WO2004028365A2

WO2004028365A2 - Method and device for determining a sleep profile

Info

Publication number: WO2004028365A2
Application number: PCT/DE2003/003086
Authority: WO
Inventors: Bernd Schöller; Matthias Schwaibold
Original assignee: MCC Gesellschaft für Diagnosesysteme in Medizin und Technik mbH & Co. KG
Priority date: 2002-09-20
Filing date: 2003-09-16
Publication date: 2004-04-08
Also published as: WO2004028365A3; DE10243937A1; EP1542585A2; AU2003275922A1

Abstract

The invention relates to a method and a device for determining a sleep profile. At least one signal is detected by at least three electrodes and fed to an evaluation device. The signal detection is related to mixed signals having fractions of EEG-signals, EOG-signals and EMG-signals. A first electrode is arranged in the region of the forehead of the person, a second electrode is arranged in the lateral region below an eye and a third electrode is positioned on the neck area of the person. The signals are subjected to program-controlled signal processing by an evaluation device.

Description

Method and device for determining a sleep profile

The invention relates to a method for determining a sleep profile, in which at least one signal is detected via three electrodes and fed to an evaluation device, in which a first electrode is positioned in the area of a person's head, and in which mixed signals with proportions of EEG are used by the electrodes. Signals, EOG signals and EMG signals are recorded and fed to the evaluation device.

The invention further relates to a device for determining a sleep profile, which has at least three electrodes for recording mixed signals with portions of an EEG signal, an EOG signal and an EMG signal, and in which the electrodes are connected to an evaluation device. Such methods and devices are already known in different embodiments. DE-OS 100 42 813 describes an arrangement with three electrodes which are arranged together in a forehead area of a patient. DE 198 82 266 T 1 explains an arrangement using two electrodes.

A major problem when using the devices and methods according to the prior art is that the electrodes used are arranged at a relatively short distance from one another. The dense arrangement of the electrodes relative to one another means that only small potential differences are measured. Due to the superimposition of interference signals, the detection of sleep states is only possible with imprecision.

The object of the present invention is to improve a method of the type mentioned in the introduction in such a way that both ease of use and high measuring accuracy are supported.

This object is achieved according to the invention in that a first electrode is positioned in the area of a person's forehead, a second electrode in the area laterally below an eye and a third electrode as a reference electrode and in that the signals are subjected to signal processing by the evaluation device under program control.

Another object of the present invention is to construct a device of the type mentioned in the introduction in such a way that ease of use is achieved and high measuring accuracy is supported. This object is achieved in that at least two of the electrodes are positioned relative to one another by a head holder, the contour of which is adapted to a head contour of a person such that a first electrode after the head holder has been placed on the head of the person in the area of a forehead, a second electrode is arranged in the area below an eye and a third electrode as a reference electrode and that the evaluation device is provided with a signal processing module.

By positioning the electrodes in the area of the forehead, the area laterally below an eye and the neck, a relatively large distance between the electrodes is provided, which leads to increased potential differences. In addition, the areas in question are usually only weakly or not at all hairy, so that good contact of the electrodes with a skin surface is provided. The signal processing in the area of the evaluation device makes it possible to differentiate between different signal types and to evaluate them separately or in combination with one another. The evaluation leads to a high quality of information with regard to the respective sleep states being achieved.

Good access to the signals to be recorded is provided by using the electrode in the region of the person's forehead as the active electrode.

Good measurement technology is also supported by positioning the electrode in an area above an eye of the person. Advantageous potential differences can be detected by using the electrode below the eye as the active electrode.

Favorable electrode positioning is provided in that the electrode is positioned below the eye relative to a center line of the head of the person with respect to the electrode in the forehead region diagonally and opposite.

To ensure a good quality of analysis with regard to the sleep states to be determined, it is proposed that signal processing be carried out to distinguish between EEG signals, EOG signals and EMG signals.

Adaptability to patient-specific circumstances is supported in that the electrodes are arranged such that they can be moved relative to one another.

Improved user comfort is provided in that the electrodes are connected relative to one another by headbands.

To further improve noise immunity, it is proposed that electrical signal amplification be carried out at a short distance from the electrodes.

