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Original research
Lung volume changes during apnoeas in preterm infants
  1. Vincent D Gaertner1,
  2. Andreas D Waldmann2,
  3. Peter G Davis3,4,5,
  4. Dirk Bassler1,
  5. Laila Springer6,
  6. David Gerald Tingay4,5,7,
  7. Christoph Martin Rüegger1
  1. 1 Newborn Research, Department of Neonatology, University Hospital and University of Zurich, Zurich, Switzerland
  2. 2 Department of Anesthesiology and Intensive Care Medicine, Rostock University Medical Center, Rostock, Germany
  3. 3 Newborn Research Centre and Neonatal Services, The Royal Women's Hospital, Melbourne, Victoria, Australia
  4. 4 The University of Melbourne, Melbourne, Victoria, Australia
  5. 5 Murdoch Children's Research Institute, Melbourne, Victoria, Australia
  6. 6 Department of Neonatology, University Children’s Hospital, Tübingen, Germany
  7. 7 Department of Neonatology, The Royal Children's Hospital, Parkville, Victoria, Australia
  1. Correspondence to Dr Vincent D Gaertner, Department of Neonatology, University Hospital Zurich, Zurich, Switzerland; vincent.gaertner{at}usz.ch

Abstract

Objective Mechanisms of non-invasive high-frequency oscillatory ventilation (nHFOV) in preterm infants are unclear. We aimed to compare lung volume changes during apnoeas in preterm infants on nHFOV and nasal continuous positive airway pressure (nCPAP).

Methods Analysis of electrical impedance tomography (EIT) data from a randomised crossover trial comparing nHFOV with nCPAP in preterm infants at 26–34 weeks postmenstrual age. EIT data were screened by two reviewers to identify apnoeas ≥10 s. End-expiratory lung impedance (EELI) and tidal volumes (VT) were calculated before and after apnoeas. Oxygen saturation (SpO2) and heart rate (HR) were extracted for 60 s after apnoeas.

Results In 30 preterm infants, 213 apnoeas were identified. During apnoeas, oscillatory volumes were detectable during nHFOV. EELI decreased significantly during apnoeas (∆EELI nCPAP: −8.0 (−11.9 to −4.1) AU/kg, p<0.001; ∆EELI nHFOV: −3.4 (−6.5 to −0.3), p=0.03) but recovered over the first five breaths after apnoeas. Compared with before apnoeas, VT was increased for the first breath after apnoeas during nCPAP (∆VT: 7.5 (3.1 to 11.2) AU/kg, p=0.001). Falls in SpO2 and HR after apnoeas were greater during nCPAP than nHFOV (mean difference (95% CI): SpO2: 3.6% (2.7 to 4.6), p<0.001; HR: 15.9 bpm (13.4 to 18.5), p<0.001).

Conclusion Apnoeas were characterised by a significant decrease in EELI which was regained over the first breaths after apnoeas, partly mediated by a larger VT. Apnoeas were followed by a considerable drop in SpO2 and HR, particularly during nCPAP, leading to longer episodes of hypoxemia during nCPAP. Transmitted oscillations during nHFOV may explain these benefits.

Trial registration number ACTRN12616001516471.

  • intensive care units, neonatal
  • neonatology
  • respiratory medicine

Data availability statement

Data are available on reasonable request. De-identified individual participant data and statistical analysis codes are available from 3 months to 2 years following article publication to researchers who provide a methodologically sound proposal, with approval by an independent review committee (‘learned intermediary’). Proposals should be directed to christoph.rueegger@usz.ch to gain access. Data requestors will need to sign a data access or material transfer agreement approved by USZ.

https://doi.org/10.1136/archdischild-2022-324282

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    Data availability statement

    Data are available on reasonable request. De-identified individual participant data and statistical analysis codes are available from 3 months to 2 years following article publication to researchers who provide a methodologically sound proposal, with approval by an independent review committee (‘learned intermediary’). Proposals should be directed to christoph.rueegger@usz.ch to gain access. Data requestors will need to sign a data access or material transfer agreement approved by USZ.

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    Footnotes

    • Contributors VDG and CMR conceptualised and designed this post hoc analysis. VDG analysed the data and wrote the first draft of the manuscript. VDG acts as guarantor of the article. ADW developed the electrical impedance tomography (EIT) analysis software and performed EIT data extraction. VDG and CMR reviewed all apnoea sequences. PGD, DB, LS, DGT and CMR developed the concept and design of the initial study. LS and CMR were involved in patient recruitment and conducted the EIT measurements. CMR supervised the project. All authors participated in data interpretation and revised the manuscript for important intellectual content.

    • Funding VDG received an Endeavour Research Fellowship by the Australian Government (ERF_RDDH_5276_2016), PGD is supported by the Victorian Government Operational Infrastructure Support Programme (Melbourne, Australia) and the National Health and Medical Research Council (Practitioner Fellowship GNT 1059111), LS received a grant from the German Research Society (LO 2162/1-1), DGT received Career Development Fellowships by the NHMRC (GNT 11123859 and 1057514), and CMR was supported by the Swiss National Science Foundation (Early Postdoctoral Mobility fellowship P2ZHP3_161749) and the Swiss Society of Neonatology (Milupa Fellowship Award).

    • Competing interests VDG and CMR declare that they received an EIT monitor free of charge for a different research project by SenTec AG. All other authors declare that they have no conflict of interest.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.