U.S. patent application number 16/190675 was filed with the patent office on 2019-06-06 for detection appliance and method for observing sleep-related breathing disorders.
This patent application is currently assigned to RESMED R&D GERMANY GMBH. The applicant listed for this patent is RESMED R&D GERMANY GMBH. Invention is credited to Dieter Heidmann, Dieter KLAUS, Stefan MADAUS, Caspar Graf von STAUFFENBERG, Harald VOGELE.
Application Number | 20190167187 16/190675 |
Document ID | / |
Family ID | 34258383 |
Filed Date | 2019-06-06 |
![](/patent/app/20190167187/US20190167187A1-20190606-D00000.png)
![](/patent/app/20190167187/US20190167187A1-20190606-D00001.png)
![](/patent/app/20190167187/US20190167187A1-20190606-D00002.png)
![](/patent/app/20190167187/US20190167187A1-20190606-D00003.png)
![](/patent/app/20190167187/US20190167187A1-20190606-D00004.png)
![](/patent/app/20190167187/US20190167187A1-20190606-D00005.png)
![](/patent/app/20190167187/US20190167187A1-20190606-D00006.png)
![](/patent/app/20190167187/US20190167187A1-20190606-D00007.png)
![](/patent/app/20190167187/US20190167187A1-20190606-D00008.png)
![](/patent/app/20190167187/US20190167187A1-20190606-D00009.png)
![](/patent/app/20190167187/US20190167187A1-20190606-D00010.png)
View All Diagrams
United States Patent
Application |
20190167187 |
Kind Code |
A1 |
MADAUS; Stefan ; et
al. |
June 6, 2019 |
DETECTION APPLIANCE AND METHOD FOR OBSERVING SLEEP-RELATED
BREATHING DISORDERS
Abstract
A detection appliance and a method detect and evaluate a
measuring signal that is indicative of breathing of a sleeping
person, in connection with the observation of sleep-related
breathing disorders. Instruments also detect signals that are
indicative of breathing of a patient. The aim provides solutions
that enable a reliable examination in terms of occurrence of
sleep-related sleeping disorders, in the usual surroundings of the
person concerned. In a first form, a mobile detection appliance is
provided with a sensor device for detecting a nasal flow signal
indicative of a nasal respiratory gas flow, and/or a respiratory
flow signal indicative of an oral respiratory gas flow, in addition
to an electronic data processing unit comprising a memory device
and processing the signals indicative of temporal course of the
nasal and oral respiration. The data processing device is
configured to store data indicative of temporal course of the
respiratory flow signals.
Inventors: |
MADAUS; Stefan; (Krailling,
DE) ; STAUFFENBERG; Caspar Graf von; (Gauting,
DE) ; VOGELE; Harald; (Gauting, DE) ;
Heidmann; Dieter; (Geretsried, DE) ; KLAUS;
Dieter; (Weilheim, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
RESMED R&D GERMANY GMBH |
Martinsried |
|
DE |
|
|
Assignee: |
RESMED R&D GERMANY GMBH
MARTINSRIED
DE
|
Family ID: |
34258383 |
Appl. No.: |
16/190675 |
Filed: |
November 14, 2018 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10570503 |
Jun 14, 2006 |
10154811 |
|
|
PCT/EP04/09857 |
Sep 3, 2004 |
|
|
|
16190675 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 5/087 20130101;
A61B 5/6831 20130101; A61B 5/6825 20130101; A61B 5/1135 20130101;
A61B 5/4818 20130101; A61B 5/113 20130101; A61B 5/7232
20130101 |
International
Class: |
A61B 5/00 20060101
A61B005/00; A61B 5/113 20060101 A61B005/113; A61B 5/087 20060101
A61B005/087 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 3, 2003 |
DE |
103 40 654.9 |
Claims
1. A mobile device comprising: a sensor device configured to
acquire a respiratory flow signal indicative of a respiratory gas
flow; an electronic data processing device configured to process
the respiratory flow signal, and a memory device; wherein the
electronic data processing device is configured to initiate a
process for storing of data indicative of a temporal course of the
respiratory flow signal to the memory device; and wherein the
mobile device further comprises an interface device configured to
transmit the stored data to an external analysis system.
2. A mobile device according to claim 1, wherein the interface
device is configured to transmit the stored data wirelessly to the
external analysis system.
3. A mobile device according to claim 2 wherein the interface
device is an infrared interface.
4. A mobile device according to claim 1, wherein the sensor device
configured to acquire the respiratory flow signal indicative of the
respiratory gas flow is connected to a mask device.
5. A mobile device according to claim 1, further comprising a power
supply which is formed by a battery device.
6. A mobile device according to claim 1, wherein the electronic
data processing device is configured to: terminate the initiated
process for storing of data by evaluation of a time criterion;
and/or terminate the initiated process for storing of data when the
respiratory flow signal fulfils a shutdown criterion within a
shutdown time window.
7. A mobile device according to claim 1, wherein the external
analysis system is configured to generate evaluation features from
the respiratory flow signal indicative of the respiratory gas flow
and to generate at least one evaluation result by subjecting the
evaluation features to an associative analysis.
8. A mobile device according to claim 7, wherein the evaluation
features are generated based on correlation criteria.
9. A mobile device according to claim 8, wherein the correlation
criteria are applied to a first derivative and/or a second
derivative of the temporal course of the respiratory flow
signal.
10. A mobile device according to claim 7, wherein flow-limited
breathing is recognised based on the associative analysis of the
evaluation features.
11. A mobile device according to claim 7, wherein at least one part
of the evaluation features is generated under consideration of a
first derivative and/or a second derivative of the temporal course
of the respiratory flow signal.
12. A mobile device according to claim 1, wherein the mobile device
is configured such that the stored data is visualisable by a user
terminal.
13. A mobile device according to claim 7 wherein the external
analysis system comprises a computer.
14. A mobile device according to claim 1 wherein the electronic
data processing device is configured with said process for storing
of data by a data processing program, the data processing program
being reproduced into the mobile device via the interface
device.
15. A method for a mobile device comprising: acquiring, with a
sensor of a mobile device, a respiratory flow signal indicative of
a respiratory gas flow; initiating, with an electronic data
processing unit of the mobile device, a process for storing of data
indicative of a temporal course of the respiratory flow signal to a
memory of the mobile device; and transmitting, with an interface
device of the mobile device, the stored data to an external
analysis system.
16. A method according to claim 15, wherein the interface device
wirelessly transmits the stored data to the external analysis
system.
17. The method according to claim 16 wherein the interface device
is an infrared interface.
18. A method according to claim 15, wherein for the acquiring, the
sensor is connected to a mask device.
19. A method according to claim 15, further comprising powering the
mobile device with a battery.
