The AERATOR (Aerosolisation and transmission of SARS-CoV-2 in healthcare settings) study took place during the COVID-19 pandemic. It aimed to understand whether so-called aerosol generating procedures, such as inserting a breathing tube, produced aerosols in significant numbers.
AERATOR was led by anaesthetic, intensive care, infectious disease and respiratory clinicians at Southmead Hospital and aerosol scientists at the University of Bristol. The study was supported by the National Institute for Health and Care Research Biomedical Centre (NIHR BRC) Bristol.
Respiratory aerosols are tiny droplets produced when people breathe, talk and cough. They are the main way respiratory infections such as COVID-19 are transmitted.
The team used PLUME (Portable low-background unit for measuring exhaled aerosol), a cutting-edge device to monitor aerosol production in real time in ultraclean theatre environments usually used for orthopaedic and neurosurgery. This enabled them to study aerosols in a healthcare setting for the first time.
The study found that most of the aerosol generating procedures considered high risk produced less aerosol emission than coughing or talking.
Based on this and other evidence, Public Services Delivery Scotland has published updated transmission-based precautions guidance. Reflecting the latest evidence on how respiratory infections spread, the guidance introduces a more consistent, risk-based approach to infection prevention and control across Scotland’s NHS Boards, care homes and wider health and care settings.
The guidance moves on from procedure-focussed risk assessment to a more holistic consideration of the type of respiratory infection, the patient’s symptoms and the healthcare professional’s exposure and own risk factors. This has effectively ended the use of the term ‘aerosol generating procedure’ in risk assessments. It will lead to a major change in how personal protective equipment (PPE) is deployed in healthcare settings.
Wales has followed Scotland’s lead and adopted the same risk-based approach. Whilst the English guidelines were the first to remove some of the procedures from the original aerosol generating procedures list, they are yet to drop the list completely.
Andy Shrimpton, Academic Clinical Lecturer in Anaesthesia at the University of Bristol, who conducted many of the studies during his PhD, said:
“The AERATOR study challenged long-held assumptions about which medical procedures generate aerosols and therefore potentially increase the risk of infection transmission. By using innovative technology to measure aerosols directly in healthcare settings, we were able to show that many procedures previously considered high risk actually produce fewer aerosols than normal breathing, coughing or talking.”
Tony Pickering, Professor of Neuroscience and Anaesthesia at the University of Bristol and Consultant Anaesthetist at Bristol NHS Foundation Trust, said:
“It is extremely unusual to see this evidence so rapidly shape national guidance. Scotland’s adoption of a risk-based approach reflects a growing understanding that infection prevention measures should be proportionate to the actual risk. This will help ensure that patients continue to receive safe, effective care while supporting healthcare staff to make evidence-based decisions about the precautions they use.”
James Dodd, Respiratory Consultant at Bristol NHS Foundation Trust, Professor of Respiratory Medicine at the University of Bristol and respiratory theme co-lead at NIHR BRC: Bristol, said:
"This is a fantastic example of how bringing together expertise from across specialties can answer important clinical questions and deliver real-world impact for patients and healthcare systems.
“The AERATOR study combined the skills of respiratory clinicians, anaesthetists, physical scientists, engineers and infection prevention experts to challenge conventional wisdom using robust scientific evidence.
“To see research led from Bristol shape national policy and improve infection control guidance demonstrates the power of collaborative working across organisations and disciplines. It highlights how research conducted in our hospitals can influence practice far beyond our region."