Forced oscillation measurements in the first week of life and pulmonary outcome in very preterm infants on noninvasive respiratory support

BACKGROUND: We aimed at investigating whether early lung mechanics in non-intubated infants below 32 weeks of gestational age (GA) are associated with respiratory outcome. METHODS: Lung mechanics were assessed by the forced oscillation technique using a mechanical ventilator (Fabian HFOi, ACUTRONIC Medical Systems AG, Hirzel, Switzerland) that superimposed small-amplitude oscillations (10 Hz) on a continuous positive airway pressure. Measurements were performed during regular tidal breathing using a face mask on days 2, 4, and 7 of life. Respiratory system resistance (Rrs) and reactance (Xrs) were computed from flow and pressure. RESULTS: One hundred and seventy-seven measurements were successfully performed in 68 infants. Infants had a mean (range) GA of 29.3 (24.1-31.7) weeks and a birth weight of 1257 (670-2350)g. Xrs was associated with the duration of respiratory support (R-2 = 0.39, p < 0.001). A multilevel regression model, including Xrs and GA, explained the duration of respiratory support better than GA alone (R-2 = 0.51 vs. 0.45, p = 0.005, likelihood ratio test). CONCLUSION: Assessment of Xrs in the first week of life is feasible and improves prognostication of respiratory outcome in very preterm infants on noninvasive respiratory support.