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

Influence of vitamins and food on the fluorescence spectrum of human urine

OBJECTIVES

Fluorescence spectroscopy of human urine is a method with the potential to gain importance as a diagnostic tool in the medical field, e.g., for measuring Coproporphyrin III (CPIII) as an indicator of cancer and acute types of porphyria. Food can change human urine's color, which could influence the urine fluorescence spectrum and the detection of CPIII in urine. To determine if there is a noticeable influence on the urine fluorescence spectrum or on the detection of CPIII in urine, 16 vitamin supplements, and three food items were tested. Such investigation may also prevent false interpretation of measured data.

METHODS

Urine samples were collected before and after (overnight, ca. 8 h) intake of each test substance. Samples were investigated by fluorescence spectrum analysis. At excitation wavelengths from 300 to 500 nm and emission wavelengths from 400 to 700 nm excitation-emission-matrices were measured. Data obtained from urine before intake were compared to the data from overnight urine. Furthermore, the investigation of any interference with the CPIII concentration was performed at an excitation wavelength of 407 ± 3 nm and emission wavelengths of 490-800 nm.

RESULTS

Only vitamin B2, but none of the other tested substances, showed noticeable influence on the urine fluorescence spectrum. None of the tested substances showed noticeable interference with the recovery rate of CPIII.

CONCLUSIONS

The correct interpretation of measured data by fluorescence spectroscopy is possible with the exception if vitamin B2 supplementation was performed; thus, the consumption of vitamin B2 supplements before fluorescence testing of the patient's urine should be avoided and/or must be requested. CPIII concentrations could reliably be measured in all cases.

Protocol of a randomised controlled trial to assess medical staff's inhalation exposure to infectious particles exhaled by patients during oesophagogastroduodenoscopy and the efficacy of surgical masks in this context

BACKGROUND

Aerosol-generating procedures such as oesophagogastroduodenoscopy (OGD) result in infectious particles being exhaled by patients. This substantially increases the medical staff's risk of occupational exposure to pathogenic particles via airway inhalation and facial mucosal deposition. Infectious particles are regarded as a key route of transmission of SARS-CoV-2 and, thus, represents a major risk factor for medical staff during the ongoing COVID-19 pandemic. There is a need for quantitative evidence on medical staff's risk of multiroute exposure to infectious particles exhaled by patients during OGD to enable the development of practical, feasible and economical methods of risk-reduction for use in OGD and related procedures. This randomised controlled trial (RCT)-Personal protective EquiPment intervention TrIal for oesophagogastroDuodEnoscopy (PEPTIDE)-aims to establish a state-of-the-art protocol for quantifying the multiroute exposure of medical staff to infectious particles exhaled by patients during real OGD procedures.

METHOD AND ANALYSIS

PEPTIDE will be a prospective, two-arm, RCT using quantitative methods and will be conducted at a tertiary hospital in China. It will enrol 130 participants (65 per group) aged over 18. The intervention will be an anthropomorphic model with realistic respiratory-related morphology and respiratory function that simulates a medical staff member. This model will be used either without or with a surgical mask, depending on the group allocation of a participant, and will be placed beside the participants as they undergo an OGD procedure. The primary outcome will be the anthropomorphic model's airway dosage of the participants' exhaled infectious particles with or without a surgical mask, and the secondary outcome will be the anthropomorphic model's non-surgical mask-covered facial mucosa dosage of the participants' exhaled infectious particles. Analyses will be performed in accordance with the type of data collected (categorical or quantitative data) using SPSS (V.26.0) and RStudio (V.1.3.959).

ETHICS AND DISSEMINATION

Ethical approval for this RCT was obtained from the Ethics Committee of Peking Union Medical College Hospital (ZS-3377). All of the potential participants who agree to participate will provide their written informed consent before they are enrolled. The results will be disseminated through presentations at national and international conferences and publications in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT05321056.

