A randomized, controlled trial of aminophylline in ventilatory weaning of premature infants

To determine whether maximal inspiratory force predicts successful neonatal extubation, and whether aminophylline affects maximal inspiratory force or the success rate of extubation.

Double-blind, prospective, randomized, placebo-controlled trial.

Tertiary level neonatal intensive care unit.

A total of 20 ventilated, preterm, newborn infants: birth weight < 2.5 kg; gestation < 35 wks.

Intravenous aminophylline 4 mg/kg bolus followed by 2.5 mg/kg every 6 hrs x three doses, then 1.5 mg/kg every 6 hrs; or placebo. Drug administration began when infants were receiving an FIO2 of < 0.4 and were progressively weaning from assisted mechanical ventilation. A standardized weaning protocol was instituted, and patients were extubated when they were able to tolerate a mechanical ventilatory rate of < 5 cycles/min.

Occlusion pressures, including maximal inspiratory force, were measured before aminophylline and daily until endotracheal extubation. Arterial blood gases were measured every 3 hrs, and 24-hr cardiac and respiratory recordings were performed postextubation. Three of ten aminophylline-treated patients failed extubation compared with two of ten placebo infants (p = nonsignificant). Mean apnea frequency postextubation was 0.02/hr in the aminophylline group compared with 0.3/hr in the placebo group (p < .05). Aminophylline had no effect on successful extubation or on maximal inspiratory force. Maximal inspiratory force was not correlated with the success of extubation. Apnea frequency postextubation was significantly reduced by aminophylline.

Aminophylline is an effective prophylaxis for postextubation apnea in the preterm infant but does not affect maximal inspiratory force or increase the success rate of extubation in this patient population.