key: cord-0881404-zpqrm0a3
authors: Cubillos, J.; Querney, J.; Rankin, A.; Moore, J.; Armstrong, K.
title: A multipurpose portable negative air flow isolation chamber for aerosol generating medical procedures during the COVID-19 pandemic
date: 2020-04-27
journal: Br J Anaesth
DOI: 10.1016/j.bja.2020.04.059
sha: 2d709b295d267319f77e9aa399066b54e34dd265
doc_id: 881404
cord_uid: zpqrm0a3

nan

Editor -The rapid and devastating progression of the COVID-19 pandemic is driving innovation, collaboration, and a need for solutions at an exceptional rate. The risk of transmission during aerosol-generating procedures such as bag mask ventilation, tracheal intubation/extubation, tracheostomy, cardiopulmonary resuscitation, manual noninvasive ventilation and bronchoscopy is alarming. 1 The widespread concern for a shortage and lack of appropriate personal protective equipment (PPE) compounds this frightening outcome and can lead to noncompliance of protective guidelines for health care providers up to the point that we are allowing extended use and reuse of N95 respirators.

The current gold standard to manage COVID-19 suspected or confirmed patients is enhanced PPE and airborne isolation in negative pressure rooms if available, 2-3 however, these are a very limited resources in a pandemic situation. Strategies like negative air flow in rooms and wards have been considered in the past to try to mitigate and reduce the risk of nosocomial transmission of viruses. Unfortunately, newer evidence suggests that the COVID-19 model of droplet/aerosol spread and transmission might be too simplistic as the virus can remain in aerosols for hours and on surfaces for days [4] [5] [6] [7] . Tthe Centers for Disease Control and Prevention now recommends wearing of masks by the general population 8 .

Humanity is in the midst of an unprecedented health crisis. It is probable that beyond the ongoing surge there will be a second wave of cases and eventually recurring viral outbreaks in the community. At the London Hospitals in London, ON, Canada, we recognize the need for viable solutions to protect healthcare providers, especially during aerosol-generating procedures. A reasonable approach to address this objective is the creation of a physical barrier that helps protect healthcare providers and the surrounding environment. Two methods recently explored and described in the literature and social media are generating much interest: 1) a simple covering of the patient with a plastic drape over the upper body, 9 and 2) a partially enclosed working space 10 . Our proposal adopts concepts learned from both approaches; however, we added significant functional improvements while keeping the idea as simple and reproducible as possible for others to replicate.

We created a rigid cubic frame chamber that relies almost exclusively on materials available at hardware stores, which is then draped with a clear plastic bag. Our goal are that it is: 1) constructed with readily available and affordable materials, 2) acceptable to users, 3) portable to allow its use as an isolation device in different locations and scenarios of healthcare providing facilities, 4) effective as a physical barrier that allows creation of an enclosed continuous negative air-flow environment through suction/vacuum mechanisms, 5) allows oxygen delivery and nebulization of infection control chemicals, and 6) shared with the wider medical community so that healthcare teams can customize and adapt the frame concept to their needs.

Using a collaborative feedback approach with researchers at the Robarts Research Institute and Western University, we shared ideas amongst a design team. Working in person, by email, videoconferencing, and utilizing CAD software and 3D printers, we conducted several design and testing cycles. Each step involved simulated activities to qualitatively assess the functionality of the initial idea and subsequent designs. Airway devices are supported on hooks, which increases the working space available.

During a simulated airway management training session of our COVID-19 intubation team, direct vision, communication and maneuverability were accomplished for 12 operators.

Even though our results are preliminary and qualitative in nature, we demonstrate proof of concept for an additional physical barrier during aerosol-generating procedures.

We believe that this easily constructed barrier, as well as others, have the potential to protect healthcare providers in caring for confirmed or suspected COVID-19 patients.

These include patients undergoing monitored anesthesia care or regional anaesthesia, treated with noninvasive ventilation, in overcrowded emergency department or wards, in endoscopy/bronchoscopy suites, in radiology suites and during patient transportation.

We acknowledge that further research and testing are necessary to quantify the contamination level within the multipurpose portable negative air flow protection isolation chamber and whether it is possible to inactivate any virus before removal and doffing of the plastic drape and frame. We remain concerned that healthcare providers may develop a false sense of security if these barriers are used, so we strongly emphasize that local guidelines for PPE be maintained, and that new devices being developed during this healthcare crisis are used mainly as an additional complementary resource, not a replacement, to face the undeniable scarcity of PPE.

The authors declare no conflicts of interest. 

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