Estimation of subglottal pressure with intraoral pressure.

A method of estimating subglottal pressure through intraoral pressure has been reported in the literature. In order to determine its clinical usefulness, however, the method should be tested against direct measurements made on subjects with pathologic larynges. The present study was designed to compare intraoral pressure versus subglottal pressure, as measured with a sensing tube inserted through a tracheal stoma. Results showed that intraoral pressure of /i:pi:/ was almost equivalent to subglottal pressure of /i:/ when the latter was smaller than about 25 cmH20. When subglottal pressure exceeded this value, however, the intraoral pressure was smaller than the subglottal pressure. We conclude that the magnitude of subglottal pressure is not invariably identical with intraoral pressure.