difference and is called "total pulse modulation TPM" when ΔI is the total diastolic-systolic plethysmographic pulse difference.

Generally XPM is set for the terms PPM and TPM, so: XPM e {PPM, TPM}. ,.

ΔI and I and thus XPM are physiological measurement parameters P, which are incorporated into the formation of measured value variables MW. The parameters have physiological significance, and are in the present case a measure of the pulse-cyclic change in vessel thickness.

Here, for example, 2 measuring wavelengths λ _A and λ _B are used to form a measured value variable by means of the parameters P. This is called Ω _AB :

In this case, Ω _{AB is} the measured value variable with respect to the two wavelengths λ _A / λ a.

This is followed by the definition of the wavelength-dependent Hb partial parameters η _A and η _B :

This results in the determination of the hemoglobin concentration CHb:

(A)

16 with the important special cases that the extinctions for the water absorption at λ _{A are} sufficiently small:

^ ¹ AB ^'S H2O, B, τ> \

^{Hb =} n ⁷ IA - Ω ¹¹ AB - n ⁷ IB ⁽⁾

and if in addition the Hb absorption at the wavelength λ _B ZU is negligible:

In this case (C) the hemoglobin concentration is to be determined as a linear function of the measured variable Ω _AB . The determination equations for the hemoglobin concentration c _H b exemplified here contain a measured value variable Ω _AB , which in turn is formed by the system parameters XPM _A and XPM _B. For exemplary explanation of the adaptive calibration, the basic relationship (A) is considered:

The target variable Z in this case is c _H b- The first measured value variable used here is Ω _AB . The determination of hemoglobin saturation in the hemoglobin partial parameters η _A and η _B requires further measured value variables. For the presented 4 Hb fractions, it is possible to determine the associated Hb saturations saθ ₂ , saDe, SaCO and saMet over 4 wavelengths. With 4 wavelengths, it is known that 6 (= h * 4 * (4 ~ 1)) different measured value variables can be formed from 2 wavelengths. From these at least 3 linearly independent measured value variables are extra ^¬ hiert, which are required for the calculation of Saettigungen. The parameters XPM of each wavelength are included in these measured value variables.

The described equation (A) includes extinction coefficients ε, which are determined in biological tissues by two basic processes:

- wavelength-dependent absorption of photons. Wavelength-dependent scattering on the tissue.

Of these two elementary processes, scattering plays a dominant role in biological media. For a broad wavelength range, the number of scattering processes per unit length in muscle / fat and connective tissue exceeds that of the absorption processes by a factor of 5 - 10.

The multiple scattering in biological tissues, in particular on biological fine structures such as cell boundaries, causes a considerable lengthening of the resulting photon paths and thus an increase in the absorption probability.

The determination of the total hemoglobin concentration according to (A) requires the consideration of the tissue / thickness and substance - specific size change of the extinction coefficients in the tissue.

This is done by the principle of initial or automatic adaptive calibration.

The adaptive calibration corrects the following influences:

• the histoanatomy - described by the parameter Histo, is corrected by a correction factor Alpha α The photon attenuation of non-pulsatile constant tissue, for example the venous blood filling, primarily described by the parameter Imin, is corrected by a correction factor Tauτ

• the change in thickness, for example of a pulsating vessel, primarily described by the parameter TPM, is corrected by a correction factor Sigma

Each extinction coefficient ε of a substance x depends on physiological basic quantities such as imine and TPM. This applies to all wavelengths A, B which contribute to the formation of a measured value variable MV _A B.

