Abstract
The vital capacity was measured in 8 subjects before and immediately after exerting a positive pulmonary pressure of 40 mm. Hg for 5 sec. In the standing position an avg. increase of 147 ml. was obtained by this Valsalva maneuver. In the supine position an avg. increase of 306 ml. was obtained. In all but one case these differences were significant at the 1% level.
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