I’ve been studying the doffing of Infectious Disease PPE since 2003. It started when a health care worker and old friend, Bruce, asked me to come to Toronto during the SARS crisis. Bruce started SARS by caring for patients at St Michael’s Hospital, and then transitioned to training health care workers on donning and doffing PPE. Per St. Michael’s protocol in 2003, a doctor or nurse had to pass Bruce’s day-long boot camp before being allowed to work the intensive care units.
This is where we started dissecting doffing. The training lab at St Michael’s had an observation window where Bruce would watch everyone doff. Sometimes, Bruce’s would stand near a trainee and make an ‘ENH!’ noise every time they self-contaminated during doffing. Think of the noise from that old Operation game when one removes the funny bone and hits the sidewall – ENH! This was especially alarming given that Bruce possesses a genuinely calming bedside manner - such a penetrating response was completely out of character. He also did this with me during our apparel development. To this day, 18 years later, when I see anyone self-contaminate during doffing, Bruce’s ‘ENH!’ rings in my head.
Dr. Randy Wax at Mount Sinai Hospital in Toronto investigated the various PPE options available in 2003 and was the first to introduce us to the idea of using fluorescent markers to visualize and measure self-contaminations during doffing. Randy’s methodology back then was to divide the body into a grid of 100 squares using a laser raster scan, take a fluorescent picture before and after doffing, and then count the number of fluorescent/contaminated squares before and after doffing. Brilliant.
Since 2003, we have used fluorescent markers and video to analyze doffing. I’ve studied the doffing research and watched countless doffs since 2003. For every doffing video, I made notes on when, where, and how the health care worker self-contaminates. After 18 years, numerous self-contamination patterns and lessons emerged.
One lesson: it helps to view doffing from a statistics perspective. If a PPE ensemble generates 5-6 or 8-10 self-contaminations per doff, and that ensemble is doffed 1000 times each day, then that generates 5000-6000 or 8000-10,000 self-contaminations per day. Apply the same math when gowns are doffed one million times per day in the US in 2020. (Source: White House Covid-19 Supply Chain Task Force.)
The question then becomes: how many of those 800 million self-contaminations lead to health care worker infection? And after X infections, how many of those infections lead to serious illness or death?
The best way to answer those questions is to never have to ask them in the first place. In other words, the theoretical ideal for Infectious Disease PPE is zero contaminations during usage and zero self-contaminations during doffing.
So, the first goal in doffing minimizes the quantity of self-contaminations. This is primarily a function of the apparel used, and to a lesser extent, training. More on this below. For now, it is important to note that the great training and mediocre PPE will never match mediocre training and great Infectious Disease PPE. Louis Hamilton driving a Ford Camry (0 to 60 MPH in 9 seconds) loses to an average driver in an FI car (0 to 60 MPH in 2.3 seconds).
The second goal in doffing reduces the quality of self-contaminations. I would take 10 self-contaminations on my pant shins before one self-contamination near the eyes. This is where the hodgepodge of current PPE fails most miserably. Removing an N95 mask brings contaminated hands or gloves in proximity, and inadvertently in contact, with one’s face. It is an incredibly error prone doffing step. Watch 100 people doff an N95 mask, and you will often see contaminated fingers and gloves inadvertently come in contact with the face. The mitigation effort here is repeated hand washing during the doffing process. Repeated hand washing sounds good in theory, but in practice, is a mess. Go into five hospitals and see how many practitioners repeatedly hand wash according to instructions. Even the instructional video advocating repeated hand washing (four times in their doffing process!) fails to have the patience to follow its own doffing regimen (11:55 mark.)
What are the constructive takeaways from my years dissecting doffing to help health care workers? Here are seven tips.
(1) Video breakdowns should be part of all PPE training. Watching oneself doff is incredibly illuminating since individual practitioners tend to repeat self-contaminations. Health care workers learn quickly when a video shows them how and when they are self-contaminating. Professional athletes all use video to improve their game, and so should health care professionals, who have a lot more to lose. Every health care worker improves their doffing after watching a video of their self-contamination habits.
(2) Layering PPE does not compensate for bad individual layers. Instead, layering PPE introduces several doffing problems. First, one has to doff multiple disparate pieces (more pieces = more error prone steps … stats!!!) Second, more PPE layers trap more heat, which leads to perspiration. With a sweaty forehead, self-contaminations above the eyes can get into the eyes, effectively increasing the target area of the mucous membranes. Sound improbable? This study shows 87% of practitioners with facial contamination after two aerosol generating procedures. Now add some sweat to those fluorescent markers on the forehead and see where they go. Avoiding self-contaminations of the mucous membranes is a priority, so sweating should be avoided. China produced thousands of infected health care workers with the below layered ensemble. Layering bad Infectious Disease PPE can add the doffing risks of multiple layers.
