Effect of posture on oxygenation, lung volume, and respiratory mechanics in premature infants studied before discharge

Objectives. To determine if the prone versus the supine posture was associated with higher oxygenation levels in prematurely born infants before discharge, whether any such effect was explained by alterations in lung volume or respiratory mechanics, and if the changes were greater in oxygen-dependent infants. Patients. Twenty infants (10 oxygen-dependent), median gestational age 30 (range: 27-32) weeks, were studied at a median postconceptional age of 35 weeks (range: 32-38 weeks). Methods. On 2 successive days, infants were studied both supine and prone; each posture was maintained for 3 hours. Oxygen saturation was continuously monitored and at the end of each 3-hour period; compliance and resistance of the respiratory system and functional residual capacity (FRC) were measured. Results. Overall, the median oxygen saturation and FRC were significantly higher in the prone position; compliance of the respiratory system and resistance of the respiratory system were not significantly affected by posture. Differences in oxygen saturation and FRC were significantly higher in the prone posture in the oxygen-dependent, but not the nonoxygen-dependent infants. Conclusions. Superior oxygenation in the prone posture in oxygen-dependent premature infants studied before discharge could be explained by higher lung volumes.