Venous plasma (total) bupivacaine concentrations following lower abdominal field block

Following local anaesthesia of the lower abdominal wall, in patients undergoing laparoscopic sterilization (n = 16), using 0.5% plain bupivacaine 40 ml (n = 8), or 0.5% bupivacaine with 1:200000 adrenaline (n = 8), venous plasma (total) bupivacaine concentrations were measured (gas-liquid chromatography) at intervals up to 2 h after the local anaesthetic was injected. Mean peak plasma venous concentration achieved following 0.5% plain bupivacaine was 2.23 +/- 0.24 micrograms ml-1 (mean +/- SEM), while the mean peak concentration following 0.5% bupivacaine with adrenaline was 0.98 +/- 0.10 micrograms ml-1 (mean +/- SEM). At all sampling times up to and including 45 min after the injection of local anaesthetic, the plasma concentrations were significantly less in the bupivacaine with adrenaline group when compared with the group in whom a plain solution was used.