Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
  • A61B5/6887—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient mounted on external non-worn devices, e.g. non-medical devices
  • A61B5/6892—Mats
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/103—Measuring devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
  • A61B5/11—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor or mobility of a limb
  • A61B5/113—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor or mobility of a limb occurring during breathing
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F5/00—Orthopaedic methods or devices for non-surgical treatment of bones or joints; Nursing devices ; Anti-rape devices
  • A61F5/56—Devices for preventing snoring
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/08—Measuring devices for evaluating the respiratory organs
  • A61B5/0816—Measuring devices for examining respiratory frequency

Definitions

• the present invention relates to a device and method for detecting and recording the snoring of a patient.
• One sleep linked disorder is obstructive sleep apnea.
• a patient suffering this disorder undergoes while asleep repeated episodes of obstruction of their upper airway. During these episodes of obstruction there is a period, which can typically range between 10-40 seconds, when there is no airflow through the airway into the lungs of a patient. This state usually terminates due to arousal of the patient.
• a sufferer may only undergo a few episodes of obstruction over a night of 6-8 hours of sleep. In more severe cases, the episodes can occur repeatedly with tests showing that some sufferers undergo 400-500 episodes of obstruction in a single night's sleep.
• Such high levels of obstruction and the resulting repeated falls in oxygen level to the brain can lead to major health problems, and sufferers are known to have increased mortality, probably because of increased morbidity due to cardiovascular diseases and stroke.
• Sufferers also exhibit high levels of daytime sleepiness which increases the risk of a sufferer being involved in a traffic or industrial accident. It is now recognised that at any one time about 10% of males and about 5% of females suffer from some form of sleep apnea.
• Obstructive sleep apnea is now widely recognised by its array of daytime symptoms including daytime sleepiness and also by witnessed episodes of "stop breathing" by a bed partner. Heavy snoring is, however, the most common and characteristic sign of sleep apnea.
• Snoring is almost universally known and is characterised by noise generated in the throat of a sleeping individual. Snoring is in fact so tightly coupled with sleep that its presence is a positive and diagnostic indication that an individual is asleep.
• Snoring is a noise which is typically generated by vibration of the air conduction tube at the level of the throat. It usually occurs during inspiration (breathing in) but sometimes occurs during expiration (breathing out) and sometimes during both phases of the sleeping cycle. Snoring occurs when, with sleep, there is a loss of muscle tone in the muscles of the throat which are needed to keep the throat open. This loss in muscle tone narrows the air passages leading to inadequate levels of airflow into the lungs. This drop in airflow is detected and the body's reflexes automatically produce increased efforts to breathe. These increased efforts produce greater degrees of suction pressure in the air passages which then in turn cause the walls of the throat to vibrate and flutter. Snoring commonly originates in the oropharyngeal area of the throat.
• the soft palate which is a mobile structure which hangs down from the roof of the mouth in the back of the throat, acts to determine which of the two pathways are connected to the breathing tube.
• snoring is generated when the soft palate flutters. This fluttering leads to pressure oscillations within the airway and sounds are then generated when other structures in and around the airway are vibrated producing harmonics which can be heard.
• the pattern of snoring typically changes. Instead of the sound of regular rhythmical snoring occurring at a time sequence identical to the breathing cycle there are typically bursts of a few loud snoring breaths, separated by a longer period of silence of 15-50 seconds indicative of obstruction. This sequence usually occurs in a regularly occurring pattern over many minutes or even hours.
• a particular problem with recording sound alone is that it is also difficult to separate other sounds such as someone talking, a door slamming, the radio or television in the background, a car or truck passing outside, or even someone else's snoring in the room.
• an independent measure of respiration is typically used to timelock the sound of snoring to the breathing cycle.
• Typical devices for measuring respiration are thermistors and pressure transducers that are attached to the patient and measure airflow at the mouth or nose or other devices also attached to the patient which monitor chest movement. Disclosure of the Invention
• the present invention consists in a device for detecting the snoring of a patient comprising signal processing means having signal receiving means to receive electrical signals generated by a pressure or acceleration detector, the detector being capable of generating a first electrical signal representative of sub-audible vibrations of the airway of the patient which are present during a snore.
• the present invention consists in a method for detecting the snoring of a patient comprising the steps of placing a pressure or acceleration detector in position relative to a patient for a period of time while the patient is asleep, producing from the detector a first electrical signal representative of sub-audible vibrations in the airway of the patient which are present during a snore.
• the detector is capable of generating a second electrical signal representative of the breathing cycle of the patient. While the breathing rate of a human can vary significantly due to such factors as illness or exertion, the frequency of the breathing cycle of a sleeping human typically lies in the range of greater than 0Hz and less than or equal to 2Hz.
• the advantage of having the detector generate a second electrical signal representative of the breathing cycle is that the occurrence of the sub-audible vibrations can be time-locked to the breathing cycle. If the peaks in the first electrical signal occur during inspiration or expiration, this provides confirmation that the first electrical signal being received is in fact indicative of the sub-audible vibrations present in the airway during a snore.
• the detector can also be capable of generating a third electrical signal representative of the movement of the patient during sleep. Such movements might include the patient rolling over, turning of the head and large or small movements of the legs and arms.
• This third signal can be used to provide further discrimination between signals representing vibration of the patient's airway during a snore and other noises or movements by the patient that will result in signals being generated by the detector.
