Acute effects of vecuronium on pulmonary function and hypoxemic episodes in preterm infants.

BACKGROUND: Varying effects of pancuronium on neonatal pulmonary mechanics have been documented, including a decrease in pulmonary compliance or no significant change in compliance; but measurements of respiratory mechanics or quantification of episodes of hypoxemia in preterm newborns receiving vecuronium (Norcuron, Bedford Labs, Bedford, OH, USA) have not been reported. The objective of the present study was to quantify the short-term effects of vecuronium on pulmonary mechanics and episodes of hypoxemia in preterm infants receiving mechanical ventilation.

METHODS: A total of 15 preterm infants (birthweight 610-1560 g, gestational age 25-32 weeks, postnatal age 0.2-22 days) was studied. The initial dose of vecuronium used for the study was 0.2 mg/kg i.v. Measurements of respiratory mechanics were obtained 1 h prior to and 1 h after the initial dose of vecuronium at comparable ventilator settings and fractional inspired oxygen concentration (FiO(2)). Dynamic respiratory compliance and respiratory resistance were calculated by two-factor least mean square analysis. Pulse oximeter oxygen saturation (SpO(2)) was measured during both 1 h intervals with the Nellcor N-200 oximeter, a computer, and a software program for quantification of episodes of hypoxemia. Heart rate and blood pressure were also monitored.

RESULTS: There were no significant differences in tidal volume, respiratory compliance, or respiratory resistance when comparing measurements obtained before and after vecuronium administration. However, fewer episodes of hypoxemia (SpO(2) < 85%, P = 0.025; and SpO(2) < 80%, P = 0.04) were observed during muscle relaxation. No significant changes in heart rate or blood pressure were noted.

CONCLUSIONS: The preliminary data indicate: (i) a single dose of vecuronium does not significantly change respiratory compliance or respiratory resistance in preterm infants and (ii) during muscle relaxation fewer episodes of desaturation (hypoxemia) are observed.