Surgery – Respiratory method or device – Means for supplying respiratory gas under positive pressure
Reexamination Certificate
1997-05-07
2001-07-03
Lewis, Aaron J. (Department: 3761)
Surgery
Respiratory method or device
Means for supplying respiratory gas under positive pressure
C128S204260, C128S205240
Reexamination Certificate
active
06253764
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to apparatus for the control of delivery pressure of air or breathable gas in continuous positive airway pressure (CPAP) treatment or assisted respiration. The CPAP treatment may be by way of delivery of a single therapeutic pressure of in a bi-level manner or an automatically adjusting CPAP manner.
BACKGROUND OF THE INVENTION
CPAP is a well known treatment for the temporary relief of conditions including obstructive sleep apnea (OSA) and snoring. By this technique, air (or other breathable gas) at a pressure elevated above atmospheric pressure is constantly supplied to the entrance to a patient's airway (by the nasal and/or oral route) by means of known arrangements of masks or nasal prongs. The elevated air pressure acts as a pneumatic splint of the patient's airway in the vicinity of the oro- and hypo-pharynx, reducing or eliminating the occurrences of apneas or hypopneas during sleep. A bi-level CPAP device delivers two distinct pressures during the patient's respiratory cycle; a relatively lower pressure during exhalation and a relatively higher pressure during inhalation. An automatically adjusting CPAP device may operate to provide a relatively low background pressure which increases to a therapeutic pressure on a needs basis, and preferably at a time to prevent the onset of an apnea.
Assisted respiration similarly provides a supply of air (or other breathable gas) at a pressure elevated above atmospheric pressure, although is concerned more with providing a sufficient flow of air (or other breathable gas), rather than regulating the pressure of air to a continuous (constant) level in the case of CPAP treatment.
In recent times, CPAP apparatus have been constituted by a nose and/or mouth mask coupled by a flexible air (or other breathable gas) delivery tube to a controllable flow generator. The flow generator includes a speed-controlled brushless DC motor connected with a fixed vane turbine. Control of the CPAP treatment pressure delivered to a patient's airway is conducted at the flow generator by speed control of the motor in response to signals issued by a microprocessor.
Whilst this arrangement provides satisfactory treatment of conditions such as OSA and snoring, it is desirable for alternative arrangements to be devised that can remove the pressure controls from the remote flow generator to being at or near the patient mask. This may lead to a reduction of the cost of CPAP treatment apparatus by removing the need for a power supply, microprocessor controller, motor and turbine. A practical concern in such an arrangement is that the mask not be made too heavy so as to disturb the patient in wearing the mask during sleep. Prior art delivery pressure controls located at a mask, such as breathing apparatus worn by military pilots, are heavy and cumbersome and not suitable to being worn during sleep when a patient's neck and shoulder muscles necessarily need to be in a relaxed state.
It is an object of the present invention to provide delivery pressure control apparatus that can be incorporated at or near a patient mask and that is not uncomfortable or cumbersome to the patient when worn during sleep.
SUMMARY OF THE INVENTION
Accordingly, in a first aspect, the present invention discloses a pressure control apparatus for CPAP treatment or assisted respiration, said apparatus comprising:
an inlet chamber for connection to a primary supply of air or other breathable gas at a pressure at or above a maximum treatment pressure;
an outlet chamber for communication with a mask or the like;
a diaphragm for communication with a portion of said outlet chamber;
means to provide a predetermined force to said diaphragm;
a first valve means operable to open a flow path between said outlet chamber and said inlet chamber in response to deflection of said diaphragm in a first direction; and
a second valve means operable to provide an exhaust path from said outlet chamber to atmosphere in response to deflection of said diaphragm in a second direction opposite first direction; and
wherein when the pressure of gas in said outlet chamber produces a force on the diaphragm below said predetermined force the force differential on said diaphragm causes it to deflect in said first direction and cause said first valve means to open and to cause an equilibrating flow of gas from said inlet chamber, and further wherein when the pressure of gas in said outlet chamber produces a force on the diaphragm above said predetermined force the force differential on said diaphragm causes it to deflect in said second direction and cause said second valve means to open.
In a second aspect, the present invention discloses a method of administering CPAP treatment using the pressure control apparatus of the first aspect.
In a third aspect, the present invention discloses a method of administering assisted respiration using the pressure control apparatus of the first aspect.
In a fourth aspect, the present invention discloses a delivery pressure control apparatus for CPAP treatment or assisted respiration, said apparatus comprising:
an input chamber for connection to a supply of air at a pressure at or above maximum treatment pressure;
a pressure reducing means or flow restricting means for communication with said supply of air to provide air at a reduced pressure corresponding to a treatment pressure to a sensing chamber;
an outlet chamber for communication with a mask or the like;
a diaphragm arranged between a portion of the outlet chamber and a portion of the sensing chamber;
first valve means located between said outlet chamber and said inlet chamber and operable to open a flow path between said outlet chamber and said inlet chamber upon deflection of said diaphragm; and
a second valve means located between said outlet chamber and atmosphere, and operable to provide an exhaust path to atmosphere from said outlet chamber on opposed deflection of said diaphragm; and
wherein when the pressure of air in said outlet chamber reduces below the pressure of air in said sensing chamber said diaphragm deflects to operate said first valve means to cause an equilibrating flow of air from said inlet chamber, and further wherein when the pressure of air in said outlet chamber exceeds that of said sensing chamber, said diaphragm deflects to open said exhaust path from said outlet chamber.
In an advantageous form, the pressure reducing means or flow restricting means is controllable to select a desired therapeutic or treatment pressure.
Advantageously, the first and second valve means can comprise a valve body that can block an opening constituting said flow path and an opening constituting said exhaust path respectively, and an elongate tail extending away from the valve body to the distal end of the tail being engaged by said diaphragm.
In a fifth aspect, the present invention disclose CPAP treatment apparatus comprising:
(a) a supply of air at a pressure at or above maximum treatment pressure;
(b) a mask for continuous delivery of air at a treatment pressure elevated above atmospheric pressure; and
(c) delivery pressure control apparatus integral of, or proximate to said mask, said apparatus including:
an input chamber for connection to said supply of air;
a pressure reducing means or flow restricting means for communication with said supply of air to provide air at a reduced pressure corresponding to a treatment pressure to a sensing chamber;
an outlet chamber for communication with said mask;
a diaphragm arranged between a portion of the outlet chamber and a portion of the sensing chamber;
first valve means located between said outlet chamber and said inlet chamber and operable to open a flow path between said outlet chamber and said inlet chamber upon deflection of said diaphragm; and
a second valve means located between said outlet chamber and atmosphere, and operable to provide an exhaust path to atmosphere from said outlet chamber on opposed deflection of said diaphragm; and
wherein when the pressure of air in said outlet chamber reduces b
Lewis Aaron J.
Pillsbury & Winthrop LLP
ResMed Ltd.
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