Physiological effects of standard oxygen therapy, high-flow nasal cannula, and helmet CPAP in acute bronchiolitis: a randomized cross-over study

Objectives Acute viral bronchiolitis (AVB) is a major cause of hospitalization for children in developed and developing countries. Nasal high flow (NHF) therapy improves oxygenation and reduces respiratory drive by enhancing carbon dioxide wash-out. However, little is known about the physiological effects of non-invasive helmet continuous positive airway pressure (h-CPAP) and NHF on respiratory work of breathing (WOB) in pediatric patients with AVB. The present study measured esophageal pressure time product over 1 min (PTPes*min −1 ), as a close surrogate for WOB during standard oxygen therapy (SOT), NHF delivered at incremental flow rates, and h-CPAP in hospitalized patients with AVB. Methods This is a physiological randomized crossover study with four 20-min steps: SOT delivered by a Venturi mask; NHF2 set at 2L/kg*min −1 PBW; NHF3 set at 3L/kg*min −1 PBW; and h-CPAP with PEEP 7 cmH 2 O. PTPes *min −1 , pressure rate product (PRP), respiratory and other physiological parameters were collected towards the end of each step. Results Ten hypoxemic children with AVB were enrolled. PTPes*min −1 , respiratory rate (RR), PRP, and heart rate (HR) decreased progressively from h-CPAP to NHF3, NHF2, and SOT ( p < 0.01). Transcutaneous carbon dioxide tension (tcCO 2 ) was lower during h-CPAP, NHF3, and NHF2 than during SOT ( p < 0.001). SpO 2 :FiO 2 was higher during h-CPAP than with all other support ( p < 0.01). Conclusions In pediatric patients with AVB, h-CPAP was associated with lower WOB, better oxygenation, and lower tcCO 2 than with SOT and NHF trials. Trial registration Clinicaltrials.gov NCT0368968 6 Registered 1 August 2018.