Effect of immersion on intrapulmonary pressure

Abstract

Pressure-volume relaxation curves have been determined for relaxed, breath-holding subjects lying and sitting in air and water. Immersion in water resulted in a marked increase in intrapulmonary pressure, the whole pressure-volume curve appearing to be shifted along the pressure axis. From the regression equations of the four curves the pressures at normal relaxed chest volume were calculated, and the center of pressure of the immersed chest shown to lie 19 cm below and 7 cm behind the sternal angle. The significance of this to the positioning of a diver's demand valve is discussed. center of pressure of thorax; immersion and chest volume; eupneic pressure; diving physiology; underwater respiration Submitted on September 10, 1964