Effect of High-Flow Nasal Cannula on Thoraco-Abdominal Synchrony in Pediatric Subjects After Cardiac Surgery

Abstract

BACKGROUND: We previously reported the effects of high-flow nasal cannula (HFNC) oxygen therapy on thoraco-abdominal synchrony. This study was designed to clarify the effect of HFNC on thoraco-abdominal synchrony in pediatric subjects after cardiac surgery and to investigate HFNC optimal flow in this population. METHODS: Thoraco-abdominal synchrony was evaluated with respiratory inductive plethysmography. After extubation, we delivered oxygen via face mask for 30 min to subjects with mild to moderate respiratory failure. Each subject then randomly received either 1 or 2 L/kg/min via HFNC for 30 min, followed by the other flow level via HFNC for 30 min. After HFNC, face mask delivery was resumed. Rib cage and abdominal movement were converted into volumes and 2 quantitative indexes: maximum compartmental amplitude/tidal volume (VT) ratio and phase angle. RESULTS: Ten subjects of median (interquartile range) age 7 (6–14) months and weighing 6.5 (5.3–8.8) kg were enrolled. Compared with the first delivery via face mask, breathing frequency, maximum compartmental amplitude/VT, phase angle, and minute volume significantly decreased at 2 L/kg/min (P < .05 for all) but not at 1 L/kg/min. PaCO2 did not differ among oxygen therapies. None of the measured variables differed between first and second face mask periods. CONCLUSIONS: After cardiac surgery, HFNC oxygen therapy at 2 L/kg/min improved thoraco-abdominal synchrony and decreased breathing frequency in pediatric subjects. (Clinical trial registration: UMIN000023426.)