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.
Robison
C
C
Department of Anaesthetics, Princess Margaret Rose Orthopaedic Hospital, Fairmilehead, Edinburgh.
Ray
D C
DC
McKeown
D W
DW
Buchan
A S
AS
D000328:Adult; D000368:Aged; D000772:Anesthesia, Local; D002045:Bupivacaine / Q000097:blood*; D004837:Epinephrine / Q000494:pharmacology*; D005260:Female; D005267:Femoral Nerve; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D009407:Nerve Block; D011897:Random Allocation; D012584:Sciatic Nerve
D002045:Bupivacaine; D004837:Epinephrine