DE10319361A1 - Measurement of vegetative balance for care of patient's health using biofeedback and achieving of sympathetic-vagus nerve balance by monitoring parameters including heart rate variability - Google Patents

Abstract

The measurement system includes electrodes (308) for picking up ECG (electrocardiogram) signals connected to an ECG measurement circuit (301). A pulse wave latency pickup electrode (307) is connected to a pulse wave latency measurement circuit (302). The measurement circuits are connected to an analog/digital converter (303). A pulse wave latency circuit (304) sends a signal to a data processing circuit (305), which is connected to a display unit (306).

Description

The The invention relates to an apparatus and a method for measuring the vegetative balance.

Next the arbitrary, somatosensory nervous system, which is the control of the human Is subject to consciousness and, for example, controls our muscles, There is the autonomic nervous system, which is the internal organ system controlled and not arbitrary is to be influenced. The autonomic nervous system is therefore too referred to as autonomic nervous system. The latter is essentially from two big ones Subsystems built, the opposite effects on the organ systems have: The parasympathetic system predominates in peace, it serves the maintenance of the inner environment and regeneration. The sympathetic nervous system is active in stressful situations. Under his influence are the cardiovascular system and metabolism converted to outward delivery (fight / flightreactions).

As Vegetative balance is the balance of sympathetic to parasympathetic activity. Disorders of the vegetative balance are usually characterized by a predominance of sympathetic activity with simultaneous absence of parasympathetic influence.

Such disorders the vegetative balance can as a result of acute and prolonged stress situations, Chronic stress and as a symptom of common diseases such as diabetes or coronary heart disease. From numerous studies is known to be longer ongoing disturbances the vegetative balance causes extensive health damage for example, in an increased mortality or the increased occurrence of potentially life-threatening events like knocking down a heart attack. Therefore, there are different approaches, disorders of to measure vegetative balance and the latter by biofeedback methods Cheap to influence. Biofeedback is understood in this context the immediate audiovisual presentation currently derived physiological sizes of a People. By "making visible" own, otherwise not direct experience of physiological processes makes it easier for the person examined to these physiological processes in one for him cheap Way to change. Numerous studies have confirmed that biofeedback methods are suitable for the physiological processes in the desired Way to influence.

On A known method for measuring the vegetative balance is, for example the measurement of skin conductance as described e.g. in the so-called "lie detectors" is performed. In the latter, however, the biofeedback is missing, because the measured Skin resistance to the examinee is not displayed. Meanwhile, however, systems are already on the market, the biofeedback on skin conductance use it to change in the vegetative balance.

This Procedure is however only conditionally suitable to the sympathiko-vagale Balance to measure because the skin is exclusively sympathetic innervated is and changes not measurable at the parasympathetic branch of the autonomic nervous system are.

Further known method for measuring and influencing the vegetative Balance is based on the determination of heart rate variability. among them one understands the fluctuations of the heart rate from heart beat too Heartbeat. These fluctuations are an expression of the healthy too every time instead of regulating the heart rate. Lack the former or are they diminished, this is a serious indication of possible diseases of the autonomic nervous system. The main source of heart rate variability at rest is the influence of breathing. With calm and deep breathing follows the Heart rate of breathing, respiratory rate and heart rate are coupled. This condition is also called "respiratory sinus arrhythmia." The cause of this is shifts in the blood volume within the thorax as a result of deep breathing, the to different fillings of the heart and thus to different, variable with the breath Lead stroke volumes. This leads to rhythmic fluctuations in blood pressure. The Vegetative nervous system tries to adjust these fluctuations to balance the heart rate. Since the respiratory sinus arrhythmia over the mediated parasympathetic branch of the autonomic nervous system becomes and becomes sympathetic with dwindling parsympathetic and growing Reduced influence, their size is a useful one Measure of the condition the sympathic-vagal balance.

To accurately determine heart rate variability, the heartbeat must be accurately recorded. An electrocardiogram (ECG) is usually recorded or the heartbeat is determined from a photoplethysmographic signal. To quantify the heart rate variability, various methods are common, which can be divided into two large groups (time domain vs. frequency domain). Time domain methods are, for example, classical statistical methods such as mean and variance, methods in the frequency domain are based on frequency analysis methods, eg spectral analysis using FFT (Fast Fourier Transformation).

