Elsevier

The Journal of Pediatrics

Volume 167, Issue 2, August 2015, Pages 274-278.e1
The Journal of Pediatrics

Original Article
Spontaneously Breathing Preterm Infants Change in Tidal Volume to Improve Lung Aeration Immediately after Birth

https://doi.org/10.1016/j.jpeds.2015.04.047Get rights and content

Objective

To examine the temporal course of lung aeration at birth in preterm infants <33 weeks gestation.

Study design

The research team attended deliveries of preterm infants <33 weeks gestation at the Royal Alexandra Hospital. Infants who received only continuous positive airway pressure were eligible for inclusion. A combined carbon dioxide (CO2) and flow-sensor was placed between the mask and the ventilation device. To analyze lung aeration patterns during spontaneous breathing, tidal volume (VT), and exhaled CO2 (ECO2) were recorded for the first 100 breaths.

Results

Thirty preterm infants were included with a total of 1512 breaths with mask leak <30%. Mean (SD) gestational age and birth weight was 30 (1) weeks and 1478 (430) g. Initial VT and ECO2 for the first 30 breaths was 5-6 mL/kg and 15-22 mm Hg, respectively. VT and ECO2 increased over the next 20 breaths to 7-8 mL/kg and 25-32 mm Hg, respectively. For the remaining observation period VT decreased to 4-6 mL/kg and ECO2 continued to increase to 35-37 mm Hg.

Conclusions

Preterm infants begin taking deeper breaths approximately 30 breaths after initiating spontaneous breathing to inflate their lungs. Concurrent CO2 removal rises as alveoli are recruited. Lung aeration occurs in 2 phases: initially, large volume breaths with poor alveolar aeration followed by smaller breaths with elimination of CO2 as a consequence of adequate aeration.

Section snippets

Methods

This study was carried out at The Royal Alexandra Hospital, Edmonton, Canada, a tertiary perinatal center admitting ∼350 infants with a birth weight of <1500 g annually to the neonatal nursery. The Royal Alexandra Hospital Research Committee and Health Ethics Research Board, University of Alberta, and the Health Ethics Research Board approved the study and granted deferred consent. After admission to the neonatal intensive care unit, parental consent was requested. Between June 2013 and July

Results

The clinical team attended a total of 436 deliveries, and the research team attended 297 deliveries. Twenty-five infants were excluded because parents did not consent to use the recorded data. A total of 242 infants were excluded because 47 did not require any respiratory support, 12 received only free-flow oxygen, and 183 received PPV at any given time leaving 30 infants eligible for this study (Table). A total of 3200 breaths were analyzed (1688 [53%] were excluded with mask leak >30%),

Discussion

In utero, the airways are liquid-filled and the lungs do not take part in gas exchange, which occurs across the placenta. At birth, lung liquid has to be cleared from the airways to allow air entry to generate FRC and facilitate gas exchange.6 To achieve lung aeration term and preterm infants use various breathing patterns within the first minutes after birth,15, 16 and the majority of preterm infants cry and breathe spontaneously after birth.1 For this study, we analyzed the first 100 breaths

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    Q.M. was supported in part by an Alberta Innovates, Health Solutions Summer Studentship. M.O’R. is supported by a Molly Towell Perinatal Research Foundation Fellowship. G.S. is a recipient of the Heart and Stroke Foundation/University of Alberta Professorship of Neonatal Resuscitation and a Heart and Stroke Foundation of Canada Research Scholarship. The authors declare no conflicts of interest.

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