20. A method according to claim 15, further comprising, with the
electronic data processing unit: terminating the initiated process
for storing of data by evaluation of a time criterion; and/or
terminating the initiated process for storing of data when the
respiratory flow signal fulfils a shutdown criterion within a
shutdown time window.
21. A method according to claim 15, further comprising generating,
with the external analysis system, evaluation features from the
respiratory flow signal indicative of the respiratory gas flow and
generating at least one evaluation result by subjecting the
evaluation features to an associative analysis.
22. A method according to claim 21, wherein the evaluation features
are generated based on correlation criteria.
23. A method according to claim 22, wherein the correlation
criteria are applied to a first derivative and/or a second
derivative of the temporal course of the respiratory flow
signal.
24. A method according to claim 21, wherein flow-limited breathing
is recognised based on the associative analysis of the evaluation
features.
25. A method according to claim 21, wherein at least one part of
the evaluation features is generated under consideration of a first
derivative and/or a second derivative of the temporal course of the
respiratory flow signal.
26. A method according to claim 15, further comprising generating
the stored data in a visualization by a user terminal.
27. A method according to claim 21 wherein the external analysis
system comprises a computer.
28. A method according to claim 15, further comprising configuring,
by a data processing program, the electronic data processing unit
with said process for storing of data, the data processing program
being reproduced into the mobile device via the interface device.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/570,503, filed on Jun. 14, 2006, which is a
national phase entry under 35 U.S.C. .sctn. 371 of International
Application No. PCT/EP2004/009857 filed Sep. 3, 2004, published in
English, which claims priority from German Patent Application No.
DE 103 40 654.9 filed Sep. 3, 2003, all of which are incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] The invention relates to a detection appliance and a method
for acquiring and evaluating a measuring signal that is indicative
of the breathing of a sleeping person, in connection with the
observation of sleep-related breathing disorders. The invention
also relates to instruments for acquiring signals that are
indicative of the breathing of a patient.
BRIEF SUMMARY OF THE INVENTION
[0003] For the purposes of investigating sleep-related breathing
disorders, so-called polysomnograph devices are known which
typically possess multiple measurement channels for acquiring
measurement signals relating to physiological state indicators for
the patient. As can be seen in the patent application DE 101 64
445.0 originating from the present applicant, the acquisition of
ECG and blood pressure signals for the purposes of diagnosing a
patient with regard to his/her breathing characteristics during a
sleeping phase, and the recording of these signals together with
signals that describe the breathing activity of the patient, is
known. These signals describing the breathing activity of the
patient can be generated by means of so-called thermistors or
pneumotachographs. The acquired signals can be visualized in
temporal relationship to one another and evaluated as part of a
review by a medical specialist. Based on the medical specialist's
evaluation, it is possible to determine whether any respiratory
disorders that may be present can be prevented by the supply of
respiratory gas at an elevated pressure (CPAP therapy) Suitable
therapy parameters can also be determined as part of the review by
a medical specialist.
[0004] When investigating persons with signs of sleep-related
respiratory disorders, examination of the generated measurement
signals can, in practice, lead to different findings in some
circumstances, in particular in regard to the type and severity of
obstruction-related impairment of the respiratory passages and in
regard to the evaluation of the general physiological state of the
patient. When an evaluation of the symptoms is inadequate, the
problem arises that a therapy need that may exist is not
recognized, or therapy parameters are selected that do not
adequately take into consideration the actual physiological
requirements, or at least limit the comfort of the therapy.
[0005] The decision by the affected person to submit to an
investigation of possible sleep-related respiratory disorders in a
sleep laboratory is often not taken until the secondary symptoms of
the OSA disorder are already significantly impacting on how the
disorder is experienced. The burden that OSA places on the affected
person when already in an advanced stage makes a precise diagnosis
of the illness more difficult.
[0006] The aim of the invention is to provide solutions that enable
an especially reliable investigation into the occurrence of
sleep-related breathing disorders, in particular in the usual
surroundings of the person concerned.
[0007] To this end, in a first form of embodiment, a mobile
detection appliance is provided, said appliance comprising a sensor
device for acquiring a nasal flow signal that is indicative of a
nasal respiratory gas flow, and/or a respiratory flow signal that
is indicative of an oral respiratory gas flow, in addition to an
electronic data processing unit which comprises a memory device and
is used to process the respiratory flow signals that are indicative
of the temporal course of the nasal and oral respiration, said data
processing device being configured in such a way that it stores
data that is indicative of the temporal course of the respiratory
flow signals.
[0008] This provides an advantageous means, via a detection
appliance suitable for self-application in the home area, i.e. in
the familiar surroundings of the affected person, of detecting
characteristic features of breathing during the sleep phase in a
manner that enables the physiological state of the affected person
to be determined with an especially high degree of reliability. In
can then be assessed on the basis of a standardized, computer-based
analysis of the measurement results whether, and if so in what
severity OSA symptoms are present, and whether a more in-depth
examination by means of a sleep laboratory should be
recommended.
[0009] The data processing unit, or a signal transmission circuit
preceding it, is in preference configured in such a way that it is
possible to test whether a given acquired respiratory flow signal
fulfils prescribed signal quality criteria. Should the acquired
signal not fulfil certain recording of indicate the criteria, it is
possible to suppress the signal, or recording entries that temporal
locations of signals that were classified as invalid.
[0010] The data processing unit is in preference designed in such a
way that it has access to a time-keeping device so that the data
that is indicative of the respective respiratory gas flow can be
recorded in conjunction with time information.
[0011] The data processing unit is in preference implemented in
conjunction with a data compression system enabling the acquired
time-dependent signals to be recorded in compressed form.
[0012] The data processing unit is also in preference configured in
such as way that the recording process is initiated by a switching
impulse initiated by the user. It is possible to make the
generation of the switching impulse conditional upon the pressing
of a switch button for a prescribed minimum duration of, for
example, 3 seconds.
[0013] The data processing unit can be configured in such a way
that it stores the data when the acquired respiratory flow signals
fulfil a certain criterion, for example a prescribed periodicity
criterion.
[0014] The detection appliance comprises in preference a pressure
measurement connection to which can be connected a measurement
cannula, a pair of measurement cannulae, or a bundle of measurement
cannulae. The first measurement cannula can be connected to a nasal
pressure measurement spectacle facility for acquiring a
back-pressure signal obtained from the respiratory gas flow out of
the nasal openings. The second measurement cannula can be connected
to the user in such a way that it can be used to collect a signal
indicative of the gas flow via the mouth of the user, if
present.
[0015] It is possible to equip the detection appliance with a
second pressure measurement connection, also intended for detecting
nasal respiration, in order to acquire a second nasal respiration
flow signal. The ability to acquire two pressure measurement
signals makes it possible to operate the detection appliance in
such a way that it can separately acquire the respiratory flow
signals from each of the left and right nasal openings
respectively.
