key: cord-0833745-vprl94qy
authors: Zhang, Mingzhu; Emery, Andrew Robert; Tannyhill, R. John; Zheng, Hui; Wang, Jingping
title: Surgical Masks or N95 respirators for OMF Surgery during COVID-19 pandemic
date: 2020-08-27
journal: J Oral Maxillofac Surg
DOI: 10.1016/j.joms.2020.08.024
sha: 331941200dd34003aca417a76758c587fc9bc77c
doc_id: 833745
cord_uid: vprl94qy

PURPOSE: Coronavirus Disease 2019 (COVID-19) has caused suffering and death around the world. Careful selection of facial protection is paramount for preventing virus spread among healthcare workers and preserving mask and N95 respirator supplies. METHODS: This paper is a comprehensive review of literature written in English and available on Pubmed comparing the risk of viral respiratory infections when wearing masks and N95 respirators. Current international oral and maxillofacial surgery guidelines for mask and N95 respirator use, patient COVID-19 disease status, aerosol producing procedures were also collected and incorporated into a workflow for selecting appropriate facial protection for oral and maxillofacial surgery procedures during the current pandemic. RESULTS: Most studies suggest N95 respirators and masks are equally protective against respiratory viruses. Some evidence favors N95 respirators, which are preferred for higher risk procedures when aerosol production is likely or when the COVID-19 status of a patient is positive or unknown. N95 respirators may also be used for multiple patients or reused depending on the type of procedure and condition of the respirator after each patient encounter. CONCLUSION: N95 respirators are preferred over masks against viral respiratory pathogens, especially during aerosol generating procedures or when a patient’s COVID-19 status is positive or unknown.

The primary route for the spread of COVID-19 is through aerosolized droplets that are expelled during coughing, sneezing, or breathing. Health care workers (HCWs) caring for patients with COVID-19 are at high risk for nosocomial transmission, especially during various aerosol generating procedures. Meanwhile, the shortage of personal protective equipment (PPE) has made it difficult to continue working safely and to reduce the risk of exposure to virus particles and infection among HCWs. Oral and maxillofacial surgeons (OMSs) are particularly vulnerable as they perform surgeries in and around the mouth and face, and commonly perform inoffice anesthesia via IV sedations and general anesthetics. As a result, OMSs accept great risk caring for patients and require deliberate and thoughtful PPE selection, particularly when choosing mouth and nose coverings.

The purpose of this study was to compare the protective effects of masks and N95 respirators against SARS-CoV-2 and similar viruses. The investigators hypothesized that aerosol generating procedures with COVID-19 positive or unknown patients would require respirators, and that non-aerosol generating procedures and asymptomatic patients may be safely treated with medical or surgical masks. The specific aims were: 1) compare the protective effects of masks and N95 respirators against SARS-CoV-2 and similar viruses, 2) compare recommendations for masks and N95 respirators in low and high risk OMS procedures, 3) apply N95 extended use and reuse policies to OM surgery, and 4) create a workflow for selecting facial PPE based on OMS procedure type, patient risk, and reusability of N95 respirators.

The study was designed to make a comprehensive review of the efficacy of PPE for mouth and nose protection, especially in OM surgery. N95 respirators and surgical masks, which are the most common forms of facial PPE, were selected as the predictors. To address the research purpose, the investigators designed and implemented a comprehensive review modeled after the Cochrane Collaboration's recommendations for systematic reviews. Publication searching was conducted using PubMed and the study population was composed of all publications on the topic of "coronavirus", "COVID-19","SARS-CoV-2", "Aerosol and droplet transmission", "N95 respirators", "Surgical mask"; "Personal Protective Equipment (PPE)"; "Maxillofacial J o u r n a l P r e -p r o o f procedures", "Oral and Maxillofacial Surgeons (OMFSs)" between January 1, 2000 and July 7, 2020). Peerreviewed articles or followed clinical trial results were included in the study sample. We also checked government websites (CDC) and hospital websites for policies regarding COVID-19 protection. Publications were excluded from analysis if studies were focused on laboratory exposure simulations, non-health care workers, other types of respirators and surgical masks, and written languages other than English. Laboratoryconfirmed respiratory infection or influenza-like illness was screened as the outcome for review and analysis. A descriptive summary and table of the reviewed publications was made, as shown in the result part.

