By Betty Tran, MD, MSc
Associate Professor of Medicine, Division of Pulmonary and Critical Care Medicine, Northwestern University Feinberg School of Medicine, Chicago
SYNOPSIS: This study of hospitalized adults with COVID-19-related hypoxemic respiratory failure found that initiation of high-flow nasal oxygen on the wards was safe, resulted in comparable intubation and mortality rates, and led to less time in the intensive care unit.
SOURCE: Janssen ML, Türk Y, Baart SJ, et al. Safety and outcome of high-flow nasal oxygen therapy outside ICU setting in hypoxemic patients with COVID-19. Crit Care Med 2024;52:31-43.
This was a pragmatic, prospective, observational cohort study that aimed to evaluate the safety and outcomes associated with high-flow nasal oxygen (HFNO) initiated outside the intensive care unit (ICU) (ward starters) compared to in the ICU (ICU starters) in patients with acute hypoxemic respiratory failure (AHRF) due to COVID-19. Adult patients were recruited from 10 hospitals in the Netherlands between Dec. 1, 2020, and July 1, 2021. Ultimately, 608 patients were included, of whom 379 (62.3%) were ward starters and 229 (37.7%) were ICU starters of HFNO. Overall, 186 out of the 379 ward starters (49%) were transferred to the ICU after admission.
In a propensity-matched cohort comparing ward vs. ICU starters to account for more severe hypoxemia and higher mortality scores in the ICU-starter group (n = 107 in each group), intubation rates were comparable (53.3% vs. 59.8%, respectively; P = 0.42) as well as time between HFNO initiation and intubation, mortality rates, hospital-free days, and ventilator-free days. The number of ICU-free days was higher for ward starters compared to ICU starters at day 28 (median difference, four days; P < 0.001) and day 60 (P = 0.02).
In comparing intubated ward starters vs. ICU starters, both groups had similar severity of hypoxemia before intubation based on partial pressure of oxygen (PaO2)/fractional inspiration of oxygen (FiO2), rates of prone positioning, intubation events (e.g., hypotension), mortality rates, hospital-free days, and ventilator-free days. However, the number of ICU-free days at day 28 was significantly higher for HFNO ward starters compared to ICU starters (median 10 vs. six days, respectively, interquartile range [IQR], 1-19 days; P = 0.04).
Using multivariate logistic regression analysis, clinical predictors for ICU admission were explored among ward starters. Higher respiratory rate (odds ratio [OR], 1.09) and higher oxygen use before HFNO start (OR, 3.35 for < 15 L/min; OR, 3.57 for 15 L/min) were associated with higher odds of ICU admission. Conversely, higher oxygen saturation (OR, 0.87) and a longer duration of symptoms (OR, 0.88) were associated with a significantly decreased risk of ICU admission.
COMMENTARY
The COVID-19 pandemic put unprecedented capacity strain on ICUs internationally. In response, medical centers explored triaging some patients with AHRF due to COVID-19 to treatment with HFNO in non-ICU beds with promising results that showed this intervention could be safe and feasible.1,2 Now, four years since worldwide recognition of the COVID-19 pandemic, HFNO often is used as first-line intervention in this patient population and has been associated with reduced need for invasive mechanical ventilation and mortality, although whether this represents a true cause-effect phenomenon or reflects selection bias based on lesser disease severity remains unclear.3 The study by Janssen et al continues to explore the pragmatic use of HFNO specifically outside the ICU for COVID-19-related AHRF, using a larger sample size and data from multiple centers compared to prior studies.
This study mainly confirms that initiation of HFNO on wards is not only safe and feasible in this patient population, but it also can result in significantly less time in the ICU with no excessive mortality or morbidity. The downstream effects of this study could include improving ICU capacity strain, reducing healthcare costs, and potentially reducing other ICU complications, such as delirium and hospital-acquired infections.
This study also brings up a few notable points. The ability to initiate and continue HFNO on the wards (or in any non-ICU setting) was not standardized at the study level given its pragmatic design. This likely varied within a range of AHRF severity and comfort level between different hospitals. Although the study showed that most of the patients with AHRF related to COVID-19 could be managed safely outside the ICU, the decision of how best to treat individual patients remains a personalized judgment call on the part of the medical provider. Factors such as concurrent acute hypercapnic respiratory failure, other active medical diagnoses (outside of mortality and Sequential Organ Failure Assessment scores), and staffing details were not included.
Finally, extrapolation of this therapy for use in patients with AHRF from a variety of causes, not just COVID-19, also has been shown to be safe and feasible. Among 346 patients with AHRF from a variety of causes requiring HFNO, two-thirds were able to receive HFNO entirely out of the ICU, and more than 50% avoided the ICU altogether during their hospital stay.4 However, implementation of HFNO outside the ICU required a detailed protocol documenting indications/contraindications for HFNO and processes for device set-up and management, hospital staff education (respiratory therapists, medical house staff, nursing), respiratory therapist support and evaluation at least every four hours, and systematic review of patient safety and adverse events.4
In summary, although resource-intensive, the ability to provide HFNO appropriately in non-ICU settings may result in unloading tight ICU resources without excess morbidity and mortality and can be a viable option depending on the specific practice/medical setting.
REFERENCES
- Calligaro GL, Lalla U, Audley G, et al. The utility of high-flow nasal oxygen for severe COVID-19 pneumonia in a resource-constrained settings: A multi-center prospective observational study. EClinicalMedicine 2020;28:100570.
- Colombo SM, Scaravilli V, Cortegiani A, et al. Use of high flow nasal cannula in patients with acute respiratory failure in general wards under intensivists supervision: A single center observational study. Respir Res 2022;23:171.
- Al-Dorzi HM, Kress J, Arabi YM. High-flow nasal oxygen and noninvasive ventilation for COVID-19. Crit Care Clin 2022;38:601-621.
- Jackson JA, Spilman SK, Kingery LK, et al. Implementation of high-flow nasal cannula therapy outside the intensive care setting. Respir Care 2021;66:357-365.
