Effect of body position on ventilation distribution in healthy newborn infants: an observational study.

Objectives: Newborn infants have unique respiratory physiology compared with older children and adults due to their lungs' structural and functional immaturity and highly compliant chest wall. To date, ventilation distribution has seldom been studied in this age group. This study aims to assess the effect of body position on ventilation distribution in spontaneously breathing healthy neonates.

Design: Prospective observational study.

Setting: Maternity wards of Oulu University Hospital.

Patients: 20 healthy, spontaneously breathing, newborn infants.

Interventions: Electrical impedance tomography data were recorded with a 32-electrode belt (Sentec AG, Landquart, Switzerland) in six different body positions in random order. Ventilation distribution was retrospectively assessed 10 minutes after each position change.

Main Outcome Measures: In each position, regional tidal impedance variation (ΔZ) and ventral-to-dorsal and right-to-left centre of ventilation were measured.

Results: The mean global ΔZ was the largest in supine position and it was smaller in prone and lateral positions. Yet, global ΔZ did not differ in supine positions, ventilation distribution was more directed towards the non-dependent lung region in supine tilted position (p<0.001). In prone, a reduction of global ΔZ was observed (p<0.05) corresponding to an amount of 10% of global tidal variation in supine position. In both lateral positions, tidal ventilation was distributed more to the corresponding non-dependent lung region.

Conclusions: Prone or lateral body positioning in healthy spontaneously breathing newborns leads to a redistribution of ventilation to the non-dependent lung regions and at the same time global tidal volume is reduced as compared with supine.