High-Flow Nasal Cannula Oxygen in Adults: An Evidence-based Assessment.

High-flow nasal cannula oxygenation has distinct advantages over other oxygen devices because of its unique effects on respiratory physiology. In particular, adjustable oxygen delivery and flow-dependent carbon dioxide clearance reduce work of breathing and better match inspiratory demand during respiratory distress. Historically, few studies had evaluated whether the physiologic effects of these devices translated into clinical benefit. However, recent publications have begun to address this knowledge gap. High-flow nasal cannula oxygenation has been shown to have similar, and in some cases superior clinical efficacy compared with conventional low-flow oxygen supplementation and noninvasive positive pressure ventilation in acute hypoxemic respiratory failure. High-flow nasal cannula oxygenation also prevents reintubations in medical and postoperative surgical populations, provides preoxygenation for laryngoscopy, and supports oxygenation during bronchoscopy. This review examines the evidence for high-flow nasal cannula oxygenation use in adults, including a focus on the unique effects of high flow on respiratory physiology and keys for tailoring flow for specific clinical scenarios.