The WO 00/51677 describes such a method for measuring the vegetative Balance based on heart rate variability, calculated using spectral analysis.

• • Die Bestimmung der Herzratenvariabilität mittels der Spektralanalyse ist sehr anfällig für Artefakte. Falsch erkannte Herzschläge verändern die Periodizität des Signals und führen so zu Fehlbestimmungen der sympathiko-vagalen Balance.
• • Die Frequenzanalyse setzt relativ lange (im Minutenbereich) Aufnahmezeiten voraus, bevor mit der Berechnung der Herzratenvariabilität begonnen werden kann.
• • Die oft verwendete Einteilung des gemessenen Frequenzspektrums in Frequenzbänder und die Zuordnung einzelner Bänder zu entweder sympathischer oder parasympathischer Genese ist zu simplifizierend und wird dem tatsächlichen Sachverhalt nicht gerecht.
• • Menschen mit chronischen Störungen der sympathiko-vagalen Balance haben oft eine sehr eingeschränkte Herzratenvariabilität schon in Ruhe, so dass sich eine akute Verschlechterung der Balance, z.B. durch akuten Stress, in der Herzratenvariabilität kaum mehr erfassen lässt.

The determination of heart rate variability by spectral analysis, however, has several disadvantages:

• • The determination of heart rate variability by means of spectral analysis is very susceptible to artifacts. False heartbeats alter the periodicity of the signal, leading to false positives in the sympatho-vagal balance.
• • Frequency analysis requires relatively long (in the minute range) recording times before calculating heart rate variability.
• • The often used division of the measured frequency spectrum into frequency bands and the assignment of individual bands to either sympathetic or parasympathetic genesis is too simplistic and does not do justice to the actual situation.
• • People with chronic disorders of sympatho-vagal balance often have very limited heart rate variability already at rest, so that an acute deterioration in balance, eg due to acute stress, can hardly be captured in the heart rate variability.

In contrast, lies The invention is based on the object, an improved and above all reliable Method and an improved and reliable device for determining indicate the sympatho-vagal or vegetative balance. This The object is achieved with the features of the claims.

The Invention is based on the basic idea, for reliable detection the sympatho-vagal or vegetative balance suitable parameters the heart rate variability with suitable pulse wave velocity parameters to one Measure of the vegetative Balance to link.

Pulse wave velocity is understood to mean the velocity of propagation of the pressure wave along the arterial vascular system, triggered by the ejection of the heartbeat volume into the aorta during the ejection phase (systole). If the blood pressure in the arterial system increases, so does the pulse wave velocity. Conversely, the pulse wave velocity decreases as the blood pressure drops. From changes in the pulse wave velocity can therefore be concluded that changes in blood pressure. That's how it describes DE 102 49 863 (post-published) a method for the precise determination of blood pressure from the pulse wave velocity.

A simple method to determine the pulse wave velocity is the measurement of the pulse wave latency between two measuring points. Join the propagation of the pulse wave along the arterial vascular system with two sensors, the pulse wave latency refers to the time which needs the pulse wave to go from sensor 1 to sensor 2 reach. As you generally the distance between the sensors If you do not know, you usually do without the determination of Propagation speed and leaves it at the pulse wave latency. To simplify the measurement effort, you often take the ECG signal for sensor 1. The second sensor is e.g. a photoplethysmographic measuring arrangement, consisting of a transmitter and a receiver of light of a suitable Wavelength, causing changes Blood volume in the skin either by means of transmission or can be determined by reflection.

Since the mechanical heart action is closely coupled to the ECG, one can equate the time of the blood ejection and thus the beginning of the pulse wave approximately with the appearance of the R-wave in the ECG. 2 shows a typical waveform, as measured by a measuring device for obtaining heart rate variability (ECG signal 201 ; R wave 203 ) and pulse wave latency 204 (Pulse wave signal 202 ; Beginning of the peripheral pulse wave 205 ) is registered. This gives a useful estimate of the pulse wave latency, which allows a conclusion on the direction and approximate size of the blood pressure change. Numerous studies have shown that the pulse wave latency calculated by the above method correlates well with the systolic blood pressure. A precise indication of the systolic and diastolic blood pressure is not possible.