Thus, the parameter ε _x depends on the spectroscopically recorded basic parameters:

Imine (λ _A ) Iminlλβ)

TPM (λ _A )

- TPM (λ _B ) and these quantities are for adaptive calibration by

Modification of extinctions ε _{x used} . It generally applies:

ε _x = f (imine (λ _A ); imine (λ _B ); TPM (λ _A ); TPM (λ _B ))

For example, for four wavelengths, there are 16 (transcutaneous) extinctions:

X _x : SHbDe (Ai), SHbO ₂ (A ₁ ), SHbCO (X ₁ ), SH ₂ O (Ai)

A ₂ : SHbDe (A ₂ ), SHbO ₂ (A ₂ ), SHbCO (A ₂ ), SH ₂ O (A ₂ ) A ₃ : ^ HbDe (A ₃ ), SHbO ₂ (A ₃ ), SHbCO (A ₃ ), SH ₂ O (A ₃ )

A ₄ : SHbDe (A ₄ ), SHbO ₂ (A ₄ ), SHbCO (A ₄ ), SH ₂ O (A ₄ )

According to the invention, at least one of the extinctions is corrected by means of the (auto) adaptive calibration. Preferably, at least two extinctions are corrected by means of the autoadaptive calibration.

The correction takes place, for example, according to the following formula:

£ sub, corr (Ax) = £ ^" sub, Base (A x) ^' k (sub, A x)' [1 + σ (A y, sub, Ax) TPM A y] Ssub, corr (A x) = £ ^" sub, base (A x) ^' k (sub, A x)' [1 + τ (A y, sub, Ax) imine A y]

AlIg: Ssub, corr (A x) = £ sub, base (A x) 'k (sub, A x)' [1 + α (A y, sub, Ax) variable A y]

Where:

Sub: Substance to which extinction coefficient refers.

σ (Ay, sub, Ax): Adaptive calibration parameter which corrects the absorbance value of the substance sub at the wavelength Ax by the influence of the total pulse modulation TPM at the wavelength Ay.

τ (Ay, sub, Ax): Adaptive calibration parameters which the absorbance of the substance at the sub wavelength Ax rigiert I _min kor at the wavelength Ay ^¬ by the influence of the basic signal.

α (Ay, sub, Ax): Adaptive calibration parameter which measures the extinction value of the substance sub at the wavelength Ax corrected the influence of a spectroscopically measured variable at the wavelength Xy.

£ ^' _s u _b5B ase (/ l <x): Underlying of the extinction coefficient of the substance sub at the wavelength Xx.

k (sub, Xx): Adaptive multiplier of the base value of the extinction coefficient of the substance sub at the wavelength λx.

For example, the corrections are made according to a correction table representing the total amount of adaptive calibration. This is exemplified below for the wavelength X _A • '

The correction factors α, τ and ς are empirically determined, statistically verified using a reference collective, and are provided in the area of the device in a nonvolatile memory and / or are transmitted electronically, optically or electromagnetically for calibration.

The functional relationship between the adaptive parameters P, which change the extinction coefficients as system parameters, is also based on an empirical reasoning Statistical analysis based on calibration data.

According to one embodiment, it is provided to use at least one linking function which is suitable for sufficiently correcting the transcutaneous measured values.

The adaptively corrected determination relationship then results from the equation (A):

With:

For this purpose, different linking functions in the region of the device are preferably executable. Particularly preferably, the selection is made to which linking functions are to be applied, for example in the case of a plausibility check of the transcutaneous measured values.

It is also thought possible to allow the user to select the linking function to be used. For example, depending on age and / or physiology and / or skin color, a physician may dictate the linkage function to be used.

The selection of linking functions is particularly preferably carried out automatically, for example, after inputting relevant information. Turning data and / or a plausibility check of transcutaneous measured values.

Advantageously, the linking function is retrievably stored in a non-volatile memory, which can be arranged in the region of a CPU.

The selection of the linking function is particularly advantageously carried out via a look-up table.

1 shows a schematic diagram of the constant calibration,

2 shows a schematic diagram of the adaptive calibration,

3 shows the influence of the fluctuation of imine, TPM and omega on the cHb concentration,

4 shows the effectiveness of the auto-adaptive calibration on the example of the determination of cHb measured values,

Figure 5 shows the effectiveness of auto-adaptive calibration in signal stabilization and

Fig. 6 shows a typical layer model for illustrating the principles of pulse spectroscopy.

