Sequential application of oxygen therapy via high-flow nasal cannula and noninvasive ventilation in acute respiratory failure: an observational pilot study.

BACKGROUND: The aim of this study was to evaluate the clinical efficacy of humidified oxygen via high-flow nasal cannula (HFNC) alternating with noninvasive ventilation (NIV) in acute hypoxemic respiratory failure (AHRF).

METHODS: We performed a prospective observational study in a 12-bed ICU of a university hospital. All subjects with a PaO2 /FIO2 of ≤300 mm Hg with standard mask oxygen and a breathing frequency of > 30 breaths/min or signs of respiratory distress were included and treated with HFNC first and then NIV. Ventilatory parameters, blood gases, and tolerance were recorded during 2 consecutive sessions of NIV and HFNC. Outcome was assessed after continuation of this noninvasive strategy.

RESULTS: Twenty-eight subjects with AHRF were studied, including 23 (82%) with ARDS. Compared with standard oxygen therapy, PaO2 significantly increased from 83 (68-97) mm Hg to 108 (83-140) mm Hg using HFNC and to 125 (97-200) mm Hg using NIV (P<.01), whereas breathing frequency significantly decreased. HFNC was significantly better tolerated than NIV, with a lower score on the visual analog scale. The non-intubated subjects received HFNC for 75 (27-127) h and NIV for 23 (8-31) h. Intubation was required in 10 of 28 subjects (36%), including 8 of 23 subjects with ARDS (35%). After HFNC initiation, a breathing frequency of ≥30 breaths/min was an early factor associated with intubation.

CONCLUSIONS: HFNC was better tolerated than NIV and allowed for significant improvement in oxygenation and tachypnea compared with standard oxygen therapy in subjects with AHRF, a large majority of whom had ARDS. Thus, HFNC may be used between NIV sessions to avoid marked impairment of oxygenation.