Lines that disturb the patient can be avoided by carrying out a wireless signal transmission. Effective data transmission is also supported in that a wireless short-range telemetry method is used for signal transmission.

A fail-safe data transmission method that can be carried out with little energy expenditure is realized in that the Bluetooth method is used for signal transmission.

A high quality of information is also supported in that a pattern recognition is carried out for signal processing.

An evaluation within a large parameter range is facilitated in that signal processing is carried out using fuzzy logic.

Exemplary embodiments of the invention are shown schematically in the drawings. Show it:

1 is a schematic representation of an overall device,

2 shows a representation to illustrate a positioning of a head holder with three electrodes in the area of a patient's head,

3 shows a block diagram for further illustration of the overall device,

4 shows a block diagram to illustrate a first embodiment of a signal detection part, 5 is a block diagram illustrating a second embodiment of the signal detection part,

6 is a block diagram illustrating a third embodiment of the signal detection part,

7 is a block diagram illustrating a fourth embodiment of the signal detection part,

8 is a block diagram illustrating a fifth embodiment of the signal detection part,

9 is a block diagram illustrating a structure of a diagnostic part,

10 is a block diagram illustrating a second embodiment of a diagnostic part,

11 is a block diagram illustrating a third embodiment of a diagnostic part,

12 is a block diagram to illustrate signal processing when creating a sleep profile,

13 is a diagram to illustrate a first sleep profile,

14 is an illustration to illustrate a second sleep profile,

15 is an illustration to illustrate a third sleep profile, 16 is an illustration to illustrate a fourth sleep profile,

17 shows a representation to illustrate a fifth sleep profile,

Fig. 18 is a diagram illustrating a sixth sleep profile and

Fig. 19 is a diagram illustrating a seventh sleep profile.

1 shows a schematic illustration of a special exemplary embodiment of an overall arrangement for determining a sleep profile. A head holder (2) with electrodes (3, 4, 5) is positioned in the area of a person (1). A transmitter (6) is also arranged in the area of the head holder (2) and is wirelessly coupled to a receiver (7). The receiver (7) is arranged in the area of a base station (8). The base station (8) records the signals transmitted to the receiver (7). The base station (8) can contain a graphic user interface (9) and can be equipped with software modules for automatic signal analysis.

The base station (8) is equipped with a device for transmitting data to a central storage device (10). The storage device (10) can be implemented, for example, as an electronic patient file.

Fig. 2 also shows a special embodiment of the arrangement of the head holder (2) in the region of a head (12) of the person (1). It can be seen that the electrode (3) in the area of a forehead (13), the electrode (4) in an area laterally below an eye (14) and the electrode (5) in the area of a neck (15) of the person (1). The area of the neck (15) also includes the neck area of the person (1).

In the exemplary embodiment, the head holder (2) is made from strips, two horizontal strips and two essentially vertical strips being used.

Fig. 2 illustrates that the electrode (3) is laterally offset relative to a head center line such that the positioning takes place approximately above an eye of the person (1). The electrode (4) is arranged laterally offset below the eye (14) and on the outside in such a way that a diagonally opposite arrangement is realized with respect to a center line of the head (12) relative to the electrode (3).

The electrode (3) in the area of the forehead (13) and the electrode (4) below the eye (14) are generally designed as active electrodes. The electrode (5) in the area of the neck (15) or the neck serves as a reference electrode. The potential differences between the electrodes (3, 4, 5) provide mixed signals with parts of EEG signals, EOG signals and EMG signals. Using the evaluation unit (11), a distinction is made between the individual signals, for example by pattern recognition or digital filtering. The signal processing can in particular be carried out using fuzzy logic. To enable individual positioning of the electrodes (3, 4, 5) in the area of the head holder (2), it is possible to equip the head holder (2) with adjusting devices. For example, it is possible to change the position of the strips shown relative to one another or to move the electrodes (3, 4, 5) along the strips. It is also contemplated to provide the headgear (2) with a quick-release fastener so that the person (1) can easily put the headgear (2) on before going to bed.

