TOURNIQUET RELEASE - SYSTEMIC AND METABOLIC EFFECTS

The pneumatic tourniquet produces ischemic changes in limbs. The effec ts of tourniquet release on systemic blood pressure and metabolic para meters were studied in 11 adult patients undergoing total knee replace ment under general anesthesia. Mean arterial pressure (MAP) decreased rapidly after the release of the tourniquet, becoming significant at 3 min and remaining significantly depressed up to 15 min post release. Arterial pH, PaO2, PaCO2, lactate acid, and potassium changed signific antly after the release, but normalized within 30 min. These results a re notably different from a previous study in a similar patient popula tion undergoing knee replacement under epidural anesthesia. Compared t o patients under epidural anesthesia, patients receiving general anest hesia with mechanical ventilation are unable to compensate for the met abolic load caused by the tourniquet release, as the latter group are unable to alter their ventilatory rate. In elderly patients with decre ased cardio-pulmonary reserve, this may be of clinical importance. (C) Acta Anaesthesiologica Scandivanica 40 (1996)