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Lookup NU author(s): Dr Zheyi Liew, Dr Alan Fenton, Dr Sundeep Harigopal, Dr Saikiran Gopalakaje, Dr Malcolm Brodlie
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY. Published by BMJ.Objective: High-flow nasal cannula (HFNC) therapy is increasingly used in preterm infants despite a paucity of physiological studies. We aimed to investigate the effects of HFNC on respiratory physiology. Study design: A prospective randomised crossover study was performed enrolling clinically stable preterm infants receiving either HFNC or nasal continuous positive airway pressure (nCPAP). Infants in three current weight groups were studied: <1000 g, 1000-1500 g and >1500 g. Infants were randomised to either first receive HFNC flows 8-2 L/min and then nCPAP 6 cm H2O or nCPAP first and then HFNC flows 8-2 L/min. Nasopharyngeal end-expiratory airway pressure (pEEP), tidal volume, dead space washout by nasopharyngeal end-expiratory CO2 (pEECO2), oxygen saturation and vital signs were measured. Results: A total of 44 preterm infants, birth weights 500-1900 g, were studied. Increasing flows from 2 to 8 L/min significantly increased pEEP (mean 2.3-6.1 cm H2O) and reduced pEECO2 (mean 2.3%-0.9%). Tidal volume and transcutaneous CO2 were unchanged. Significant differences were seen between pEEP generated in open and closed mouth states across all HFNC flows (difference 0.6-2.3 cm H2O). Infants weighing <1000 g received higher pEEP at the same HFNC flow than infants weighing >1000 g. Variability of pEEP generated at HFNC flows of 6-8 L/min was greater than nCPAP (2.4-13.5 vs 3.5-9.9 cm H2O). Conclusions: HFNC therapy produces clinically significant pEEP with large variability at higher flow rates. Highest pressures were observed in infants weighing <1000 g. Flow, weight and mouth position are all important determinants of pressures generated. Reductions in pEECO2 support HFNC's role in dead space washout.
Author(s): Liew Z, Fenton AC, Harigopal S, Gopalakaje S, Brodlie M, O'Brien CJ
Publication type: Article
Publication status: Published
Journal: Archives of Disease in Childhood: Fetal and Neonatal Edition
Year: 2019
Volume: 105
Issue: 1
Pages: 87-93
Print publication date: 16/12/2019
Online publication date: 23/05/2019
Acceptance date: 03/05/2019
Date deposited: 06/06/2019
ISSN (print): 1359-2998
ISSN (electronic): 1468-2052
Publisher: BMJ Publishing Group
URL: https://doi.org/10.1136/archdischild-2018-316773
DOI: 10.1136/archdischild-2018-316773
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