Digital Enhancement of the Peripheral Admittance Plethysmogram

Limb segment pulse volume (PV) is the maximum change in the volume (V) of a limb segment during the cardiac cycle. Peak net inflow (PNI) is the maximum value of dV/dt during the cardiac cycle. These parameters are difficult to measure because they are so small (PV is approximately 0.0003 ×V). As a result, conventional analog plethysmographic measurements of PV and PNI are inherently inaccurate and difficult to reproduce. A digital enhancement (DE) technique using selective signal averaging to improve PV and PNI reproducibility is described.