Effect of skin flap ischemia and surgical stress on plasma endothelin-1 levels

Vasospasms within the microvasculature of a flap can be a cause of ischemia and flap non-viability. Endothelin-1 (ET-1), a 21-amino acid polypeptide isolated from vascular endothelium culture media, is reported to be one of the most potent vasoconstrictors known, the authors have investigated whether skin flap ischemia and/or surgical stress had an influence on the plasma level of ET-1 in 5 cases of an intra-oral reconstruction using a radial forearm flap from October 1992 to March 1993. After the flap had been subjected to 2 hours of ischemia, blood was drawn from the venous effluent of each flap and the ET-1 content was evaluated. It was found that the plasma ET-1 levels of the flap had not significantly changed compared with the ET-1 level in the peripheral venous blood. Further, the plasma ET-1 levels after general anesthesia did not differ significantly from the pre-anesthetic levels, although the plasma ET-1 levels did significantly increase during the operation and were greater than the preoperative levels. Finally, the plasma ET-1 levels on postoperative day 1 tended to decrease compared with their levels during the operation. These results suggest that surgical stress influences the plasma ET-1 level. In the future, the measurement of ET-1 levels in flaps exposed to over 2 hours of ischemia should be investigated. Further, one thing that remains to be clarified is whether ET-1 is among the factors responsible for partial necrosis in skin flaps and the genesis of the no-reflow phenomenon.