Some health care systems continue to struggle with large numbers of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)–infected patients, but epidemiologic models1 have predicted that many others will be faced with a lower but variable prevalence of disease. The time course of the pandemic is unpredictable, and there is the possibility that the SARS-CoV-2 virus could become endemic, as with some other coronaviruses.2,3 The virus will produce significant recurrent outbreaks of infection until there is “herd immunity”a4 from broad application of a vaccine or until a sufficient proportion of people have been infected naturally, assuming that there is a long-lasting and protective immune response. Despite the lack of herd immunity, less affected facilities are progressively resuming elective procedures. In some instances, procedural volumes and anesthesia workload may be even larger than before the SARS-CoV-2 pandemic due to a worldwide backlog of approximately 28 million procedures that were delayed in preparation for the surge of patients infected with SARS-CoV-2.5 Delays in performing nonurgent surgery have resulted in both hardship for patients and lost revenue for health care facilities and providers.
Among the challenges will be protecting patients and providers from recurrent outbreaks of disease while increasing procedure throughput. We present here an approach to routine anesthesia care in the setting of variable prevalence of SARS-CoV-2 infection. We should emphasize that the approach we describe applies to patients who are not known or suspected to be infected with SARS-CoV-2. Patients known or suspected of being infected require a more elaborate approach, as previously described.6–9
In response to the human immunodeficiency virus (HIV) epidemic during the early 1980s, the Centers for Disease Control and Prevention (CDC) encouraged a policy of “Standard Precautions,” which were outlined in a guidance document. As reported by the CDC, “The 1987 document recommended that blood and body fluid precautions be consistently used for all patients regardless of their bloodborne infection status. This extension of blood and body fluid precautions to all patients is referred to as ‘Universal Blood and Body Fluid Precautions’ or ‘Universal Precautions.’ Under universal precautions, blood and certain body fluids of all patients are considered potentially infectious for HIV, hepatitis B virus (HBV), and other bloodborne pathogens.”10 A key feature of these recommendations is that all patients are considered to be potentially infected. The universal precautions approach, now more commonly known as standard precautions, recognizes the imperfections of testing for disease, including limitations in the availability of testing and falsely negative test results, which may occur for a variety of reasons. Today, most health care providers routinely practice standard precautions against bloodborne infection, such as the wearing of nonsterile examination gloves to prevent contact with blood and other fluids and prevention of needle stick injuries.
Before the SARS-CoV-2 pandemic, most anesthesia providers infrequently experienced the need for precautions against transmissible respiratory infectious organisms, the most common examples being tuberculosis and seasonal influenza. However, the SARS-CoV-2 pandemic is only the most recent of a series of novel respiratory virus epidemics that have occurred in the 21st century (SARS-CoV, 2003; H1N1 influenza, 2009; Middle East respiratory syndrome coronavirus [MERS-CoV], 2012). We are now faced for the foreseeable future with the need for an approach not only to bloodborne threats such as HIV and hepatitis viruses but also to respiratory disease threats, especially SARS-CoV-2. Should we practice respiratory precautions for anesthesia care, that are analogous to “standard bloodborne precautions”? Should we implement certain respiratory precautions for the duration of the SARS-CoV-2 pandemic or even beyond the pandemic?
We would argue that the answer to these questions is “Yes, we should practice certain respiratory precautions for the duration of the SARS-CoV-2 pandemic.” Our knowledge of SARS-CoV-2 virology and epidemiology is evolving rapidly, and a comprehensive review is beyond the scope of this article. However, there are several key aspects of SARS-CoV-2 infection to consider. First, SARS-CoV-2 is spread by respiratory droplets (≥5 μm), by contact with fomites, and by airborne transmission (<5 μm; ie, droplet nuclei).11–13 In all likelihood, there is a continuum of droplet and airborne spread of many respiratory pathogens.14–16 While the relative importance of airborne spread for SARS-CoV-2 is unknown, aerosolizing procedures, such as airway management, are thought to increase the risk of airborne spread of respiratory viruses.17–19 Second, there is evidence that SARS-CoV-2 can be spread by asymptomatic and presymptomatic patients.20–23 A substantial portion, if not the majority, of infected persons are asymptomatic.22,24,25 Third, testing for SARS-CoV-2 infection is problematic because of the limited availability of testing in many places and false-negative results.26,27 While the rate of false-negative tests is uncertain and may vary greatly depending on the particular circumstances, available evidence suggests that this frequency could be substantial.26–34 Given the possibility of airborne spread and the practical difficulty of determining who is infected, we propose a strategy similar to standard bloodborne precautions. For the time being, we should assume that any patient may be infected with SARS-CoV-2.
Table 1. -
Recommended Infection Prevention Precautions
Respirator mask during anesthetic care
Such as N-95 or FFP-2. Assumes abundant supply of masks. Conservation efforts should be implemented if in short supply.
Ordinary surgical masks in public areas of the health care facility and operating room complex (“universal masking”)
Recommended by CDC. Assumes abundant supply of masks. Reusable cloth masks could be used if surgical masks are not available in sufficient quantities.
