On 13 March 2020, Dr. Michael J. Ryan, Chief Executive Director of the WHO Health Emergencies Programme, stated:

“One of the great things in emergency response and anyone who’s involved in emergency response will know this, if you need to be right before you move you will never win. Perfection is the enemy of the good when it comes to emergency management. Speed trumps perfection and the problem in society we have at the moment is everyone is afraid of making a mistake. Everyone is afraid of the consequences of error, but the greatest error is not to move. The greatest error is to be paralyzed by the fear of failure.”35

Here, we review evidence regarding transmission of COVID-19 as well as research findings prior to the present COVID-19 pandemic including those on SARS, middle east respiratory syndrome (MERS), and influenza A (H1N1). While details regarding SARS,36 MERS, and influenza may not be completely applicable, they provide models from which to work. Our recommendations align with current PPE recommendations of Ontario Public Health (6 April 2020)31 and the PHAC (24 February 2020).37 We present the rationale for our proposal of a third tier of PPE specifically for high-risk AGMPs not previously outlined by Ontario Public Health, the PHAC, or the WHO.

Likely the best information we have at present is found in a 2012 systematic review of SARS-CoV-infected healthcare providers based on their participation of a variety of AGMPs.29 Healthcare providers participating in specific AGMPs were compared with other healthcare providers not participating in these specific procedures, with the results expressed as odds ratios (Table 1). The primary studies tended to be small cohort or case-control studies with variable follow-up. As a result, some AGMPs have measures of association with wide 95% confidence intervals, reflecting the imprecision of what is currently known. Across multiple studies, the most consistent association with healthcare provider infection was tracheal intubation.29

Table 1 contains examples of AGMPs that are known to be high-risk because of exposure to a high concentration of aerosols. Unfortunately, the risk of aerosol production is unknown for many AGMPs. Current airway management, including primary use of videolaryngoscopy, supraglottic device placement for rescue oxygenation, and the simplification of cricothyrotomy in “can’t intubate, can’t oxygenate” emergencies may play a role in changing these odds ratios during COVID-19 compared with SARS. Healthcare provider risk during extubation of patients with SARS or COVID-19 disease currently remains unknown. Arguably, extubation is a higher risk procedure compared with intubation given the lack of neuromuscular blockade, spontaneous ventilation, and patient coughing risk.

For PPE in the context of COVID-19, WHO, PHAC and other organizations have made recommendations for two different tiers of PPE precautions: droplet and contact precautions for direct patient care not involving AGMPs, and airborne, droplet, and contact precautions when aerosol generation is expected (e.g., AGMPs). There are specific healthcare provider exposure areas identified for certain high-risk AGMPs32 that airway managers may encounter. Both the potential for contamination at the wrist (despite a single pair of gloves) and at the neck have been reported.16,38,39

Given the increased risk of transmission from high-risk AGMPs that airway managers and their airway assistants will be performing, and evidence of incomplete coverage provided by standard airborne, droplet, and contact precautions alone, we propose modifications that include head and neck protection as well as a second pair of gloves.40 These additions address the heavy respiratory secretion contaminant load that occurs with high-risk AGMPs.41 Our recommendations advocate for a three-tiered approach to PPE (Fig. 2):

Figure 2 Decision-making for appropriate PPE in COVID-19 for anesthesiologists and other airway managers. The decision as to the most appropriate personal protective equipment (PPE) to use in COVID-19 patients is based on the clinical care being undertaken. For care not involving high-risk aerosol-generating medical procedures (AGMP), use droplet and contact precautions, which include a surgical mask with face-shield, Association for the Advancement of Medical Instrumentation (AAMI)-level 2 gown, and single gloves, as shown in panel A (used with permission from Lockhart et al.).38 For a healthcare provider present in the room during an AGMP, use airborne, droplet, and contact precautions which include an N95 respirator, eye shield, head covering, AAMI level-2 gown, and single gloves, as in panel B. If you are performing (or directly assisting in) the AGMP itself, then airborne, droplet, and contact precautions should be worn that additionally include a AAMI level-3 gown, neck cover, and 2 pairs of gloves (both panels C and D are considered equivalent levels of PPE) Full size image

(1) Droplet and contact precautions (2) Airborne, droplet, and contact precautions (3) Airborne, droplet, and contact precautions for high-risk AGMPs.

The COVID-19 patient should wear a surgical mask whenever possible. Surgical masks, also called face masks, are loose-fitting and inhibit droplet transmission of viral or bacterial diseases.42 N95 respirators are tight-fitting and prevent inhalation of 95% of airborne particles.42 Given the variation of facial size and proportions, N95 masks must be “fit-tested” to ensure an adequate user seal. Proper donning of an N95 mask (i.e., not pinching the nose bridge but ensuring it fits along the entire maxilla) is a critical step in adequate PPE.43

Personal protective equipment for droplet and contact precautions includes a surgical mask, eye protection (goggles or procedure mask with face-shield), an Association for the Advancement of Medical Instrumentation (AAMI) level-2 gown, and gloves that overlap the gown sleeve enough to prevent wrist exposure during movement.40 Gowns may offer better protection than aprons.40

Personal protective equipment for airborne, droplet, and contact precautions consist of head covering, eye protection, N95 respirator, an AAMI level-2 (or higher) gown, and a single pair of gloves overlapping the gown sleeve enough that movement does not expose the wrists.40 We recommend airborne, droplet, and contact precautions be maintained for the period of time required to disperse airborne particles as per local IPAC guidelines. The expected dispersal of airborne particles in a room (as a function of air changes per hour) has been reported by US Centers for Disease Control (Table 2).34 The role that airborne particles (< 5–10 µm) play in the spread of COVID-19 disease remains unclear. Nevertheless, it has been shown to occur opportunistically19 during the SARS-CoV spread.20 The addition of airborne precautions to the usual recommendation of droplet and contact precautions is likely not required for most routine patient care situations. Once the recommended dispersal times following an AGMP has elapsed, droplet and contact precautions can be resumed.