Fig. 2 shows schematically an amplifier (16) arranged at a short distance from the electrodes (3, 4, 5). In principle, it is possible to use both a common amplifier (16) for all electrodes (3, 4, 5) or amplifiers (16) individually assigned to each of the electrodes (3, 4, 5).

Different types of electrodes can be used as electrodes (3, 4, 5). For example, the use of adhesive electrodes or dry electrodes is contemplated.

A wireless short-range telemetry element can be used as the transmitter (6), which carries out a signal transmission using Bluetooth technology. In particular, it is also contemplated to equip the head holder (2) with a battery for mains-independent operation. The battery can be implemented as a disposable battery or as a rechargeable battery.

The base station (8) serves to receive and record the transmitted signals. A relatively simple constructional implementation of the base station (8) can be achieved using a data logger with interface for reading out the data via network, memory card or with a direct connection to an evaluation PC. The evaluation unit (11) for signal analysis can be implemented in the base station, but it is also possible to implement the evaluation unit (11) as an independent device. It is also conceivable to equip the base station (8) with an interface for reading out the data via mobile / telephone landline or data networks or to use storage media.

3 shows a schematic block diagram to illustrate the overall arrangement. The electrodes (3, 4, 5) are connected to a digitization or impedance measurement via amplifiers (16) and / or analog filters. A connection to signal processing is established via a first buffer. In connection with digitization, the signal quality is checked and an error is detected. Corresponding evaluation information is fed to a user interface for users. The output signals of the signal processing are fed to a second buffer and then forwarded to a display device. A diagnosis can be made here by experts. Finally, the data can be archived.

The overall arrangement in FIG. 3 is basically divided into the three components of the head holder (2), the mobile or stationary recording unit and the evaluation unit. As will be explained further in the following exemplary embodiments, the mobile or stationary recording unit can be wholly or partly integrated in the area of the head holder (2) or in the area of the evaluation unit. So between the components probably wired couplings or decoupled wireless connections can be realized. The recording unit can basically be implemented as a data logger, a PDA-like system and as a mobile or stationary computer. A computer with independent or Internet-based software and data storage can be used to implement the evaluation unit.

4 shows a first embodiment variant for the signal detection part. Some parts of this are only explained optionally, since these parts can also be integrated into the diagnostic part shown in FIGS. 9 to 11.

The signal processing includes the creation of the sleep profile. Simple signal processing parts such as filtering, compression and threshold value checks can be integrated in all modules.

The embodiment in FIG. 4 corresponds to the system shown in FIG. 3 in the left part of the drawing. An analog cable connection between the electrodes (3, 4, 5) and the amplifier (16) is provided here. Only the electrodes are arranged in the area of the head holder (2), the amplifier (16) is arranged in the area of the base station (8) as a mobile or stationary recording unit.

In the modified embodiment in Fig. 5, the arrangement of the amplifier (16) and any analog filters in the area of the head holder (2). The amplifiers (16) are connected to the mobile or stationary recording unit in a similar manner via a cable connection. In the embodiment according to FIG. 6, the digitization or the impedance measurement is also arranged in the area of the head holder (2). A connection to the mobile or stationary recording unit is made, for example, via a cable with digital data transmission or via short-range wireless communication.

According to the embodiment in FIG. 7, the control of the signal quality as well as an error detection and a first temporary storage in the area of the head holder (2) are implemented. Another buffer and a module for carrying out remote telemetry or for feeding data into data networks is arranged in the area of the mobile or stationary recording unit. A data transfer between the buffers can be digitally wired, it is also conceivable to use wireless short-range communication or remote telemetry here as well. The use of data or telephone networks, mobile radio or the Internet is also possible. Finally, data can also be exchanged using storage media.

In the embodiment according to FIG. 8, the signal processing is also implemented in the area of the head holder (2). The same methods and devices that have already been described in connection with FIG. 7 can be used for the data transmission between the respective buffers.

9 shows a possible embodiment variant for the diagnostic part. Here, too, some parts are only shown optionally, since integration into the signal detection part already explained can also take place. Signal processing is understood to be the creation of the sleep profile. Simple signal processing parts such as filtering, compression and threshold value checks can also be integrated in all modules.

