Positional effects on lung mechanics of ventilated preterm infants with acute and chronic lung disease

Background: The role of prone position in preterm infants has not been completely clarified. We investigated prone versus supine posture-related changes in respiratory system resistance (Rrs) and reactance (Xrs) measured by the Forced Oscillation Technique (FOT) in mechanically ventilated preterm newborns. Methods: Patients were studied in the supine versus prone positions in random order. Oxygen saturation, transcutaneous partial pressure of oxygen (ptcO2), carbon dioxide (ptcCO2), Rrs and Xrs were measured in each position. Results: Nine patients with respiratory distress syndrome (RDS) and nine with evolving broncho-pulmonary dysplasia (BPD) were studied. Rrs was, on average, 9.8 (1.3, 18.3 as 95%CI) cmH2O*s/l lower in the prone compared to the supine position (P=0.02), while no differences in Xrs, ptcO2, ptcCO2, and breathing pattern were observed between postures. Only patients with evolving BPD showed a significant reduction of Rrs from 69.0±27.4 to 53.0±16.7 cmH2O*s/l, P=0.01. No significant correlations were found between changes in lung mechanics and ptcO2, ptcCO2, or breathing pattern. Conclusions: On short-term basis, prone positioning does not offer significant advantages in lung mechanics in mechanically ventilated infants with RDS, while it is associated with lower Rrs values in patients with evolving BPD.