Does abstinence from smoking or a transdermal nicotine system influence atracurium-induced neuromuscular block?

The purpose of the present study was to investigate the interaction of chronic smoking and the actions of atracurium (ATR). Twenty nonsmokers (NON-SMOK) were compared with 80 smokers,who were randomized into three groups: 30 patients received 21 mg/d transdermal nicotine system greater than or equal to 10 h before fentanyl/thiopental/N2O/O-2/isonurane an esthesia (TD-NICO), whereas the abstinent group received a placebo transdermal system (ABST, n = 30). The TD-NICO and ABST groups refrained from smoking for at least 10 h before the induction of anesthesia A third group was allowed to smoke until 1-3 h before anesthesia (SMOK, n = 20). Neuromuscular block was monitored using a Relaxograph(TM) (Datex, Helsinki,Finland). The electromyographic response was recorded from the first dorsal interosseus muscle of the hand. The inspiratory isoflurane concentration was kept constant at 0.7 vol% in all patients. After an initial bolus dose of 0.5 mg/kg ATR, no significant difference was observed among the groups regarding onset time and maximal neuromuscular block In Group ABST, the duration of block until 25% recovery of T1 was 482 +/- 10.1 min,which was significantly longer (analysis of variance post hoc tests) than in Groups TD-NICO, SMOK, and NON-SMOK (42.7 +/- 7.1, 41.4 +/- 10.4 and 42.8 +/- 7.3 min, respectively). The maintenance dose of ATR in Group ABST (0.23 +/- 0.03 mg.kg(-1).h(-1)) was smaller than in Groups TD-NICO, SMOK, and NON-SMOK (0.30 +/- 0.07, 0.32 +/- 0.06, and 0.32 +/- 0.05 mg.kg(-1).h(-1), respectively). We conclude that abstinence from smoking increases the duration of ATR-induced neuromuscular block and reduces the maintenance dose of ATR in smokers. Perioperative use of a transdermal nicotine system prevents these abstinence-induced changes in duration and maintenance-dose. Implications: The purpose of the present study was to investigate the interaction of chronic smoking and atracurium. Smokers who refrain from smoking for >10 h require a smaller maintenance dose of atracurium than nonsmokers. However, using a transdermal nicotine system prevents the decrease in maintenance dose during abstinence.