Physiological effects of high-flow nasal cannula therapy in preterm infants.
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ABSTRACT: 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.
SUBMITTER: Liew Z
PROVIDER: S-EPMC6951230 | biostudies-literature | 2020 Jan
REPOSITORIES: biostudies-literature
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