[0016] The detection appliance comprises in preference a facility
to detect chest expansion. The facility for detecting the chest
expansion may comprise a strap element that can be fitted around
the chest area of the user. It is possible to design this strap
element in such a way that a signal that is indicative of the
extension of the strap, or the load on the strap can be derived
(e.g. changes in the electrical resistance of an embedded
conductor). It is also possible to provide the detection appliance
with a means of detecting the load on the strap. In particular, it
is possible to provide the detection appliance with a loop feature
by means of which the extension of the strap, or the forces on the
strap can be acquired. It is also possible to provide the detection
appliance with pressure or force detection structures by means of
which the force exerted by a strap located on top of these force
detection structures can be acquired. The strap for detecting the
chest expansion can also serve to fasten the detection appliance to
the user.
[0017] The recording process can, in preference, be ended by means
of a switching signal triggered by the user. This switching signal
can in particular be generated by the switch, in particular a press
button, previously used to switch on the appliance. It is also
possible to configure the detection appliance in such a way that
the recording process can be ended as a result of the fulfilment of
a time criterion. In particular, it is possible to end the
recording process when it has reached a prescribed duration of, for
example, 9.5 h.
[0018] It is also possible to end the recording process under
switch control if the acquired respiratory flow signal fulfils a
certain switch-off criterion within a certain switch-off time
window. It is possible to limit the recording capacity to a
specific number of recordings, in particular to two recordings.
[0019] According to a special form of embodiment of the present
invention, the detection appliance can be provided with an
interface device for transmitting the recorded data to an external
analysis system. This interface device is in preference provided in
the form of a USB interface or an infrared interface.
[0020] It is also possible, in an especially advantageous manner,
to design the detection appliance in such a way that the memory
device incorporated in the recording device is removable. Such a
memory device can be in the form of a card or, in particular, a USB
flash stick. By first creating an entry in the memory device, it is
possible to record personal data on the storage medium. On the
basis of this initial recording, it is possible to pre-configure
the detection appliance or to ensure that the acquired data is
correctly assigned to the specific user.
[0021] The configuration of the data processing unit is in
preference set by a data processing program, where this data
processing program is in preference modifiable or substitutable.
The reproduction of the data processing program in the detection
appliance can occur via the previously mentioned interface device,
additional interface devices or the storage medium.
[0022] Along with an in preference intuitive and easy-to-use switch
device, the detection appliance is also provided with indicator
devices for indicating the operational readiness or the functional
state of the detection appliance. It is possible to signify the
recording readiness of the detection appliance by the periodic
blinking of a signal diode.
[0023] The detection appliance comprises in preference a power
supplying device which may, for example, take the form of a battery
unit. The battery unit is in preference as compact as possible so
that the detection appliance can be designed to be flat and
miniature and possess little weight.
[0024] The data processing unit is in preference coupled to a
calibration device for calibrating the respiratory flow signal. The
calibration device can be designed in such a way that it can
perform an automatic adjustment of the system to the acquired
signal level.
[0025] According to a special form of embodiment of the present
invention, the detection appliance is built in such a way as to
feature a structural component that is compatible with a playback
unit the construction of which corresponds to that of a Game
Boy.
[0026] It is possible to design the detection appliance in such a
way that at least one portion of it can be introduced into the
insertion slot of a Game Boy.
[0027] According to a special form of embodiment of the present
invention, the detection appliance is designed in such a way as to
comprise a base module to which can be coupled a recording transfer
module.
[0028] The detection appliance is in preference designed with such
a Game Boy compatible structure. This enables the recorded data to
be visualized via an intuitive, simply-to understand user interface
on a conventional end-user device and, if necessary, to be
processed with regard to selected properties.
[0029] The supply of power and the conversion of the pressure
signal occurs in preference in the base module. To this end, the
base module comprises in preference a battery compartment and a
pressure sensor.
[0030] The recording module comprises in preference a data
processing unit that is configured in such a way that it records
onto a memory device data that is indicative of the temporal course
of the breathing. The recording module can be provided with an
interface device for reading the recorded data. It is possible to
connect the memory device to the recording module in a detachable
manner so that is possible to separate the memory device from the
recording module and introduce it into another system for further
evaluation and visualization.
[0031] The acquisition of the respiratory signal can, as an
alternative to acquisition using a nasal cannulation arrangement,
also occur by means of other measuring equipment.
[0032] According to the invention, the initially stated aim can be
solved by means of a method for the provision of an evaluation
result that is indicative of the physiological state of a person
and is based on measurement signals associated with the breathing
of that person, where evaluation characteristics are generated from
said measurement signals through the use of several analysis
systems and a least one evaluation result is generated from a
result generation step based thereon in which the evaluation
characteristics are subjected to an associative analysis, whereby
said measurement signals are recorded by a mobile detection
appliance applied by the affected person in the course of a signal
acquisition phase preceding the analysis.
[0033] This provides an advantageous means of creating a quantity
of data from the signal collection carried out at home by the user
over a continuous period of approx. 6 to 8 hours based on which
evaluation characteristics can be generated from which can be
obtained reliable evaluation results obtained in a standardized
repeatable manner that can in an advantageous manner form the basis
of a subsequent diagnosis and thereby facilitate a standardized
preliminary evaluation.
[0034] The associative analysis of the respiratory properties
determined for the individual breaths can cover a time frame that
spans, for example, a prescribed number of breaths, e.g. 30, or an
adaptively optimised number of breaths. It is also possible, in
particular for the purposes of assessing the physiological state of
the user, for example as the basis for a medical diagnosis, to
perform certain correlation operations over a time window spanning
sleep phase related periods, selected time segments or the entire
measurement period. According to an especially advantageous
embodiment of the invention, correlation operations are used to
select raw data and/or intermediate results that allow
characteristic values, in particular indices, to be generated in an
especially reliable manner.
[0035] According to an especially advantageous embodiment of the
invention, the associative analysis forms the basis of a
physiological characterization of the symptoms that may be present
in the person being examined.
[0036] According to an especially advantageous embodiment of the
invention, the evaluation characteristics are generated on the
basis of correlation criteria, in particular statistical analysis
systems, that allow, for example, commonalities with preceding
breaths, or in preference adaptively optimised reference criteria,
e.g. of reference breaths, to be evaluated. The correlation
criteria can, in particular, be applied to the first and/or second
derivative of the acquired respiratory gas flow. The generation of
the characteristic features of each breath can occur with the aid
of statistical methods. The associative analysis of the properties
determined for each breath can also occur with the aid of
statistical methods.
[0037] Using the evaluation characteristics generated for each
breath or specific breath sequences, a feature array can be
progressively filled that describes a time window, at least for
selected evaluation characteristics, that is at least as big as the
smallest time window used in the associative analysis of the
evaluation characteristics.
