New research has found that the use of non-invasive breathing support to treat moderate to severe COVID-19 infection, isn’t linked to a heightened infection risk, as currently thought.

The study by researchers at Queen’s University Belfast (Belfast, Northern Ireland) shows the use of non-invasive breathing support, commonly known as continuous positive airways pressure (CPAP) and high-flow nasal oxygen (HFNO), produced little measurable air or surface viral contamination, and not more than simple oxygen therapy.

CPAP delivers a steady level of pressurised air and oxygen through a face mask to assist breathing; HFNO delivers oxygen at high flow rate through two small tubes in the nose. Both CPAP and HFNO have been thought to be ‘aerosol generating procedures’ which expose healthcare staff and other patients to a heightened infection rate. CPAP and HFNO have been thought to generate particles containing virus capable of contaminating the air and surfaces nearby, necessitating additional infection control precautions such as segregating patients and wearing protective gear to prevent the risk of aerosol transmission.

The research involved 30 patients with moderate to severe COVID-19 across three hospitals in the UK. The patients were divided into three groups of 10 and given either supplemental oxygen, CPAP, or HFNO to compare the amount of air and surface environmental contamination with SARS-CoV-2. Each patient was swabbed for SARS-CoV-2 and had three air and three surface samples collected from the immediate vicinity where healthcare workers provide care. The presence of viral RNA was detected by PCR targeting two viral genes, and positive or suspected-positive samples were then cultured for any demonstration of viable virus.

Overall, 21 (70%) patients tested positive for SARS-CoV-2 by PCR nasopharyngeal swab at the time of assessment. But only 4 out of 90 (4%) air samples were PCR positive. Neither the use of CPAP nor HFNO nor coughing were associated with significantly more environmental contamination than supplemental oxygen use. Of the total of 51 positive or suspected-positive samples by viral PCR detection, only one sample from the nasopharynx of an HFNO patient was shown as biologically viable in cell culture assay. The study has prompted the researchers to call for a thorough reassessment of the infection control measures deployed for the non-invasive ventilation support methods.

“Our study builds on the combined work of ISARIC and the RECOVERY-RS trial, which looked at COVID-19 admissions and the use of non-invasive ventilatory support, or NIV, to treat moderate-to-severe disease,” said Dr. Christopher Green, Consultant Physician in Infectious Diseases at University Hospitals Birmingham NHS Foundation Trust and Senior Clinical Lecturer at the University of Birmingham. “Although more research is needed to confirm our findings, this is the first indication that NIV care such as CPAP or HFNO may not justify their current classification of being 'aerosol-generating' procedures.” 

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