High-flow nasal cannula therapy as apneic oxygenation during endotracheal intubation in critically ill patients in the intensive care unit: a systematic review and meta-analysis.

We conducted a systematic review and meta-analysis to assess the clinical efficacy of high-flow nasal cannula (HFNC) therapy as apneic oxygenation in critically ill patients who require endotracheal intubation in the intensive care unit (ICU). This systematic review and meta-analysis included six randomized controlled trials and a prospective study identified in PubMed, Embase, Cochrane Library, and the Web of Science until August 18, 2019. In this meta-analysis including 956 participants, HFNC was noninferior to standard of care during endotracheal intubation regarding incidence of severe hypoxemia, mean lowest oxygen saturation, and in-hospital mortality. HFNC significantly shortened the ICU stay by a mean of 1.8 days. In linear meta-regression interaction analysis, the risk ratio of severe hypoxemia decreased with increasing baseline partial oxygen pressure (PaO2 ) to fraction of inspired oxygen (FiO2 ) ratio. In subgroup analysis, HFNC significantly reduced the incidence of severe hypoxemia during endotracheal intubation in patients with mild hypoxemia (PaO2 /FiO2 > 200 mmHg; risk difference, -0.06; 95% confidence interval, -0.12 to -0.01; number needed to treat = 16.7). In conclusion, HFNC was noninferior to standard of care for oxygen delivery during endotracheal intubation and was associated with a significantly shorter ICU stay. The beneficial effect of HFNC in reducing the incidence of severe hypoxemia was observed in patients with mild hypoxemia.