Novel Use of Vitamin B2 as a Fluorescent Tracer in Aerosol and Droplet Contamination Models in Otolaryngology

Abstract

Objective: During the COVID-19 era, a reliable method for tracing aerosols and droplets generated during otolaryngology procedures is needed to accurately assess contamination risk and to develop mitigation measures. Prior studies have not investigated the reliability of different fluorescent tracers for the purpose of studying aerosols and small droplets. Objectives include (1) comparing vitamin B2, fluorescein, and a commercial fluorescent green dye in terms of particle dispersion pattern, suspension into aerosols and small droplets, and fluorescence in aerosolized form and (2) determining the utility of vitamin B2 as a fluorescent tracer coating the aerodigestive tract mucosa in otolaryngology contamination models. Methods: Vitamin B2, fluorescein, and a commercial fluorescent dye were aerosolized using a nebulizer and passed through the nasal cavity from the trachea in a retrograde-intubated cadaveric head. In another scenario, vitamin B2 was irrigated to coat the nasal cavity and nasopharyngeal mucosa of a cadaveric head for assessment of aerosol and droplet generation from endonasal drilling. A cascade impactor was used to collect aerosols and small droplets ≤14.1 µm based on average aerodynamic diameter, and the collection chambers were visualized under UV light. Results: When vitamin B2 was nebulized, aerosols ≤5.4 µm were generated and the collected particles were fluorescent. When fluorescein and the commercial water tracer dye were nebulized, aerosols ≤8.61 µm and ≤2.08 µm respectively were generated, but the collected aerosols did not appear visibly fluorescent. Endonasal drilling in the nasopharynx coated with vitamin B2 irrigation yielded aerosols ≤3.30 µm that were fluorescent under UV light. Conclusion: Vitamin B2’s reliability as a fluorescent tracer when suspended in aerosols and small droplets ≤14.1 µm and known mucosal safety profile make it an ideal compound compared to fluorescein and commercial water-based fluorescent dyes for use as a safe fluorescent tracer in healthcare contamination models especially with human subjects.

Droplet and Aerosol Generation With Mastoidectomy During the COVID-19 Pandemic: Assessment of Baseline Risk and Mitigation Measures With a High-performance Cascade Impactor

“…A solution of 1 g/L vitamin B2 (riboflavin) in 0.9% normal saline was prepared as fluorescent irrigation. This was found to be a better marker for fine aerosols than fluorescein ( 10 ). For trials that included irrigation, the fluorescent irrigant was applied by an assistant via a squeeze bottle in a pulsatile fashion of about one pulse per second to keep the field appropriately moist.…”

“…Generated debris particles with a smaller aerodynamic diameter have a lower tendency to be collected until the final impaction stages. To ensure that the collected aerosols originated from the specimen, Vitamin B2 was used as a fluorescent tracer in the irrigation, coating the entire mastoid drilling surface ( 9 , 10 ). The goals of this study were to objectively characterize whether aerosols of an aerodynamic diameter known to enter the airway are generated during mastoidectomy, map the field contamination of visible debris, and to test aerosol mitigation strategies.…”

One year into the COVID-19 pandemic: What do we know so far from studies assessing risk and mitigation of droplet aerosolisation during endonasal surgery? A systematic review

“…Macroscopically visible droplet spread was assessed in six studies, all of which used florescent tracers to map droplet spread [13][14][15][16][17][18] . All of these studies demonstrated that use of a high-speed drill aerosolised droplets outside of the nasal cavity.…”

“…All of these studies demonstrated that use of a high-speed drill aerosolised droplets outside of the nasal cavity. [13][14][15][16][17][18] No detectable droplet spread was detected in two studies considering use of non-powered "cold" instrumentation, 13,14 and one assessing utilisation of an ultrasonic aspirator (UST-2001; Stryker Co., USA). 14 Both Sharma et al (2020) 14 and Leong et al (2021) 15 found that microdebrider use on cadaveric nasal mucosa had the propensity to generate extranasal droplets seen on examination under UV light.…”

“…[13][14][15][16][17][18][19][20][21][22][23][24] Endonasal surgery performed using either cold steel or powered instrumentation has the propensity to be aerosol generating with both macroscopically visible droplets and particles <10μm detected outside the nasal cavity during simulated surgery. [13][14][15][16][17][18][19][20][21][22][23][24] Clinical applicability of this review Regardless of vaccination status and testing, appropriate PPE use should remain mandatory for all healthcare professionals involved in endonasal rhinological and skull base surgery. Indeed, studies have demonstrated that close adherence to PPE use, particularly with use of FFP3 level masks, is effective at preventing COVID-19 infection.…”