Acrylic plastic “aerosol box” endotracheal intubation hood for COVID-19

In an effort to limit virus aerosolization during endotracheal intubation of patients suspected to be COVID-19 positive, many have begun intubating through hoods, drapes or tents. One example is the “aerosol box” created by Taiwanese anesthesiologist Dr. Hsien Yung Lai.¹ A hood can be thought of as analogous to a face shield, only placed closer to the patient and meant to protect multiple team members. A barrier located closer to the patient may stop more aerosolized droplets from reaching the healthcare team. It is not a substitute for essential Personal Protective Equipment (PPE) such as a face shield and respirator, and is not meant to take the place of a Powered Air Purifying Respirator (PAPR) or negative pressure room. It is not meant to be air tight. It is simply an adjunctive barrier aimed at limiting the amount of virus that reaches the team’s PPE.

The design was developed by Dr. Hsien Yung Lai, who placed the plans online for others to use.² We located a Facebook post with plans for a revised design.^3,4 Knowledge about the box’s effectiveness is limited because it was developed quickly as a response to a crisis. One evaluation experiment in video form can be found online.⁵ One company in the United States has begun making and shipping the boxes.⁶

We built the box from the revised plans.

We elected not to add the square access hole on the side of the box. We contacted a local plastics shop, who was able to make the box for us. The cost of the box was 180 US Dollars. It is made of ¼ inch acrylic plastic sheets. The edges are rounded off to make the box easier to handle and prevent snagging or scratching when inserting hands. Between uses, the box is cleaned by wiping with virucidal wipes. We have used hydrogen peroxide wipes as well as 70% isopropyl alcohol.

The videos below demonstrate an approach to using the box. Note that we are using a bag-valve-mask (BVM) with a viral filter for preoxygenation in order to filter the patient’s exhalation. This particular BVM does not have a one-way valve on the expiratory port, so it requires a PEEP valve (which is a one-way valve) installed there so that room air is not pulled in with inhalation. In this demonstration we connect the patient directly to a ventilator after intubation, connecting the viral filter directly to the patient’s endotracheal tube.

In the video below we have added a disposable plastic drape to the back of the box to further limit droplet exposure from that side.

We support the protection of healthcare workers during this crisis. Thank you to Dr. Hsien Yung Lai for making these designs available.

References

1. Focus Taiwan-CNA English News. Taiwanese doctor creates cheap protective device amid virus crisis - Focus Taiwan. Focus Taiwan - CNA English News. https://focustaiwan.tw/society/202003220009. Published March 22, 2020. Accessed April 2, 2020.
2. Aerosol Box - Design. https://sites.google.com/view/aerosolbox/design. Accessed April 2, 2020.
3. Firdaus Hariri. Facebook post. https://www.facebook.com/firdaus.hariri/posts/10158238860567769. Accessed April 2, 2020.
4. Firdaus Hariri. Facebook post. https://www.facebook.com/firdaus.hariri/posts/10158246739087769. Accessed April 2, 2020.
5. Aerosol Box Evaluation. https://vimeo.com/401646409. Accessed April 2, 2020.
6. Physician Protection Box. Windy City Plastics. https://www.windycityplastics.com/physician-protection-box. Accessed April 2, 2020.