• the pressure or acceleration detector can be placed on or under the mattress of a bed on which the patient will sleep. This arrangement is particularly advantageous as there is no discomfort caused to the patient by the attachment of any sensors. This arrangement also avoids the high risk of detachment or disconnection of sensors attached to the patient during the long hours of sleep.
• the detector could also be attached to the bed frame or incorporated in a pillow as well as or instead of on or under the mattress.
• the detector may be attached to a hearing aid placed in the ear of the patient.
• the pressure detector can comprise a piezoelectric transducer while the accelerometer can comprise an integrated circuit containing a floating piezoelectric transducer.
• the detector comprises one or a plurality of sheets of piezoelectric plastics material such as polyvinylidene fluoride (hereinafter called PVDF) or an analogue or family derivative thereof.
• PVDF polyvinylidene fluoride
• the material is highly sensitive, producing relatively larger voltages in response to extremely small movements. It can. for example, act as a highly sensitive microphone detecting low levels of sound pressure.
• the microphone property of PVDF is used to essentially "listen" to the sub-audible vibrations of the patient's airway causing the characteristic audible sound of snoring.
• the invention takes advantage of the physical properties of this plastic, which is robust, to characterise the vibration of the airway during snoring and the breathing cycle of the patient, to identify the dominant frequency components of these actions and. by comparison, to positively separate each action thus allowing the generation of electrical signals which can be recorded and identified as that of the vibration of the airway and breathing movements.
• the piezoelectric plastics material may consist of a layer of this material attached to a firm rubber or plastic backing sheet, with or without an air space. Multiple layers of the piezoelectric material throughout a mattress may also be utilised where appropriate.
• the detector detects movements of low frequency (ie: 0-2
• the detector will also detect the fluttering sub-audible vibrations of the patient's airway which are the underlying cause of the audible sound of snoring. These vibrations, which typically occur between 10-100 Hertz, are also digitally processed and amplified to give a signal representative of the fluttering vibrations in the airway which are indicative of snoring in the patient.
• the signals may then be displayed in real time to allow a clinician to monitor if snoring is occurring and, if so, to determine the snoring pattern and the intensity of that snoring.
• the signals may also be stored and processed to produce an output for later analysis.
• the first and second signals could also be compared by a comparator means which would compare the first and second electrical signals and produce an output indicative of the comparison. For example, if on comparison the first electrical signal does not coincide with inspiration or expiration as determined from the measured breathing cycle, the comparator means could indicate that the measured first electrical signal is in fact not representative of airway vibrations.
• the measured snoring pattern can also be compared with the breathing cycle to determine if partial upper airway obstruction or apnea is occurring.
• the most common apnea is obstructive apnea in which there is no airflow through the airway.
• the present device could readily identify or allow identification of such apneas.
• a typical apnea episode there will be cycles in which there are a series of inspirations with snoring detected, and then a series of inspiratory movements without snoring.
• the occurrence of an apnea episode will further be confirmed by analysis of the breathing movements against the closed airway and expiratory efforts being made to open the airway.
• the present invention is particularly advantageous for those circumstances where a patient is suffering upper airway partial obstruction without the symptom of audible or at least heavy snoring.
• the present invention is, therefore, suitable for the detection of upper airway dysfunction in infants which is not or at least not readily detected by methods or devices adapted to detect and monitor the audible sounds of snoring.
• a sound transducer or microphone may be placed proximate the patient.
• the electrical signals generated from this transducer can be used to cross-check against the signals being received from the detector typically placed under the patient on the bed.
• the signal from the transducer could be used in two main ways.
• the output from the device described herein can be used to provide a signal to control the operation of a positive airway pressure device, such as a nasal continuous positive airway pressure (nasal CPAP) device being used by the patient to alleviate the symptoms of sleep apnea.
• a positive airway pressure device such as a nasal continuous positive airway pressure (nasal CPAP) device being used by the patient to alleviate the symptoms of sleep apnea.
• Nasal CPAP is the current treatment of choice for patients with sleep apnea. In this treatment, the patient breathes from a nose mask which has a slightly higher atmospheric pressure. This pressure in turn splints open the upper airway preventing snoring and apnea. Modern versions of this device adjust the pressure automatically according to the presence or absence of snoring.
• Detection of the sub-audible airway vibrations using the device described herein could provide a second cross ⁇ check signal, or act as the major controlling signal for a nasal CPAP device.
• Another application of this principle would be the use of an implantable version of the sensor to provide the controlling signal for electrical pacing of the upper airway to treat snoring or apnea.
• the recorded display of the output could utilise analogue and digital recorders and paper hard copies.
• a preferred method would record the output digitally on disk for later replay or in real time on a computer screen.
• the invention includes software for the display of long-term information.
• FIG. 1 is a diagrammatic view of a device for detecting and recording the snoring pattern of a patient according to the present invention:
• Fig. 2 is an amplitude versus time print-out from a device according to the present invention depicting the output when a patient is not snoring
• Fig. 3 is an amplitude versus time print-out depicting the output from a snoring patient
• Fig. 4 is an amplitude versus time print-out depicting the output from a patient entering an apnea episode
• Fig. 5 is an amplitude versus time print-out depicting the output from a patient coming out of an apnea episode.
• a device for detecting and monitoring the snoring pattern of a patient is generally depicted as 10 in Fig. 1.
• the device 10 includes a piezoelectric polyvinylidene fluoride (PVDF) sheet sensor 11 placed on a mattress 12 which supports a sleeping patient 13.
• the sensor 11 is placed on the mattress 12 such that the sensor 11 lies under the torso of the patient 13 when the patient is asleep on the mattress 12.
• the piezoelectric PVDF for use as the sensor 11 is available from a number of sources.
