THE PHYSIOLOGICAL-BASIS FOR NONCONVENTIONAL VASCULAR PERFUSION

It is traditionally thought that the exchange of oxygen occurs only at the capillary level, with both arterial inflow and venous outflow req uired. However, as early as 1970, studies have indicated that signific ant arteriolar and venular diffusion of O-2 and CO2 occurs. The precap illary and postcapillary diffusion of oxygen and carbon dioxide and th eir potential regulation via the Bohr effect are key elements in under standing the success of nonconventional vascular perfusion (arterializ ed venous, total arterial, total venous), where the capillary circulat ion is bypassed. In retrograde ''reverse-flow'' island flaps, there is an anterograde blood flow through the capillary bed, with nonconventi onally reversed flow within the arterial and venous systems, respectiv ely. The reversal of venous flow is best explained as a combination of valvular insufficiency and the existence of vein-vein bypass channels via the venae comitantes.