[Metabolic changes caused by an extremities tourniquet and its modification by anesthesia procedures]

In 3 groups of 15 patients, respectively, we studied metabolic changes following tourniquet-release after operations of lower extremity. The influence of different anesthetic methods was evaluated by blood-gas-analyses up to 30 minutes after blood-circulation of the lower limb had been reinstalled. Our results demonstrate, that the patients under regional anesthesia with spontaneous respiration (group 1) could preserve their metabolic equilibrium with minor changes within the physiologic range. The intubated patients with controlled respiration (group 2) revealed a marked metabolic acidosis after tourniquet-release with insufficient respiratory compensation. Initial values were not reached within 30 minutes. The patients of group 3 (controlled respiration with a 25% increase of the normal minute volume for a period of 5 minutes after release of the tourniquet) had a less severe acidosis than those of group 2. The beneficial influence of spontaneous respiration in compensating metabolic acidosis--even in aged patients--following an ischemic tourniquet has been demonstrated by this investigation. Short-term hyperventilation seems to be the therapeutic tool in patients with controlled respiration to compensate for metabolic acidosis up to a certain extent.