For this review, 8 studies were included to assess the effectiveness of surgical masks versus N95 respirators in protecting against viral respiratory infection. Of the 8 studies, 5 were RCTs, 1-6 1 was a cohort study, 7 and 2 were case-control studies 8, 9 (Table 1) . Six studies were extracted from a previously published meta-analysis 10 and the results showed no significant difference between N95 respirators and surgical masks in the associated risk of laboratory-confirmed respiratory infection (RCTs: OR 0.89, 0.64-1.24; cohort study: OR 0.43, 0.03-6.41; case-control studies: OR 0.91, 0.25-3.36) and influenza-like illness (RCTs: OR 0.51, 0.19-1.41). In addition, a large randomized clinical trial (RCT) performed in China 5 was included in Table 1 , which showed that rates of all outcomes of infection were lower in the N95 groups, while another large RCT performed in the US showed there was no significant difference in the incidence of laboratory-confirmed influenza 6 .

The WHO's recommendations about when to use a surgical mask versus an N95 respirator based on pathogens and situational risks were used to create Table 2 . Table 3 converts the information from Table 1 and   Table 2 into recommendations for OMSs and anesthesiologists based on the dichotomy of a patient's fever status charted against the type of patient encounter area. International guidelines on mask and respirator use during COVID-19 from oral-maxillofacial surgery associations, journals, and relevant government websites cited in the oral-maxillofacial surgery literature are represented in Table 4 . [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] The mask or respirator most frequently cited for each scenario is represented by the highest tally of checkmarks associated with each J o u r n a l P r e -p r o o f scenario. Overall, N95 respirators were the favorite in all scenarios, except when performing non-aerosolgenerating medical procedures (non-AGMPs) on symptomatic patients, which favored surgical masks, and when performing aerosol-generating medical procedures (AGMPs) on COVID positive patients, which favored N99 respirators. Table 4 also collates global oral-maxillofacial surgery recommendations pertaining to facial PPE during COVID-19, with a comparison of mask/respirator rating systems used in the United States and Europe, as seen in the right two columns. [25] [26] [27] [28] [29] [30] Tables 2 through 4 , and supplementary literature on facial PPE, 18,31-33 helped form the workflow seen in Figure 1 for mask or respirator selection prior to an AGMP or non-AGMP. It also provided a workflow following AGMPs when deciding eligibility for respirator re-use, extended use, or replacement. The workflow for mask or respirator selection starts with patient COVID status, then assesses procedure type (AGMP or non-AGMP), followed by procedure length, and secondary layers of facial protection. Following an AGMP, there is then the question of visible mask contamination, which then leads to disposal if present, potential extended use if patient has respiratory symptoms, or re-use if the patients are symptom free.

For viruses causing acute respiratory diseases (ARD), the main mode of transmission is by contact, droplets, and aerosols or airborne particles. Droplet transmission refers to large particles (>5 μm) that have very low risk of transmission beyond 1-2 m and sink rapidly in the air. In contrast, airborne transmission allows for relatively long-distance travel over 2m by aerosols of multiple different sizes. Aerosols can vary in size and include small droplets and droplet nuclei. Aerosols <5-10μm in diameter follow airflow streamlines, and transmission may be over a short or long range. Small aerosols (<5μm) can reach the alveolar spaces. Large aerosols (<10μm) can penetrate below the glottis, 34,35 while those >20μm fall mostly under the influence of gravity without following airflow streamline 34 .

Aerosols are produced during everyday activities such as breathing, coughing, sneezing, or talking.

Healthcare workers are often exposed to higher aerosol levels during AGMP 36 which are various, but include J o u r n a l P r e -p r o o f the following: (1) bronchoscopy, cardiopulmonary resuscitation, manual ventilation, tracheal intubation, sputum induction suctioning, and nebulizer treatment; (2) noninvasive ventilation such as bilevel positive airway pressure (BiPAP) therapy, ccontinuous positive airway pressure (CPAP) therapy, and high-frequency oscillatory ventilation (HFOV); (3) oral-maxillofacial surgeries that utilize lasers, or pneumatic or electric tools, such as rotary drills and saws. These procedures can either mechanically create and disperse aerosols or provoke patients to produce aerosols, and are recognized as essential sources of respiratory virus transmission in hospitals 37 .

