Monitoring acute skin-flap failure.

Reliable and repeatable means for the objective postoperative monitoring of skin flaps is a necessity. If a failing free flap can be recognized early, it can be salvaged by revision of the appropriate anastomoses. For the threatened distal portion of a conventional flap, external factors, such as kinking or hematoma, may be corrected or drug therapy instituted. We have analyzed blood from stab wounds in experimental pig flaps for pO2, pCO2, pH, and hematocrit. The results were compared with fluorescein penetration and flap surface temperature. The most significant finding was hematocrit readings of threatened flaps (54 percent) elevated above those of control flaps (35 percent). pH readings in the jeopardized flaps were 0.4 units below control. These two measures proved to be more reliable than intermittent temperature readings. In contrast to the fluorescein test, which can be used only once, stab wound analysis is repeatable at any time in the postoperative period. It can be effectively used to follow dynamic changes within a skin flap.