Changes in respiratory mechanics at birth in preterm infants: A pilot study.

Objective: We aimed to measure lung mechanics at birth by the forced oscillation technique (FOT) for assessment of the initial degree of lung aeration and the short-term aeration changes after applying different respiratory support strategies.

Methods: Eighteen preterm infants (gestational age = 29-36 week) were randomized to receive either continuous positive airway pressure (CPAP) at 5 cmH O only or combined with a sustained inflation (SI; 15 seconds at 25 cmH O after 5 seconds of CPAP) at birth. We assessed the respiratory system reactance at 5 Hz (X increases with lung volume recruitment at a given distending pressure) at 2, 40, and 150 seconds after initiation of CPAP. k-Means clustering of the initial X value (X ) stratified newborn into either infants with lower (lowerX ; X  < -280 cmH O*s/L) and higher (higherX ; X  > -240 cmH O*s/L) initial degree of lung volume recruitment.

Results: Initial values were highly heterogeneous. In the LowerX group, X increased with time, with SI-patients showing significantly higher values at 150 seconds than the non-SI group (X  = -89 ± 27 cmH O vs -274 ± 58 cmH O). In the higherX group, X did not improve with time, regardless of the respiratory strategy, suggesting a lack of lung recruitment. Moreover, 75% of infants receiving SI in the higherX group experienced a transient loss of aeration after the maneuver.

Conclusions: Preterm newborns present initially with highly heterogeneous lung aeration at birth that significantly impacts the effectiveness of the subsequent lung volume recruitment strategy. FOT may represent a valuable tool for individualizing a respiratory resuscitation at birth as it is noninvasive and may be applied simultaneously to respiratory support.