Hemodynamics of the Finger Photo-plethysmogram: Examinations with Emphasis on Normalized Pulse Volume

Abstract

Normalized pulse volume (NPV) is expressed as PGac/PGdc. Here, PGac and PGdc are the alternate and direct current components of the finger photo-plethysmogram (PG), respectively. In the present review, using a theoretical pressure-volume curve, we first examined the effects of increases in vascular resistance and elevations of blood pressure on these PG indices during rest and mental stress. It was confirmed that NPV was directly proportional to the pulsating component of the arterial blood volume, whereas PGac and PGdc were hemodynamically much more complicated. Notably, as a stress marker, NPV was predicted to be more sensitive than the other two indices. Next, the effects on these PG indices (especially, on NPV) during mental stress and rest, with both cases occurring under a threatening situation, were examined. Finger raising was suggested to make the Law of Initial Values work moderately by reducing the increases in vascular resistance even during the threatened mental stress. Reservations concerning the use of NPV in basics and applications are discussed.View full abstract