Aerosol release, distribution, and prevention during aerosol therapy: a simulated model for infection control

Aerosol therapy is used to deliver medical therapeutics directly to the airways to treat respiratory conditions. A potential consequence of this form of treatment is the release of fugitive aerosols, both patient derived and medical, into the environment and the subsequent exposure of caregivers and bystanders to potential viral infections. This study examined the release of these fugitive aerosols during a standard aerosol therapy to a simulated adult patient. An aerosol holding chamber and mouthpiece were connected to a representative head model and breathing simulator. A combination of laser and Schlieren imaging was used to non-invasively visualize the release and dispersion of fugitive aerosol particles. Time-varying aerosol particle number concentrations and size distributions were measured with optical particle sizers at clinically relevant positions to the simulated patient. The influence of breathing pattern, normal and distressed, supplemental air flow, at 0.2 and 6 LPM, and the addition of a bacterial filter to the exhalation port of the mouthpiece were assessed. Images showed large quantities of fugitive aerosols emitted from the unfiltered mouthpiece. The images and particle counter data show that the addition of a bacterial filter limited the release of these fugitive aerosols, with the peak fugitive aerosol concentrations decreasing by 47.3-83.3%, depending on distance from the simulated patient. The addition of a bacterial filter to the mouthpiece significantly reduces the levels of fugitive aerosols emitted during a simulated aerosol therapy, p≤ .05, and would greatly aid in reducing healthcare worker and bystander exposure to potentially harmful fugitive aerosols.

Infection risk of SARS-CoV-2 in a dining setting: Deposited droplets and aerosols

Considering that safe-distancing and mask-wearing measures are not strictly enforced in dining settings in the context of SARS-CoV-2, the infection risks of patrons in a dining outlet (e.g., a cafe) is assessed in this study. The size-resolved aerosol emission rate (AER) and droplets deposition rate (DDR) on dining plates from speaking were obtained through chamber measurements and droplet deposition visualization via fluorescent imaging technique (FIT), respectively. The AER from speaking was 24698 #/min in the size range of 0.3-5.5 μm, while the DDR was 365 #/min in the size range of 43-2847 μm. Furthermore, an infection risk model was adopted and revised to evaluate the infection risk of 120 diners for a "3-h event" in the cafe. In a four-person dining setting around a rectangular table, a diner seated diagonally across an infected person posed the least infection risk due to the deposited droplets on dining plates. The deposited droplets on a dining plate were dominant in possible viral transmission as compared to the long-range airborne route when a diner shared a table with the infected person. Yet, long-range airborne transmission had the potential to infect other diners in the cafe, even resulting in super-spreading events. A fresh air supply of 12.1-17.0 L/s per person is recommended for the cafe to serve 4-20 diners concurrently to minimize infection risks due to aerosols. Current ventilation standards (e.g., 8-10 L/s per person) for a cafe are not enough to avoid the airborne transmission of SARS-CoV-2.

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

Objectives

As we pass the anniversary of the declaration of a global pandemic by the World Health Organisation, it invites us to reflect upon the inescapable changes that coronavirus has wrought upon ENT and, in particular, rhinological practice. As it remains unclear when we will emerge from the shadow of COVID‐19, a critical analysis of the evidence base on both the assessment and mitigation of risk is vital for ENT departments worldwide. This article presents a systematic review of the literature examining articles which consider either the quantification of risk or strategies to mitigate risk specifically in the setting of rhinological surgery.

Design

Systematic literature review.

Results

The literature search yielded a total of 3406 returns with 24 articles meeting eligibility criteria. A narrative synthesis stratified results into two broad themes: (1) those which made an assessment as to the aerosolisation of droplets during sinus surgery, further sub‐divided into work which considered macroscopically visible droplets and that which considered smaller particles; (2) and those studies which examined the mitigation of this risk.

Conclusion

Studies considering the aerosolisation of both droplets and smaller particles suggest endonasal surgery carries significant risk. While results both highlight a range of innovative adjunctive strategies and support suction as an important intervention to reduce aerosolisation, appropriate use of personal protective equipment (PPE) should be considered mandatory for all healthcare professionals involved in rhinological surgery. Studies have demonstrated that close adherence to PPE use is effective in preventing COVID‐19 infection.