[0038] According to a particularly advantageous embodiment of the
invention, the evaluation characteristics are generated in such a
way that they include, for example, evaluation characteristics that
provide information about the duration of a breath and/or, for
example, characteristic information about what can be considered
normal breathing. Based on these evaluation characteristics, it is
possible to determine as part of the associative analysis the
duration of periods of normal breathing.
[0039] Furthermore, the evaluation characteristics are by
advantageous means generated in such a way that they contain
information about the occurrence of any flow limitation features in
the individual breaths or, in preference, also certain
representative information relating to flow limitations. Based on
an associate analysis of the evaluation characteristics obtained
for these flow-limited breaths, it is possible to describe the
duration of certain properties of the, at least in part,
flow-limited breathing sequences.
[0040] Evaluation characteristics can also be generated for periods
in which no breathing activity was registered, and these can be
used to determine the length of any apnoea sequence phases and/or
generate characteristic features for the properties of these apnoea
phases as part of an associative analysis. These evaluation
characteristics include, in preference, information about the type
of the apnoea phases, e.g. whether the apnoea phase can be
classified as central, obstructive or a combination of these (mixed
apnoea phase).
[0041] According to an especially advantageous embodiment of the
invention, such evaluation characteristics are also generated for
snoring phases, phases with Cheyne-Stokes breathing and
hypoventilation phases.
[0042] The evaluation characteristics also include in preference
data or information from which the body position, the head position
and, in preference, also the degree of rotation of the neck can be
derived. The evaluation characteristics may already contain data
indicative of the sleep phases.
[0043] The generated evaluation characteristics are in preference
saved with reference to a given recorded breath or taking into
account their time location. That is, the generated evaluation
characteristics can be associated with a defined time window--or
the associated breath in the case of normal breathing.
[0044] It is also possible, as part of the associative analysis, to
generate a snoring index.
[0045] It is also possible, as part of the associative analysis, to
generate a sleeping phase index. In conjunction with the
respiratory phase analysis, it is possible to distinguish between
inspiratory (relevant to obstruction) and expiratory (less
relevant) snoring. It is also possible, as part of the associative
analysis, to generate a periodic respiration index. It is also
possible, as part of the associative analysis, to generate a
respiration volume index.
[0046] The respiratory gas flow can be measured either at ambient
pressure or under a defined modified respiratory gas pressure.
[0047] In preference, at least some of the evaluation
characteristics are generated by considering the first and second
derivative of the temporal course of the respiratory gas flow.
[0048] According to a further form of the present invention, the
initially stated aim is also solved by means of an appliance for
carrying out the previously described method, said appliance
comprising a measurement signal input device and a computing device
for the provision of several analysis systems, where the analysis
systems are used to generate evaluation characteristics from said
measurement signals and at least one evaluation result is generated
from a result generation step based thereon, and where the
computing device is configured in such a way as to subject the
evaluation characteristics to an associative analysis.
[0049] In the course of detecting the respiratory activity of the
user on the basis of data that is indicative of the respiratory gas
volumetric flow rate, it is possible to recognize actual individual
breaths. The beginning and end of the inspiration and expiration
phase of a breath can, for example, be determined in conjunction
with an examination of the first and second derivative of the
respiratory gas flow signal along with consideration of the likely
tidal volume. Based on the evaluation results, it is possible to
determine the duration of the breath phases, the actual volume of
each breath and the breathing pattern.
[0050] The physiological state of the person under examination can
also be determined through statistical analysis of the properties
of several successive breaths. A reduction in raw data can be
achieved on the basis of an extraction of the characteristics of
each individual breath. Based on the statistical analysis of the
properties of several successive breaths, it is possible to
differentiate between obstruction-related snoring and
non-obstruction-related snoring. This enables oscillation
properties associated with snoring events to be characterized
without the need for a microphone device.
[0051] The occurrence of any snoring-related oscillations can be
detected on the basis of the temporal course of the respiratory
signal. It is therefore possible, for example, to extract the
pressure oscillations caused by snoring from the signals generated
by suitable pressure sensing devices. In particular, it is possible
to classify snoring events according to their point of origin (soft
palate, larynx . . .) on the basis of a frequency and amplitude
analysis, e.g. Fast Fourier analysis.
[0052] Based on an associative analysis of the evaluation
characteristics, the following obstructive sleep disorders (OSA) in
particular can be recognized:
[0053] Apnoea, hypopnea, flow-limited breathing, and stable and
unstable breathing.
[0054] A respiratory disorder is classified as an apnoea event if a
breathing cessation is detected the duration of which exceeds a
predefined period of, for example, 10 seconds.
[0055] A hypopnea event can be considered to be present if, for
example, it is identified that three breaths that have been
classified as normal are followed by at least two but at most three
larger breaths. A further criterion that can be used is the
difference in inspiratory volume of the breaths under
consideration.
[0056] A flow limitation can be identified in a particular breath
being examined if the respiratory gas flow exhibits certain plateau
zones or multiple maxima during the inspiratory phase.
[0057] Any high frequency oscillations evident in a pressure signal
can, in conjunction with the respiratory flow signal, be classified
as inspiratory or expiratory snoring. The generated evaluation
characteristics with regard to the occurrence of snoring can be
used as input for the associative analysis used to generate the
evaluation results.
[0058] The inventive acquisition and evaluation of signals that are
indicative of the respiratory gas flow can provide information for
describing and visualizing the physiological state of a person, in
particular with regard to an illness connected with sleep-related
respiratory disorders. The inventive signal acquisition and
evaluation can be used to configure respiratory devices.
[0059] In a particular form of embodiment of the invention, at
least two of the following are applied in combination:
[0060] The degree of statistical certainty of the evaluation or
classification results obtained is determined.
[0061] For each breath, breath-specific characteristics are
determined on the basis of defined analysis procedures.
[0062] These analysis procedures specifically consider the
inspiratory process, the expiratory process, the transition between
the aforementioned processes, the properties of the respiratory gas
flow vs time curve within each breathing cycle, combinatorial
analysis of the characteristics of the temporal course of the
respiratory gas flow within a given breath.
[0063] The commonalities between breaths is determined.
[0064] Differences or temporal changes in the breath
characteristics are determined and taken into consideration when
assessing the physiological state of the user.
[0065] Based on a multi-variate analysis of individual
characteristics, evaluation results are generated that describe the
physiological state or physiological properties in a standardized
parametric manner.