• the PVDF presently used by the inventor in experiments of the device 10 was provided in a special applications designs kit provided by AMP Incorporated, Valley Forge, PA, United States of America, through the Australian distributor, Irendos Pty Limited of Glen Iris. Victoria. Australia.
• the sensor 11 is connected by appropriate electrical leads 14 to an electronic amplifier device 15 which amplifies the voltage signals generated by the sensor 11.
• the amplified signals are then passed to a digital signal processing circuit 16 which is adapted to discriminate from the signals output by the sensor 11 signals representative of the breathing cycle of the patient and of episodes of airway vibrations which are the underlying cause of the audible sound of snoring.
• the typical breathing cycle of a resting human is 12-14 breaths a minute. This breathing rate can increase or decrease significantly due to such factors as exertion and illness. It is. however, typical for the breathing cycle of a sleeping human to lie somewhere in the range 0.01-2 Hz.
• the signal processing circuit 16 is adapted to identify signals having a frequency in this range.
• the underlying vibrations of the airway that lead to the audible sound of snoring are inaudible.
• the vibration frequency of the airway during a snore is typically in the range 10-lOOHz.
• the signal processing circuit 16 is, therefore, also adapted to identify signals having a frequency in this range.
• the amplified signals output by the signal processing circuit 16 in the two frequency ranges can be fed to a display means 17 such as is depicted in Fig. 1.
• the display means can comprise a paper printer 18. a cathode ray oscilloscope and/or computer based display.
• the clinician monitoring the patient 13 could view the display in real-time to monitor the breathing cycle and. if present, episodes of airway vibration representative of snoring by the patient 13.
• the signals output from the signal processing means 16 are stored in a digital recording system 19 and computer memory for later playback and analysis by the clinician.
• the present application is particularly suitable for detecting the occurrence of sleep apnea in a patient where the patient reports with other telltale symptoms such as daytime sleepiness and complaints of heavy snoring.
• the sensor 11 Prior to the patient laying on the mattress 12, the sensor 11 will be appropriately mounted on the mattress 12 and electrically connected by leads 14 to the amplifier 15.
• the signal processing circuit 16 and the display means 17 will be turned on ready to monitor and record the signals detected by the sensor 11 during sleep.
• the patient 13 will then be allowed to lay on the mattress 12 and fall asleep in the normal manner.
• the device 10 is particularly advantageous as it does not require the attachment of special sensors to the skin of the patient which reduces clinician involvement and also reduces any potential discomfort to the patient 13.
• the patient 13 will typically be monitored for an entire evening so as to ensure a good picture of the patient's sleeping cycle is available for review by the clinician.
• the device 10 will monitor and store the breathing cycle of the patient 13.
• the device 10 also detects and stores episodes of snoring.
• the clinician by reviewing the print-out of signals in the frequency range 10-lOOHz can determine if snoring is occurring by watching for the characteristic vibration of the patient's airway on inspiration or expiration of the patient. If a signal is detected in the 10- 100Hz range which is not at inspiration or expiration, then this signal cannot relate to snoring and can be dismissed as a another noise created by the patient 13 or the surrounding environment.
• the advantage of detecting snoring is that it is a diagnostic indication to the clinician that the patient 13 is asleep. This has the advantage of not requiring the connection of further sensors to the patient such as EEG sensors which are typically used in the prior art to monitor if a person is actually asleep during sleep pattern studies such as studies attempting to detect episodes of sleep apnea in a patient.
• EEG sensors which are typically used in the prior art to monitor if a person is actually asleep during sleep pattern studies such as studies attempting to detect episodes of sleep apnea in a patient.
• the pattern of vibrations stored by the device 10 can be reviewed to determine the occurrence of episodes of sleep apnea. These episodes can be identified by gaps in the snoring cycle as when the airway obstructs, the patient 13 will make inspiratory movements without detection of a corresponding snore from the patient.
• the device 10 can readily detect the occurrence of the airway vibrations which are present during a snore of the patient.
• the amplitude versus time print-outs depicted as Figs. 2-5 represent small portions of the types of outputs that might be generated by the device 10 described herein during actual use.
• FIG. 2 A typical output from the device 10 for a sleeping patient undergoing normal respiration is depicted in Fig. 2.
• the breathing cycle signal generated by device 10 is depicted by curve 21.
• the curve 21 depicts the quite rhythmical nature of a person's breathing cycle that can be expected during sleep with portion 21a representative of inspiration and portion 21b representative of expiration.
• Line 22 depicts the signal generated by the sensor 11 in the frequency range 10-lOOHz.
• the erratic nature of the output 22 in Fig. 2 is representative of small movements being made by the patient 13. There is , however, no signal being received indicative of the sub-audible vibrations present in the airway during snoring by the patient.
• Fig. 3 represents a typical output from the device 10 for a snoring patient.
• the rhythmical nature of the patient's breathing cycle is depicted by curve 21.
• the output from the sensor 11 in the frequency range 10-lOOHz depicted as line 22 reveals relatively short regions of increased amplitude 23 which coincide with inspiration 21a by the patient.
• the regions of increased amplitude 23 represent the sub-audible vibrations present in the airway of the patient 13 during a snore.
• a clinician reviewing the output depicted in Fig. 3 could conclude that the patient was snoring at the time of this output. As snoring is a diagnostic indication of sleep, the clinician could also conclude that the patient was asleep at the time of this output.
• Figs 4 and 5 represent the typical outputs for a patient entering and leaving a sleep apnea episode, respectively.
• a sequence of snores 23 are detected in output 22 followed by no significant signals.
• the breathing cycle 21 becomes disrupted followed by a sequence of inspiratory movements which result in no snores occurring.
• the output depicted in Fig. 4 would indicate the occurrence of a sleep apnea episode.
• This sequence is continued in Fig. 5 where a period of no snores and short inspiratory movements is followed by the resumption of snoring and normal inspiratory movements.
• the episode of apnea depicted in Figs. 4 and 5 can in the case of heavy sufferers occur continually throughout the night.