Fig. 3 shows the influence of the variation of MV Imine (venous blood filling), TPM (thickness change) and Omega - each for two wavelengths - on the cHb concentration. The percentage change is between 30% and 110%. In this time range between 20 and 70 sec, the determined concentration for cHb changes due to the fluctuation the TPM parameter by 1 g / dl. FIG. 1 illustrates the need to compensate for the variation in MV by calibration.

4 shows the effectiveness of the autoadaptive calibration on the example of the determination of cHb measured values. Shown is the change in cHb concentration in g / dl in the time domain of the measurement of about 110 seconds. The top row of measurements (6) shows the result of a constant calibration

K _v = constant. The fluctuation of the cHb value by +/- 2 g / dl within a short period of time can be recognized. The middle row of measurements (5) shows the result of a homogeneous calibration K _v = not constant The lowest row of measurements (4) shows the result of an inhomogeneous autoadaptive calibration K _v = not constant. It can be clearly seen that the variation of the cHb value is lower when using the auto-adaptive calibration. Essentially, the cHb value is 14-15 g / dl and thus varies by only +/- 1 g / dl.

FIG. 5 shows the effectiveness of auto-adaptive calibration in signal stabilization. In the time range of 20 seconds to 80 seconds, in this embodiment, a movement of the patient takes place. Due to the movement, the measurement signal for cHb becomes inaccurate. Autoadaptive calibration (7) almost completely compensates for the motion artifact and stabilizes the cHb reading. According to the invention, the auto-adaptive calibration is used to determine the measured value, for example for cHb, to +/- 1 g / dl. A simpler constant calibration (8) is not sufficient to compensate the patient movement so that the measured value for cHb remains accurate to +/- 1 g / dl. The difference in signal quality, between constant calibration and auto-adaptive calibration, is 2 g / dl in this embodiment. Fig. 6 shows a typical layer model for illustrating the principles of pulse spectroscopy. Shown is the attenuation of the light intensity by the absorption on the one hand in the non - pulsating tissue part (constant tissue) and the weakening within the pulsating tissue part (pulsatile blood space), which causes the pulsating fluctuation of the exiting light intensity.

Preferably, autoadaptive calibration is used to determine at least one ingredient of body tissue. For this purpose, at least one source of electromagnetic radiation and, spaced from the source of electromagnetic radiation, at least one photoreceiver are arranged adjacent to the body tissue. The source of electromagnetic radiation emits at least two wavelengths selected from a range of _{400nm ± 15% / 460} ^ _{1 ± 15% # 480} ^ _±

15%, 520 nm ± 15%, 550 nm ± 15%, 560 nm ± 15%, 606 nm ± 15%, 617 nm ± 15%, 620 nm ± 15%, 630 nm ± 15%, 650 nm ± 15% , 660 nm ±, 705 nm ± 15%, 710 nm ± 15%, 720 nm ± 10%, 805 nm ± 15%, 810 nm ± 15%, 880 nm ± 15%, 905 nm ± 15%, 910 nm ± 15%, 950 nm ± 15%, 980 nm ± 15%, 980 nm ± 15%, 1050 nm ± 15%, 1200 nm ± 15%, 1310 nm ± 15%, 1380 nm ± 15%, 1450 nm ± 15 %, 1600 nm ± 15%, 1800 nm ± 15%.

Radiation is generated from the source of electromagnetic radiation, which is conducted through the body tissue and hits the photoreceptor after passage through the body. The measurement signals of the photoreceiver are fed to an evaluation device and the evaluation device determines, depending on the number of wavelengths, at least one measured value variable which is indicative of the residual intensity of the radiation after passing through the body tissue. An analyzer fractionates at least two parameters from a measured value variable. meter, wherein at least one parameter represents a variable size of the body tissue at the time of beam passage. Linking the at least one measured value variable with at least one parameter and at least one constant results in the amount of at least one constituent of the body tissue at the time of the beam passage.

Claims

Patent claims

1. A method for correcting the results of the measurement of physiological variables, wherein at least one physiological variable is determined, which can be influenced by physiological and / or external influences, characterized in that the result of the measurement of at least one physiological size taking into account possible influencing physiological and / or external influences is corrected by a calibration.