Although WO 00/51677 mentions the method of pulse wave latency measurement (there called PTT for "Pulse Transit Time") in connection with disturbances of the vegetative balance, but in a completely different context: WO 00/51677 basically aims at the property of different organ systems It is important to achieve certain patterns of oscillation and to synchronize the patterns of different organ systems, the pulse wave latency being considered as a measure of the state of the blood vessel musculature is only partially correct, because the pulse wave latency correlates primarily with the blood pressure and not with the current contraction of the blood vessel SSE. Often, both blood pressure and contraction of the vascular musculature go hand in hand. This is by no means always the case. Especially at rest, in a relaxed state, the parasympathetic influence predominates, whereas the sympathetic nervous system is largely inactive. However, the parasympathetic nerve does not innervate the blood vessel muscles at all. These are controlled exclusively by the sympathetic nervous system. Therefore, the well-measurable fluctuations in pulse wave latency at rest are the result of blood pressure changes in the rhythm of respiration. In WO 00/51677, although the registration of the pulse wave latency (PTT) is addressed, but only to determine which branch of the autonomic nervous system contributes to the performance in a particular frequency range. From the pulse wave latency itself no conclusions about the state of the vegetative balance are drawn in the cited patent.

According to the invention Pulse wave latency as a measure of the current Blood pressure placed in the physiologically correct context, and through Combination with heart rate variability a reliable procedure to determine the vegetative balance.

Our own studies confirm the reliable determination of the autonomic balance by linking heart rate variability and pulse wave latency. So shows 1 the course of heart rate variability 101 (top picture), Pulse wave latency 102 (middle picture) and subjectively perceived stress load 103 (lower picture) when switching from relaxation to stress and back to a relaxed state. The heart rate variability and the pulse wave latency in the relaxed starting situation were set as 100%, changes in the further course were expressed as a relative value in percent. Shown is the course of mean (bold) and standard deviation. According to the invention, the parameters customary in the clinical practice of vegetative diagnostics for describing heart rate variability and pulse wave latency are preferred. For example, standard deviation, coefficient of variation, or RMSSD (root mean square of successive differences) are particularly preferred as parameters for heart rate variability, since these are easy to calculate and easy to use. It is therefore not necessary according to the invention to resort to the more complex parameters of the frequency analysis, although frequency analysis methods can in principle also be used. In other words, the invention makes it possible to do without the more complex parameters of frequency analysis. The pulse-wave latency is usually expressed as time in milliseconds, a measure proportional to the blood pressure curve is the reciprocal of the pulse-wave latency multiplied by a constant k.

The changes in heart rate variability and pulse wave latency may be different for each human and in each stress situation. For this reason, the use of a calibration method for determining the individual vegetative reaction width is preferred according to the invention. Preference is given, for example, to the classical neurological test methods for the clinical diagnosis of vegetative disorders such as Ewing test, Valsalva maneuver and deep breathing (respiratory sinus arrhythmia). According to the invention, such a test method is carried out automatically and evaluated automatically for the target parameters of the heart rate variability and the pulse wave latency. Taking into account the calibration, a transformation function T is now applied both to the current measured values of the heart rate variability and to the current measured values of the pulse wave latency. The transformation function T can now be used to unambiguously determine for each time t where the parameters of the heart rate variability (HRV) and pulse wave latency are to be classified within the available vegetative response width. HRV trans (t) = T (HRV measured (t)) (1) HRV _trans (t): transformed HRV parameter at time t, denotes the location within the vegetative reaction space
T: transformation function
HRV _measured (t): currently determined HRV parameters at time t

Preferably, the following transformation function is applied to heart rate variability: HRV trans (t) = ((HRV measured (T) -HRV Eichungmin ) / (HRV Eichungmax -HRV Eichungmin ) (2) HRV _trans (t): transformed HRV parameter at time t; denotes the location within the vegetative reaction space
HRV _measured (t): currently determined HRV parameters at time t
HRV _{Calibration min. Minimum} value of the HRV from the calibration
HRV _calibration maximum value of the HRV from the calibration