The use of PPE for high-risk AGMP precautions should be reserved for healthcare providers only directly involved in the performance of high-risk AGMPs—e.g., airway managers and assistants. In addition to the airborne, droplet, and contact precautions above, we recommend neck covering, a gown with AAMI level-2 (or higher), and two sets of gloves that overlap the gown sleeve enough to prevent wrist exposure during movement (Fig. 2). In a 2019 Cochrane review of PPE, double gloving was associated with less contamination than single gloving (relative risk, 0.36; 95% confidence interval, 0.16 to 0.78).40 It also allows the healthcare provider performing airway management to doff a heavily soiled pair of gloves without breaching their overall PPE.

Limiting the number of people in the room when a high-risk AGMP is taking place is critical as it reduces the number of people exposed and assists in preserving the PPE supply. Due to the nature of high-risk AGMPs, it may not be possible for the patient to wear a surgical mask; however, if possible, one should be donned by the patient.27

There is some controversy over whether neck covering is required when performing high-risk AGMPs, we would advocate for its inclusion as long as it does not impair the operator’s neck movement, particularly during airway management. Neck protection helps decrease the droplet contamination shown to occur in this area.38,39 We recognize that neither neck nor head protection is included in the current WHO15 or PHAC37 guidelines for high-risk AGMPs. While the airway managers’ wrists are easily decontaminated through requisite hand-washing both during and after the doffing procedure, the neck and head areas are not. The neck area has been identified as a zone of high contamination during simulated airway management AGMPs.38,39 While the head and neck do not contain mucous membranes, they are in close proximity above and below facial mucous membranes. If contaminated, these exposed areas could serve as a source of further contamination both during the PPE doffing process or afterwards during clothing removal. This is particularly true when removing other clothing in an over-the-head fashion (e.g., surgical scrubs or sports bras). Therefore, we propose head and neck covering, when done properly in a coordinated manner with other PPE equipment, could potentially reduce the risk of subsequent self-contamination by reducing the amount of skin exposure and contamination at the outset while preforming high-risk AGMPs. We also advocate for the availability of resources to allow healthcare providers access to shower facilities after directly participating a high-risk AGMP, if possible. While a post-doffing shower has not been studied, there is likely little harm.

Importantly, there may be certain situations where personnel not directly involved in the high-risk AGMP must remain in the room—e.g., cardiac arrest or fetal distress. There is no clear guidance to inform the optimal PPE strategy in these situations and research is ongoing. Nevertheless, the International Liaison Committee on Resuscitation currently recommends that (assuming the patient is not already tracheally intubated) during chest compressions, the same PPE be used as for other AGMP, which is currently identified as airborne, droplet, and contact precautions.44 Defibrillation, a time sensitive intervention, should be considered during the donning of high-risk AGMP PPE. An automated chest compression device (e.g., LUCAS Chest Compression System; Stryker Medical, Portage, MN, USA) should be considered to decrease healthcare provider exposure.45 Therefore, the minimum amount of PPE worn by all providers during cardiac arrest resuscitation should consist of airborne, droplet, and contact PPE. If any airway management is required, those directly involved and unable to step away (or out of the room) should don PPE with airborne, droplet, and contact precautions for high-risk AGMPs.45

Disposable shoe covers may or may not increase risk of self-contamination during the doffing process as evidence is only from small studies.46 Coveralls with an integrated hood (i.e., “bunny suit”) may theoretically have the advantage of simplifying the doffing process (e.g., by removing a single garment that integrates gown, neck cover, and head cover). Nevertheless, doffing a one-piece coverall can also be complex and must be practiced. It does not eliminate the need for a doffing spotter or person to guide the doffer through the doffing process. There is currently no direct evidence that one combination of specific PPE for high-risk AGMP has any advantage over another. As long as the principles of the protection required for high-risk AGMP PPE are applied, the exact combinations of the various enhanced PPE components are likely not as important.

An important factor to consider is practitioner familiarity with PPE—that is, the more unfamiliar staff is with PPE, the more likely they will incorrectly don and doff it, leading to potential contamination. Therefore, primacy should be given to PPE that is safe and most familiar to healthcare providers. Similarly, it is important to stay informed and in discussion with institutional IPAC representatives. We discourage healthcare professionals from creating and using their own combinations of PPE without discussion and approval with their IPAC.

A power air-purifying respirator (PAPR) incorporates headgear with either a full body coverall, or separate head and shoulders covering only. A PAPR is not routinely recommended during the care of COVID-19 patients undergoing an AGMP but may be used in some institutions.47 Power air-purifying respirators have a hose attached to a high efficiency particulate air (HEPA) filter and its use theoretically eliminates the need for an N95 respirator. As such, it may be useful for healthcare providers who cannot be fitted with an N95 respirator. Nevertheless, some healthcare providers also don an N95 respirator inside the PAPR to help reduce self-contamination during the doffing process, or to maintain protection against airborne viral inhalation after doffing outside of the patient room in the absence of negative pressure or negative flow isolation. Again, we recommend liaising with local institutional IPAC personnel to inform these types of decisions. The positive pressure generator can be noisy and may impede hearing (and potentially even vision) during an AGMP. Training and practice with the institutional PAPR are required to prevent breaching of the PPE during procedures and/or self-contamination during doffing.