The use of high-flow oxygen through a nasal cannula significantly reduced the need for invasive mechanical ventilation and sped time to recovery among hospitalized COVID-19 patients, compared with conventional oxygen therapy, according to a multicenter randomized clinical trial published yesterday in JAMA.
Researchers in Colombia and Brazil studied the outcomes of 220 patients with severe COVID-19 randomly assigned to either high-flow oxygen or conventional oxygen therapy in emergency and intensive care units in three Colombian hospitals from August 2020 to January 2021. Patients were followed until Feb 10, 2021.
The high-flow technique delivers a mixture of heated and humidified oxygen and air through the nose at high flow rates, while conventional oxygen therapy consists of a limited flow of oxygen through nasal prongs, cannula, or masks.
While international guidelines and early observational studies proposed using high-flow oxygen to initially treat patients with severe COVID-19, the study authors said there was little supporting evidence.
Lower intubation rates
After exclusion of 8 patients who withdrew consent and who 13 transferred to other hospitals for administrative reasons, 199 were included in the analysis. Median patient age was 60 years, and 32.7% were women.
The rate of intubation among 99 patients given high-flow oxygen was 34.3%, compared with 51.0% among the 100 patients assigned to conventional oxygen therapy (hazard ratio [HR], 0.62). The median time to recovery in the two groups was 11 vs 14 days (HR, 1.39).
Thirteen patients on high-flow oxygen had suspected bacterial pneumonia, as did 17 of those on conventional oxygen therapy, and bacteremia was found in 7 versus 11, respectively. Seventy-seven patients (77.8%) in the high-flow oxygen group recovered by 28 days, compared with 71 (71.0%) in the conventional oxygen therapy group. The HR for death by day 28 was 0.49 in the high-flow oxygen group compared with the conventional oxygen group, or a 51% risk reduction.
High-flow oxygen was associated with lower risk of intubation at days 7 and 14. Median ventilator-free days by day 28 was 28 in the high-flow oxygen group, versus 24 in the conventional oxygen group (adjusted odds ratio, 0.77). The need for kidney replacement therapy was similar in both groups, as were in-hospital and intensive care unit length of stay and proportion of adverse events.
Averting ventilator complications
The authors noted that the use of high-flow oxygen could prevent complications of invasive mechanical ventilation, sedation, delirium, and neuromuscular paralysis. It could also preserve important resources during pandemic surges, they added.
"Although previous studies have suggested that delay in intubation is related to increased mortality rates in patients with acute hypoxemic respiratory failure, high-flow oxygen therapy seems to be safe, as it is not associated with higher mortality rates or longer recovery times despite nonimmediate intubation in cases that eventually require it," the researchers wrote.
Early relief of shortness of breath could theoretically limit patient lung injury, which should improve clinical outcomes, they said.
"A strategy providing high-flow oxygen therapy at very early stages of respiratory failure could theoretically offer some physiological advantages including improvement of inspiratory effort, minute volume, respiratory rate, lung volumes, dynamic lung compliance, transpulmonary pressure, and lung homogeneity," the authors wrote.