Analogously, the pulse wave latency (PWL) is transformed: PWL trans (t) = T (PWL measured (t)) (3) PWL _trans (t): transformed PWL parameter at time t; denotes the location within the vegetative reaction space
T: transformation function
PWL _measured (t): currently determined pulse-wave latency parameter at time t

A preferred transformation function for the pulse wave latency analogous to (2) is: PWL trans (t) = ((PWL measured (T) -PWL Eichungmin ) / (PWL Eichungmax -PWL Eichungmin ) (4) PWL _trans (t): transformed pulse-wave latency parameter at time t; denotes the location within the vegetative reaction space
PWL _measured (t): currently determined pulse-wave latency parameter at time t
PWL _{calibration min. Minimum} value of the pulse wave _latency from the calibration
PWL _{calibration max} Maximum value of the pulse wave _latency from the calibration

According to the invention. the specific vegetative balance audiovisually represented so the tested person feedback on the current situation to give.

For the audiovisual presentation of the current autonomic balance, a linear representation is possible, but in this form of presentation, changes in the normal, desirable range of autonomic balance cause changes in the appearance as well as changes in the abnormal range. More preferable, therefore, is a representation which suppresses fluctuations in the normal range more than fluctuations in the abnormal range, or the change from abnormal to normal, and vice versa. This is achieved according to the invention by applying a mapping function A to the transformed parameters of heart rate variability and pulse wave latency. HRV fig (t) = A (HRV trans (t)) (5) HRV _abb (t): HRV parameters at time t; denotes a virtual location within a vegetative reaction space with emphasis on changes in the abnormal area
A: picture function
HRV _trans (t): transformed HRV parameter at time t

A preferred mapping function is: HRV fig (t) = 1-e (HRV trans (t) · k) (6) HRV _abb (t): HRV parameters at time t; denotes a virtual location within a vegetative reaction space with emphasis on changes in the abnormal area
HRV _trans (t): transformed HRV parameter at time t
k: constant

Analogously, the mapping function is also applied to the parameters of the pulse wave latency: PWL fig (t) = A (PWL trans (t)) (7) PWL _abb (t): pulse wave _latency parameter at time t; denotes a virtual location within a vegetative reaction space with emphasis on changes in the abnormal area
A: picture function
PWL _trans (t): transformed pulse-wave latency parameter at time t

A preferred mapping function for this is again: PWL fig (t) = 1-e (PWL trans (t) · k) (8) PWL _abb (t): pulse wave _latency parameter at time t; denotes a virtual location within a vegetative reaction space with emphasis on changes in the abnormal area
PWL _trans (t): transformed pulse-wave latency parameter at time t
k: constant

From the parameters of the heart rate variability and the pulse wave latency according to equations (5) and (7), the function G is used to calculate a quantity H of the vegetative balance. H (t): = G (HRV fig (T); PWL fig (t)) (9) H (t): measure of the vegetative balance at the time (t)
G: Function G generates the descriptive size of the vegetative balance from heart rate variability and pulse wave latency
HRV _abb (t) see Equation 5
PWL _abb (t) see Equation 7

A preferred function G is shown in equation (10). H (t): = a 1 · HRV fig (t) + b 1 · PWL fig (t) (10) H (t): measure of the vegetative balance at the time (t)
HRV _abb (t) see Equation 5
PWL _abb (t) see Equation 7
a ₁ : Weighting of heart rate variability parameters
b ₁ : Weighting of pulse wave latency parameters

The Size H (t) will now be in a preferred embodiment presented to the user in an appropriate audiovisual form. For example, the size H (t) as the angular velocity of a rotating ball on a computer screen be implemented. Is the vegetative balance in the norm, turns the ball is slow, or resting. With increasing deviation from the norm, the ball spins faster and faster.

The function G of equation 9 is in a further preferred embodiment by a Schar of functions G _1-n replaced, so that a set of measures H _1-n results. H 1-n (t): = G 1-n (HRV fig (T); PWL fig (t)) (11) H _1-n (t): measure of the vegetative balance at time (t)
G _1-n : set of functions G _1-n generates the descriptive quantities H _{1 -n of} the vegetative balance from heart rate variability and pulse wave latency
HRV _abb (t) see Equation 5
PWL _abb (t) see Equation 7

By suitable, multi-channel audiovisual representation of the resulting quantities H _{1 -n} , the status and the course of the vegetative balance is preferably displayed more comprehensively than would be possible with a single size H. Thus, for example, by a function G ₁ in a quantity H ₁ more the heart rate variability component and by a function G ₂ in a size H ₂ more emphasize the pulse wave latency component. Assigning H ₁ eg the angular velocity around the vertical axis and H ₂ eg the angular velocity around a horizontal axis gives a motion pattern which gives both the overall status of the vegetative balance and an indication of the location of the disturbance, either in the area of heart rate or blood pressure regulation.