BRIEF DESCRIPTION OF THE DRAWINGS
[0066] Further particulars and characteristics of the invention can
be found in the following description in conjunction with the
drawings. They show:
[0067] FIG. 1a a perspective view of a first embodiment of the
inventive detection appliance;
[0068] FIG. 1b a sketch illustrating a nasal cannulation
arrangement for detecting the respiratory gas flow by means of
back-pressure measurement in the region of the nasal openings;
[0069] FIG. 1c a sketch illustrating a cannulation arrangement for
detecting the respiratory gas flow by means of pressure measurement
in the interior of a one-way filter mask;
[0070] FIG. 1d a sketch illustrating a means of attaching the
detection appliance to the user with the aid of a strap fitted
around the chest;
[0071] FIG. 1e a sketch illustrating a second embodiment of the
inventive detection appliance with several connection segments used
to connect pressure measurement cannulae for the separate detection
of nasal and oral respiration;
[0072] FIG. 1f a sketch illustrating a concept for monitoring
respiration by measuring signals that are indicative of the
respiratory gas flow through the left nasal opening, the right
nasal opening and the mouth of the user;
[0073] FIG. 1g a sketch illustrating a nasal spectacle arrangement
with integrated cannula for detecting oral respiration;
[0074] FIG. 1h a sketch illustrating a concept for monitoring
respiration by taking measurements with the aid of a full-face
mask;
[0075] FIG. 1i a sketch illustrating an acquisition device intended
for application to the nose of the user;
[0076] FIG. 1j a sketch illustrating a flow path design suitable
for the acquisition device according to FIG. 1i;
[0077] FIG. 1k a sketch illustrating an acquisition device intended
for nasal application which covers the nasal openings of the
user;
[0078] FIG. 1l a sketch illustrating an acquisition device intended
for attachment to the nasal opening area;
[0079] FIG. 1m a sketch illustrating another acquisition device
intended for attachment to the nasal opening area with diaphragm or
flap windows;
[0080] FIG. 1n a sketch illustrating a measurement concept with
active supply of purging air;
[0081] FIG. 2 a sketch illustrating a detection appliance of
modular design with a Game Boy compatible base module;
[0082] FIG. 3 a screenshot illustrating a possible method of
displaying the measurement data collected by the inventive means
using an evaluation device in the form of a computer, e.g. a
notebook or Game Boy;
[0083] FIG. 4a a diagram illustrating the respiratory gas flow for
a single breath;
[0084] FIG. 4b a diagram describing the temporal course of the
respiratory gas flow over a number of breaths;
[0085] FIG. 4c a diagram depicting the temporal course of the
respiratory gas pressure with individual pressure oscillations
caused by snoring; and illustrates detection of
respiration-specific features based on a pressure signal and
recognition of snoring.
[0086] FIG. 4d a diagram depicting the temporal course of the
respiratory gas flow over a number of breaths interrupted by an
apneic period; and illustrates apnea and a characteristic of
breathing cessation lasting longer than 10 seconds.
[0087] FIG. 5 a diagram describing the temporal course of the
respiratory gas flow with a hypopnea event; and illustrates
hypopnea and a characteristic of three normal breaths that are
followed by at least two, but most three large breaths. A
differential volume (AV) appears in this case.
[0088] FIG. 6 a diagram of the temporal course of the respiratory
gas flow over a number of breaths, several of which are
flow-limited; and illustrates flow limitation and a characteristic
of a limitation during inspiration that is apparent in the
breathing. A plateau, or several plateaus are formed.
[0089] FIG. 7 a diagram illustrating the temporal course of the
respiratory gas flow in the case of a, for the most part,
unimpaired stable respiration; and illustrates stable respiration
and a characteristic of the respiratory flow, i.e. the frequency,
amplitude and pattern of the breathing that is regular during a
given time period.
[0090] FIG. 8 a diagram illustrating the temporal course of the
respiratory gas flow in the case of an unstable, impaired
respiration; and illustrates unstable respiration and a
characteristic of the breathing stability that is <0.8 because
the respiratory flow is irregular. Respiratory disturbances are
occurring.
[0091] FIG. 9 a diagram depicting the temporal course of the
respiratory gas flow in which pressure signal oscillations caused
by snoring are evident; and illustrates expiratory and inspiratory
snoring and a characteristic of high frequency oscillations that
arise on the pressure signal. A temporal association of the snoring
to the respiratory flow can be established.
DETAILED DESCRIPTION
[0092] FIG. 1a shows an inventive mobile detection appliance 1
featuring a housing unit 2 into which is incorporated a pressure
sensor, not shown in detail here, that is used to acquire and
generate a respiratory flow signal that is indicative of the
respiratory gas flow. The detection appliance 1 also comprises an
electronic data processing unit incorporating a memory device for
processing the respiratory flow signal indicative of the temporal
course of the respiratory flow. The processing unit is configured
in such a way that it stores data that is indicative of the
temporal course of the respiratory flow signal.
[0093] The detection appliance 1 shown is particularly suitable for
use in the home, i.e. in the familiar surroundings of the affected
person for the purposes of recording features characteristic of the
respiration during the sleep phase in such a way that it enables
the physiological state of the affected person to be evaluated in
an adequately informative and standardized manner. On the basis of
a standardized analysis of the measurement results obtained, an
assessment can be made as whether, and if so to what degree,
symptoms of OSA are present and whether a more in-depth
investigation in a sleep laboratory should be recommended.
[0094] The data processing unit is configured in such a way that it
checks whether the acquired respiratory flow signal fulfils
prescribed signal quality criteria. In the event that the acquired
signal does not fulfil certain criteria, signal recording is
suppressed and a data entry is performed that indicates the time
locations of periods with signals that were classified as
invalid.
[0095] The data processing unit is designed in such a way that it
has access to a time-keeping device so that the data indicative of
the respiratory flow signal can be recorded in conjunction with
time information.
[0096] The data compression system implemented in conjunction with
the data processing unit allows the acquired time-dependent signals
to be recorded in compressed form.
[0097] The data processing unit is configured in such as way that
the recording process is initiated by a switching impulse initiated
by the user. Activation occurs when the switch button 3 is pressed
for a prescribed minimum duration of, for example, 3 seconds.
[0098] The data processing unit is configured in such a way that it
starts recording or saves data when the acquired respiratory flow
signal fulfils a certain criterion, e.g. a predefined periodicity
criterion.
[0099] The detection appliance 1 exhibits a first pressure
measurement connection 4 to which can be connected a measurement
cannula 5.
[0100] As shown in FIG. 1b, this measurement cannula 5 can be
connected to a nasal pressure measurement spectacle device for
registering a back-pressure event in the respiratory gas flow out
of the nasal openings 7a, 7b.
[0101] It is possible to equip the detection appliance 1 with a
second pressure measurement connection for acquiring a second
pressure measurement signal. The ability to acquire two pressure
measurement signals makes it possible to operate the detection
appliance 1 in such a way that it can separately acquire the
respiratory flow signals from the left and right nasal openings 7a,
7b respectively.
