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 200,000 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 micrograms ml-1 compared with 0.98 micrograms ml-1) (P less than 0.05). Bupivacaine concentrations were greater at all times in the plain group compared with the group receiving adrenaline. These differences were statistically significant at 10, 15 and 20 min (P less than 0.05). The greatest peak concentration recorded was 3.13 micrograms ml-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 less than 0.005), but no relationship existed in patients who received plain solution.

Comparison of complications associated with single-holed and multi-holed extradural catheters.

Adverse events associated with single-holed and multi-holed extradural catheters were compared in obstetric practice. Two hundred and forty-five patients were given an extradural block using a single-holed catheter and 229 received a block via a multi-holed catheter. There was no difference in the incidence of major side effects. Flow of fluid under gravity in the catheter was restricted significantly more often in the single-holed catheters. Blood was found significantly more often in the multi-holed catheters.