(3) Avoid unpredictable doffing steps. For example, avoid blind movements when doffing pieces near the head. Take this 2014 video of Colin Buck, a health care worker who volunteered in West Africa, who was then doffing apparel on video to show how bad the PPE used in West Africa was. (Sadly, much of the world still uses the same coveralls in 2020.) I met Colin in 2016 at Stanford University, and enumerated his self-contaminations in a list, with the most troubling being the blind removal of the head gear over his sweating head (see 3:07 of the video; and the headgear had not been sprayed like his torso.) As a second example of unpredictability, elastic recoil of any PPE (latex gloves, N95 straps, etc,) can send infected liquids flying. While odds are low that infected liquids from an elastically recoiling latex glove will strike one in the face or mucous membranes, even at 0.1% (1 in 1000), elastic recoil of infected surfaces becomes a problem with gloves are doffing 20,000,000 times per day (20,000 times). Fluorescent markers shine when illuminating the dangers of unpredictable doffing steps.
(4) No doffing partners. This is a doffing practice that emerged in the West African Ebola outbreak, where a second partner would spray diluted chlorine on the doffing practitioner. Other doffing protocols use a partner to help instruct a practitioner through a complicated doffing process. Putting a second person in proximity to contaminated materials opens the door to unnecessary risk. The remedy for a complicated doffing process is a simpler doffing process, not endangering a second person. For doffing, practice and video training are far better than endangering a real time coach.
(5) Doffing infected gloves is a problematic step. The “two glove conundrum” proceeds as follows: remove a first soiled glove with one’s second gloved hand (easy!), but now … how does one remove the second soiled glove without contaminating the now clean/bare first hand? Watch dozens of people doff and you will see multiple people inadvertently touch their face during the doffing process. Remember, many practitioners wore facial protection that prevented them from touching their face and scratching an itch for 2-4 hours, so guess what happens when one finally can? ENH! I was skeptical that this happened - until I saw it. Fluorescent markers also shine here. People have derived clever techniques to mitigate the two-glove conundrum, like the Beaking method and the ‘glove-in-glove’ technique. These techniques certainly help, but are far from perfect. First, what percentage of health care workers in 2020 knew of and used either technique? 20%? Second, even if one knows one of techniques, how frequently are they executed perfectly? 80% of the time? Even the CDC instructional video teaching 'glove-in-glove' self-contaminates himself by touching a contaminated sleeve at the 0:50 mark. (Multiply 80% into the 20% …) Then factor in a nervous and tired health care worker at the end of a 12-hour shift and fatigue’s effects. Again, it sometimes helps to view doffing in the scale of thousands or millions of doffs. Verasuit’s solution is not to touch either glove.
(6) In doffing, simple is better. Fewer doffing steps lead to fewer mistakes. A simpler process is easier to remember, especially for an exhausted practitioner, and leads to less interpretation. This instructional video removes the gown first then gloves, while this CDC instructional video for the same apparel removes the gloves first then the gown (note: when he rolls that gown at 1:47 with bare hands, the material has near zero resistance to viral penetration, so he can easily contaminate his hands with any virus on the gown.) So, two items, two possible orders in which to doff, and two different interpretations. Now add 15 pieces. If a doffing protocol requires handwashing more than three times, then it fails in practice amidst thousands of doffs and people. In general, the PPE ensemble largely determines the number of doffing steps, so …
(7) … choose apparel wisely. The failure to stockpile PPE in advance of 2020 devolved to a dangerous American mindset where any PPE is better than no PPE (this is not the case in Korea for example.) This sentiment might be true, but don’t let that obscure the difference between bad and good PPE. Verasuit on average generates less than one self-contamination per doff, typically located in the shoes or lower pants, and the doffing process is simple and designed to avoid self-contaminating one’s face and hands. Surgical apparel ensembles and general-purpose coverall ensembles were never designed or intended for safe doffing, and typically generate 5-15 self-contamination per doff, with a good number of those on the face and head.
I could add another 20,000 words on doffing – maybe another day. For now, if you are a health care worker, just be mindful that better PPE and some video training will really help.
Will has been developing PPE for Infectious Disease defense since 2003. He's worked with PPE experts and health care workers everywhere from Toronto to Geneva, Atlanta's CDC, Singapore, Korea, Stanford U, Manhattan, Cleveland, countless hospitals, and a most memorable Panera Bread in Pittsburgh. Here are some lessons and stories from the journey.