Detection of human coronavirus RNA in surgical smoke generated by surgical devices

Yokoe, Takuya; Kita, Masato; Odaka, Tokifumi; Fujisawa, Jun-ichi; Hisamatsu, Yoji; Okada, Hidetaka

BACKGROUND: Gaseous by-products generated by surgical devices—collectively referred to as “surgical smoke”—present the hazard of transmitting infective viruses from patients to surgical teams. However, insufficient evidence exists to evaluate and mitigate the risks of SARS-CoV-2 transmission via surgical smoke. AIM: To demonstrate the existence and infectivity of human coronavirus RNA in surgical smoke using a model experiment and to evaluate the possibility of lowering transmission risk by filtration through a surgical mask. METHODS: Pelleted HeLa-ACE2-TMPRSS2 cells infected with human coronavirus were incised by electric scalpel and ultrasonic scalpel, separately. A vacuum system was used to obtain surgical smoke in the form of hydrosol. RT-qPCR was used to analyse samples for the presence of viral RNA, and infectivity was determined through plaque assay. Furthermore, a surgical mask was placed centrally in the vacuum line to evaluate its ability to filter viral RNA present in the surgical smoke. FINDINGS: In this model, 1/10(6) – 1/10(5) of the viral RNA contained in the incision target was detected in the collected surgical smoke. The virus present in the smoke was unable to induce plaque formation in cultured cells. In addition, filtration of surgical smoke through a surgical mask effectively reduced the amount of viral RNA by at least 99.80%. CONCLUSIONS: This study proved that surgical smoke could carry human coronavirus, though viral infectivity was considerably reduced. In clinical settings, surgical mask filtration should provide sufficient additional protection against potential coronavirus— including SARS-CoV-2—infection facilitated by surgical smoke.