By the described devices and methods of the invention will a precise one and powerful System for measuring and influencing the vegetative balance disposal posed.

The The invention will be described below with reference to the accompanying drawings explained in more detail. Show it:

1 the course of heart rate variability, pulse wave latency and subjectively perceived stress levels when switching from relaxation to stress and back to a relaxed state;

2 a typical ECG waveform and pulse wave signal; and

3 an embodiment of the device according to the invention.

The device according to the invention has a device 301 for recording the ECG, as well as another device 302 for recording the peripheral pulse wave signal, corresponding sensors for the ECG (sensors 308 ) and the pulse wave signal (sensor 307 ), an A / D converter 303 to which the signals of the recorded ECG and the pulse wave signal are supplied, and an interface 304 on. About the interface 304 is a data processing unit 305 connected, which converts the measured biosignals in one or more sizes of the vegetative balance. About an audiovisual edition 306 an output of the currently determined variables takes place in the sense of a biofeedback.

Preferably, the measuring recording devices 301 and 302 for ECG and pulse wave as well as the A / D converter in a common housing 309 accommodated. The sensors 307 (For example, photoplethysmographic sensor) and 308 for Pulwellen and ECG are mounted on the outside of the housing or arranged in corresponding openings of the housing. In such an embodiment, the user is able to grasp the housing with both hands and thereby place the fingers on the corresponding sensors or to touch them, so that the ECG and pulse wave signal can be detected via one or more fingers of each hand. The detected signals are A / D converted and via the interface of the data processing unit 305 fed for processing. In the data processing unit, the measured parameters are linked together and then by means of the output unit 306 brought to view. In this way, the housing can 309 as a mobile unit detached from the data processing unit 305 transported and used individually. For example, the acquired data is telemetered to the data processing unit 305 passed. In an alternative embodiment, the devices are for data acquisition 301 . 302 . 303 . 304 . 307 and 308 together with the data processing unit 305 and the output unit 306 housed in a common housing, which is preferably portable, such as a pocket PC or a mobile phone.

The Output unit serves to give the user a biofeedback on the current To give situation. This can be over Sound and / or picture happen. Preference is given to the representation by means of a ball whose angular velocities depend on the recorded parameters vary, as already explained above.

The sensor 307 for registering the peripheral pulse wave in the preferred embodiment shown operates according to the photoplethysmographic reflection method with a light emitter of a wavelength between 700 and 1200 nm and is designed with a sensitive in this wavelength range light receiver.

Alternative to those in the housing 309 provided sensors are the sensor for registration of the ECG and / or the sensor for registering the peripheral pulse wave at body parts other than the hands attached, for example, on the chest or the arms (ECG), or on the ear (Pulswel le).

Further preferred is additional another sensor for determining the Hautleitwiderstandes provided.

In a preferred embodiment becomes the method according to the invention or the device according to the invention for the treatment of hypertension and vegetative dysfunctions, e.g. used in diabetic autonomic neuropathy.

101

course the heart rate variability at different load levels

102

course Pulse wave latency at different stress levels

103

course the subjective perceived stress at different

stress levels

201

ECG signal

202

Pulse wave signal

203

R wave

204

Pulse wave latency

205

beginning the peripheral pulse wave

301

measuring device ECG

302

measuring device Pulse wave latency

303

A / D converter

304

interface

305

device for data processing

306

display device

307

sensor for registration of the peripheral pulse wave

308

sensors to register the ECG

309

Housing of data collection

Claims (20)