2. The method according to claim 1, characterized in that the result of the measurement of at least one physiological size, taking into account any influencing physiological and / or external influences by a constant calibration is adapted.

3. The method according to claim 1 or 2, characterized in that the result of the measurement at least a physiological size is corrected taking into account possible influencing physiological and / or external influences by a homogeneous and / or inhomogeneous adaptive calibration.

4. The method according to claim 1 or 2, characterized in that the result of the measurement of at least one physiological size is corrected taking into account possible influencing physiological and / or external influences by an auto-adaptive calibration.

5. The method according to any one of claims 1 to 4, characterized in that correction factors are taken into account in the calibration.

6. The method according to any one of claims 1 to 5, characterized in that the correction factors have previously been determined empirically.

7. A method for correcting the results of the measurement of physiological variables, wherein at least one physiological variable is determined, which can be influenced by physiological and / or external influences, characterized in that at least one measured value variable is extracted from the result of the measurement of at least one physiological variable, which serves to determine at least one correction factor and that the result of the measurement of the physiological quantity is linked to the correction factor in order to determine the physiological and / or ex- individually and automatically compensate for internal influences.

8. The method according to any one of claims 1 to 7, characterized in that for the measurement, the pulsatile blood circulation curves at different wavelengths, with reference to known absorption spectra of biological substances, are determined in order to determine the absolute and / or relative concentration of Zielgrδße.

9. The method according to any one of claims 1 to 8, characterized in that the target size cHb according to the formula

⁸ H10, A ' ^C H20 ^ O AB ^{' S} H2O, B

⁰ Hb ~

Ω _AB - η _B - η _A

is determined.

10. The method according to any one of claims 1 to 9, characterized in that the physiological parameters represent measurement results of patient plethysmograms and the measured value variables are generated by linking the plethysmogram values and system parameters from the application site and / or the measurement methodology (transmission or Re - Flektion) and / or the electro-optical and / or mechanical sensor design.

11. The method according to any one of claims 1 to 10, characterized in that measured value variables and system parameters are used to correct the results of the measurement of physiological variables.

12. Method according to claim 11, characterized in that the measured value variable is indicative of the residual intensity of the transmitted radiation and an analyzer fractionates at least two parameters of the measured variable.

13. A method for determining at least one ingredient of a body tissue, wherein adjacent to the body tissue at least one source of electromagnetic radiation and spaced from the source of electromagnetic radiation at least one photoreceiver are arranged and in which the source of electromagnetic radiation, a radiation of different wavelengths is generated and by the body tissue is passed and hit a photoreceiver, which supplies the measured values to an evaluation device and in which the evaluation device determines at least one measured value variable depending on the number of wavelengths, which consists of at least two parameters.

14. The method according to any one of claims 1 to 13, characterized in that at least one parameter represents a variable size of the body tissue at the time of the beam passage and a linkage of the at least one Meßwe ^' rtvaria- blen with at least one parameter and at least one constant is performed and that the result of the linkage represents the target size at the time of the beam passage.

15. The method according to any one of claims 1 to 14, characterized in that the source of electromagnetic radiation emits at least two wavelengths selected from a range of substantially 400 microns to 1500 microns.

16. The method according to any one of claims 1 to 15, characterized in that the source of electromagnetic radiation emits at least three wavelengths of substantially 805 nm, 905 nm and 1450 nm.

17. The method according to any one of claims 1 to 16, characterized in that the number of possible measured variable depends on the number of wavelengths used and substantially half the number of wavelengths multiplied by the number of wavelengths minus one determines the number of possible measured value variables ,

18. The method according to any one of claims 1 to 17, characterized in that the number of possible measured value variables at three wavelengths used is at least three.

19. The method according to any one of claims 1 to 18, characterized in that at least one measured value variable Ω is a derived size of the plethysmograms of at least two emission wavelengths at the time of beam passing.

20. The method according to any one of claims 1 to 19, characterized in that at least one measured value variable PPM represents the partial pulse modulation, the pulse modulation of at least one wavelength at least two times.

