• J E Tetzlaff, J Andrish, J O'Hara, J Dilger, and H J Yoon.
• Department of General Anesthesiology, Cleveland Clinic Foundation, OH 44195, USA.
• J Clin Anesth. 1997 Nov 1;9(7):542-5.

Study ObjectiveTo evaluate the quality of pain control achieved with continuous local anesthetic infusion via a femoral nerve catheter, and to determine the optimum concentration of bupivacaine necessary to maintain pain control after full surgical anesthesia is established with 0.5% bupivacaine.DesignRandomized, prospective study.SettingTertiary care teaching center.Patients25 ASA physical status I and II patients scheduled to undergo arthroscopically-aided anterior cruciate ligament (ACL) reconstruction by one surgeon, and who were willing to accept a femoral nerve catheter for postoperative pain control.InterventionsAll patients received general anesthesia with propofol/alfentanil (10 ml/1 ml) mixture and nitrous oxide/oxygen (60%/40%) mixture via endotracheal tube. After induction of general anesthesia, a femoral nerve catheter was inserted with the aid of a nerve stimulator, and 20 ml of 0.5% bupivacaine was administered. The surgery was completed in a standard manner and the patients were randomized into three groups for the concentration of local anesthetic to continue the pain relief into the recovery phase. On awakening, all patients were determined to have a functioning femoral nerve catheter. Group 1 received 0.0625% (n = 8) bupivacaine, Group 2 0.125% (n = 9) bupivacaine, and Group 3 0.25% (n = 8) bupivacaine; all doses were initiated in a blinded manner at 0.12 ml/kg/hr. Patients also received intravenous patient-controlled analgesia with morphine via demand mode only, with a 1.0 mg dose and a 6 minute lock-out interval.Measurements And Main ResultsPain was determined at defined intervals by visual analog scale (VAS). Data collected included demographics, VAS scores, and total morphine administered. All patients were pain-free on emergence from general anesthesia. No patient required parenteral opioid for pain control while in the postanesthesia care unit. There were no significant differences in pain scores among groups, and average pain scores (2.5 to 4.0) indicate good pain control throughout the entire hospitalization. There were no complications.ConclusionsLow concentrations of bupivacaine delivered via femoral nerve catheter after an established femoral nerve block can provide excellent postoperative pain control after ACL reconstruction.

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