DISCUSSION
COVID-19 is transmitted through droplet spread, with limited evidence of aerosol spread through droplet nuclei.5 Polymerase chain reaction testing of nasal, nasopharyngeal, and oropharyngeal swabs remain the gold standard for diagnosis, and is performed worldwide. Nasoendoscopy is a common procedure performed by otolaryngologists. Till date, there has been no definitive evidence of droplet or aerosol generation during nasoendoscopy or upper respiratory tract swabs.
Our study demonstrates that droplets clearly form only under three scenarios during nasoendoscopy. From this, we suggest the following ways to reduce droplet dispersal. Firstly, when only nasal access is required, the face mask should only be pulled down enough to expose the nares. Secondly, while adequate topical nasal decongestion and anesthesia can reduce the tendency of sneezing, nasal sprays are in itself an aerosol generating procedure, and exhalation through the nose during a spray results in large amounts of droplet production. Hence, use of nasal sprays should be avoided if possible, and if used, procedurists should be in full personal protective equipment prior to performing the nasal spray. Patients should be instructed to inhale gently during the spray and avoid immediate exhalation. Adequate time should be given for sufficient anesthesia prior to commencement of nasoendoscopy. Thirdly, droplets formed from speech can be mitigated with the face mask over the patient’s mouth. Lastly, withdrawal of the swabs and scope should be performed in a slow and controlled fashion, to reduce potential dispersion of droplets when the capillary bridge of mucus breaks up.
A technical limitation of our study is that our equipment can only adequately assess droplet formation. Aerosols below 10 micrometers (10 μm) are unlikely captured in the images. Studies on aerosol production during similar procedures are ongoing, with the caveat that significant aerosol transmission has yet to be proven in the spread of COVID-19.5 Nonetheless, this will provide crucial complementary information as aerosols remain suspended in air longer and have a higher risk of penetrating deeper in the airway.6