key: cord-0836143-fiadxpar
authors: George, Ajith; Prince, Mark; Coulson, Chris
title: Correspondence‐Technical Note: Safe Nasoendoscopy Assisted Procedure in the Post COVID‐19 Pandemic Era
date: 2020-05-31
journal: Clin Otolaryngol
DOI: 10.1111/coa.13591
sha: 8d65331c6221912b30f2976a0ad98ea49edcccfb
doc_id: 836143
cord_uid: fiadxpar

For centuries it has been humankind's instinct to cover the mouth and nose when coughing or sneezing. Common sense would dictate this instinctively reduces the dispersion of aerosol and droplets and thus the spread of contact and airborne infections.

MR AJITH GEORGE (Orcid ID : 0000-0002-5132-0915) MR CHRISTOPHER COULSON (Orcid ID : 0000-0002-3991-5473) Article type : Technical Note Correspondence-Technical Note:

For centuries it has been humankind's instinct to cover the mouth and nose when coughing or sneezing. Common sense would dictate this instinctively reduces the dispersion of aerosol and droplets and thus the spread of contact and airborne infections.

Aerosol generating procedures (AGPs) have become a new byword for procedures that put clinicians at increased risk of contracting COVID-19. Whilst the title suggests the risk is simply in aerosols, the science is much more interesting. Droplets and aerosols are different, with the distinction between them based on size. Whilst experts disagree on the absolute size when an aerosol becomes a droplet, the general acceptance is that anything bigger than 50 microns (0.05mm) is a droplet and those smaller are aerosols.

In most contagious respiratory infections, the principal transmission agents are droplets (1). This is due to the relatively high viral load in a droplet, purely due to its large size, and also the fact that large droplets have weight, and so gravity pulls them down onto surfaces that others can touch -so passing it on. This is why washing hands is so effective against droplet spread.

Aerosol transmission is thought to be a much less frequent cause of transmission, mainly due to the very small viral load (given the aerosol itself is by definition very small). However,

This article is protected by copyright. All rights reserved it is clearly more concerning as these very light particles, can travel large distances.. That said, it is thought to only play a minor role in transmission compared to droplet spread. This observation supports the well-known concept that covering the mouth does indeed reduce droplet production.

On impact with smooth surfaces droplets disperse to smaller sizes and can aerosolise.

Similarly impact onto soft surfaces absorbs droplets reducing their projection as well as the tendency to aerosolise (3).

As the pandemic plateaus in countries across the world various strategies are to be considered to return to a new normal. This would facilitate the resumption of diagnostic services whilst maintaining the protection to healthcare workers. One suggestion is the use of facemasks to help reduce the risk of inadvertent droplet dispersion (2) . Despite the 'soft surface' barrier masks create, in the ENT setting, facemasks obscure access to the nasal cavity thus preventing nasoendoscopy.

The 'SNAP' (Safe Nasoendoscopic Airway Procedure) developed by endoscope-i Ltd (West Midlands, UK) is a single-use, valved endoscopic port, retrofitted to any surgical mask ( Figure 1) , permitting entry of a 4mm flexible and rigid endoscope to examine the naso and

This article is protected by copyright. All rights reserved pharyngolarynx. The valve, a 10.9 mm cylindrical tube truncated by two opposing 45 degree inclined membranes 700 microns thick, approaches a point but terminates in a 700 micron thick and 500 micron wide plateau, creating a 'duck bill' formation The valves are formed using a FFF (fused filament fabrication) 3D printing technique with a Flashforge Creator Pro 3D printer. The plateau atop the valve serves to provide a reference for introducing a slit using a hardened steel razor blade that is 400 microns thin. The blade is mounted in a jig to ensure angle, penetration depth and position are controlled as it is driven through the membrane. These measures ensure that the valve opening is observably consistent and less than 50 microns.

Once the SNAP is fitted to a surgical mask, any cough or sneeze generated during the procedure is caught within the mask. The valve is configured such that pressure from the patient side will serve to collapse the walls of the valve membrane thereby further sealing 

 Droplets produced by coughing or sneezing carry a higher viral particle load and can be reduced by wearing a surgical mask in turn helping reducing infection transmission  The SNAP device is an effective and safe method of providing access to the nasal cavity during nasoendoscopy whilst also providing a barrier of a surgical mask to protect against droplet dispersion  Reducing the exposure to pathogens for all healthcare works facilitates a return of

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