FIG. 9 essentially shows the right part of the overall system according to FIG. 3, the mobile or stationary recording unit being equipped with a module for carrying out remote telemetry, feeding data into data networks and for generating a direct digital connection. Communication between the recording unit and the evaluation unit can in turn take place using all technical methods and devices that have already been described in connection with FIG. 7.

According to the embodiment in FIG. 10, the signal processing was transferred from the evaluation unit to the mobile or stationary recording unit. Otherwise, the structure essentially corresponds to the illustration in FIG. 9.

According to the embodiment in FIG. 11, with the exception of data archiving, all functional components are arranged in the area of the mobile or stationary recording unit. A connection to the data archiving is made via suitable data networks.

The process sequence when performing signal processing to create a sleep profile with discrete and / or continuous transitions is further explained in FIG. 12. The already described mixed signals or separate signals for EEG, EOG and EMG can be used as input signals. After parameter extraction, standardization, conditioning and plausibility tätskontrolle. It is also possible to perform artifact detection and removal.

A pattern recognition by a classifier can take place, for example, using artificial neural networks. Even after the pattern recognition, a standardization, conditioning and plausibility check as well as, if necessary, an artifact recognition and elimination are carried out.

After the evaluation of the data, the information about the context is compiled, in particular about parameters and patterns in a time window. A transparent set of rules for creating the sleep profile can be generated from this data, for example using neural networks or fuzzy systems. Finally, there is a post-correction, plausibility check and smoothing of the generated curves.

13 shows an exemplary sleep profile in which a distinction is made between waking states, light sleep (LS), deep sleep (SWS) and REM or paradoxical sleep. Modified sleep profiles are also shown in FIGS. 14, 15, 16, 17, 18 and 19. The sleep profiles differ essentially in the way they are displayed in order to facilitate evaluations based on different criteria.

The base station (8) can be connected to an evaluation PC by cable or via a Bluetooth interface. Indirect connections via telephone networks, for example analog, via ISDN or via mobile radio are also possible. There is also an integration into local ones Networks or data transfer possible using the Internet.

In principle, it is possible to use the signal processing described to create a classic hypnogram according to the authors Rechtschaffen and Kales or other types of sleep profiles. In particular, it is also possible to generate sleep profiles with discrete or continuously merging states. A distinction is made between waking and sleeping states when generating the sleep profiles. In the case of sleep states, a distinction is made between light sleep, deep sleep and REM sleep. A quasi-continuous calculation and display enables simultaneous statements about the micro and macro structure of sleep and thus improves the manual or automatic assessment of sleep quality. The calculation and display can take place with a temporal resolution of less than 10 ms and an at least partially smooth transition between the sleep states. The microstructure can be analyzed in particular by means of a fragmentation, which comprises the detection of aronals and microaronals.

Basically, it is possible to use the measurement signals of other sensors in the signal evaluation and thereby evaluate information about additional body functions. Such additional sensors can relate to breathing, the cardiovascular system and the execution of movements. Using the 3 electrodes (3, 4, 5), two unipolar or one bipolar lead can be obtained, for example. In theory, each of the electrodes (3, 4, 5) can be used as a passive electrode, but the structure described above proves to be advantageous. In the event that only a single unipolar If derivation is to be determined, it is possible to short-circuit two of the electrodes (3, 4, 5). For the electrode (3) in the area of the forehead (13) of the person (1), it proves to be particularly advantageous to arrange it in an area between an eyebrow and the hairline. For the electrode (4) laterally below the eye (14), it proves to be expedient to position it about 3 cm above the zygomatic bone. As an alternative to the arrangement of the reference electrode shown in the region of the neck (15), it can also be arranged in the neck behind the ear or above the mastoid.

As an alternative to the Bluetooth method for implementing the short range telemetry method described by way of example, it is also possible to use the DECT method, IrDA method or to use a radio module.

In general, the method explained includes both signal acquisition using the electrodes, signal processing, the presentation of the results, and support in producing a diagnostic statement. The device explained can be used to screen measurement data, to support the establishment of a diagnosis by the attending doctor and to carry out a therapy check for the most common sleep disorders. In particular, it is intended for use in connection with sleep disorders such as OSAS, insomnia, periodic limb movements and narcolepsy.

