MICROCIRCULATORY RESPONSE TO SURGICAL TRAUMA IN COMPOSITE-TISSUE TRANSFER

A rat cremaster muscle-flap model for direct in vivo microcirculatory studies was combined with a rat hind-limb amputation/replantation mode l, to evaluate changes related to transfer trauma. Forty-eight inbred Sprague-Dawley rats were studied in two experimental groups. In a cont rol group, the cremaster muscle was dissected as an island tube flap, transposed into the hind limb, and anchored at ankle level. No amputat ion was performed. In a second composite-limb-cremaster-graft group, t he limb, with the inserted cremaster muscle flap, was amputated at mid -thigh level, and transferred to a recipient animal. In both groups, a t follow-up periods of 1, 24, 48, and 72 hr, the cremaster flap was wi thdrawn from the limb and prepared for microcirculatory studies. The f ollowing parameters were measured: vessel diameters, RBC velocities, c apillary density, and leukocytes in the postcapillary venules. Arterio lar and venular diameters, as well as RBC velocity values, were compar able in both groups. However, the composite isografts presented 50 per cent more leukocytes sticking to the lumen of the postcapillary venule s (p < 0.05) immediately following transfer. In addition, a significan t decrease (12 percent) in the number of perfused capillaries was obse rved in the composite grafts throughout 72 hr. In this study on compos ite tissue transfer, trauma alone compromised the microcirculatory int egrity of the tissue and proved to act as an independent factor. This should be considered during allotransplantations, where the addition o f a rejection factor can further compromise graft survival.