Characterization of Aerosols Generated During Patient Care Activities

Abstract

In this study, significant aerosol generation was only observed during NMA, both alone and during bronchoscopy. Minimal viable bacteria were recovered, mostly common environmental organisms. Although more research is needed, these data suggest that some of the procedures considered to be aerosol-generating may pose little infection risk to HCP.

Potential for occupational exposures to pathogens during bronchoscopy procedures

“…The finding that bronchoscopy was not associated with elevated mean ultrafine and respirable aerosol concentrations ( Table 2), is consistent with O'Neil et al, [3] who used these same instruments (and others), and observed aerosol number and mass concentrations to be elevated only during bronchoscopies with nebulized medication administration. However, Lavoie et al, [4] who used a Ultraviolet Aerodynamic Particle Sizer (UV-APS) to measure particles 0.5-15 mm diameter, found that the number concentrations of fluorescent particles (containing biological materials) and non-fluorescent particles were 3-times and 124-times greater during bronchoscopy procedures than at the beginning or end of the day (occupancy at these times was not described), respectively.…”

“…With respect to the former limitation, interpretation of these data for infection risk among healthcare workers requires an assumption about the concentration of pathogens in respiratory secretions and aerosols. The UV-APS instruments, such as have been used by others, [3,4] are able to identify bioaerosols, but are not able to distinguish between pathogens, commensal microorganisms, and other particles of biological origin, such as human epithelial cells including human skin cells. Future work should capitalize on epidemics and pandemics, such as Thompson et al, [5] to characterize pathogen emission, transport, and fate during bronchoscopy procedures.…”

“…Paired t-tests found that the mean aerosol concentrations were not statistically significantly different during the procedure than after the procedure (average difference 55.5 #/cm 3 [95%CI À55. 3, 166] and 0.004 mg/m 3 [95%CI À0.0002, 0.008]). To explore the relatively high aerosol concentrations measured before the procedure, the analysis was repeated using only the aerosol concentrations measured over the 4 min prior to the procedure (rather than 20 min), and while this approach led to slightly lower particle number and mass concentrations before the procedure, the inference was the same.…”

“…Although the sample size in this study involved observing only 18 bronchoscopy procedures, this sample size is large relative to other studies. [3,5] Repeated participation of some pulmonologists may have reduced the variance observed if they behaved similarly on multiple occasions. This is more likely a problem for the observed use and doffing of PPE than other variables measured because the individual determines how to use PPE, whereas the patient, procedure, and pulmonologist influence aerosol generation and contact patterns.…”

“…The data are limited, at least in part, because of the logistical difficulty of observing AGPs on patients with respiratory infections outside of an epidemic. [3,4] Thompson et al, [5] however, measured H1N1 (2009) pandemic influenza virus during 22 AGPs and found that the size distribution of respirable aerosols containing viral RNA was different during AGPs relative to baseline and that bronchoscopy, but not respiratory suctioning or intubation, was associated with increased median viral RNA concentrations. There may be aspects of AGPs beyond the aerosol source strength, however, that contribute to infection risk among healthcare personnel, including: proximity to the source, duration of patient contact, and the contact transmission route.…”