Two hundred and seventy years ago Antonio Maria Valsalva ("De Aure Humana," 1704) recommended forced expiration against a closed glottis, for expelling pus from an infected middle ear. This procedure, known thereafter as the Valsalva experiment or maneuver, has been used extensively in the treatment of eustachian tube obstruction. However, its potential for the study of circulatory physiology was not suspected.
Nor was this potential appreciated even when, nearly a century and a half later, Eduard Friedrich Weber (1851) found that the Valsalva maneuver caused changes in the volume of the pulse. And only after Flack1 (1920) modified the maneuver by having patients blow against a column of mercury rather than against a closed glottis did investigations of the complex physiologic changes set in motion by this procedure begin in earnest. Only during the past two decades have the diagnostic implications of these changes become apparent.
Normally, an abrupt