Plethysmography has proven to be a valuable method for studying the dynamics of peripheral vascular beds in normal and pathologic states and for evaluating the effects of drugs upon these beds. Refinements of the method, such as graded outflow hindrance and stopflow studies, have permitted separation of the pulsatile arterial inflow and venous runoff components of peripheral perfusion. The technique also lends itself to the study of such physical characteristics as viscoelasticity of the regional vascular bed under consideration.
The technique of mechanical plethysmography is laborious compared with electrical impedance plethysmography. Further, the latter method is well suited to provide input data to an analog computer. An additional use to which the method can be put is the recording of "dye" dilution curves, in this case utilizing a material of "contrasting" impedance.
This monograph, by one of the foremost proponents of the method, contains a complete review of the subject