Flexible laryngoscopy not significant aerosol-generating procedure in real-time clinical setting
The novel virus SARS-CoV-2 has engendered concern regardingperiprocedural transmission. The current international COVID-19 guidelinesstate that SARS-CoV-2 transmission is primarily through larger respiratoryfluid droplets (>5 μm diameter), while aerosols (<5 μm) are only ofnotable risk during aerosol-generating procedures (AGPs). The conventionaldefinition of AGPs is procedures that create and disperse aerosols above thebaselines of coughing, talking, sneezing, or breathing. It is essential toproperly define which procedures are aerosol generating given the high viralload in the upper airway of patients with SARS-CoV-2 infection.
It has been suggested by various authors that flexiblelaryngoscopy (FL), a commonly performed procedure in most otolaryngologypractices, is likely to be an AGP. At the outset of the pandemic, manyhospitals and clinics implemented new FL safety protocols that includedincorporating the use of personal protective equipment, limiting the number ofpatients seen in clinic, restricting FL examinations to negative pressurerooms, or enforcing room shutdowns after an examination to allow for sufficientair exchange in the room.
Amanda J. Bastien and team tested the hypothesis that FL inthe clinical setting is associated with increased aerosols over baselinephysiologic variations such as breathing and phonation. To test thishypothesis, they quantitatively measured aerosols during FL using opticalparticle sizer (OPS) instrumentation.
This prospective cohort study included 134 patients seen inthe otolaryngology clinic at a single tertiary care academic institutionbetween February and May 2021. Two optical particle sizer instruments wereused, quantifying particles ranging from 0.02 μm to 5 μm. Measurements weretaken every 30 seconds, with sample periods of 15 seconds throughout thepatient encounter. Instruments were located 12 inches from the patient's nares.Timing of events was recorded, including the start and end of physicalexamination, topical spray administration, start and end of laryngoscopy, andother potential aerosol-generating events (eg, coughing, sneezing). Dataanalysis was performed from February to May 2021.
The primary outcome was significant CP after FL comparedwith baseline physiologic variations, such as breathing and phonation.
Data were collected from 134 patients between February andMay 2021. Ninety-one encounters involved FL. Of this group, 51 patients (56%)wore no mask over their mouth during FL. There was no statistically significantCP in either visits involving FL or visits where FL was not performed. Use ofnasal spray did not result in CP in aerosol levels. Overall, neither the numberof people present in the examination room, masks over patients' mouth, theduration of the visit, nor the duration of FL were associated with mean aerosolcounts, regardless of the exposure. For larger aerosol sizes (1 μm), however,rooms with higher air exchange rates had significantly higher reductions inmean aerosol counts for visits involving FL.
The COVID-19 pandemic has required a closer examination ofairway procedures and the risk they may pose to both patients and clinicians.Given the exposure of otolaryngologists to the upper respiratory tract, thereis understandable concern that common procedures such as FL may be aerosolgenerating and as such pose a higher baseline risk of virus transmission. Thegoal of this study was to determine if FL generates aerosol counts greater thanbaseline in the clinical setting. To this end, authors used 2 different OPSinstruments and looked for baseline changes using Bayesian OCPD. This studysuggests that FL is likely not an AGP.
In this cohort study, findings support that the office FLprocedure, including topical spray administration, was not aerosol generatingin the real-time clinical setting. The nuanced understanding of the risk ofaerosol generation in common otolaryngology procedures should help informcurrent clinical practice to mitigate the risk of COVID-19 transmission as wellas with other pathogens transmissible through aerosols.
Source: Amanda J. Bastien; Kwame Wiredu; Andrew Y. Lee; JAMAOtolaryngol Head Neck Surg. doi:10.1001/jamaoto.2022.3316
