Surgical Smoke Not A Source Of Transmission Of COVID-19 Viru
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Electrocautery or surgical smoke is an unlikely source for the transmission of the SARS-CoV-2 virus for health care workers, according to research. "Despite the high viral titers used, SARS-CoV-2 was not detectable in aerosol cautery plume generated from electrocautery under any of the study conditions. By mimicking surgery on a patient with a high SARS-CoV-2 load, there was a minimum of a 9 log reduction of viral RNA with any of the electrocautery methods," wrote the authors.

The SARS-CoV-2 virus has been detected in sputum, saliva, blood, bile, and feces. Direct transmission to surgical staff from aerosolized virus in an electrocautery plume is a particular safety concern. Cautery performed in areas of high potential viral load could be risky to those in the operating room.

SARS-CoV-2 is more susceptible to higher temperatures due to the presence of a lipid bilayer. Inhalation of even small amounts of aerosolized virus appears sufficient to establish infection. However, tip temperatures of electrocautery range from 100 to 1200 °C, and as such, the temperature is potentially sufficient to inactivate SARS-CoV-2 in the plume.

The researchers applied electrocautery at 25 W using 3 different methods for 1 minute on raw chicken breast with an added 4 mL of Dulbecco modified eagle medium (DMEM) or a DMEM: blood mixture containing 1×105.7 median tissue culture infectious dose (TCID50) per mL of SARS-CoV-2 which was similar to the viral load in pulmonary sputum of a patient with symptoms.

For positive control, approximately 0.3 mL of both viral media and blood with SARS-CoV-2 was aerosolized into the chamber and collected in the same fashion. The gelatin filters were solubilized in phosphate-buffered saline and added in undiluted and 1:10 serial dilutions to VeroE6 cells to determine the TCID50 value of the vaporized virus following electrocautery.

Key findings of the study include:

• Using a cell titer glow measurement for replicating virus, they observed no virus recovered from any electrocautery performed.

• Collected aerosolized blood or media containing SARS-CoV-2 resulted in a recovery at least 3 or 4 base 10 logs higher than electrocautery or the negative control.

• The maximal theoretical recovery of SARS-CoV-2 on the gelatin filter was approximately 1×106.2 units.

• Viral RNA was readily detected in the control aerosols of both fluids in the absence of cautery.

• The lack of SARS-CoV-2 was also confirmed by the lack of viral RNA on quantitative real-time polymerase chain reaction with undiluted vapor collected on the filter.

"This suggests that electrocautery smoke is an unlikely source of SARS-CoV-2 transmission for health care workers. This study is limited by the in vitro nature of the experiment, and collecting cautery plumes from airway surgery in patients with active SARS-CoV-2 would be definitive," wrote the authors.

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