[0102] FIG. 1c shows a further variation for generating a signal
that is indicative of the respiratory gas flow. This variation
comprises a mask 17 designed in the style of a mouth protection and
made from a gas-permeable material (e.g. unidirectional filter made
from paper material). This mask 17 makes it possible to produce, in
the immediate area surrounding the mouth and nasal opening, a
pressure difference relative to the ambient level. This pressure
difference is determined in particular by the air tightness of the
mouth protection and the permeability of the mask or filter
material. Any non-linearities that may exist can be determined and
compensated for within the detection appliance.
[0103] The mask interior defined by this mouth protection which
acts as a diaphragm is connected to the detection appliance via the
measurement cannula 5. It is possible to provide the mask with flap
or valve devices 18, 19 that facilitate the inhalation process.
These valve or flap devices, in particular the degree in which they
are open, can also be used to acquire signals that are indicative
of the respiration. The signal transmission can occur by wireless
means, in particular optically for example using infrared
light.
[0104] The signal that is indicative of the respiratory gas flow
can also be acquired by means of other measurement equipment, in
particular measurement diaphragms or volumetric flow sensors.
[0105] The detection appliance 1 can provide a device 8 for
detecting chest expansion. As shown in FIG. 1d, the facility for
detecting chest expansion may comprise a strap element 9 that can
be fitted around the chest area of the user 10. It is possible to
design this strap element 9 in such a way that a signal that is
indicative of the extension of the strap, or the load on the strap
can be derived from it. It is also possible to provide the
detection appliance 1 with a means of detecting the load on the
strap. In particular, it is possible to provide the detection
appliance 1 with a loop feature 12 by means of which the extension
of the strap, or the forces on the strap can be detected. It is
also possible to provide the detection appliance 1 with pressure or
force detection structures 8 by means of which the force exerted by
the strap located on top of these force detection structures can be
detected. The strap 9 for detecting the chest expansion can also
serve to fasten the detection appliance 1 to the user. It is also
possible to use the chest strap only for fastening the detection
appliance 1 and not for detecting the chest expansion.
[0106] The detection appliance 1 can be provided with electrode
devices through which the ECG signals from the user can be acquired
by locating the detection appliance directly onto the skin of the
user. These ECG signals can also be recorded with temporal
information.
[0107] The recording process can be initiated by the user by means
of the switch button 3. It is also possible to configure the
detection appliance 1 in such a way that the recording process is
ended as a result of the fulfilment of a time criterion. In
particular, it is possible to end the recording process when it has
reached a prescribed duration of, for example, 9.5 h.
[0108] The recording process is also ended under switch control if
the acquired respiratory flow signal fulfils a certain switch-off
criterion within a certain switch-off time window.
[0109] The detection appliance 1 is provided with an interface
device 14 for transmitting the recorded data to an external
analysis system. Here this interface device is implemented as a USB
interface. The detection appliance also comprises an infrared
interface for potential-free signal acquisition. The generated
signals relating to the respiration that are obtained can be
extracted for further analysis via this infrared interface while
the appliance is in operation. The detection appliance 1 can thus
be operated as a measurement transducer.
[0110] It is also possible to design the detection appliance 1 in
such a way that the memory device is incorporated in the detection
appliance 1 in a replaceable manner or can be attached thereto.
Such a memory device can be in the form of a card or, in
particular, a USB flash stick. By first creating an entry in the
memory device, it is possible to record personal data on the
storage medium. On the basis of this initial recording, it is
possible to pre-configure the detection appliance 1 or ensure that
the acquired data is correctly assigned to the specific user.
[0111] The configuration of the data processing unit is set by a
data processing program, where this data processing program is in
preference modifiable or substitutable. The reproduction of the
data processing program in the detection appliance 1 can occur via
a ROM device or a RAM device, in particular via the previously
mentioned interface device 14, additional interface devices or the
storage medium.
[0112] Along with the in preference intuitive and easy-to-use
switch device 3, the detection appliance 1 is also provided with
indicator devices 15 for indicating the operational readiness or
the functional state of the detection appliance. In the embodiment
shown, the recording readiness of the detection appliance is
indicated by the periodic blinking of a green signal diode.
[0113] The detection appliance 1 comprises a power supplying device
which in this case takes the form of a battery unit. The battery
unit is in a compact form so that the detection appliance can be
designed to be flat and miniature and possess little weight.
[0114] The data processing unit is coupled to a calibration device
for calibrating the respiratory flow signal. The calibration device
is designed in such a way that it can perform an automatic
adjustment of the system to the acquired signal level.
[0115] FIG. 1e shows a sketch illustrating a second form of
embodiment of an inventive concept for separately registering
signals that are indicative of nasal respiration and oral
respiration respectively These signals can be acquired as pressure
signals via measurement cannulae. The signals can, in particular,
be obtained as a pressure difference signal indicating the pressure
difference relative to ambient pressure. The signals can be
normalized and edited by means of signal processing procedures. The
edited signals can be used to describe and, in particular,
visualize the temporal course of the respiration.
[0116] FIG. 1f shows a sketch illustrating a concept for monitoring
respiration by registering signals X1, X2, X3 that are indicative
of the respiratory gas flow through the left nasal opening, the
right nasal opening and the mouth of the user respectively. These
signals can, in particular, be registered via pressure measurement
cannulae. The signals X1, X2 can, for example, be collected as
back-pressure signals using a nasal spectacle device. The signal X3
can be acquired using a measurement cannula inserted in the flow
area in the region of the upper lip of the user where gas exchange
occurs during oral respiration. It is possible to collectively
evaluate the signals X1, X2, X3 in such a way that the sum of the
signals fulfils a plausibility criterion, for example with regard
to the tidal volume.
[0117] FIG. 1g shows a sketch detailing an acquisition device for
application to the nose with an integrated facility for detecting
the oral respiration. The registration device comprises a base body
30 produced from an elastomeric material, in particular silicone
rubber. The base body defines an enclosed measurement space that
includes the nose tip area 31 of the user and incorporates the
nasal openings. This enclosed measurement space is connected to the
surroundings via a measuring diaphragm device 32. The measuring
diaphragm device is designed in such a way that it provides a
relative low, but defined flow resistance between the enclosed
measurement space and the surroundings when respiratory gas is
displaced. The pressure differences arising in the enclosed
measurement space relative to the surroundings as a result of the
flow resistance of the measuring diaphragm device can be registered
via the measurement cannulae 5 and converted to obtain data that is
indicative of the nasal respiration.
[0118] The base body 30 is provided with a sensor device 33 for
registering an event that is indicative of oral respiration, in
particular, a pressure fluctuation. This pressure fluctuation can
also be transported for further recording via a measurement channel
or other signal transmission device. The application of the
measurement device provided for registering oral respiration to the
structure sitting on the nose of the user guarantees an especially
advantageous, in particular positionally stable and reproducible
arrangement of this measurement device.
