Pharmacodynamics and safety of mivacurium in infants and children under halothane-nitrous oxide anaesthesia

Objectives: To determine pharmacodynamic effects and safety of mivacurium i n paediatric patients. Study design: Multicentric, prospective, open, nonrandomized study. Patients: Forty-eight three-month-old to eight-year-old physical class ASA I or II children. Method: Anaesthesia was induced and maintained with halothane and nitrous o xide. Tracheal intubation was performed without a neuromuscular blocking ag ent. Neuromuscular blockade was measured with a strain force transducer aft er train-of-four stimulation of the ulnar nerve at the wrist every ten seco nds. A single bolus dose of mivacurium (0.2 mg . kg(-1)) was injected durin g 15 seconds in patients allocated into three groups. Group 1: three to 12- month-old infants (n = 15), group 2: one- to three-year-old children (n = 1 6) and group 3: three- to eight-year-old children (n = 17). Onset and recov ery parameters were measured in each patient. Heart rate and noninvasive ar terial blood pressure were recorded every minute for five minutes after miv acurium injection. Results: Following halothane administration for 29 and 32 min, and a FEThal othane = 1 vol%, mivacurium (0.2 mg . kg(-1)) determined a 100% neuromusmcu lar blockade in all patients. The onset time was 71 +/- 34 s (mean +/- SD) in all patients and did not differ between groups. Time to 25% and 95% reco very of the first twitch and recovery index for all the patients were 12 +/ - 3 min, 19 +/- 5 min and 4 +/- 2 min respectively and did not differ betwe en groups. No prolonged paralysis was observed. No significant changes of H R and BP occurred. Conclusions: Following 0.2 mg . kg(-1) of mivacurium in patients aged betwe en three months to eight years, a complete blockade occurs with a rapid ons et time and a short duration of action, without significant cardiovascular effect. (C) 1999 Editions scientifiques et medicales Elsevier SAS.