CPAP Effective in Patients with Acute Hypoxemic Respiratory Failure and COVID-19

Gavin D Perkins MD

A recent investigation based in England found that among patients with acute hypoxemic respiratory failure and COVID-19, continuous positive airway pressure (CPAP) significantly reduced the risk of tracheal intubation or mortality when compared to conventional oxygen therapy.

However, there was no significant difference between high-flow nasal oxygen (HFNO), another respiratory strategy featured in the study, and conventional oxygen therapy.

Though CPAP and HFNO have both been recommended for acute hypoxemic respiratory failure in patients infected with the COVID-19 virus, the effectiveness and safety of these strategies were uncertain.

Gavin D. Perkins, MD, Warwick Clinical Trials Unit at Warwick Medical School in Coventry, and fellow investigators conducted a randomized clinical trial to determine whether either CPAP or HFNO reduced the need for tracheal intubation or mortality in 30 days when compared to conventional oxygen therapy.

The Methods

Perkins and colleagues conducted the Randomized Evaluation of COVID-19 Therapy-Respiratory Support (RECOVERY-RS) trial across 48 acute care hospitals in the UK and Jersey.

RECOVERY-RS was a parallel group, open-label, adaptive, 3-group, randomized clinical trial which was essentially conducted as 2 separate trials comparing CPAP and HFNO with conventional oxygen therapy.

Patients who were 18 years and older and hospitalized with known or suspected COVID-19

were eligible if they had acute hypoxemic respiratory failure. Patients with an immediate (<1 hour) need for invasive mechanical ventilation, known pregnancy, or planned withdrawal of treatment were excluded.

Once enrolled, patients were then randomized to receive either CPAP, HFNO, or conventional oxygen therapy.

Patients in the HFNO group received heated humidified HFNO, and patients in the CPAP group received CPAP that did not permit the incorporation of any inspiratory positive airway pressure.

Investigators established the primary outcome as a composite of tracheal intubation or mortality within 30 days.

The Results

Though the trial was stopped prematurely due to declining cases of COVID-19 in the UK and the end of the funded recruitment period, investigators had already acquired significant data on each respiratory strategy.

The trial enrolled a total of 1273 randomized patients, and primary data was available for 1260.

A total of 380 patients were randomized in the CPAP group, while 418 were a part of the HFNO group and 475 underwent conventional oxygen therapy.

A total of 733 participants (377 in the CPAP group and 356 in the conventional oxygen therapy group) were included in the comparison of CPAP with conventional oxygen therapy, while 783 participants (415 in the HFNO group and 368 in the conventional oxygen therapy group) were included in the comparison of HFNO with conventional oxygen therapy.

Crossover between interventions occurred in 17.1% of all participants (15.3% in the CPAP group, 11.5% in the HFNO group, and 23.6% in the conventional oxygen therapy group).

Regarding tracheal intubation or mortality within 30 days, both occurrences were lower with CPAP (36.3) vs conventional oxygen therapy (44.4), (absolute difference, −8% [95% CI, −15% to −1%], P = .03), but not significantly different with HFNO (44.3%; 184 of 415 participants) vs conventional oxygen therapy (45.1%; 166 of 368 participants) (absolute difference, −1% [95% CI, −8% to 6%], P = .83).

Adverse events occurred in 34.2% (130/380) of participants in the CPAP group, 20.6% (86/418) in the HFNO group, and 13.9% (66/475) in the conventional oxygen therapy group.

Though investigators felt the study might have been underpowered for the comparison of HFNO versus conventional therapy, the study found that an initial strategy of CPAP significantly reduced the risk of tracheal intubation or mortality compared to conventional therapy.

The study, "Effect of Noninvasive Respiratory Strategies on Intubation or Mortality Among Patients With Acute Hypoxemic Respiratory Failure and COVID-19The RECOVERY-RS Randomized Clinical Trial," was published online in JAMA Network.