High-flow oxygen outperforms low-flow oxygen for COVID-19

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COVID-19 patients with severe illness were significantly less likely to need mechanical ventilation when treated with high flow oxygen therapy compared to conventional oxygen therapy, based on data from 220 adults.

Arterial hypoxemia is a hallmark feature of severe COVID-19 and should be managed with supplemental oxygen, but mechanical ventilation has been associated with increased mortality in these patients, write Gustavo A. Ospina-Tascón, MD, of the Fundación Valle del Lili, Cali, Columbia and colleagues.

Data from previous studies suggest a reduced need for intubation whether patients with acute hypoxemic respiratory failure are receiving high-flow oxygen therapy through a nasal cannula; However, the effect of high-flow oxygen therapy compared to conventional oxygen therapy in severe COVID-19 patients has not been explored, they say.

In a to study Posted in JAMA, researchers randomized 109 adults with severe COVID-19 to receive high-flow oxygen therapy and 111 to conventional therapy. All the patients in the open study presented with respiratory distress at baseline and an arterial oxygen partial pressure / inspired oxygen fraction ratio of less than 200. The patients were treated in three centers between August 2020 and January 2021, with final follow-up. on February 10, 2021. The median age of the patients was 60 years and 33% were female. The primary outcomes were the need for intubation and the time to clinical recovery until day 28.

A total of 34 patients in the high-flow group and 51 patients in the conventional oxygen group had to be intubated (risk ratio: 0.62; P = .03). Patients in the high-throughput group also had a significantly shorter clinical recovery time within 28 days compared to the conventional group (11 days versus 14 days). The rates of bacterial pneumonia and bacteremia were also lower in the high flow oxygen group compared to the conventional group (13.1% vs. 17.0%, respectively, and 7.1% vs. 11.0%, respectively).

The study also looked at eight secondary outcomes, including risk of intubation at 7 and 14 days, and median ventilator-free days in the first 28 days. For these outcomes, compared to conventional oxygen, high flow oxygen was significantly associated with a lower risk of intubation on day 7 (31.3% vs. 50%) and day 14 (34, 3% vs. 51.0%), and more days without a ventilator (28 days vs. 24 days). Other secondary outcomes, including the need for renal replacement therapy, length of hospital and intensive care stay, and the proportion of adverse events, were not significantly different between groups. The risk ratio for death at day 28 was not significantly different between the groups (0.49; P = .11).

“Avoiding routine intubation in COVID-19 could prevent complications related to invasive mechanical ventilation, sedation, delirium, and neuromuscular palsy, ”and preventing intubation could save resources in a pandemic, the researchers note in their discussion.

The study’s results were limited by several factors, including the open design, small sample size, and inclusion of patients from just three centers in a country, which could limit generalization, the researchers note. Additionally, using two primary endpoints could increase the risk of error, they say.

However, the results were bolstered by the consistent randomization and similarity to studies of respiratory failure from other causes, they write. The data suggests that “[I]Improving respiratory mechanics and limiting pulmonary injury could reduce clinical recovery time, assuming that some of these injuries may appear as a consequence of increased respiratory load that is insufficiently sustained during spontaneous breathing ” , say the researchers.

Data highlights the value of reducing fan usage

“Mortality in acute respiratory distress syndrome varies with the severity of ARDS, “said Setu Patolia, MD, of the University of Saint Louis medical school, in an interview.” Severe ARDS has a 45% death rate, and lung damage induced ventilator have been implicated as one of the leading causes of increased mortality in severe ARDS, ”he noted. “Intubating and placing a patient on life support is a double-edged sword. On the one hand, not intubating someone who needs to be intubated due to respiratory distress itself results in death. However, putting someone on life support in a heterogeneous lung damaged by ARDS risks injuring the normal lung, known as the “baby’s lung,” Patolia said.

The COVID-19 pandemic has highlighted the need for more research on ARDS, Patolia said. “Treating primary lung injury associated with ARDS while preventing further secondary ventilator-induced lung injury is the primary goal of ARDS therapies. Preventing intubation while supporting patients appropriately serves this purpose, ”thus the present study is particularly relevant. “In addition, the COVID-19 pandemic has highlighted the importance of resource management, especially in developing countries,” Patolia said. “Intubated patients need ICU care, and in many parts of the world ICU care is limited or non-existent,” therefore finding safe and effective alternatives to avoid intubations and ICU care should be the key. ARDS research priorities, he added.

Patolia said he found some aspects of the study’s results surprising, but others not surprising. In 2015, the FLORALI trial randomized patients with ARDS into a high-flow nasal cannula, nasal cannula, or non-invasive ventilation. The primary outcome was intubation at 28 days, and overall there was no difference between the three arms, he said. However, in this study, “patients with PaO2/ FIO2 less than 200 (moderate to severe ARDS), the high-flow nasal cannula was associated with a decrease in the rate of intubation compared to the other two arms ”, and the 90-day mortality favored the use of the nasal cannula broadband, he said. The results of the current study are comparable to the main result of the FLORALI trial, he added.

Mortality was not significantly different in the current study, but it may be related to the sample size, Patolia noted.

The results of the current study suggest that “the high-flow nasal cannula is an important tool in the treatment of patients with COVID-19 ARDS,” Patolia said. “Along with oxygen support, it provides positive expiratory pressure, decreased muscle workload, and comfort through humidified oxygen,” and it decreases the rate of intubation, he said.

As for future research, high-flow nasal cannula oxygenation could impact mortality and should be studied with a larger sample to answer this question, Patolia noted.

“In addition, based on the subgroup analysis, it appears that younger patients (age

The study was supported by the Centro de Investigaciones Clínicas, Fundación Valle del Lili, Cali, Colombia. Ospina-Tascón and Patolia did not disclose any relevant financial relationship.

JAMA. Published online December 7, 2021. Abstract

Heidi Splete is a freelance medical journalist with 20 years of experience.

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