Hand gel close to provider or personal, wearable gel dispenser
Frequent hand hygiene is essential for personal protection and protects patients from hospital-acquired infection.
Eye protection at all times during anesthesia care
Required by US Department of Labor, Occupational Safety and Health Administration Standard 1910.1030.
|HEPA filter (or similar) on exhalation side of anesthesia circuit (at least) and/or between the airway and the Y of the circuit (to filter gas in both directions)
||HEPA filter (or similar) effectively filters small particles including viruses.
|Reusable standard and videolaryngoscopes should undergo high-level decontamination or sterilization
||Recommended by CDC. Consider single-use standard and videolaryngoscopes if available and cost-effective. Be aware that some videolaryngoscopes cannot undergo high-level decontamination or sterilization (Supplemental Digital Content, Table 1, http://links.lww.com/AA/D186).
|Avoid entering anesthesia cart without performing hand hygiene first
||Contents of anesthesia cart are easily contaminated during use.
|Single-use plastic covers for parts or all of anesthesia machine and anesthesia computers, keyboards, and touchscreens
||Covers can reduce bioburden on contaminated, difficult to clean surfaces.
|Wipe anesthesia machine high touch areas with hospital antiseptic wipes (if not covered with plastic covers)
||High touch areas of anesthesia machine have been shown to be frequently contaminated.
|Double glove for airway management
||Discard the outer glove immediately following airway management to limit surface contamination.
|Enclose cell phones and other personal communications devices in plastic bags or wipe with antiseptic wipes compatible with electronic devices
||Cell phones have been shown to be contaminated with antibiotic-resistant pathogens during use in the hospital.
|Manage endotracheal tubes to minimize aerosolization following placement
||HEPA filter (or similar) on open lumen of double-lumen tube during single lung ventilation.
|Consider gowns for airway management
||Gowns could be used during airway management to protect providers’ skin and clothing from contamination. Be aware of variable permeability of gowns depending on rating.
|Consider airway management adjuncts such as covers and boxes
||Effectiveness has not been well studied and may interfere with airway management.
|Consider surgical smoke evacuation
||Risk of infection of providers by surgical smoke is unknown, but surgical smoke evacuation was a recommended practice before the SARS-CoV-2 pandemic.
|Consider how to protect the surgical team
||The surgical team should consider whether to utilize N-95 masks and whether to vacate the operating room during airway management.
|Consider discussing infection prevention measures during the “time out” (safety checklist)
||Be aware that not all providers can be fit for N-95 masks.
Key recommendations are in boldface.
Abbreviations: CDC, Centers for Disease Control and Prevention; HEPA, high-efficiency particulate air; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
We should evolve precautions that are practical, affordable, and efficient in the anesthesia setting while considering the limited availability of personal protective equipment (PPE). At the same time, we should strive to improve the supply of PPE. In Table 1, we have proposed options for respiratory precautions that can be applied to all patients during anesthesia care, along with examples of evidence in support of the effectiveness of the proposed precautions, where evidence is available. In addition, explanations for our proposal are given below.
Respirator masks such as N-95 masks (or their equivalent, such as FFP-2 in the United Kingdom and European Union) appear to provide reasonable protection against both droplet and airborne spread of viruses.35 Respirator masks are distinguished from ordinary surgical masks because they are intended to make a tight seal against the face while filtering smaller particles and thereby limit the penetration of airborne particles. The N-95 designation means that at least 95% of 0.3 μm particles are filtered by N-95 mask material.36 N-95 masks are more effective for preventing the penetration of smaller particles compared to surgical masks by approximately 10 times.37,38 Whether this translates into more effective infection prevention by N-95 masks is uncertain. A meta-analysis of physical distancing, face masks, and eye protection suggested that N-95 masks had greater effect than surgical masks for preventing transmission of SARS-CoV-2 virus.39 Another meta-analysis of clinical trials of respiratory infection prevention in health care workers by N-95 masks compared to surgical masks was inconclusive40; none of the studies specifically addressed the anesthesia care setting. A “cluster randomized pragmatic effectiveness” study of N-95 masks versus surgical masks for prevention of seasonal influenza in outpatient health care workers found no difference in the incidence of influenza.41
There is limited information about the capability of N-95 mask material to filter specific viruses. Eninger et al42 found that Bacillus subtilis phage, enterobacteriophages MS2 and T4 penetration of N-95 mask material was <5% at 85 L/min airflow. However, N-95 mask filtration capability assumes an effective seal of the mask to the face, which may be problematic. Grinshpun et al43 and Cho et al37 studied penetration of particles during N-95 mask wearing by humans and manikins and found that leakage around the mask was substantially greater than penetration through the filtering material of the mask. The National Institute for Occupational Safety and Health (NIOSH) testing of N-95 masks tests the filtering capability of the mask material36 but does not test whether particles leak around the edges of the mask. It should be noted that the fit and filtering performance of ordinary surgical masks is also highly variable.38