Landscapes

• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Public Health (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Heart & Thoracic Surgery (AREA)
• Veterinary Medicine (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Physics & Mathematics (AREA)
• Surgery (AREA)
• Molecular Biology (AREA)
• Medical Informatics (AREA)
• Pathology (AREA)
• Biophysics (AREA)
• Vascular Medicine (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Dentistry (AREA)
• Physiology (AREA)
• Otolaryngology (AREA)
• Nursing (AREA)
• Pulmonology (AREA)
• Orthopedic Medicine & Surgery (AREA)
• Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
• Orthopedics, Nursing, And Contraception (AREA)
• Investigating Or Analysing Biological Materials (AREA)

Priority Applications (6)

Applications Claiming Priority (2)

Publications (1)

Family

ID=3787391

Family Applications (1)

Country Status (7)

Cited By (15)

Families Citing this family (122)

Citations (10)

Family Cites Families (12)

• 1995
  • 1995-05-19 AU AUPN3048A patent/AUPN304895A0/en not_active Abandoned
• 1996
  • 1996-05-20 WO PCT/AU1996/000306 patent/WO1996036279A1/en not_active Ceased
  • 1996-05-20 AT AT96913389T patent/ATE253866T1/de not_active IP Right Cessation
  • 1996-05-20 DE DE69630687T patent/DE69630687T2/de not_active Expired - Lifetime
  • 1996-05-20 US US08/952,615 patent/US5989193A/en not_active Expired - Lifetime
  • 1996-05-20 JP JP53440596A patent/JP3677294B2/ja not_active Expired - Lifetime
  • 1996-05-20 EP EP96913389A patent/EP0833586B1/en not_active Expired - Lifetime

Patent Citations (10)

Also Published As

Similar Documents

Legal Events