Nasal endoscopy, room filtration, and aerosol concentrations during live outpatient encounters: a prospective, case‐control study

Abstract

Background The coronavirus disease 2019 (COVID‐19) pandemic has highlighted safety concerns surrounding possible aerosol‐generating procedures, but comparative data on the smallest particles capable of transmitting this virus remain limited. We evaluated the effect of nasal endoscopy on aerosol concentration and the role of a high‐efficiency particulate air (HEPA) filter in reducing aerosol concentration. Methods Otolaryngology patients were prospectively enrolled in an outpatient, cross‐sectional study. Demographic information and clinic room characteristics were recorded. A scanning mobility particle sizer and GRIMM aerosol monitor measured aerosols 14.3 nm to 34 μm in diameter (i.e., particles smaller than those currently examined in the literature) during (1) nasal endoscopy (± debridement) and (2) no nasal endoscopy encounters. One‐way analysis of variance (ANOVA) and Student's t test were performed to compare aerosol concentrations and impact of HEPA filtration. Results Sixty‐two patients met inclusion criteria (25 nasal endoscopy without debridement; 18 nasal endoscopy with debridement; 19 no nasal endoscopy). There was no significant difference in age or gender across cohorts. Aerosol concentration in the nasal endoscopy cohort (± debridement) was not greater than the no nasal endoscopy cohort ( p = 0.36; confidence interval [95% CI], −1.76 to 0.17 μg/m 3 ; and p = 0.12; 95% CI, −0.11 to 2.14 μg/m 3 , respectively). Aerosol concentrations returned to baseline after 8.76 min without a HEPA filter versus 4.75 min with a HEPA filter ( p = 0.001; 95% CI, 1.73–6.3 min). Conclusion Using advanced instrumentation and a comparative study design, aerosol concentration was shown to be no greater during nasal endoscopy versus no endoscopy encounters. HEPA filter utilization reduced aerosol concentrations significantly faster than no HEPA filter.

COVID-19 and rhinological surgery

“… 31 It is important to note these findings are specific to the particular HEPA filter used in the study along with other office characteristics such as room size and temperature. 31 Nonetheless, these results do indicate that HEPA incorporation can facilitate decreased room turnover time and protect both patients and clinical team members from potentially aerosolized viral particles.…”

“…30 Naturally, clinicians have sought avenues to improve air filtration, resulting in the incorporation of high-efficiency particulate air (HEPA) filters in numerous otolaryngology clinics. 30 , 31 Gill and colleagues found that HEPA incorporation into their clinics resulted in up to a 700% increase in clinical productivity per hour, as a result of decreased room turnover time. 30 They note that HEPA incorporation resulted in return of aerosol concentrations to baseline significantly faster.…”

“…30 They note that HEPA incorporation resulted in return of aerosol concentrations to baseline significantly faster. 31 Specifically, HEPA-incorporated office spaces reached baseline aerosol levels in nearly half the time and necessitated, on average, only 2.26 air changes compared to 4.18 air changes. 31 It is important to note these findings are specific to the particular HEPA filter used in the study along with other office characteristics such as room size and temperature.…”

“… 31 Specifically, HEPA-incorporated office spaces reached baseline aerosol levels in nearly half the time and necessitated, on average, only 2.26 air changes compared to 4.18 air changes. 31 It is important to note these findings are specific to the particular HEPA filter used in the study along with other office characteristics such as room size and temperature. 31 Nonetheless, these results do indicate that HEPA incorporation can facilitate decreased room turnover time and protect both patients and clinical team members from potentially aerosolized viral particles.…”

Infectious disease for the rhinologist

“…However, the use of these guidelines indiscriminately can rapidly escalate healthcare costs and increase the number of procedure downtimes unnecessarily. A recent prospective study utilizing particle sizers with an aerosol monitor showed no difference in aerosol generation and concentration between the use of nasal endoscopy without debridement and no use of endoscopy (95% CI [−0.11 to 2.14], P = 0.12), as well as between nasal endoscopy with debridement and no endoscopy (95% CI [−1.76 to 0.17], P = 0.36) [21]. This reinforces that standard infection control precautions can be taken with nasal endoscopy in at-risk patients, without the need for additional costly equipment such as powered air purifying respirators which are often used in high-risk AGPs.…”