Paralysis in the critically ill: Intermittent bolus pancuronium compared with continuous infusion

Objectives: To compare recovery times from neuromuscular blockade between t wo groups of critically ill patients in whom pancuronium was administered b y continuous infusion or intermittent bolus injection. To compare the mean pancuronium requirements (milligrams per kilogram per hour) and to assess t he incidence of prolonged recovery times (>12 hrs) and residual muscle weak ness. Design: Prospective, observational cohort. Setting: Intensive care unit in a university-affiliate hospital. Patients: A total of 30 mechanically ventilated patients who required pharm acologic paralysis. Patients were excluded if they had renal failure (creat inine clearance <30 mL/min), heart rate >130 beats/min, hepatic failure, pe ripheral nerve disease or myopathy, stroke, spinal cord damage, or myasthen ia gravis. Interventions: Patients were assigned to receive pancuronium either by cont inuous infusion (n = 14) or intermittent bolus (n = 16). Depth of paralysis was titrated to maintain one or two responses to Train-of-Four stimulation with an accelerograph and desired clinical goals. Recovery time was define d as time from discontinuation of muscle relaxant until the amplitude of th e fourth twitch, measured every 15-30 min using an accelerograph, was 70% t he amplitude of the first twitch (Train-of-Four greater than or equal to 0. 7). Measurements and Main Results: These patients included the only three patie nts with status asthmaticus in our study. The groups were similar with resp ect to age, sex, weight, Acute Physiology and Chronic Health Evaluation II score, mode of ventilation, creatinine clearance, indications for paralysis , and duration of pancuronium administration. The median time for patients to recover from paralysis was 3.5 hrs (95% confidence interval, 1.82-5.18) in the infusion group vs. 6.3 hrs (95% confidence interval, 3.40-9.19) in t he intermittent bolus group (p = .10). Less drug was administered in the in termittent group (mean, 0.02 +/- 0.01 mg/kg/hr) than by infusion (mean, 0.0 4 +/- 0.01 mg/kg/hr; p < .001). Six patients (five in the infusion group an d one in the intermittent group) developed persistent severe muscle weaknes s. In addition, six different patients (three from each group) had prolonge d recovery >12 hrs. Conclusions: Our study suggests that recovery time after paralysis with con tinuous infusion is faster than that after intermittent bolus injection. Al though more pancuronium was administered in the continuous-infusion group, recovery time was not prolonged as a consequence. It is uncertain whether p ancuronium given by infusion increases the risk of persistent muscle weakne ss.