Characterization of experimental and clinical bioaerosol generation during potential aerosol-generating procedures

Doggett, Nathan; Chow, Chung-Wai; Mubareka, Samira

Abstract Background During medical procedures with the potential to produce aerosols such as bronchoscopy, intubation or cardiopulmonary resuscitation, healthcare workers (HCWs) may be exposed to infectious bioaerosols. This is of particular concern when high consequence pathogens such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are circulating. Thus far thousands of HCWs have been infected, 14.8% of these have severe disease and several have died1. However, the determinants of aerosol generation during such procedures and their relative risk to HCWs remain poorly characterized. Research Question. We sought to characterize aerosols produced during airway intubation using an uninfected translational animal model and in human subjects undergoing elective aerosol-generating procedures. We also determined the particle size distribution of generated particles. Study Design and Methods. Aerosol generation was measured during highly controlled experimental (pig) intubations (N=16) and elective bronchoscopies in uninfected patients (N=49) using an optical particle counter (OPC). Recovery of normal respiratory flora was used as a surrogate for pathogen dispersion. Results There was a small but significant (p = 0.03) decrease in 0.3 μm particles during highly controlled pig intubations compared to baseline. The concentration of 1.0 μm and 5.0 μm aerosol particles did not significantly change though oral bacteria were collected from the air. For elective patient bronchoscopies, there was a significant decrease in the generation of larger particles (1.0 μm and 5.0 μm) compared to baseline (p < 0.01), however, 18 of 39 (46%) of patients showed increased aerosol production in 0.3 μm sized particles, 4 of whom demonstrated significant increases. Interpretation. While the total amount of aerosols produced during intubation and bronchoscopy did not increase significantly relative to pre-procedural levels, a small number of participants showed a significant increase in submicron particle emission, meriting further research to delineate determinants of fine particle production during aerosol-generating procedures.