No tachyphylaxis during postoperative continuous epidural 0.125% bupivacaine infusion

The sensory level of analgesia and motor blockade were measured in 12 healthy patients undergoing gynecological laparotomy during combined epidural and general anesthesia. After the initial dose of 12 ml of plain bupivacaine 0.125%, a continuous epidural infusion of bupivacaine 0.125%, 12 ml/h, was initiated for pain treatment scheduled for 32 hours. No patients received narcotics. Initial level of sensory analgesia was Th6.8 ± 0.8 to S2.4 ± 1.1 (mean ± SEM). During the postoperative period six patients maintained the initial bilateral level of sensory analgesia and motor blockade. Five patients had a unilateral blockade. One patient had sufficient bilateral analgesia for 12 hours, but requested to withdraw from the study without giving a reason. Acute tolerance (tachyphylaxis) was not observed during the study, but half of the patients had a unilateral block.