The first breaths after birth-early lung function in healthy term infants

It remains unclear how the lung is aerated after birth in human infants.

We aimed to describe volume changes over the first breaths of life.

Prospective observational study in healthy infants after vaginal delivery.Electrical impedance tomography data were collected continuously after birth.

End-expiratory lung volume (EELV), tidal volume (VT) and markers for regional ventilation distribution including center of ventilation (CoV), silent spaces, functional lung size (FLS), and coefficient of variation (CV) for each of the first 10 breaths and at each full minute until 10 min after birth.Ten thousand five hundred forty-six breaths from 46 infants were analyzed. During the initial 5 breaths of life, EELV increased rapidly, and VT were approximately 3-fold higher than post-transitional VT (linear mixed model, both P <.001). During the initial 2 breaths, there were unique regional inhomogeneities with preferential ventilation occurring sequentially in the right and left lung (CoVRL first vs second breath: 29.2 ± 12.3 vs 53.5 ± 9.5, post hoc test, Padj = .003), before resolving quickly to a more even distribution of lung volume (decrease in CV, LMM: P <.001). Finally, the lung periphery is less ventilated during the initial 10 breaths, which improves over the subsequent 10 min (increase in FLS, LMM: P <.001).

This study visualizes and characterizes the first breaths of life, describing lung physiology during this crucial -moment. Functional residual capacity is largely established within the first 5 breaths. The first breaths are characterized by large VT and show highly interesting regional inhomogeneities, likely reflecting complex anatomical and positional factors.