Background: All newly born infants need to aerate their lung in order to generate functional residual capacity (FRC). The respiratory mechanisms of a successful transition of newborn infants after birth are largely unknown. Objective: Thus, our aim was to describe intrapulmonary gas flows over the first breaths of life immediately following delivery, thereby describing mechanisms pertaining to initial lung liquid absorption after birth. Design/Methods: Prospective observational study analysing electrical impedance tomography (EIT) recording from term born infants delivered by vaginal birth. Immediately after birth, an EIT belt was attached to the infant’s thorax and data were continuously collected from the first breath until ten minutes after birth. End-expiratory lung volume (EELV) and tidal volumes were assessed breath-by-breath over the first ten breaths and subsequently at each minute until ten minutes after birth using a custom-built Matlab code. Results: Overall, data from 46 infants were analysed. At least the second breath was recorded in 33 infants (72%). The first breaths of life were characterised by a large tidal volume (approximately twice the regular tidal volume) and contributed largely to the generation of functional residual capacity. More than 50% of the final FRC was generated with the first breath and FRC further increased strongly over the first five breaths, after which it plateaued. FRC was largely generated in the central regions over the first five breaths after birth.
Conclusion(s): Respiratory transition in term infants is facilitated by the first five breaths in most infants. These breaths are characterised by large tidal volumes, longer expiration times and an increase in end-expiratory lung volume. By describing intrapulmonary volume changes immediately after birth in healthy infants, we can decipher mechanisms by which newborn infants manage to transition from a fluid-filled to an air-filled lung.
.jpg "Vincent D. Gaertner, MD BSc (he/him/his) photo")
