Apnoeic oxygenation via high-flow nasal cannula oxygen combined with non-invasive ventilation preoxygenation for intubation in hypoxaemic patients in the intensive care unit: the single-centre, blinded, randomised controlled OPTINIV trial

High-flow nasal cannula oxygen (HFNC) has the potential to provide apnoeic oxygenation. We decided to assess in a proof-of-concept study whether the addition of HFNC to non-invasive ventilation (NIV) could reduce oxygen desaturation during intubation, compared with NIV alone for preoxygenation, in severely hypoxaemic intensive care unit (ICU) patients with respiratory failure. We conducted a randomised, controlled, single-centre trial with assessor-blinded outcome assessment in patients admitted to the ICU. Hypoxaemic patients requiring orotracheal intubation for respiratory failure were randomised to receive preoxygenation using HFNC [flow = 60 L/min, fraction of inspired oxygen (FiO(2)) = 100 %] combined with NIV (pressure support = 10 cmH(2)O, positive end-expiratory pressure = 5 cmH(2)O, FiO(2) = 100 %) in the intervention group or NIV alone in the reference group prior to intubation. The primary outcome was the lowest oxygen saturation (SpO(2)) during the intubation procedure. Secondary outcomes were intubation-related complications and ICU mortality. Between July 2015 and February 2016, we randomly assigned 25 and 24 patients to the intervention and reference groups, respectively. In both groups the main reasons for respiratory failure were pneumonia and ARDS. During the intubation procedure, the lowest SpO(2) values were significantly higher in the intervention group than in the reference group [100 (95-100) % vs. 96 (92-99) %, p = 0.029]. After exclusion of two patients from analysis for protocol violation, no (0 %) patients in the intervention group and five (21 %) patients in the reference group had SpO(2) below 80 % (p = 0.050). We recorded no significant difference between the groups in intubation-related complications or ICU mortality. A novel strategy for preoxygenation in hypoxaemic patients, adding HFNC for apnoeic oxygenation to NIV prior to orotracheal intubation, may be more effective in reducing the severity of oxygen desaturation than the reference method using NIV alone.