Physiologic Effects of High-Flow Nasal Cannula in Healthy Subjects

BACKGROUND: High-flow nasal cannula (HFNC) is increasingly used in the management of acute and chronic respiratory failure. Little is known about the optimal settings for HFNC. This study was designed to assess the dose effect of HFNC on respiratory effort indexes and respiratory patterns in spontaneously breathing adults. METHODS: ], esophageal pressure-time product, and work of breathing). Secondary outcomes included breathing pattern parameters and blood gases. Dead-space ventilation and washout were calculated based on minute ventilation, breathing frequency, and Radford equations. RESULTS: < .001). Capillary [Formula: see text] was stable in all the tested conditions. The calculated dead-space ventilation was reduced by half with HFNC. CONCLUSIONS: HFNC did not significantly modify work of breathing in healthy subjects. However, a significant reduction in the minute volume was achieved, capillary [Formula: see text] remaining constant, which suggests a reduction in dead-space ventilation with flows > 20 L/min. (ClinicalTrials.gov registration NCT02495675).