Delivering Care From an Unstable Evidence Base: The Evolving Care of Coronavirus Disease 2019 Through the Lens of High-Flow Nasal Oxygen.

1704 www.ccmjournal. org November 2020 • Volume 48 • Number 11 On March 6, 2020, the first patient diagnosed with coronavirus disease 2019 (COVID-19) at our institution was admitted to the Emory Serious Communicable Disease Unit (SCDU), which was initially established for the care of patients with Ebola and other special pathogens. The demand for ICU beds quickly outstripped the SCDU capacity: within days, we converted ordinary ICUs to receive the influx of COVID patients. Our teams struggled with fear, anxiety, and uncertainty about our safety and that of our families. We struggled much more wondering about the best care for our patients. Our institutional guidelines initially recommended against the use of both noninvasive positive pressure ventilation (NIPPV) and high-flow nasal oxygen, also referred to as heated high-flow nasal cannula and high-flow nasal cannula. This recommendation emerged from a desire to avoid unnecessary staff exposure to aerosolized viral particles. Global guidance in March 2020 similarly cautioned against high-flow nasal oxygen, out of concern for limited efficacy and high failure rates (1). During those early weeks, patients under our care who remained hypoxemic or tachypneic despite a 100% nonrebreather mask were promptly intubated. As believers in the robust data supporting the use of high-flow nasal oxygen who have been using it as part of our armamentarium to care for patients in the last several years (2, 3), we could not dismiss our nagging doubt that we may have been doing a disservice to our patients by withholding this modality. Upon further review of evidence demonstrating minimal additional air dispersion as compared with traditional face masks (4), our institutional guidelines were relaxed on March 25, 2020, to allow for the use of high-flow nasal oxygen. It was at this time that we initially were assigned to review the article by Xia et al (5), published in this issue of Critical Care Medicine. They reported their experience caring for 43 patients with COVID-19 who were treated with high-flow nasal oxygen at three tertiary-care hospitals in Wuhan, China, in the earliest days of the outbreak. Just under half of the patients in their cohort failed high-flow nasal oxygen, requiring escalation to either noninvasive or invasive mechanical ventilation. Patients who failed were older, more commonly male, and had a lower oxygen saturation (Spo 2 ) at admission. They were also more likely to have an increase in their respiratory rate (RR) and a decrease in their ratio of Spo 2 /Fio 2 to RR (ROX) index after initiation of high-flow nasal oxygen. As has been reported in other settings (6), patients with failure of high-flow nasal oxygen had a high mortality rate (65%), whereas no patients died among those who did not require escalation of their respiratory support. Although this was not a randomized trial of high-flow nasal oxygen use, it offers some reassurance to providers that there is a role for this modality in the treatment of COVID-19 and identifies clinical risk factors for treatment failure. The early experience of Xia et al (5) from Wuhan felt like a lifeline in March when the manuscript first reached our hands. Several months later, many of us have cared for our own patients with COVID-19 and these early data no longer feel novel. Yet, it is important that they are published and read. In reviewing and publishing this report, the editors have faced the “challenge of discerning signal amidst noise,” steadily walking the fine line between expediting critical reporting and ensuring a thorough and comprehensive review process (7). Surprisingly, there are few data to guide our use of highflow nasal oxygen in COVID-19. As of July 9, 2020, a search of the terms “high-flow nasal oxygen” and “high-flow nasal cannula” on LitCovid, a curated hub of articles related to COVID-19 in PubMed, revealed 37 articles written in English, out of more than 30,603 total articles. Thirteen of those articles were reviews or guidelines, three reported on the use of high-flow nasal oxygen in periprocedural settings, 10 were observational studies that reported the use of high-flow nasal oxygen in their cohorts but did not explicitly focus on the modality, eight were small case series of fewer than 10 patients—leaving just three articles reporting on patient *See also p. e1079.