Regional Ventilation Distribution in Non-Sedated Spontaneously Breathing Newborns and Adults Is Not Different

Background: In adults, ventilation is preferentially distributed towards the dependent lung. A reversal of the adult pattern has been observed in infants using radionuclide ventilation scanning. But these results have been obtained in infants and children with lung disease. In this study we investigate whether healthy infants have a similar reverse pattern of ventilation distribution. Study Design: Measurement of regional ventilation distribution in healthy newborn infants during non-REM sleep in comparison to adults. Methods: Twenty-four healthy newborns and 13 adults were investigated with electrical impedance tomography (EIT) in supine and prone position. Regional ventilation distribution was assessed with profiles of relative impedance change. The phase lag between dependent and non-dependent ventilation was calculated as a measure of asynchronous ventilation. Results: In newborns and adults the geometric center of ventilation was centrally located in the lung at 52.2 +/- 6.2% from anterior to posterior and at 50.5 +/- 14.7%, respectively Using impedance profiles, ventilation was equally distributed to the dependent and non-dependent lung regions in newborns. Ventilation distribution in adults was similar Phase lag characteristics of the impedance signal showed that infants had slower emptying of the dependent lung than adults. Conclusion: The speculated reverse pattern of regional ventilation distribution in healthy infants compared to adults could not be demonstrated. Gravity had little effect on ventilation distribution in both infants and adults measured in supine and prone position. Pediatr Pulmonol. 2009;44:851-858. (C) 2009 Wiley-Liss, Inc.