Tidal volumes in spontaneously breathing preterm infants supported with continuous positive airway pressure.

OBJECTIVE: To describe changes in tidal volume (VT) and their correlation to changes in oxygen saturation and heart rate in spontaneously breathing preterm infants immediately after birth.

STUDY DESIGN: In this prospective observational, 2-center study, a flow sensor was attached to the facemask of spontaneously breathing infants born at <37 weeks' gestational age who received continuous positive airway pressure (CPAP) immediately after birth. Respiratory function, heart rate, and oxygen saturation were continuously recorded during spontaneous breathing.

RESULTS: Fifty-five infants (mean [SD] gestational age 31 [26-36] weeks and birth weight 1647 [500] g) received mask CPAP in the delivery room. CPAP was started at a median (IQR) 90 (60-118) seconds after birth and was delivered for 720 (300-900) seconds. Median VT ranged between 4.2 and 5.8 mL/kg with the individual VT varied between 0.9 and 19.8 mL/kg. Overall, VT increased over the first few minutes after birth and decreased thereafter. The increase in saturation after birth lagged behind the published normal ranges for spontaneously breathing preterm infants without CPAP.

CONCLUSIONS: The 50th percentile for spontaneous VT in preterm infants during mask CPAP ranged from 4.2 to 5.8 mL/kg, with wide individual variation observed in the first minutes after birth. Preterm infants requiring CPAP after birth may take longer to achieve so-called "normal" saturation targets.