The risk of aerosol exposure lies in the potential they have to carry infectious organisms, mainly viruses.

The family of Coronaviridae contains viruses that are known to be transmitted between humans routinely through an aerosol route, such as Middle East Respiratory Syndrome Coronavirus (MERS-CoV) and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). During the SARS outbreak in 2003, many HCWs suffered severe illness and death, suggesting nosocomial transmission of Coronavirus is significantly associated with AGMPs 37,38 . Therefore, reducing exposure to aerosol production is vitally important to the safety of healthcare workers.

More than 1700 HCWs had confirmed COVID-19 in China due to lack of self-protection as of February 11, 2020 39 . Meanwhile, one case report described 41 HCWs (85% wearing surgical masks, and the rest wearing N95 respirators) who were exposed for at least 10 minutes during AGMPs, including intubation, extubation, and non-invasive ventilation. After 2 weeks of quarantine, it was reported that no one developed symptoms, and all COVID-19 Polymerase chain reaction (PCR) tests were negative 40 . This raises the question as to what the safety efficiency is for the use of surgical masks combined with other standard procedures compared with using respirators during COVID-19 pandemics. Masks and respirators are recommended for diseases spread by droplet transmission and aerosol transmission, but recommendations and terminology differ among the various different guidelines 41 .

A surgical mask prevents aerosol produced by the wearer from spreading to the patient or into the environment, which is the original design purpose. At the same time, it can be used as a liquid barrier to prevent the wearer from being contaminated by blood and large droplets 42 . The N95 respirator is a National Institute for Occupational Safety and Health (NIOSH) certified respiratory protection device designed to reduce aerosol exposure. The term "N95" indicates that the respirator blocks at least 95 percent of test particles of 300 nm.

Laboratory studies have shown that the most penetrating particle size (MPPS) of N95 respirators is 0.03-0.1μm , and of surgical masks it is approximately up to 0.3μm 43 . Surgical masks may not provide substantial protection from aerosol of at least up to 0.5μm 43 . Furthermore, it has been shown that for nano-sized airborne viral agents, the blocking ability of some N95 respirators may be less than 95%, which was even lower for surgical masks 42 . Both SARS-CoV-2 and SARS-CoV are about 85 nm in size 44 , and it can be inferred that the new coronavirus that causes COVID-19 is of similar size. Table 2 shows the risk situations described in influenza guidelines 45 and recommendations according to World Health Organization (WHO) 46 . It is recommended for HCWs in direct contact with infected patients to wear N95 respirators, not surgical masks, during the current COVID-19 epidemic.

There have been several clinical studies comparing the effectiveness of N95 respirators and medical masks on the protection of the virus's infection. As shown in Table 1 , six studies included in meta-analysis 10 showed no significant difference between N95 respirators and surgical masks in terms of protective effect. At the same time, this review collected 23 surrogate exposure studies which showed that N95 respirators were associated with less filter penetration, less face-seal leakage and less total inward leakage under experimental laboratory conditions. Similarly, the remaining two studies from Table 1 indicated that the N95 was superior in one situation 5 and equal to the surgical mask in the other one 6 . The mixed results of these studies fail to identify the superior choice for facial PPE among N95 respirators and surgical masks, and thus indicate that more RCTs are needed to make a clinical conclusion. However, some sources advocate for the use of respirators in some risk situations, as shown in Table 2 45 . In addition to using masks and respirators, successful prevention of disease spread also relies on education programs, user compliance, and other preventative hygiene protocols.

There are few studies analyzing the cost-effectiveness of masks. A study conducted during the influenza season in China showed that the cost of wearing an N95 in order to prevent a single case of a clinical respiratory illness (CRI) was US $490-$1230 more than if only medical masks were worn. In a high incidence period, the incremental cost can even be much lower, which suggests continuously using respirators may be a cost-effective choice when there is a pandemic like COVID-19 47 . This information provides new evidence for effective allocation of medical resources and medical decision making at the present time.