Method for determining the vegetative balance by linking of heart rate variability and Pulse wave latency. The method of claim 1, comprising the steps of: (A) continuously acquiring an electrocardiogram (ECG) to determine the heart rate variability; (B) continuously detecting the peripheral pulse wave to determine the Pulse wave latency from the time difference between a characteristic point on the pulse wave or derived therefrom Signal and a characteristic point on the ECG or it derived signal; and (c) determining the vegetative balance from the parameters determined in steps (a) and (b), heart rate variability and pulse wave latency. The method of claim 1 or 2, further comprising Step auditive and / or visual output of the determined vegetative Balance. The method of claim 1, 2 or 3, further comprising Calibration to determine the individual vegetative response width. Method according to one of the preceding claims, wherein on the specific values of heart rate variability and the specific values the pulse wave latency a transformation is applied. The method of claim 5 when dependent on claim 4, with the transformation for heart rate variability: HRV _trans (t) = ((HRV _measured (t) -HRV _{calibration min} ) / (HRV _calibration max _-HRV calibration _min ), with HRV _trans (t): transformed HRV parameter at time t, HRV _measured (t): currently determined HRV parameters at time t, HRV _{calibration min} : minimum value of HRV from calibration, HRV calibration _max : maximum value of HRV from calibration, and transformation for pulse wave latency: PWL _trans (t) = ((PWL _measured (t) -PWL calibration _min ) / (PWL _calibration max _-PWL calibration _min ), with PWL _trans (t): transformed pulse-wave _latency parameter at time t, PWL _measured (t): currently determined _Pulse wave _latency parameter at time t, PWL _{Calibration min Minimum} value of the pulse wave _latency from the calibration, PWL _{Calibration max} : Maximum value of the pulse wave _latency from the calibration. The method of claim 6, wherein an imaging function is applied to the transformed parameters. Method according to claim 7, having the mapping function for heart rate variability: HRV _abb (t) = 1-e (HRV _trans (t) * k), with HRV _abb (t): HRV parameter at time t, HRV _trans (t) : transformed HRV parameters at time t, k: constant, and the mapping function for the pulse wave latency: PWL _abb (t) = 1-e (PWL _trans (t) · k), with PWL _abb (t): pulse wave latency parameter to Time t, PWL _trans (t): transformed pulse-wave latency parameter at time t, k: constant. The method of claim 8, wherein the association of heart rate variability and pulse wave _latency is done with the equation: H (t): = a _1. HRV _abb (t) + b _1. PWL _abb (t), with H (t): measure of vegetative balance at time (t), HRV _abb (t): mapped heart rate variability, PWL _abb (t): mapped pulse wave _latency , a ₁ : weighting of heart rate variability parameters, b ₁ : weighting of pulse wave latency parameters. The method of claim 9, wherein a group of functions is generated. Method according to one of claims 2 to 10, wherein in step (b) a photoplethysmographic method for detecting the pulse transit time is used. A method according to any one of claims 2 to 11, further comprising Step Detecting the skin conductance. Device for determining vegetative balance with a device ( 301 ) for acquiring an electrocardiogram (ECG), a device ( 302 ) for detecting a peripheral pulse wave and a data processing unit ( 305 ), which links the recorded parameters to a measure of the vegetative balance. Apparatus according to claim 13, wherein the pulse wave detection means ( 302 ) a photoplethysmographic sensor ( 307 ) having. Apparatus according to claim 14, wherein the sensor ( 307 ) is operable by a reflection method and has a light emitter of a wavelength between 700 and 1200 nm and a sensitive in this wavelength range light receiver. Apparatus according to claim 14, wherein the sensor ( 307 ) is operable by a transmission method and has a light emitter of a wavelength between 700 and 1200 nm. Device according to one of claims 13 to 16, wherein the ECG detection device ( 301 ) and the pulse wave detection device ( 302 ) in a housing ( 309 ) are arranged, wherein sensors ( 308 ) of the ECG detection device and sensors ( 307 ) of the pulse wave detection device ( 302 ) are arranged on the housing wall such that an ECG and pulse wave signal is registered by touching the sensors with one or more fingers of each hand. Device according to one of claims 13 to 17, further comprising a data output unit ( 306 ). Apparatus according to any one of claims 13 to 18, further comprising Sensor for measuring the skin conductance. Use of a method according to one of the claims Determining high blood pressure and autonomic dysfunction especially diabetic autonomic neuropathy.