EFFECT OF ADRENALINE ON PLASMA CONCENTRATIONS OF BUPIVACAINE FOLLOWING LOWER LIMB NERVE BLOCK

Twenty-two patients undergoing total knee arthroplasty received combined sciatic plus femoral "3 in 1" blocks as adjuncts to general anaesthesia. Eleven patients received 0.375% bupivacaine 45 ml (168.75 mg) with adrenaline 1 in 200000 and the remaining 11 received plain solution according to a previously prepared, randomized list. The mean maximum plasma bupivacaine concentration was significantly greater with plain solution than when adrenaline was added (1.66 μg ml −1 compared with 0.98 μg ml −1 ) ( P P −1 in one patient receiving plain bupivacaine. No patient developed signs of systemic toxic effects. Peak plasma concentrations were related inversely to body weight in patients receiving solution containing adrenaline ( P