Original Research ARTICLE
Increasing respiratory effort with 100% oxygen during resuscitation of preterm rabbits at birth
- 1The Ritchie Centre, Hudson Institute of Medical Research, Australia
- 2Department of Pediatrics, Leiden University Medical Centre, Netherlands
- 3Department of Obstetrics and Gynaecology, Monash University, Australia
- 4School of Physics and Astronomy, Monash University, Australia
- 5Department of Obstetrics and Gynaecology, Erasmus Medical Center, Erasmus University Rotterdam, Netherlands
- 6Women's Newborn Research Centre, The Royal Women's Hospital, Australia
- 7Murdoch Childrens Research Institute (MCRI), Australia
- 8Department of Obstetrics and Gynaecology, Melbourne Medical School, University of Melbourne, Australia
- 9John Radcliffe Hospital, United Kingdom
- 10Department of Paediatrics, Medical Sciences Division, University of Oxford, United Kingdom
- 11Leiden University Medical Center, Netherlands
- 12Department of Neonatology, Dr. von Hauner Children’s Hospital, Germany
Background: Spontaneous breathing is essential for successful non-invasive respiratory support delivered by a facemask at birth. As hypoxia is a potent inhibitor of spontaneous breathing, initiating respiratory support with a high fraction of inspired O2 may reduce the risk of hypoxia and increase respiratory effort at birth.
Methods: Preterm rabbit kittens (29 days gestation, term ~32 days) were delivered and randomised to receive continuous positive airway pressure with either 21% (n=12) or 100% O2 (n=8) via a facemask. If apnea occurred, intermittent positive pressure ventilation (iPPV) was applied with either 21% or 100% O2 in kittens who started in 21% O2, and remained at 100% O2 for kittens who started the experiment in 100% O2. Respiratory rate (breaths per minute, bpm) and breath-to-breath variability (%) were measured from oesophageal pressure recordings and functional residual capacity (FRC) was measured from synchrotron phase-contrast X-ray images.
Results: Initially, kittens receiving 21% O2 had a significantly lower respiratory rate and higher breath-to-breath variability, indicating a less stable breathing pattern than kittens starting in 100% O2 (median (IQR) respiratory rate: 16 (4–28) vs 38 (29–46) bpm, p=0.001; breath-to-breath variability: 33.3% (17.2–50.1%) vs 27.5% (18.6–36.3%), p=0.009). Apnea that required iPPV, was more frequently observed in kittens in whom resuscitation was started with 21% compared to 100% O2 (11/12 vs 1/8, p=0.001). After recovering from apnea, respiratory rate was significantly lower and breath-to-breath variability was significantly higher in kittens who received iPPV with 21% compared to 100% O2. FRC was not different between study groups at both timepoints.
Conclusion: Initiating resuscitation with 100% O2 resulted in increased respiratory activity and stability, thereby reducing the risk of apnea and need for iPPV after birth. Further studies in human preterm infants are mandatory to confirm the benefit of this approach in terms of oxygenation. In addition, the ability to avoid hyperoxia after initiation of resuscitation with 100% oxygen, using a titration protocol based on oxygen saturation, needs to be clarified.
Keywords: preterm, Respiratory effort, Oxygen, Resuscitation, Birth
Received: 29 Aug 2019;
Accepted: 07 Oct 2019.
Copyright: © 2019 Dekker, Hooper, Croughan, Crossley, Wallace, McGillick, DeKoninck, Thio-Lluch, Martherus, Ruben, Roehr, Cramer, Flemmer, Croton, Te Pas and Kitchen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Mrs. Janneke Dekker, The Ritchie Centre, Hudson Institute of Medical Research, Clayton, 3168, Victoria, Australia, email@example.com