As an alternative to evaluating only the sleep profile generated, it is also possible to combine the sleep profile with one or more parameters of respiration, oxygen saturation of the blood, heart, or. Pulse rate, body position as well as arm and / or leg movement to carry out. The device explained and the method enable use under clinical conditions, within a sleep laboratory and in particular also on an outpatient basis.

In addition or as an alternative to the properties of the method already explained, this can also be used to determine a number of further parameters. These are in particular the performance of the activity in the EEG frequency bands, for example the alpha activity, the spindle density and the SEM density. Determining these parameters supports the detection and differentiation of neurological sleep disorders, for example insomnia.

A further increase in user convenience when using the device can be achieved by transparently visualizing the recognized patterns or applied rules. Plausibility checks and post-correction of the data are supported by the display of the measured or filtered raw data.

Another field of application for the use of the device and the use of the method is the monitoring of hypersomnia and vigilance during the day and the objective detection of falling asleep while performing sleep latency or monotony intolerance tests.

With regard to the execution of the signal processing, a number of further patterns can be determined from the mixed signals by feature extraction, in particular by extraction of the frequency and amplitude distributions. In particular, these are fast and slow eye movements, alpha, theta and delta activities in the EEG, sleep spin yours and movements. Feature extraction can be supported through the use of artificial neural networks. Pre-processing of the measurement signals has proven to be advantageous in order to dampen higher-frequency signal components, in particular network disturbances of 50 Hz or 60 Hz. The use of digital filters has also proven to be advantageous.

After masking out the 50 Hz or 60 Hz network disturbances, high-frequency signal components with a frequency above 25 Hz can be evaluated to measure muscle tone. The evaluation of the muscle tone supports in particular the detection of REM sleep and deep sleep. The strength of the performance of the individual EEG frequency bands, the frequency of the occurrence of the patterns and the strength of the muscle tone can be individually standardized using the value distribution.

A sleep depth is assigned to a measurement phase to be evaluated, for example a measurement phase with a duration of one second. This is done by looking at the frequency, strength as well as the. The sequence of the recognized patterns can be viewed in a time window which is greater than or equal to the duration of the measurement phase in question. The assignment carried out can be based on rules using fuzzy logic.

According to a further embodiment, it is also contemplated that a discrete sleep profile, a so-called hypnogram, can be generated from the results of the signal processing, according to righteousness and Kales.

By using the method described, a novel sleep profile is provided, which in particular also reproduces continuous transitions from waking to light sleep to deep sleep. In terms of measurement technology, deep sleep is characterized by the fact that activities in the delta frequency range of the EEG are detected with sufficient frequency. If deep sleep is detected, the amplitude or the power of this delta activity in the sleep profile can be recognized by the strength of the rash in the direction of deep sleep. REM sleep begins and ends at fixed times, there is no continuous transition here. By defining threshold values, it can be determined which areas are clearly evaluated as waking sleep, light sleep, deep sleep or as an unclear sleep state. This helps in particular to specify the time periods of the occurrence of these states in absolute or percentage.

As an alternative to the positioning of the electrode arranged in the region of the patient's neck when the measuring method was carried out, it is also possible to position this electrode in the region of the patient's chin, neck, upper body or earlobe.

As an alternative or in addition to the exemplary arrangement of the reference electrode in the region of the patient's neck, it is also possible to position it differently, for example on the earlobe, neck, chin or on the patient's upper body.

Claims

P a t e n t a n s r u c h e

Method for determining a sleep profile, in which at least one signal is detected via at least three electrodes and fed to an evaluation device, in which a first electrode is positioned in the area of a person's head, and in which mixed signals with parts of EEG signals, EOG, are generated by the electrodes Signals and EMG signals are detected and fed to the evaluation device, characterized in that a first electrode (3) in the area of a forehead (13) of the person (1), a second electrode (4) in the area laterally below an eye (14 ) and a third electrode (5) is positioned as a reference electrode and that the signals are subjected to signal processing by the evaluation device (11) under program control.

2. The method according to claim 1, characterized in that the electrode (3) in the region of the forehead (13) of the person (1) is used as an active electrode.