[0119] The measuring diaphragm 32 can take the form of a mesh,
screen or even woven fabric element. As later remarked in
connection with FIG. 1n, it is possible to purge the enclosed
measurement space by supplying a breathable gas, in particular
ambient air. This makes it possible to ensure an adequate exchange
of air even when respiration is particularly shallow. It is also
possible to shift the pressure signal registered via the cannulae 5
into the positive region when the respiration is shallow. An
under-pressure will then only arise when the inspiration flow is
greater than the purging flow.
[0120] FIG. 1h shows a sketch for acquiring a signal representing
combined nasal and oral respiration using a mask device 35 covering
the nose and mouth regions. The mask device can be produced from an
air-permeable material or, as shown here, provided with a flap or
measuring diaphragm device 32.
[0121] FIG. 1i illustrates an acquisition device for registering a
signal indicative of nasal respiration. Similar to the variant
according to FIG. 1, this registration device comprises a base body
30 that defines an enclosed measurement space incorporating the tip
of the nose. The base body 30 is produced from a plastic material,
in preference a transparent elastomeric material.
[0122] The base body 30 comprises a mounting ridge 36 following the
bridge of the nose. The mounting ridge 36 has been provided with
mounting wings 37. The mounting ridge 36 and the mounting wings 37
can be fixed in place on the user by means of adhesive strips or,
if necessary, can be designed to be self-adhesive in specific
areas. Flexible inserts, in particular wire segments can be
incorporated into the mounting ridge 36 and/or mounting wings 37
allowing the acquisition device to be adapted to the particular
nasal structure of the user.
[0123] The base body 31 defines an air exit section 38 through
which a displacement of respiratory gas from/to the nasal air
passages and the surroundings can occur. The air exit section 38
can be designed so as to provide a defined flow resistance so that
a signal based on the prevailing pressure in the enclosed
measurement space and indicative of the respiration can be
acquired, e.g. via the cannula 5 shown here.
[0124] The base body 31 can be designed in such a way, in
particular in the area adjacent to the nasal openings when in the
applied position, that an especially advantageous acquisition of
the nasal respiratory gas flow is possible. An especially suitable
construction is sketched in FIG. 1j.
[0125] It is not essential for the base body 31 to be produced from
plastic material. It is also possible to produce it from paper,
cellulose, fibre or other materials, in particular those suitable
for once-off use. Sections of the interior of the base body can be
provided with foam material or other padding material in order to
achieve airtightness or padding, in particular in the nose bridge
area.
[0126] The base body 31 presented in cross-section and in a
simplified manner in FIG. 1j is provided with a sealing lip
structure 40 which seals off the enclosed measurement space from
the surroundings.
[0127] The enclosed measurement space contains an air-guiding
structure that sits on the nose of the user in the area surrounding
the nasal openings. In this embodiment example, the air-guiding
structure is designed in such a way that it allows separate signals
for the left and right nasal flow to be collected.
[0128] The air-guiding structure comprises a baffle 41 that diverts
the air flowing through the nasal openings. A pressure measurement
port 42 is provided in a typical back-pressure location of the
diversion path created by the baffle. The pressure prevailing in
each of the pressure measurement ports can be acquired via a
measurement cannula 5.
[0129] The base body 31 shown here in cross-section has been
produced from an elastomeric material. Elastic insertion channels
43 are provided in the area of each pressure measurement port into
which can be inserted a plug-in connector 44 for attaching the
respective cannula 5.
[0130] The diversion path is designed in such a way that it diverts
the air flow by about 180.degree. Each pressure measurement port 42
is located in the area where diversion occurs.
[0131] The baffle 41 can be designed in such a way that is
elastically flexible and provides a passage of larger
cross-sectional area at higher respiratory gas flow rates. It is
also possible to detect the respiratory gas flow based on the
deflection of the baffle. To avoid blockage of the pressure
measurement port 42, it is possible to introduce a purging air
flow, either permanently or intermittently, into the measurement
cannula 5.
[0132] FIG. 1k shows an acquisition device with acquisition
elements 50 introduced into each of the nasal openings and fastened
by means of a ridge 36 resting on the bridge of the nose. The
acquisition elements 50 are produced from an elastomeric material
and contoured in such a way that they can be applied to the nasal
opening area of the user in an advantageous manner. The acquisition
elements form measurement channel sections through which it is
possible to acquire the nasal respiratory gas flow. It is possible
to introduce the measurement channel section into a measurement
diaphragm or flap device 32 with the aid of which a defined flow
resistance or a flow effect advantageous to the signal collection
can be obtained.
[0133] FIG. 1l shows an acquisition element with two elastic
connector pieces 51, 52 that can be introduced in each respective
nasal opening, and an axial support providing base section 53. In
this embodiment example, both connector sections 51, 52 open out
into a common measurement channel section 54 which in turn opens
out into the surroundings via a measurement diaphragm.
[0134] FIG. 1m, which is in the form of a simplified
cross-sectional sketch, shows a further variation of a device for
acquiring signals that are indicative of the nasal respiratory gas
flow. In this embodiment example, the connection sections 51, 52
are provided with bellow structures 51a, 51b.
[0135] The acquisition device forms two measurement channels 55, 56
that are in connection with the surroundings via diaphragm or flap
elements 57, 58. The flap elements 57, 58 are set into a
circumferential groove located in the opening region of each
measurement channel 55, 56.
[0136] Acquisition of each respective pressure signal in the region
of the measurement channels occurs via the pressure measurement
port sections 59, 60.
[0137] The signal collection can, as previously described, occur
via a cannula 5 or a directly connectable or insertable measuring
transducer 61. A signal that is indicative of the pressure in the
respective measurement channel can be converted to an electrical or
optical signal by means of the measurement transducer 61.
[0138] FIG. 1n shows, in sketch form, a measuring arrangement in
which purging air is actively introduced into an enclosed
measurement space defined by an acquisition device. To this
purpose, a purging-air line 70 has been provided that opens into
the enclosed measurement space. The purging air can be supplied via
a fan device or, in preference, via a static pumping device, e.g.
gear pump or other volumetric pumping device F.
[0139] The air displacement occurring between the enclosed
measurement space and the surroundings can be detected by means of
a pneumotachograph 71 and recorded for further analysis by the
detection appliance 1. The thereby produced offset of the
respiratory gas flow signal can be taken into consideration in the
analysis procedure. The purging-air line 70 can have a small
cross-section of, for example, 10 mm.sup.2. The purging volume can
vary within the range of 1 to 5 l/min.
[0140] FIG. 2 shows a variation of the detection appliance 1
exhibiting a structural component 20 that is compatible to a
playback unit 21 whose construction corresponds to that of a Game
Boy. The detection appliance is thereby designed in such a way that
at least one portion of it can be introduced into the insertion
slot 22 of a Game Boy.
[0141] The detection appliance 1 is designed in such a way that it
comprises a base module 23 to which a recording transfer module 20
can be coupled.
