Surgery – Respiratory method or device – Means for supplying respiratory gas under positive pressure
Reexamination Certificate
1998-12-08
2002-06-04
Weiss, John G. (Department: 3761)
Surgery
Respiratory method or device
Means for supplying respiratory gas under positive pressure
C128S204180, C128S204210, C128S204260
Reexamination Certificate
active
06397845
ABSTRACT:
The present invention relates to apparatus for controlling gas delivery to a patient. The apparatus may provide a diagnostic and/or a therapeutic function. The diagnostic function may include monitoring and/or diagnosis of physiological variables associated with the patient. The therapeutic function may include application of controlled gas delivery to the patient.
The apparatus of the present invention is particularly useful for investigation, diagnosis and treatment of sleep, respiratory and sleep related respiratory disorders, sleep propensity and fatigue and will be described herein in that context. Nevertheless it is to be appreciated that it is not thereby limited to such applications.
Sleep apnea syndrome is a respiratory disorder affecting between 4 and 5% of the population and is now well documented in a number of reputable medical journals. Sufferers of this debilitating disorder suffer reduced sleep efficiency, excessive blood pressure, cardiovascular effect ranging from mild to fatal, amongst other adverse health consequences and risks. It is recognised that an increase in upper airway resistance attributed to relaxation of upper airway muscles during sleep, contributes to cessation of breathing at frequent intervals during an Obstructive Sleep Apnea (OSA) patient's sleep. OSA is now relatively well documented and understood within the respiratory and sleep medical fields.
In the early 1980's a development commonly referred to as Continuous Positive Air Pressure (CPAP) was discovered as a front line cure for OSA (Sullivan). CPAP is a device which applies a continuous positive air pressure to the patient's airway by way of a nasal mask. This nasal mask is worn by the patient during sleep and a positive air pressure is applied to the patient's airway in order to keep the patients airway open and prevent a collapse of the patient's airway, which would otherwise lead to OSA.
Development of CPAP devices have been pursued by a range of manufacturers across the world and a number of variations of CPAP have also been introduced to the market place. These variations include, inter alia:
Demand Positive Air Pressure (DPAP) which is a device that supplies positive air pressure by detecting the patients respiratory cycle and applies the air pressure when the patient ‘demands’ this:
Bi positive air pressure (BIPAP), which is a device that allows two states of positive pressure and monitors the patient's respiration and delivers air pressure depending on whether the patient is undergoing inspiration or expiration; and
Variable Positive Air Pressure (VPAP) which is a device that delivers a varying air pressure depending upon the patient's respiration cycle.
Other devices have been developed to automatically adjust air pressure delivered to a patient during sleep.
Whilst the prior art recognizes that respiratory disorders such as apnea or hypopnea may be addressed by applying positive air pressure to a patient, it has failed to recognize that even without the presence of respiratory events such as hypopnea or apnea (as detected or diagnosed by conventional means) upper airway resistance can exist and results in a reduction of a patient's sleep efficiency. The apparatus of the present invention may diagnose such upper airway resistance by detecting arousals. Arousals may be detected, for example, from a shift in frequency of the patients Electroencephalogram (EEG) and/or Electro-oculogram (EOG).
It is therefore recognised that even after treatment for OSA by application of the above mentioned CPAP or variations thereof, a patient can still experience arousals or micro-arousals during a night's sleep. These arousals and micro-arousals can be due in part to the fact that the air pressure required to be delivered to the patient to prevent OSA can vary depending upon the patients sleep position, sleep state and other factors such as intake of alcohol or drugs consumed prior to sleeping. The arousals and micro-arousals may be linked or associated with respiratory disorders.
It has been shown that many arousals or micro-arousals can occur during a patient's sleep. The present invention may provide apparatus for monitoring the patient's physiological variables and to diagnose corresponding physiological states including sleep, arousal and respiration events while at the same time controlling delivery of gas to a patient via a nasal or nasal and oral mask. The apparatus can in one mode be adapted to diagnose physiological states and in another mode adjust the pressure of air delivery to the patient to a level which accurately reflects the patient's state of wakefulness, sleep or arousal.
Due to the complex and varying states of sleep and broad range of sleep disorders that can be diagnosed, many different physiological variables (raw data) and events (derived data) may be monitored and/or analysed. While some positive air pressure devices exist which can monitor respiratory parameters, the present applicant is not aware of any prior art device which is able to monitor and diagnose a comprehensive range of both sleep and respiratory parameters. The monitored variables/events can include one or more of the following:
EIectroencephalogram
(EEG)
Electro-oculogram
(EOG)
Electro-myogram
(submental EMG from muscles under the chin)
Electro-myogram
(diaphragm EMG from respiratory effort
Electro-myogram
(other EMG reflecting muscle and nerve
activity either by invasive or non-invasive
monitoring)
Status of patient position
Breathing and snoring
(via microphone)
sounds
Leg movements
(Left and/or Right legs)
Electrocardiogram
(ECG)
Oximetry
(S
2
O
2
- Oxygen saturation);
Carbon dioxide
CO
2
monitoring
Respiratory effort
(Abdominal, thoracic or otherwise)
Airflow
(Nasal or oral)
Continuous Positive
(monitoring of patients mask pressure during
Airflow Pressure
application of CPAP treatment)
CPAP mask temperature
(monitoring of CPAP mask air temperature for
breathing activity and airflow of patient)
CPAP mask sound
(monitoring for patients breathing sounds
within CPAP mask).
These sounds include snoring, wheezing and
other disordered breathing sounds
Status of lights
Graphic processing of video image (allows determination of whether patients eyes are open or closed)
Patient digital video recording and graphic processing techniques for determination of eye lid activity (ie status of patient eyes being opened or closed—relative to fully closed or fully opened eyes status).
Time and date stamping of monitored physiological data, video and sound.
Infrared Video monitoring (for night studies)
Complex sound analysis (accurate full bandwidth or limited bandwidth recording and analysis of breathing sounds).
Physiological events: ie ECG arrhythmia, EEG spike detection, EEG spindles amongst others
Endoscopy
Breath by breath analysis-pnuemotachograph
3D imaging
Infrared eye detection for fatigue and sleep monitoring
EEG delta and alpha-wave detection
Delta Wave detections and related sleep/fatigue/impairment detection
Mattress Device: monitoring of patient sleep state and respiratory parameters by using a mattress sensor device. The matress device can be used to monitor a patient's electro-oculogram, sleep state, arousals, position, electrocardiogram. There are presently two types commercially available mattress devices; Static Charge-sensitive Bed (SCSB) and polyvinylidene fluoride (PVDF-piezoelectric plastic).
The apparatus of the present invention may monitor and diagnose a patient's EEG, EMG, EOG, position, breathing/snoring sounds and other variables/events while; at the same time control treatment such as positive air pressure. The positive air pressure treatment may be adjusted dynamically to suit the patients prevailing:
sleep state, respiratory events (ie OSA, central apnea, hypopnea, mixed apnea)
position (different air pressure may be required depending upon the patient's sleep position),
arousals status (ie micro arousals may occur due to insufficient or excessive pressure),
snoring (varying degrees of pressure may be required
Compumedics, Ltd.
Fulbright & Jaworski L.L.P.
Weiss John G.
Weiss, Jr. Joseph F.
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