Effect of body position on ventilation distribution in preterm infants on continuous positive airway pressure

Rationale: Although continuous positive airway pressure is used extensively in neonatal intensive care units, and despite the belief that positioning is considered vital to the maintenance of good lung ventilation, no data exist on regional ventilation distribution in infants on continuous positive airway pressure ventilatory support. Objectives: To investigate the effect of body position on regional ventilation in preterm infants on continuous positive airway pressure ventilatory support using electrical impedance tomography. Design: Randomized crossover study design. Setting: Neonatal intensive care unit. Patients: Twenty-four preterm infants on continuous positive airway pressure were compared to six spontaneously breathing preterm infants. Interventions: Random assignment of the order of the positions supine, prone, and quarter prone. Measurements and Results: Changes in global and regional lung volume were measured with electrical impedance tomography. Although there were no differences between positions, regional tidal volume was increased in the posterior compared with the anterior lung (p < .01) and in the right compared with the left lung (p < .03) in both the spontaneously breathing infants and in the infants on continuous positive airway pressure. The posterior lung filled earlier than the anterior lung in the spontaneously breathing infants (p < .02), whereas in the infants on continuous positive airway pressure the right lung filled before the left lung (p < .01). There was more ventilation inhomogeneity in the infants on continuous positive airway pressure than in the healthy infants (p < .01). Conclusions: This study presents the first results on regional ventilation distribution in preterm infants on continuous positive airway pressure using electrical impedance tomography. Gravity had little impact on regional ventilation distribution in preterm infants on continuous positive airway pressure or in spontaneously breathing infants in the supine or prone position, indicating that ventilation distribution in preterm infants is not gravity-dependent but follows an anatomical pattern.