Cisatracurium-induced neuromuscular blockade in anticonvulsant treated neurosurgical patients

Patients treated with the anticonvulsants phenytoin or carbamazepine are re sistant to steroidal neuromuscular blocking agents. We studied the effect o f cisatracurium on onset, duration, and speed of recovery from neuromuscula r blockade (NMB) in acutely anticonvulsant treated patients ([< 2 weeks] [A A]), chronically anticonvulsant treated patients ([> 2 weeks] [CA]) and pat ients not on anticonvulsants ([controls] ICI). After internal Review Board approval, 10 AA, 14 CA, and 14 C neurosurgical patients were studied. Anest hetic induction was midazolam, fentanyl, and thiopental, and maintenance wa s fentanyl and 0.5 MAC isoflurane in O-2. The evoked compound electromyogra m of the hypothenar eminence was monitored (TOF supramaximal stimulus at 2 Hz every 20 seconds). Baseline TOF was established, then cisatracurium (0.2 mg/kg) was administered IV. Onset (time to maximal paralysis), duration [t ime to recovery of first twitch (T1) to 25% of baseline] and speed of recov ery (time of recovery from 10%-25% of baseline) were recorded. Data were an alyzed using ANOVA. Onset(C = 4 +/- 2, AA = 3 +/- 1, CA = 3 +/- 1.5 minutes ) and duration (C = 69 +/- 13, AA = 64 +/- 19, CA = 59 +/- 19 minutes) were not different among the groups (P > .7). Speed of recovery was significant ly faster in both AA (6 +/- 2 minutes) and CA (6 +/- 3 minutes) than in C ( 12 +/- 9 minutes) patients (P < .05). (Data = mean +/- SD). Onset and durat ion of cisarracurium-induced neuromuscular relaxation was not affected by a cute or chronic anticonvulsant treatment, but speed of recovery was signifi cantly faster. Frequent NMB monitoring is necessary to detect the greater s peed of recovery in anticonvulsant-treated patients during cisatracurium mu scle relaxation.