Does Spontaneous Minute Ventilation Predict Readiness for Extubation in Mechanically Ventilated Preterm Infants? • 1778

To test the hypothesis that comparison of spontaneously-generated to mechanically-generated minute ventilation would be a useful predictor of readiness for extubation in preterm infants weighing less than 2500 grams who required mechanical ventilation for > 24 hours, an observational study was performed in neonatal intensive care units at two institutions.

Sixty-four preterm infants ≤ 2500 grams at birth (Table) were evaluated by comparing spontaneously-generated minute ventilation to mechanically-generated minute ventilation prior to each infant's first attempt at extubation. Expiratory minute ventilation was measured using the BIRD Partner IIi Monitor® (Bird Products Corp., Palm Springs, CA). After reaching predetermined ventilator settings (FiO₂ ≤ 0.35, PIP ≤ 20 cm H₂O, and control rate≤ 20 bpm), infants were extubated if spontaneously-generated minute ventilation after a 10 minute trial of endotracheal CPAP (ventilator rate = 0) was ≥ 50% of mechanically-generated minute ventilation during assist/control ventilation.

Table 1 No caption available.

Of the 64 infants who had a successful trial and were extubated, 55 (86%) remained extubated for at least 24 hours. Of the nine infants who failed extubation, seven developed apnea, one developed stridor, and one developed progressive respiratory acidosis. There were no differences between the group which was successfully extubated and the group which failed extubation with respect to gestational age, birth weight, or age at time of extubation. Thus, a spontaneous minute ventilation of ≥ 50% of mechanically-generated minute ventilation predicted readiness for extubation in 86% of the patients in this observation. When the study group was stratified by birth weight above/below 1250 grams, the positive predictive values were 89% and 83%, respectively. The results were similar in each institution.

This minute ventilation test is easy to perform and objectively assesses the readiness for extubation of low birth weight infants who have been weaned to modest ventilatory support.