REVERSAL OF DOXACURIUM AND PANCURONIUM NEUROMUSCULAR BLOCKADE WITH NEOSTIGMINE IN CHILDREN

Recovery after doxacurium and pancuromium neuromuscular blockade and their acceleration by neostigmine have not been compared in children. Therefore, 60 paediatric surgical patients aged 2-10 yr (ASA 1-2) were studied. They were randomized to receive doxacurium 30 mu g . kg(-1) or pancuronium 70 mu g . kg(-1) iv during propofol, fentanyl, isoflurane and nitrous oxide anaesthesia. Electromyographic (EMG) responses of the adductor pollicis to train-of-four (TOF) stimulation of the ulnar nerve were recorded every ten seconds using a Datex NMT monitor. Six patients in each relaxant group received neostigmine (0, 5, 10, 20 and 40 mu . kg(-1)) with atropine by random allocation when first twitch height (T-1) had recovered to 25% of control. Spontaneous recovery after ten minutes was similar following doxacurium (mean +/- SEM values of 45.0 +/- 3.9 vs 49.5 +/- 10.0% for T-1 and 25.2 +/- 3.8 vs 14.8 +/- 3.6% for TOF ratios ). Dose responses to neostigmine were calculated from the log dose vs logit of T-1 or TOF ratio after ten minutes. Neostigmine-assisted recovery was not different in the two groups, with ED(70) and ED(90) doses for T-1 of 14.3 +/- 1.8 and 25.7 +/- 2.7 mu g . kg(-1) for doxacurium and 12.5 +/- 1.7 and 25.3 +/- 2.3 mu g . kg(-1) for pancuronium. Time to recovery of TOF ratio to 70% after neostigmine 40 mu . kg(-1) was 2.3 +/- 1.0 and 4.2 +/- 1.7 min (P = NS) following pancuronium and doxacurium, respectively. Adjusted recovery due to neostigmine alone (spontaneous recovery subtracted from the total) required two to three times higher doses of neostigmine. Thus, in children, the spontaneous recovery and reversal of neuromuscular blockade is similar with doxacurium and pancuronium. However, compared with previous adult studies, they recover twice as quickly from doxacurium neuromuscular blockade and neostigmine antagonism is achieved at 25-50% of the adult doses.