RESUMO
OBJECTIVE: To compare breathing patterns and lung function in the supine, lateral, and prone positions in oxygen-dependent preterm infants. STUDY DESIGN: Respiratory function in preterm infants receiving nasal continous positive airway pressure therapy for mild respiratory failure was evaluated by respiratory inductive plethysmography. Infants were randomized to supine, left lateral, and prone positions for 3 hours. A nest provided a semiflexed posture for the infants placed in the left lateral position, similar to the in utero position. Tidal volume (Vt), phase angle between abdominal and thoracic movements, rib cage contribution to Vt, and dynamic elevation of end-expiratory lung volume were measured. RESULTS: Fraction of inspired O2 was similar in the 3 positions for 19 infants (mean gestational age, 27±2 weeks; mean birth weight, 950±150 g; mean postnatal age, 17±5 days). However, arterial O2 saturation and Vt were higher in the left lateral and prone positions than in the supine position (P<.05). The phase angle between abdominal and thoracic movements was lower and rib cage contribution to Vt was higher in the left lateral and prone positions than in the supine position (P<.05). Dynamic elevation of end-expiratory lung volume was greater in the supine position than in the left lateral and prone positions (P<.05). CONCLUSION: In oxygen-dependent preterm infants, both the left lateral and prone positions improve lung function by optimizing breathing strategy. In the neonatal intensive care unit, the left lateral position can be used as an alternative to the prone position for mild respiratory failure.
