Abstract

This study was undertaken to determine if blood pressure elevation associated with the use of a pneumatic tourniquet during lower extremity surgery is related to the type of anesthesia used. A possible hormonal cause for the blood pressure elevation was also sought. Thirty patients undergoing operation on the leg requiring use of a tourniquet were divided into three equal groups. Each group received either general, spinal, or epidural anesthesia. A blood sample was collected before induction of anesthesia, immediately before inflation of the tourniquet, 30 minutes after inflation, and 5 minutes after deflation of the tourniquet. Plasma concentrations of norepinephrine, epinephrine, cortisol, and glucose were assayed. Systolic, diastolic, and mean blood pressures and pulse rate were recorded every minute during induction of anesthesia and then at 5-minute intervals using an automated blood pressure monitor. Thirty minutes after inflation of the tourniquet, mean blood pressure rose only in the general anesthesia group. No change in plasma norepinephrine concentration was observed in any group. A fall in plasma epinephrine concentration occurred after the induction of spinal anesthesia. Five minutes after the tourniquet was released, plasma cortisol concentration rose in the general anesthesia group as did norepinephrine concentration in the epidural group. The cause of the blood pressure elevation during general anesthesia could not be ascribed to activation of the hypophyseal-adrenal axis. Other possibilities are discussed.