THE INFLUENCE OF DIABETES ON FREE FLAP TRANSFER .2. THE EFFECT OF ISCHEMIA ON FLAP SURVIVAL

Insulin-dependent diabetes mellitus causes microangiopathic changes in many tissues, including skin and muscle. It is not known if such changes are detrimental to free flap transfer, particularly after extended ischemia. To address this issue, we used an experimental design by using a syngeneic rat strain (Lewis) for free groin flap and muscle flap transplantations from streptozotocin-induced diabetic rats (2 month's duration of symptoms) to normal rats. Flaps from age-matched normal donors were transplanted to normal recipients for control comparisons. Groin flaps were stored ischemically for 12 or 18 hours at room temperature, or for 48 hours in the cold (4-degrees-C) before transplantation. Flap survival and vascular patency were assessed at 7 days. Cutaneous maximus muscle flaps were transplanted to the groins of recipients after 6 hours of room temperature ischemia. Vascular patency, muscle viability, flap weight change (edema), and dehydrogenase activity were assessed after 2 days of reperfusion. Seventy percent, 67%, and 73% of diabetic groin flaps survived after 12, 18, or 48 (cold) hours of ischemia, respectively, in comparison with 90%, 73%, and 87% of normal flaps undergoing the same respective ischemia periods. The differences were not significant, even when the data were pooled (p > 0.1). Muscle flaps also showed no significant differences for the parameters studied. These results support the use of microvascular reconstructive surgery in diabetic patients, suggesting that moderate ischemic challenges do not compromise free flap transfer or extremity replantation.