New aerosol studies show that the risk of COVID-19 infection is significantly lower

Since the beginning of the COVID-19 pandemic, there has been much debate about the dangers of hospital staff due to anesthesia. Concerns are that inserting a tube into the patient’s airways before surgery (intubation) or finally removing the tube (extubation) produces a fine mist of small particles (called an aerosol) that causes the COVID-19 virus. This includes the possibility of spreading to nearby staff.

This risk was determined to be very high, so the procedure was classified as an “aerosol production procedure” (AGP), respiratory and high levels. Personal protective equipment (PPE) is worn on a daily basis and then surgery is stopped. Operating room Aerosols are removed and special cleaning is performed. These requirements have dramatically delayed surgery and contributed to the vast waiting list of surgery at the United Kingdom National Health Service (NHS) and similar problems in hospitals around the world. Despite the estimated risk, no direct aerosol measurements were taken during hospital anesthesia treatment.

New research published in anesthesia The Association of Anaesthetists (Journal of the Association of Anaesthetists) shows that these procedures may produce only a small portion of previously thought aerosols. This raises the question of whether the procedure needs to be designated for AGP and provides an opportunity to dramatically speed up surgery.

In this study, Dr. Jules Brown (North Bristol NHS Trust, Bristol, UK), Professor Jonathan Reed (University of Bristol, Faculty of Chemistry, Bristol Aerosol Research Center), Professor Tim Cook (Royal United Hospitals Bath NHS Foundation Trust, UK Bath, UK) University of Bristol School of Medicine) and Professor Tony Pickering (University of Bristol, University of Physiology, Pharmacology and Neuroscience), and colleagues.

To address this lack of evidence, the author real timeHigh-resolution environmental monitoring in an ultra-clean ventilation operating room during anesthesia procedures for insertion and removal of tubes into the patient’s airways. The authors also studied procedures such as airway suction and “mask ventilation” when an anesthesiologist takes over a patient who is breathing prior to tube insertion. Simply put, they were able to quantify the aerosol produced during all these procedures in a real clinical setting and compare it to the aerosol produced by a single cough. Recorded the insertion of 19 tubes and the removal of 14 tubes.

Unexpectedly, the authors found that inserting a tube produces about one-thousandth of the aerosol produced by a single cough. Tube removal produced more aerosol, especially with a weak cough, but still less than 25% of the aerosol produced by a spontaneous cough.

“These findings should trigger a reassessment when specific measures need to be used to protect against viral infections from aerosols in the operating room. The gradual reduction of these high levels of protection is It has a significant impact on our ability to provide healthcare to patients within the NHS and internationally, “explains the author.

“If you agree that these procedures do not produce aerosols, you can reduce the amount of PPE you wear and the significant delay that currently exists between one patient leaving the operating room and the start of the next case. You can get rid of it, “they add.

“The results suggest that tube insertion during anesthesia should not be considered a high-risk procedure,” the authors say. “No increase in aerosol particles was detected during repeated trials of face mask ventilation, airway suction, or intubation. This reflects typical clinical practice by experienced anestheticians and aerosol generation. It gives you even more peace of mind about the low level of. “

The authors explain that removing the tube can cause a cough when the patient’s natural respiratory reflex returns, which produces a detectable aerosol for about 5 seconds. They say: “In our study, the number of particles behind the head was significantly reduced compared to above the patient’s face, so staff could either use techniques to reduce cough or simply leave the anesthesiologist. The risk of exposure to aerosols can be further reduced. “

The authors note that their research has some limitations. “These procedures provided reassuring evidence for aerosol outbreaks, but did not directly study the risk of SARS-CoV-2 infection and were based on the widely accepted association between aerosol outbreaks and infection risk. You need to be aware that you are interpreting it, “they explain.for Safety reasonsThis study was conducted not in patients with COVID-19, but in other patients to demonstrate the aerosols actually produced during these procedures common during anesthesia and intensive care.

They conclude that: “Precautionary measures introduced by many hospitals around the world to mitigate the risks posed by viral aerosols reduce operating room sales, reduce hospital productivity, and wait for elective and cancer surgery. Increased. More important considerations are related to cost and limited supply. PPE needs to target the appropriate medical environment based on risk. Our result is the initiation of anesthesia. It raises important questions about the need for these precautions at the time and at the end. These results should help inform future PPE guidelines by providing evidence of relative risk. .of aerosol Generations associated with tracheal intubation and extubation. ”

Provided by AAGBI