3. The method according to claim 1 or 2, characterized in that the electrode (3) is positioned in an area above an eye (14) of the person (1).

4. The method according to any one of claims 1 to 3, characterized in that the electrode (4) below the eye (14) is used as an active electrode.

5. The method according to any one of claims 1 to 4, characterized in that the electrode (4) is positioned below the eye relative to a center line of the head (12) of the person (1) with respect to the electrode (3) in the forehead region diagonally and opposite ,

6. The method according to any one of claims 1 to 5, characterized in that a signal processing to distinguish between EEG signals, EOG signals and EMG signals is carried out.

7. The method according to any one of claims 1 to 6, characterized in that the electrodes (3, 4, 5) are arranged to be positionally variable relative to one another.

8. The method according to any one of claims 1 to 7, characterized in that the electrodes (3, 4, 5) are connected by headbands.

9. The method according to any one of claims 1 to 8, characterized in that an electrical signal amplification with a small distance to the electrodes (3, 4, 5) is carried out.

10. The method according to any one of claims 1 to 9, characterized in that a wireless signal transmission is carried out.

11. The method according to any one of claims 1 to 10, characterized in that a wireless short-range telemetry method is used for signal transmission.

12. The method according to any one of claims 1 to 11, characterized in that the Bluetooth method is used for signal transmission.

13. The method according to any one of claims 1 to 12, characterized in that a pattern recognition is carried out for signal processing.

14. The method according to any one of claims 1 to 13, characterized in that signal processing is carried out using fuzzy logic.

15. Device for determining a sleep profile, which has at least 3 electrodes for detecting mixed signals with portions of an EEG signal, an EOG signal and an EMG signal, and in which the electrodes are connected to an evaluation device, characterized in that at least two the electrodes (3, 4, 5) are positioned relative to one another by a head holder (2), the contour of which It is adapted to a head contour of a person (1) that a first electrode (3), after placing the head holder (2) on the head (12) of the person (1) in the area of a forehead (13), a second electrode (4 ) is arranged in the area laterally below an eye (14) and a third electrode (5) as a reference electrode and that the evaluation device (11) is provided with a signal processing module.

16. The apparatus according to claim 15, characterized in that the electrode (3) in the region of the forehead (13) is designed as an active electrode.

17. The apparatus according to claim 15 or 16, characterized in that the electrode (3) is arranged laterally offset in the region of the forehead relative to a center line of the head (12).

18. Device according to one of claims 15 to 17, characterized in that the electrode (4) below the eye (14) is designed as an active electrode.

19. Device according to one of claims 15 to 18, characterized in that the electrode (4) is positioned below the eye relative to a center line of the head (12) diagonally and opposite to the electrode (3) in the region of the forehead.

20. Device according to one of claims 15 to 19, characterized in that the signal processing module is at least partially designed as software.

21. The apparatus according to claim 20, characterized in that the software is designed for signal differentiation.

22. Device according to one of claims 15 to 21, characterized in that the electrodes (3, 4, 5) in the region of the head holder (2) are arranged in a position-changing manner.

23. Device according to one of claims 15 to 22, characterized in that the head holder (2) is formed from head straps.

24. Device according to one of claims 15 to 23, characterized in that an amplifier (16) is arranged at a short distance from at least one of the electrodes (3, 4, 5).

25. Device according to one of claims 15 to 24, characterized in that a wireless signal transmission path is formed between a transmitter (6) arranged in the region of the head holder (2) and a receiver (7) arranged in the region of a base station (8) ,

26. Device according to one of claims 15 to 25, characterized in that a signal transmitter with a functional sequence is designed in accordance with a wireless short-range telemetry method.

27. The device according to one of claims 15 to 26, characterized in that at least one data transmission path is equipped with an interface according to the Bluetooth technology.

28. Device according to one of claims 15 to 27, characterized in that the evaluation device (11) is provided with a fuzzy logic.

29. Device according to one of claims 15 to 28, characterized in that the electrodes (3, 4, 5) are connected to detect a unipolar lead.

30. Device according to one of claims 15 to 29, characterized in that one of the electrodes (3, 4, 5) is arranged in the mastoid area and is connected as a passive electrode.