| 摘要 |
A tracheostoma valve includes a tubular housing with an inner aperture at an inner end, and a smaller outer aperture at an outer end. The inner end of the valve is for being attached to a stoma of a patient. A shaft is positioned axially within the housing, and a rigid piston is slidable along the shaft. The piston has a smaller diameter than the interior diameter of the tubular housing, so that air can flow around it. The piston is movable between an open position intermediate of the inner and outer apertures, and a closed position against the outer aperture. The piston is biased by a spring to the open position when the air pressure is relatively low, such as during relaxed respiration, so that air may flow through the valve in either direction. At a high enough expiratory air pressure, such as that used for producing speech, the spring is collapsed and the piston is moved against the outer aperture. Expiratory air is thus diverted from the trachea into the pharynx through a conventional voice prosthesis positioned there between for producing speech.
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