Regional ventilation distribution in the first 6 months of life.

Electrical impedance tomography (EIT) has been used to study regional ventilation distribution in neonatal and paediatric lung disease; however, little information has been obtained in healthy newborns and infants. Data on regional ventilation distribution and regional filling characteristics were obtained using EIT in the neonatal period, at 3 and 6 months of age, in spontaneously breathing infants during non-rapid eye movement sleep. Regional ventilation distribution was described using regional end-expiratory and end-inspiratory impedance amplitudes, and geometric centre of ventilation. Regional filling characteristics were described with the phase lag or lead of the regional impedance change in comparison to global impedance change. 32 infants were measured in the supine position. Regional impedance amplitudes increased with age but regional ventilation distribution remained unchanged in all infants at any age, with the dependent (posterior) lung always better ventilated. Regional filling characteristics showed that the dependent lung filled during inspiration before the nondependent lung during all follow-up measurements. Regional ventilation distribution and regional filling characteristics remained unchanged over the first 6 months of life, and the results obtained on regional ventilation distribution are very similar to those in adult subjects.