MYOELECTRIC AND MECHANICAL CHANGES ELICITED BY ISCHEMIC PRECONDITIONING IN THE FELINE HINDLIMB

Tourniquet use is fraught with potential complications. For example, i schemia produced by the tourniquet may lead to nerve and muscle injuri es. One technique shown in cardiovascular and free-flap surgery to imp rove the viability of muscle subjected to ischemia is preconditioning. This technique involves an initial brief period of ischemia, followed by reperfusion before a prolonged ischemic episode. The purpose of th is study was to explore ischemic preconditioning as a method to reduce tourniquet-related morbidity. In six cats, one leg was preconditioned by 10 min of tourniquet-induced ischemia followed by 10 min of reperf usion. The contralateral limb was not preconditioned. Both limbs under went 1 h of tourniquet inflation followed by a 2-h recovery period. Is ometric force and electromyographic (EMG) amplitude were recorded thro ughout the procedure at 20-min intervals in both medial gastrocnemius muscles. Analysis of variance (ANOVA) with repeated measures shows tha t, after 60 min of tourniquet application, maximal isometric force was significantly larger in the preconditioned group. Furthermore, the EM G amplitude during recovery was found to be significantly larger in th e preconditioned limbs. These results suggest that preconditioning Imp roves skeletal muscle viability in vivo. Further research is needed, h owever, to assess the long-term effects of this technique, and to deli neate appropriate preconditioning protocols that would improve surgica l outcome without significantly increasing the complexity of the proce dures. (C) 1997 Elsevier Science Ltd.