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expert reaction to preprint from the RECOVERY-RS trial looking at respiratory interventions in COVID-19 patients with acute respiratory failure

A preprint, an unpublished non-peer reviewed study, from the RECOVERY-RS trial looks at respiratory strategies in acute respiratory failure patients with COVID-19.

This Roundup accompanied an SMC Briefing.


Dr Tom Wingfield, Senior Clinical Lecturer and Honorary Consultant Physician, Liverpool School of Tropical Medicine, said:

“The RECOVERY-RS study preprint (a study that has not yet been “peer-reviewed” by other scientists and/or experts in the field) provides valuable new evidence on the benefits of continuous positive airway pressure (CPAP) vs either high flow nasal oxygen (HFNO) or conventional oxygen therapy for people with Covid-19.*

“The study randomised more than 1000 people who had Covid-19 pneumonia with respiratory failure (low oxygen levels in their blood) to receive CPAP, HFNO, or conventional oxygen therapy.  Of note, people randomised had to be suitable for intubation and mechanical ventilation on intensive care units if they deteriorated.

“In adjusted logistic regression analyses, the study found that people randomised to receive CPAP were about 33% less likely to experience the “composite” (combined) outcome of intubation or death within 30 days than those randomised to receive conventional oxygen therapy.  Sub-analysis showed that it was predominantly a reduction in intubation rates (by 34%) that was driving this finding rather than a reduction in mortality.

“The authors translated this reduction into a “number needed to treat” that suggested that, amongst a similar population to the RECOVERY-RS study, to prevent intubation or death within 30 days of one person, 12 people would need to receive CPAP.

“Of note, HFNO was shown to provide no additional benefit to rates of intubation or death within 30 days compared to conventional oxygen therapy.

“In UK hospitals, during this current wave of Covid-19 in July and August, we have already seen improved outcomes for people hospitalised with Covid-19.  Alongside the related “RECOVERY” study’s findings of mortality reductions from treatment with dexamethasone and/or IL6-inhibitors (e.g. tociluzimab, sarilumab), the “RECOVERY-RS” study provides robust evidence of another beneficial therapeutic option for people hospitalised with Covid-19 who require oxygen.

“As Covid-19 becomes endemic and seasonal, therapeutic advances like those seen in the RECOVERY and RECOVERY-RS trials should help NHS staff and other healthcare workers to provide even better care for people admitted to hospital with Covid-19.  It will be interesting to see the results of ongoing trials into therapies that can be given to people who have tested positive for SARS-CoV-2 infection in the community in order to prevent them from deteriorating and being hospitalised.”

*Explanations of CPAP, HFNO, and conventional oxygen therapy:

CPAP is delivered using a relatively tight-fitting mask that covers the nose (or sometimes both the nose and mouth) or a see-through hood. CPAP gently blows air into the nose and throat and this “positive pressure” holds the upper airways open, which improves airflow to the lungs. CPAP can be given with different concentrations of inhaled oxygen. Many people use portable CPAP machines without oxygen at night for a condition called “obstructive sleep apnoea”. 

HFNO is humidified (moistened), warmed high-flow oxygen given through the nostrils via soft rubber tubes held in place by a headband. HFNO can provide air mixed with oxygen at higher levels than conventional oxygen therapy. HFNO is generally comfortable and well tolerated by people who use it.

Conventional oxygen therapy can be given through nasal prongs (small tubes that sit just in the entrance to the nostrils) or masks (that are not fitted as tightly as CPAP masks). The amount of oxygen that can be delivered by conventional oxygen therapy is generally more limited than HFNO or CPAP.



Preprint (not a paper): ‘An adaptive randomized controlled trial of non-invasive respiratory strategies in acute respiratory failure patients with COVID-19’ by Gavin D Perkins et al. was posted online at 00:01 UK time on Thursday 5 August 2021.  This work is not peer-reviewed.



All our previous output on this subject can be seen at this weblink:



Declared interests

None received.

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