Accelerated Onset and Delayed Recovery of D-tubocurarine Blockade with Pancuronium in Infants and Children

The effect of age on the onset and duration of action of a d-tubocurarine (DTC) neuromuscular blockade with and without pancuronium priming in children was examined. Sixty ASA physical status I or II patients in three age ranges (0-1 yr, 1-3 yr and 3-10 yr) were anaesthetized with thiopentone, halothane and nitrous oxide. Each patient received either a single paralyzing dose of DTC 0.4 mg.kg-1, or DTC 0.36 mg.kg-1 preceded three minutes earlier by pancuronium 0.007 mg.kg-1. Evoked force of contraction of the adductor pollicis was measured using train-of-four stimulation applied every 12 sec. Time to 90 per cent first twitch depression after a single dose of DTC increased with increasing age (r = 0.65, p less than 0.01), and was 1.6 min (SEM +/- 0.3) in the 0-1 yr group, 1.9 +/- 0.3 min (1-3 yr), and 5.2 +/- 1.2 min (3-10 yr). Time to ten per cent spontaneous recovery after single dose DTC was shorter in older individuals (r = 0.40, p less than 0.05), being 36.4 +/- 5.1 min in infants 0-1 yr, 30.6 +/- 4.6 min (1-3 yr), and 24.0 +/- 2.7 min (3-10 yr). Priming with pancuronium accelerated the onset significantly in all age groups with 90 per cent T1 depression occurring at 0.7 +/- 0.1 min (0-1 yr), 0.9 +/- 0.1 min (1-3 yr), and 2.1 +/- 0.6 min (3-10 yr). However, priming delayed recovery, especially in infants.(ABSTRACT TRUNCATED AT 250 WORDS)