Comparison of atracurium and pancuronium in mechanically ventilated neonates.

OBJECTIVE: To compare haemodynamic and gas exchange effects after either atracurium or pancuronium given to ventilated neonates with respiratory failure.
DESIGN: In this prospective study neonates were alternately assigned to receive either atracurium or pancuronium, intravenously.
SETTING: Paediatric and neonatal ICU in a teaching hospital. PATIENTS: 21 ventilated neonates with mean birth weight of 2293 g, suffering from respiratory distress syndrome, meconium aspiration syndrome or pneumonia were included in the study. Patients were entered if they were breathing out of phase with the ventilator and required FIO2 > 0.4 and peak inspiratory pressure (PIP) > 15 cm H2O. Exclusion criteria were unstable haemodynamics or a pneumothorax.
INTERVENTIONS: Heart rate, respiratory rate, invasive blood pressure and transcutaneous oxygen tension were monitored continuously. IV atracurium (0.3 mg/kg) or pancuronium (0.1 mg/kg) were administered. Arterial blood gas analysis was performed before and 10 min after injection of muscle relaxant. MEASUREMENTS AND
RESULTS: Atracurium caused a significant decrease in heart rate (p < 0.05), systolic and mean blood pressure (p < 0.01). There was also a slight decrease in PaO2 and PaCO2 (n.s.). Administration of pancuronium resulted in an increase in heart rate (p < 0.01) and a slight decrease of blood pressure (n.s.). PaCO2 remained unchanged, whereas PaO2 increased slightly (n.s.). The PtcO2 index (PtcO2/PaO2) decreased after atracurium and did not change after pancuronium (both n.s.). With both drugs a slight increase in alveolar to arterial oxygen tension difference was observed (n.s.). There was one episode of hypotension and one of hypoxaemia--both after pancuronium.
CONCLUSION: Both drugs may be used for muscle relaxation in neonates with respiratory failure. Atracurium however causes more cardiovascular depression, whereas the effect of pancuronium may be difficult to predict.