Mass General Brigham (MGB) is the largest health care system in Massachusetts, with 12 hospitals and more than 75,000 employees. In March 2020, extended use and reuse policies for masks and respirators have been adopted from the CDC published guidelines 31, 48 . Universal masking of all HCWs and patients with surgical masks at MGB was associated with a significantly lower rate of SARS-CoV-2 positivity among HCWs.

This association may be related to a decrease in transmission between patients and HCWs and among HCWs 49 .

Extended use of N95 respirators is allowed after AGMP in patients with presumed viral respiratory symptoms such that they can continue to be worn to see other patients, but once removed must be discarded and not redonned or reused (see Figure 1 ). If AGMP are done in patients with no symptomatology of a viral respiratory illness, then the N95 respirator may be redonned and reused after it has been doffed. Given that extended use is preferred over reuse, it is highly recommended to avoid the removal of N95 respirators as much as possible between patient encounters. At our institution, designated receptables (e.g. labeled storage containers such as a paper tray, paper bag, emesis basin) are used to store all N95 still eligible for reuse (based on above criteria).

The American Dental Association (ADA) and NIOSH recommend limiting the N95 reuse to 5 times 32 and N95 are believed to provide protection as designed for 8 hours of continuous or intermittent use 31 . With some oralmaxillofacial surgeries extending beyond 8 hours, particularly extensive orthognathic or craniofacial surgeries, resections and reconstructions, and for surgeons with longer average operating times, it may be more appropriate to wear a powered air-purifying respirator (PAPR) or controlled air purifying respirator (CAPR).

Additionally, it has also been found that SARS-CoV-2 can last up to 72 hours on plastic, cardboard, and J o u r n a l P r e -p r o o f stainless steel suggesting that donning and doffing of used, but non-soiled, respirators requires great caution so as not to contaminate the inside of the mask or oneself 50 .

Both N95 and surgical masks that are not soiled or damaged after use in clinical settings should be limited to only one work shift. In situations when N95 respirators are used in patients with viral respiratory symptoms, extended use guidelines should be applied which dictate that the N95 respirator be discarded the next time it is removed 31 .

The CDC reports that the benefit of face shields in preventing viral spread is not completely known and, as such, they advocate for cloth masks over face shields as the primary source of mouth and nose protection for the general public 51 . However, face shields worn by OMSs may serve as a second line of defense against aerosols and splatter when worn over masks or respirators. One notable consideration with adding a face shield over a mask or respirator is that many OMSs wear loupes to perform procedures which often stick out and prevent face shields from folding down completely. Some oral-maxillofacial researchers have looked into more appropriate designs that provide protection in a more customized way with the help of 3D printed face shields 52 . Properly designed face shields can ultimately help extend the usefulness of respirators, especially when in short supply. The protective effect of the face shield is especially important for AGMPs in patients without respiratory symptoms where contaminating the mask would otherwise relegate it to be discarded the next time it is doffed, as opposed to being reusable if not visibly soiled. One study of influenza-laden cough aerosols found that face shields worn by providers reduce the surface contamination of a respirator by 97% when the provider is about 18 inches from the patient 33 . This benefit could lead to greater respirator reuse over time and overall greater PPE efficiency, especially since face shields can be cleaned and continually reused. Another benefit is that face shields create a barrier preventing inadvertent or subconscious urge to scratch or touch one's own face.

In a similar fashion, wearing a surgical mask over an N95 respirator for AGMP can help prevent direct contamination of the respirator to extend its use, especially since they are re-usable and more difficult to manufacture than more simple surgical masks.

Wearing masks for extended periods of time can be uncomfortable. Wearing an N95 respirator for extended periods of time can lead to nausea, shortness of breath, complaints of visual challenges, headache, lightheadedness, and difficulty with communication 53 .

