Pulsatile and nonpulsatile cardiopulmonary bypass: review of a counterproductive controversy.

In the controversy over pulsatile and nonpulsatile perfusion, most authors have failed to recognize the fundamental physical differences between the two methods. Pulsatile perfusion is polymorphic and its form varies with both the pulsatile source and the vascular system being perfused; nonpulsatile perfusion is by definition unvarying and uniform. While many studies of hemodynamics, metabolism, organ function, microcirculation, and histology show benefits derived from pulsatile perfusion, others do not. The simplest explanation for these conflicts is that different investigators employ different forms of pulsatile perfusion, only some of which are effective. Failure to quantitate adequately the pulsatile components of flow in these studies prevents differentiation between effective and ineffective forms of pulsatile flow and makes comparison of studies difficult. Future research in this area should be directed toward definition of effective pulsatile perfusion by adequate measurement of the pulsatile components of perfusion.