Changes in lung volume and ventilation following transition from invasive to noninvasive respiratory support and prone positioning in preterm infants

Abstract

Background:To minimize secondary lung injury, ventilated preterm infants are extubated as soon as possible. To maximize extubation success, they are often placed in prone position. The effect of extubation and subsequent prone positioning on lung volumes is currently unknown.Methods:Changes in end-expiratory lung volume (ΔEELV), tidal volume (V T), and ventilation distribution were monitored during transition from endotracheal to nasal continuous positive airway pressure and following prone positioning using electrical impedance tomography. In addition, the continuous distending pressure (CDP) and oxygen need (FiO 2) were recorded.Results:Twenty preterm infants (GA 28.7 ± 1.7 wk) were included. Following extubation, the CDP decreased from 7.9 ± 0.5 to 6.0 ± 0.2 cmH 2 O, while the FiO 2 remained stable. Both ΔEELV and V T increased significantly (P < 0.05) after extubation, without changing ventilation distribution. Prone positioning resulted in a further increase in ΔEELV (P < 0.01) and a decrease in respiratory rate. V T remained stable but its distribution clearly shifted toward the ventral lung regions.Conclusion:Infants who are transitioned from invasive to noninvasive respiratory support are able to maintain their EELV and increase their V T. Prone positioning increases EELV and shifts tidal ventilation to the ventral lung regions. The latter suggests that infants should preferably be placed in prone position after extubation.