Surgery – Respiratory method or device – Means for supplying respiratory gas under positive pressure
Reexamination Certificate
1997-04-22
2001-06-05
Dawson, Glenn K. (Department: 3761)
Surgery
Respiratory method or device
Means for supplying respiratory gas under positive pressure
C128S205250, C128S204180, C128S204210
Reexamination Certificate
active
06240921
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to automated stop/start control in the administration of continuous positive airway pressure (CPAP) treatment.
2. Background of the Invention
The administration of CPAP is common in the treatment of obstructive sleep apnea (OSA) syndrome and upper airway resistance syndrome. The fundamental disclosure of CPAP is made in the specification of International Patent Application No. PCT/AU82/00063, published under WO 82/03548.
CPAP treatment effectively acts as a pneumatic split of a patient's upper airways by the provision of a positive air pressure of approximately 10 cm H
2
O, although pressures in the range of approximately 5-20 cm H
2
O are encountered. More sophisticated forms of CPAP, such as bi-level CPAP and autosetting CPAP, are described in U.S. Pat. No. 5,245,995. Common to all forms of CPAP is a nose, mouth or face mask fitted to a patient having connection via an air delivery tube to an air flow generator.
CPAP flow generators are normally switched between a standby or stop mode to a functional mode in which pressurized air or oxygen mix is supplied to the patient by a switch located on the body of, or adjacent to, the flow generator. Alternatively, a cordless radio or infra-red remote control unit can be operated by the patient at some distance from the flow generator.
In other cases the control switch (or switches), which may be electrical or pneumatic, are located in the vicinity of the patient's mask, and control signals from them are carried back to the flow generator in parallel with the interconnecting air delivery tubing. As an alternative to a nose or mouth mask, nasal prongs (cannulae) may be inserted into the nares to effect a seal between the air delivery circuit and the patient's airway. In all cases, the patient must manually depress a control button to initiate the CPAP treatment.
In this specification the term mask is to be explicitly understood as embracing a nose mask, mouth mask, nose and mouth mask and nasal prongs. Furthermore, reference to a mask being worn indicates sealing engagement with the patient's face or with the entrance to the nares. In particular, the expression “a mask being worn” embraces the embodiment of nasal prongs being inserted into the nares.
There are a number of disadvantages in the known control implementations described above. Firstly, the patient may have to reach out of bed to press a control on the flow generator. This may be difficult to do if they are already wearing the CPAP mask with its connected tubing, or if the flow generator is some distance from the bed. Secondly, a cordless remote control can be mislaid, and its batteries will run down and must be regularly charged or replaced. In some instances, too, the remote control must be directed towards the flow generator to function, however, the flow generator may be difficult to locate in a dark room. Thirdly, controls incorporated in the mask make it heavier and therefore less comfortable to wear, perhaps leading to lack of compliance with the CPAP treatment. Also, they make cleaning and disassembly more difficult for the patient using CPAP treatment apparatus at home.
SUMMARY OF THE INVENTION
It is a preferred object of the present invention to make the control of CPAP treatment, and particularly flow generators, significantly easier for patients in the start and/or stop operations.
Therefore, the invention discloses a method for controlling apparatus for the administration of continuous positive airway pressure (CPAP) treatment, the apparatus having a controllable flow generator coupled to an air delivery circuit, in turn coupled to a mask for the supply of CPAP treatment to a patient's airways, the method comprising the steps of determining that the patient is wearing said mask and, if being worn, commencing the administration of CPAP treatment.
Preferably, the determining step comprises any one or more of the steps of detecting flow of air in said air delivery circuit, detecting a pressure change in said air delivery circuit, and detecting proximity of the patient's face with said mask.
The invention further discloses a method for controlling apparatus for the administration of continuous positive airway pressure (CPAP) treatment, the apparatus having a controllable flow generator coupled to an air delivery circuit, in turn coupled to a mask for the supply of CPAP treatment to a patient's airways, the method comprising the steps of determining whether said mask is being worn by the patient and, if not being worn, ceasing CPAP treatment.
Preferably, the determining step comprises any one or more of the steps of detecting airflow in said air delivery circuit in excess of flow due to maximum CPAP treatment pressure, detecting a pressure drop in said air delivery circuit below a minimum CPAP treatment pressure, and detecting an uncontrolled change in operation of said flow generator.
The invention yet further discloses a method for controlling apparatus for the administration of continuous positive airway pressure (CPAP) treatment, the apparatus having a controllable flow generator coupled to an air delivery circuit, in turn coupled to a mask for the supply of CPAP treatment to a patient's airways, the method comprising the steps of determining whether the patient is wearing said mask and, if being worn, commencing CPAP treatment; and if not being worn, ceasing CPAP treatment.
The invention yet further discloses apparatus for controlling the administration of continuous positive airway pressure (CPAP) treatment, said apparatus having a controllable flow generator coupled to an air delivery circuit, in turn coupled to a mask for the supply of CPAP treatment to a patient's airways, and further comprising means for determining that the patient is wearing said mask, and means for commencing the administration of CPAP treatment if the mask is being worn.
Preferably, the apparatus further comprises any one or more of detection means for detecting flow of air in said air delivery circuit, detection means for detecting a pressure change in said air delivery circuit, and detection means for detecting proximity of the patient's face with the mask. Advantageously, the detection means can include a differential or static pressure transducer. Further, the detection means can include electrical circuit means mounted from said mask, the electrical characteristics of which change with proximity of the patient's face. The changing electrical characteristics can include resistance between two electrodes, capacitance between two electrodes, or the inductance of a coil means.
The invention further discloses apparatus for controlling the administration of continuous positive airway pressure (CPAP) treatment, said apparatus having a controllable flow generator coupled to an air delivery circuit, in turn coupled to a mask for the supply of CPAP treatment to a patient's airways, and further comprising means for determining whether said mask is being worn by the patient, and means for ceasing CPAP treatment if said mask is not being worn.
Preferably, the apparatus further includes detecting means for detecting air flow in said air delivery circuit in excess of flow due to maximum CPAP treatment pressure, detection means for detecting a pressure drop in said air delivery circuit continuing for a predetermined period of time, and detection means for detecting an uncontrolled change in operation of said flow generator. The detecting means can include a differential or static air pressure transducer. Further, the detecting means can include means for measuring electrical power consumption of said flow generator, or means for measuring rotational speed of said flow generator.
REFERENCES:
patent: Re. 35295 (1996-07-01), Estes et al.
patent: Re. 35339 (1996-10-01), Rapoport
patent: 3073301 (1963-01-01), Hay et al.
patent: 3099985 (1963-08-01), Wilson et al.
patent: 3502100 (1970-03-01), Jonson
patent: 3595228 (1971-07-01), Simon et al.
patent: 3726270 (1973-0
Brydon John William Ernest
Calluaud Michel
Dawson Glenn K.
Pillsbury & Winthrop LLP
ResMed Ltd.
Weiss, Jr. Joseph F.
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