1. In this study, high flow nasal cannula (HFNC) was found to be non-inferior to bilevel positive airway pressure (BiPAP) in reducing reintubation rates after cardiothoracic surgery.
2. In this study, BiPAP had a higher rate of discontinuation per patient request than HFNC.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Acute respiratory failure is a common complication of cardiothoracic surgery. This trial sought to determine whether high-flow nasal cannula (HFNC) is just as effective as non-invasive ventilation (NIV) in preventing reintubation in post-operative patients. Results showed that HFNC was not inferior to BiPAP in reintubation rates. Oxygenation was shown to improve more with BiPAP than HFNC but arterial carbon dioxide (PaCO2) was shown to decrease faster with HFNC. BiPAP did have higher rate of discontinuation of use and of skin breakdown. There was no change in mortality rates or intensive care unit hospital days between the two modes of oxygen delivery.
Strengths of the study included the large number of participants in the trial and its construction as a non-inferiority trial. This allowed the authors to prove that HFNC was no worse than NIV without having to prove its superiority. However, the major limitation of the study was the high confidence interval margins in the study for detection of non-inferiority. Consequently, it becomes difficult to assess whether the HFNC was truly non-inferior, as it could also be inferior and superior based on the wide confidence interval margins.
In-Depth [randomized controlled trial]: This study was a multicenter, randomized, non-inferiority trial that recruited 830 patients across 6 centers in France who had undergone cardiothoracic surgery and met one of the following criteria: 1) failed a spontaneous breathing trial (SBT), 2) had a successful SBT but had preexisting risk factors for post-extubation acute respiratory failure (e.g., BMI>30, LVEF<40%, prior failure to extubate), or 3) had a successful SBT followed by a failed extubation. Patients were randomized either to receive HFNC with initial FiO2 of 50% or BiPAP at an inspiratory positive airway pressure of 8 and expiratory positive airway pressure of 4, and FiO2 of 50%, with the settings of both titrated to achieve a SaO2 of 92% or higher. HFNC was discontinued if the PaO2:FiO2 ratio was ≥300 and BiPAP was discontinued when patient required it less than 4 hours a day. Reintubation, early treatment discontinuation, or changing of treatment was defined as a failure. Results showed that HFNC was not inferior to BiPAP, with a 21.9% failure rate in the HFNC group and a 21.0% failure rate in the BiPAP group (absolute difference 0.9%; 95%CI -4.9% to 6.6%; p = 0.003 for non-inferiority). Premature discontinuation of therapy was higher in the BiPAP group (with 3.6% rate for BiPAP vs. 1.6% rate for HFNC; p = 0.04). There was no difference in failure rates between the two modes of oxygen delivery in severely hypoxic patients.
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