Impact of the initial doses of rocuronium and pancuronium on subsequent maintenance for neuromuscular block

Purpose: To determine the impact of the neuromuscular blocking agent given for intubation on the duration of effect of multiple maintenance doses of p ancuronium and rocuronium. Methods: Seventy-eight subjects were randomly assigned to receive one of fo ur dosing combinations for intubation and neuromuscular maintenance: rocuro nium for intubation and maintenance, rocuronium for intubation and pancuron ium for maintenance, pancuronium for intubation and rocuronium for maintena nce, or pancuronium for both. Each time that the first twitch response retu rned to 25% of the baseline value, the duration of the dose was determined and another maintenance dose was administered. The duration of action of th e maintenance doses was compared between the groups. Results: Twitch suppression from the first maintenance dose was shorter for subjects who received rocuronium for both doses (Group RR) compared with t hat for subjects that received pancuronium (Groups PR & PP) as their intuba tion dose ( 17.6 vs 34 & 59.8 min, respectively, P < 0.05). Subjects who re ceived rocuronium followed by pancuronium (Group RP) showed a shorter durat ion of twitch suppression after the first maintenance dose than the group t hat received pancuronium for both doses (Group PP) (21.3 vs 59.8 min, P < 0 .05). By the third maintenance dose. the influence of the intubating dose o n the maintenance dose duration had essentially diminished. Conclusions: For combinations of rocuronium and pancuronium, the duration o f twitch suppression after a maintenance dose is only dependent on the firs t agent given for the first two maintenance doses administered.