It is also important to consider provider fatigue and barriers to compliance. One study found that wearing an N95 with an overlying surgical mask resulted in greater blood CO2 levels as compared to wearing an N95 alone. Although these levels of CO2 never met the definition of clinical hypercapnia (i.e. 45 mmHg or greater arterial CO2 levels), 25% of the time respirators needed to be removed due to discomfort over a 12-hour shift 53 . The CDC recommends taking scheduled breaks where providers can remove their respirator in a safe area 54 . Given the preference for extended use of respirators over reuse, we recommend avoiding respirator removal between AGMP and to block schedule AGMP patients in order to conserve supplies. Also, for longer procedures, such as in the OR, PAPR and CAPR may be more appropriate choices over N95 respirators.

Another issue is the discomfort experienced by prolonged use of masks with ear loops. This has motivated some to use ear guards or ear relief caps for face masks with ear loops 55 or alternative mask designs such as those that have two sets of strings that tie around the back of one's head. Greater mask/respirator comfort theoretically reduces the need to adjust mask leading to fewer opportunities for contamination of oneself or others and for greater overall compliance.

As OMSs and other healthcare providers struggled to acquire mask supplies during some of the busiest periods of the pandemic, community members were also asked to take precautions by wearing masks. However, with masks and respirators in short supply, many have sought out homemade or cloth masks.

Although cloth masks are not recommended for healthcare providers during direct patient care, the general public is encouraged to wear some type of mask, regardless of the type 56 . Cloth masks in particular should be washed daily with soap and water 57 . Oral-maxillofacial surgery patients presenting to the clinic or hospital J o u r n a l P r e -p r o o f should, at minimum, wear a mask, either a disposable facemask or cloth mask. Doing so provides a barrier to protect patients from one another when in the same waiting room and clinical areas.

A recent study by Bidra et al 58 showed that povidone-iodine (PVP-I) oral antiseptic rinse of various concentrations can inactivate SARS-CoV-2 within 15 seconds suggesting potential utility as an adjuvant to existing treatment algorithms for treating dental and oral-maxillofacial surgery patients with known or unknown COVID-19 status. By reducing the infectivity of oral secretions, the clinician will be afforded greater protection during AGMP in the oral-maxillofacial surgery clinic or operating room and will ultimately reduce the burden on masks and N95 respirators as the sole mechanism of preventing SARS-CoV-2 transmission. In addition, it could also reduce the infectivity of the smaller aerosols that unknowingly contaminate the provider's mask.

In the midst of COVID-19, the daily work of the OMS must continue to be carried out in a routine and orderly fashion. The question remains of how to choose among different forms of mouth and nose protection and how to then use them properly to adequately protect HCWs. Other options for mouth and nose protection are also available, such as PAPR, CAPR and elastomer half-face respirators (EHFRs) for OMSs and anesthesiologists, and barrier enclosures with/without negative pressure for patients 59 . These high-level PPE are often available in limited quantities and require complicated don/doff procedures, and are, therefore, only used in select situations. For OMSs and anesthesiologists in most countries and patient care settings, surgical masks and N95 respirators are the most commonly used daily mouth and nose protection equipment. There are two major considerations when making a choice: first, the classification of the patient--whether he/she is with or without fever, or with suspected or diagnosed COVID-19; and second, whether the procedure is in a low-or high-risk situation ( Table 2) . For OMSs and anesthesiologists, AGMPs are experienced each day in the J o u r n a l P r e -p r o o f operating room (OR) and clinic, during bronchoscopy, cardiopulmonary resuscitation, manual ventilation, tracheal intubation and extubation, suctioning and surgeries (especially using drills and ultrasonic instruments).

