Prior Elevation of Vascular Island Skin Flaps: Intolerance to Ischemia Caused by Venous Obstruction

ABSTRACT

Previous experiments in our laboratory have shown that prior elevated flaps, those elevated 24 hr prior to complete ischemia, are more tolerant of the ischemic insult than acutely ischemic flaps that have had no prior elevation. In the current study, the effect of prior elevation was observed on tolerance to ischemia caused by venous occlusion alone. Under these conditions, limited blood flow may be possible via the undamped artery, so a state of partial ischemia exists.

After seven hours of venous obstruction, acutely elevated flaps had a 50 percent survival rate at postoperative day 7. This was significantly better (p < 0.005, χ₂ test) than the 0 percent survival rate for prior elevated flaps for the same period of venous obstruction. It is speculated that the more rapid generation of cytotoxic free radicals during the period of partial ischemia is more detrimental to the prior elevated flaps that have greater blood flow, than to the controls.