The calibrated impendance plethysmograph: laboratory and clinical studies.

By careful experimental studies a calibrated impedance plethysmograph has been shown to be highly accurate (standard error = 3.8%). Its ability to measure the rate of pulsatile volume change has been extremely useful in the diagnosis of arterial insufficiency of the lower extremities. By helping in the objective definition and documentation of arterial perfusion, this instrument can greatly improve our selectivity of patients for angiography and subsequent revascularization.