Apparatus for maintaining airway patency

#Obstructive sleep apnea is a common disorder that involves tissue occlusion of the nasopharyngeal airway during sleep which impedes a patient's normal breathing cycle. Multiple sequential apnea episodes may result in severe sleep disruption of which the patient may not even be aware. Moreover, swollen tissue in the airway often results in excessive heavy snoring. Extreme sleep apnea is a serious disease which may affect as much as three percent of the adult population, and heavy snoring is much more common, particularly with overweight individuals.

#Surgical intervention is always an option in alleviating obstructive sleep apnea or heavy snoring, however, most patients prefer to address the problem with non-invasive treatment. One treatment program involves the use of continuous positive airway pressure delivered to the patient's airway to maintain the airway in a continuously open state during sleep. The equipment required to deliver continuous positive airway pressure to the airway of a patient includes a fan or blower for generating a pressurized flow through a hose coupled to a mask or nasal device which the patient places over his or her nose and uses straps about the head to fasten the device in place.

#Many patients cannot tolerate the application of continuous positive airway pressure, particularly because of the discomfort associated with exhalation against a continuous positive pressure. An attempt has been made to alleviate this problem by the provision of a method and apparatus which provides a substantially constant elevated airway pressure to the patient's airway, with periodic short term reductions of the elevated airway pressure to a pressure of lesser magnitude. A further advance in such treatment involves the application of alternative high- and low-level positive airway pressure wherein the low-level pressure coincides with the breath exhalation of the patient's breathing cycle.

#FIG. 1 is a schematic representation which illustrates both the method and basic apparatus for practicing the present invention.

#FIGS. 2 and 3 are schematic representations which illustrate the physical principles underlying the method and basic operation of the apparatus of the present invention.

#FIGS. 4 and 5 are elevational views in vertical section of a bench-test embodiment of the apparatus of the present invention.

#FIG. 1 schematically illustrates an assembly 10 including an airflow generator 12, an electromagnetic solenoid 14, a dual valve assembly 16, a normally-open electrical switch 18, and a mask 20. The airflow generator 12 may be a blower or fan of the type used to produce a pressurized airflow. The solid line arrows mark the air stream flow path, beginning with ambient air drawn into the airflow generator as indicated by arrow 22. The electric current to operate the flow generator is supplied through conductors 24 and 26, which also supply current to solenoid 14 through switch 18. The airflow generator 12 is intended to operate continuously whereby a constant head of pressurized air is maintained to the solenoid 14. However, the solenoid 14 is normally closed and will permit air passage there through to the dual valve assembly 16 only when the solenoid 14 is caused to open by switch 18.

#The dual valve assembly 16 of FIG. 1 includes a flexible circular diaphragm 28 and a disc valve 30 mounted on the diaphragm 28. In its relaxed position (not shown), the diaphragm 28 will cover and seal apertures, such as aperture 32 and aperture 34. The disc valve 30 is a circular flexible thin rubber membrane which normally seals against the inside surface of the diaphragm 28 but will flex open in response to pressurized airflow from the solenoid 14 and allow the airflow to pass through the valve arrangement and thence into mask 20.

#It should be noted that the mask 20 is provided with a normally-closed disc valve 36 which will respond to inhalation by the patient and open to permit entry of ambient air. The mask 20 is meant to be worn in sealed relation to the nose of a patient whereby ambient air during inhalation will pass into the mask past valve 36. Exhaled breath will cause valve 36 to close whereby the breath flow will be in the direction of the dotted line arrow 38 and into the dual valve assembly 16. Breath pressure entering the dual valve assembly 16 causes the disc 30 to seal against the diaphragm 28 and stretches the diaphragm 28 from a sealing linear disposition (not shown) to the position shown in FIG. 1. A spring-biased switch trigger or toggle 40 extending from switch 18 is contacted by the outwardly-flexed diaphragm 28 whereby the toggle 40 is pivoted from left to right as shown in FIG. 1. This pivoting action of the toggle 40 sets the switch internally whereby, as the diaphragm 28 relaxes, the toggle 40 will pivot back to its original position and, at the same, close internal contacts of the toggle 40 to complete the electrical circuit to the solenoid 14. The solenoid 14 is thereby caused to cycle open and then immediately re-close after having permitted a burst of pressurized air to move into the dual valve assembly 16 and past the disc valve 30 and into the mask 20. The pressurized airflow burst is directed into the nasopharyngeal airway of the patient as the patient's inhalation action occurs, and ambient air moves through valve 36 to allow the patient to complete the breath intake voluntarily. The subsequent exhalation by the patient repeats the described process whereby a pulse or burst of pressurized air is delivered to the mask 20 and thence to the patient's airway as a function of each breathing cycle.