In most cases, the patient who is undergoing surgery has been risk graded before being admitted to the operating room. In the operating room, some of the most high-risk or aerosol producing moments involve anesthesia induction and intubation, patient awakening and extubation, and during aerosol generation from surgical instrumentation 60 . Since OMSs are often aiding the anesthesiologist with routine or difficult intubations by holding jaw thrust or holding the tongue forward, they are also susceptible to aerosol generated from patient coughing. Aerosol production from coughing is especially likely during awake fiberoptic intubations for difficult airways such as for severe odontogenic infections. As a result, anesthesia clinicians have developed intubation hoods that are draped over the patient during traditional endotracheal intubation and extubation, and most recently for fiberoptic intubation 61 . For oral-maxillofacial surgical trainees and attendings, having a barrier during intubation and extubation may help augment the protection provided by wearing a respirator. Regarding AGMP from surgical instrumentation in the operating room, it is advantageous to supplement N95 respirator use with a face shield if possible, or at least an overlying surgical mask to protect respirators from direct contamination that may compromise their filtering capacity (Figure 1 ). Patients that have tested negative for COVID-19, or are afebrile and asymptomatic, can be treated with standard PPE inside the operating room as was done pre-COVID.

At the same time, OMSs and anesthesiologists are also involved in medical procedures outside the OR, such as outpatient clinics, patient transport, and care at the bedside, which do not involve a significant risk of AGMPs. However, in areas outside the OR, there exists a large number of patients and people with unknown nosocomial transmission risk. As such, it is necessary to assess the risk of each location and respond with appropriate PPE 62 . For example, the emergency room and fever clinics are more likely to have COVID-19 patients than routine outpatient clinics and wards. Table 3 summarizes the recommendations for the choice of surgical mask and N95 respirator in the daily work of OMSs and anesthesiologists and Table 4 J o u r n a l P r e -p r o o f J o u r n a l P r e -p r o o f Abbreviations: AGMP (aerosol generating medical procedure), PAPR (powered air-purifying respirator), CAPR (controlled air-purifying respirator), ASTM (American Society for Testing and Materials), BFE (bacterial filtration efficiency), PFE (particle filtration efficiency)

Note: medical masks and surgical masks are the same in this table; AGMPs were described slightly differently in each paper, but generally involve operating room procedures or the use of drills or ultrasonic instruments 

Surgical mask vs N95 respirator for preventing influenza among health care workers: A randomized trial

A cluster randomized clinical trial comparing fit-tested and non-fit-tested N95 respirators to medical masks to prevent respiratory virus infection in health care workers

Efficacy of face masks and respirators in preventing upper respiratory tract bacterial colonization and co-infection in hospital healthcare workers

A randomized clinical trial of three options for N95 respirators and medical masks in health workers

The efficacy of medical masks and respirators against respiratory infection in healthcare workers

N95 respirators vs medical masks for preventing influenza among health care personnel: A randomized clinical trial

SARS among critical care nurses

Effectiveness of precautions against droplets and contact in prevention of nosocomial transmission of severe acute respiratory syndrome (SARS)

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Chirurgie Maxillo-Faciale et Chirurgie Orale (SFSCMFCO)

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Barrier enclosure during endotracheal intubation

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Strategy of using personal protective equipment during aerosol generating medical procedures with COVID-19

• Close contact within 2 meters of the patient

• Entering infectious patient's room

• When infected patient used masks

• Routine care

• During patients' transport

• Before and after patients contact and risk of splashes into face. • Aerosol generating procedures

• Procedures involving the respiratory tract

• Laboratory specimen collection from respiratory tract

• If patients cough forcefully

• If patients do not comply with respiratory hygiene

• When patients may not be able to wear mask

• Mortuary and critical care areas

Abbreviations: PPE (personal protective equipment), RSV (respiratory syncytial viral), SARS (severe acute respiratory syndrome)

Data from World Health Organization (WHO): Infection prevention and control of epidemic-and pandemic-prone acute respiratory infections in health care

J o u r n a l P r e -p r o o f • Consistently wearing a mask or a N95 while caring for a SARS patient was protective, and consistent use of the N95 mask was more protective. • 89.4% of participants reported "always" or "sometimes" wearing their assigned devices in the respirator group vs 90.2% in the mask group. *1-6 were included in the meta-analysis: Effectiveness of N95 respirators versus surgical masks in protecting health care workers from acute respiratory infection: a systematic review and meta-analysis 10 .Abbreviations: RCT (Randomized controlled trial), CRI (credible interval), OR (odds ratio), RR (relative risk), HR (hazard rate), SARS (severe acute respiratory syndrome), HCP (health care personnel).