Pneumatically sensed respiration monitor & method

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS," one will understand how the features of this invention provide its benefits, which include reliability, low cost, and avoidance of false alarms.
The first feature of the respiration monitor of this invention is that it includes a sensing element including a pressure chamber filled with gas.
The sensing element is adapted to be placed in contact with the subject, so that the pressure in the chamber increases as the subject inhales and decreases as the subject exhales.
This sensing element may be a belt wrapped about the chest of the subject or a mat on which the subject lies while sleeping.
It typically is a balloon-like structure with walls made of an elastomeric material which is resilient.
When the subject inhales, the volume of the chamber decreases slightly, increasing slightly the pressure of the gas in the chamber.
When the subject exhales, the chamber returns to its original volume due to the resilient nature of the elastomeric material.
The second feature is a pressure switch in communication with the pressure chamber.
This switch is activated as the subject breathes.
For example, as the subject exhales the switch is opened and as the subject inhales the switch is closed.
A reverse arrangement could also be established, so that exhaling closes the switch and inhaling opens the switch.
The important consideration is that the switch is activated to change from a first state to a second state as the subject exhales and to change from the second state to the first state as the subject inhales.
The pressure switch preferably is a differential pressure switch, with a first side in communication with the gas chamber and a second side in communication with ambient pressure.
The pressure chamber includes the volume of gas in the sensing element in contact with the subject, the volume of gas in any tube connecting the sensing element to the switch, and the volume of gas in first side of the switch in communication with the tube and sensing element