21. The method according to any one of claims 1 to 20, characterized in that at least one measured value variable Cx represents the virtual concentration of an analyte in the body tissue at the time of the beam passage.

22. The method according to any one of claims 1 to 21, characterized in that at least one measured value variable TPM represents the change in thickness of the body tissue.

23. The method according to any one of claims 1 to 22, characterized in that at least one measured value variable Imin -represents the venous blood filling of the body tissue.

24. The method according to any one of claims 1 to 23, characterized in that at least one measured value variable H represents the histoanatomy of the body tissue.

25. The method according to any one of claims 1 to 24, characterized in that at least one constant can take a fixed value.

26. The method according to any one of claims 1 to 25, characterized in that at least one constant is determined.

27. The method according to any one of claims 1 to 26, characterized in that at least one constant has been determined empirically.

28. The method according to any one of claims 1 to 27, characterized in that at least one constant is stored in a non-volatile memory retrievable.

29. The method according to any one of claims 1 to 28, characterized in that at least one constant is determined and at least one further constant, which can take a fixed value, is taken into account in the determination.

30. The method according to any one of claims 1 to 29, characterized in that at least one measured value variable with at least one parameter and at least one constant are linked and the constant is not variable.

31. The method according to any one of claims 1 to 30, characterized in that at least one measured value variable with at least one parameter and at least at least one constant and the constant is variable.

32. The method according to any one of claims 1 to 31, characterized in that for determining the variable constant those wavelengths are taken into account, which also determine the at least one taken into account Meßwertvariable and also the at least one parameter.

33. The method according to any one of claims 1 to 32, characterized in that for determining the variable constant not those wavelengths are taken into account, which determine the at least one taken into account Meßwertvariable and also the at least one parameter.

34. The method according to any one of claims 1 to 33, characterized in that at least one measured value variable and / or at least one parameter can be linked to at least one constant.

35. The method according to any one of claims 1 to 34, characterized in that at least one measured value variable and / or at least one parameter and / or at least one constant are determined by an approximation.

36. The method according to any one of claims 1 to 35, characterized in that at least one measured value variable and / or at least one parameter and / or at least one constant can be adjusted by approximation.

37. Method according to claim 1, characterized in that the change in thickness of the body tissue TPM and / or the venous blood filling of the body tissue Imin and / or the histoanatomy of the body tissue H and / or the partial pulse modulation PPM are adapted by an approximation.

38. The method according to any one of claims 1 to 37, characterized in that at least one extubtion is corrected by means of the auto-adaptive calibration.

39. The method according to any one of claims 1 to 38, characterized in that the extinction of at least one ingredient of a body tissue is linked to at least one constant and the determination of this constant has been carried out via an approximation.

40. The method according to any one of claims 1 to 39, characterized in that at least one extinction of at least one ingredient of a body tissue is linked to at least one constant, wherein at least one different extinction of at least one other ingredient of a body tissue is not linked to a constant.

41. Method for the auto-adaptive calibration of at least one extinction of at least one constituent of a body tissue, characterized in that the extinction is linked to at least one measured value variable and / or at least one parameter of a measured value variable and / or at least one constant and that the result of the linking determines the quantity of the examined ingredient of the body tissue at the time of beam passage.

42. The method according to claim 41, wherein a retrievably stored result of an approximation in the method is linked to at least one measured value variable and / or at least one parameter and / or at least one constant.

43. The method of claim 41 or 42, characterized in that the extinction of at least one ingredient of a body tissue is linked to at least one constant.

44. The method according to any one of claims 41 to 43, characterized in that at least one extinction of at least one ingredient of a body tissue is linked to at least one constant, wherein at least one different extinction of at least one other ingredient of a body tissue is not linked to a constant.

5. A method for auto-adaptive calibration of at least one extinction of at least one ingredient of a body tissue, characterized in that the extinction is linked to at least one measured value variable and / or at least one parameter of a measured value variable and / or at least one constant and that the result of the linkage the amount of the examined ingredient of the body tissue at the time of beam passage.