Abstract
Measurement of beat-to-beat blood pressure and heart rate responses to the Valsalva maneuver is the basis for a highly informative autonomic function test. Whereas in the past this measurement required intra-arterial cannulation, the development of finger cuff devices that acquire arterial pressure waveforms indistinguishable from those recorded intra-arterially has made it possible to obtain accurate measurements noninvasively. In a patient with orthostatic hypotension, the pattern of blood pressure responses during and after the release of the maneuver can identify a neurogenic basis: sympathetic neurocirculatory failure. The quantifiable change in cardiac interbeat interval per unit change in systolic pressure during the maneuver can identify baroreflex-cardiovagal failure.