[0142] This recording transfer module 20 is designed as a Game Boy
compatible structure. This enables the recorded data to be
visualized via an intuitive, simply-to-understand user interface on
a conventional end-user device 21 and, if necessary, to be analysed
and processed with regard to selected properties. This makes it
possible, in particular, to output a summary result in the form of
a severity bar 28. This bar chart clearly indicates whether--and to
what extent--a treatment-relevant disorder is present, or not.
[0143] The supply of power, and the conversion of the pressure
signal acquired from the user via the cannula 5, occurs in
preference in the base module 23. To this end, the base module 23
comprises a battery compartment and a pressure sensor as well as a
switch device 24.
[0144] The recording module 20 comprises a data processing unit
that is configured in such a way that it records onto a memory
device data that is indicative of the temporal course of the
breathing. The recording module 20 can be provided with an
interface device 14 for reading the recorded data. It is possible
to connect the memory device 25 to the recording module 20 in a
detachable manner so that is possible to separate the memory device
25 from the recording module and introduce it into another system
for further analysis and visualization.
[0145] The acquisition of the respiratory signal can, as an
alternative to acquisition using a nasal cannulation arrangement 5,
also occur by means of other measuring equipment.
[0146] Using the previously stated detection appliance 1, it is
possible to obtain an evaluation result that is based on the
measurement signals associated with the breathing of the person and
which is indicative of the physiological state of the user, whereby
evaluation characteristics are generated from said measurement
signals through the use of standardized analysis systems and a
least one evaluation result is generated from a result generation
step based thereon that indicates the severity of any illness
present according to prescribed evaluation criteria, in particular
through visualization, for example, in the form of a bar chart.
[0147] The entire captured data can be input to further evaluation
procedures and, as depicted in FIG. 3, graphically visualized via a
convenient menu interface.
[0148] The inventive detection appliance, and the signal processing
method that can be performed therewith, provide an advantageous
means of creating a quantity of data from the signal collection
carried out at home by the user over a continuous period of approx.
6 to 8 hours based on which evaluation characteristics can be
generated from which can be produced reliable evaluation results
obtained in a standardized repeatable manner that can in an
advantageous manner form the basis of a subsequent diagnosis and
thereby contribute to a standardized evaluation.
[0149] Further particulars, in particular relating to the
classification and automated evaluation of the respiration, can be
found in the description that follows.
[0150] The breath 1 depicted in FIG. 4a relating to the temporal
course of the respiratory gas flow comprises an inspiratory phase I
and an expiratory phase E. The determination of the respiratory
phase boundary G between the inspiratory phase and the expiratory
phase occurs by means of simultaneous analysis of several curve
tracing criteria, in particular taking into consideration the
currently prevailing respiratory pattern and the peak values of the
respiratory gas flow and pattern, the determined tidal volume, and
taking into consideration the respiratory phase periods of
preceding breaths.
[0151] The respiratory gas flow trace depicted in FIG. 4a describes
the change in respiratory flow over time for a single unimpaired
breath. The breath can be evaluated on the basis of temporal
relationships, e.g. of the inspiration and expiration time to one
another, or other properties, e.g. the total breath duration. In an
especially advantageous embodiment of the invention, the quotient
of the inspiration time and the total breath duration is calculated
in order to recognize changes in the breathing.
[0152] FIG. 4b depicts the changes in respiratory gas flow over a
longer time frame. As is evident in the diagram, the individual
breaths vary in particular with respect to the minima and maxima
that occur. The horizontal line 2 drawn on the diagram illustrates
the statistically most probable maximum respiratory flow occurring
in the inspiratory phases. A statistical analysis can also be
performed on the inspiration time, expiration time and total breath
duration over several breaths (in preference 10 breaths).
[0153] FIG. 4c depicts the temporal course of a signal that is
indicative of the respiratory gas pressure and in which the signal
exhibits oscillation sequences 3a, 3b, 3c, 3d and 3e caused by
snoring. The pressure fluctuations caused by snoring can be
captured via a pressure detection device located close to the user,
for example, a respiratory-gas pressure measurement hose. It is
possible to capture such pressure fluctuations via a microphone
unit.
[0154] FIG. 4d shows the temporal course of the respiratory gas
flow for several breaths 1 that are interrupted by a period of
breathing cessation 5. The period of breathing cessation 5 detected
on the basis of the respiratory gas flow exhibits a duration that
exceeds a predefined limit value of, for example, 20 seconds and is
therefore classified as an apnoea phase. Both the breaths detected
before the period of breathing cessation 5 in this diagram and
those that follow it show flow-limitation characteristics that are
recorded and associated with the relevant breath.
[0155] FIG. 5 shows a temporal course of the breathing gas flow
that contains a hypopnea phase 6. A hypopnea phase 6 is considered
to be present when three breaths 1 that are classified as normal
are followed by at least two but at most three breaths whose volume
differential relative to the three preceding breaths exceeds a
prescribed limit value.
[0156] FIG. 6 shows a temporal course of the respiratory gas flow
over several breaths where the first 4 visible breaths 1 show
flow-limitation characteristics. These flow-limitation
characteristics are recognizable in the displayed course of the
respiratory gas flow on account of the plateau 7 shapes therein and
the presence of several local maxima 8. In the displayed breaths,
the flow-limitation characteristics occur, in each case, in the
inspiratory phase of the relevant breaths 1. The first 4 breaths 1
displayed here are followed by three further, in part, flow-limited
breaths 14 that can be associated with a hypopnea phase and which,
in part, also display flow-limitation characteristics.
[0157] FIG. 7 shows the temporal course of the respiratory gas flow
for a respiration period classified as stable. The flow of
respiratory gas, the breathing frequency, the amplitude and
breathing pattern of the respiratory gas flow are regular within a
prescribed region that can be defined by means of a time range or a
given number of breaths. The breathing stability in the respiratory
gas flow history displayed here lies above the breathing stability
limit value of 0.86. A statistical analysis can also be performed
on the inspiration time, expiration time and total breath duration
over several breaths (in preference 10 breaths). In the phase of
stable respiration shown here, no respiratory disturbances (OSA)
are evident.
[0158] FIG. 8 shows a temporal course of the respiratory gas flow
over several breaths where the respiratory flow is irregular during
the time period shown and in which respiratory disturbances (OSA)
are evident for particular breaths. A statistical analysis can also
be performed on the inspiration time, expiration time and total
breath duration over several breaths (in preference 10 breaths). In
the implementation example shown here, the breathing stability
index lies under a limit value of, in preference, 0.911.
[0159] FIG. 9 shows a temporal course of the respiratory gas flow
in relation to a respiratory-gas pressure signal. The
respiratory-gas pressure signal contains phases of high-frequency
oscillations which, in the present example, can be associated with
inspiratory snoring.
* * * * *