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