Considering that nearly every anesthetic involves airway management and the potential production of aerosolized respiratory secretions, we and others (see below) recommend that an N-95 or better respirator should be used by anesthesia providers for every anesthetic procedure regardless of SARS-CoV-2 infection test results. Because most anesthesia providers routinely wear ordinary surgical masks while providing anesthetic care, the routine use of an N-95 mask would ideally be a relatively minor modification of usual practice, while probably providing greater protection than an ordinary surgical mask. The routine use of an N-95 or similar respirator in the operating or procedure room has been recommended during the SARS-CoV-2 pandemic by the American Society of Anesthesiologists (ASA),44,45 the American Association of Nurse Anesthetists,45 the Anesthesia Patient Safety Foundation,45 the American College of Surgeons,46 the Academy of Otolaryngology-Head and Neck Surgery,47 and by an editorialist of the Journal of the American Medical Association.48
Despite the advisability of using N-95 and similar respirator masks to provide protection from respiratory viruses, these masks have serious limitations.35 Users must be “fit tested” to assure that there is an adequate seal between the mask and face. In the United States, employers are required by government regulation to perform fit testing.49 Facial hair typically prevents an adequate seal. Users have to be fitted to a specific brand and model of mask. If the particular mask is not available, users have to be fit tested for a different mask. Some providers may not be successfully fitted to any available N-95 mask; under these circumstances, the use of a powered air purifying respirator (PAPR) or fit-tested elastomeric mask could be considered (see below). Even for users who have been successfully fitted to a mask, the seal may not be perfect and may leak during use. Coffey et al50 studied 18 different N-95 respirators and found wide variation in performance. They determined that some respirators had “good fitting” performance and some had “poor fitting” performance and that fit testing was more beneficial for the “poor fitting” masks. N-95 respirators are intended for single use only, although during times when respirator masks are in short supply, judicious reuse can be considered, as previously described.51–55 Wearing a standard facemask over the N-95 respirator could help to preserve the N-95 for reuse by preventing gross contamination by splashes, although doing so may increase the work of breathing.56 Many users of N-95 masks report difficulty breathing as there is more airflow resistance than with surgical masks. Some users report nasal stuffiness, discomfort, and even skin breakdown from prolonged use of N-95 masks. Lee and Wang57 found that an N-95 respirator increased inspiratory and expiratory nasal resistance by over 100% and decreased airflow by an average of 37%. Some N-95 masks have unfiltered exhalation valves to make breathing easier; however, these would not be desirable in the operating or procedure room as it could expose the sterile field to unfiltered air.
The use of PAPRs has been suggested for airway management of patients with known or probable SARS-CoV-2 infection.6 The main advantages of PAPRs are a theoretically greater level of protection and elimination of the need for fit testing; providers who cannot be fitted to an N-95 could use a PAPR. However, when compared to the N-95 respirator, PAPRs seem unlikely to be adopted for use in routine anesthesia care because of their cost, complexity, and limited availability. Potential disadvantages of PAPRs include difficulty hearing due to fan noise, complicated cleaning protocols required for reuse, possibly greater risk of contamination during removal, possibility of malfunction, discomfort during prolonged use, and greater need for provider training. Concerns have been raised about whether use of PAPRs could result in contamination of a sterile field (because the exhaled gas is not filtered); however, a study by Howard et al58 suggested that PAPRs should be at least as effective as surgical masks in this respect. A clarification of appropriate use of PAPRs in the operating room was recently issued by the Association of periOperative Registered Nurses (AORN), ASA, and Anesthesia Patient Safety Foundation (APSF).59
Reusable elastomeric respirators are another option that is seldom considered in health care. Elastomeric respirators are tight fitting reusable masks made of rubber or synthetic material, with replaceable filter elements.60 Fit testing is required, as with an N-95 respirator. Some elastomeric respirators have unfiltered exhalation valves that should be avoided near sterile fields. A recent consensus report of the National Academy of Sciences, Engineering and Medicine and the CDC concluded that elastomeric respirators could be a viable option for respiratory protection in health care for both routine and surge use.61
Development of improved respirator masks is urgently needed due to the performance shortcomings and logistical difficulties posed by existing N-95, PAPR, and elastomeric respirators as noted above. An ideal, improved respirator should be inexpensive to produce in large quantities, should make a highly reliable air-tight seal for a wide range of faces (possibly avoiding or minimizing the need for fit testing), and should make breathing easy and comfortable. Reusable respirators should be easily cleaned and decontaminated. Novel designs for respirators are beginning to emerge (Figure 1).
Respirator masks should be produced in much larger quantities to address the current shortage (see Practical Difficulties below). Shortages have led to designs for “homemade” respirator masks.62
RESPIRATOR MASKS FOR THE SURGICAL TEAM
Anesthesia-related airway management is the portion of the surgical procedure most likely to result in aerosolization and risk of spreading infection from patients with unrecognized SARS-CoV-2 infection, aside from surgical cases directly involving the airway. If N-95 or similar masks are readily available, equipping the entire operating room team is an option; however, as previously noted, not all persons can be successfully fitted for an N-95 mask. If N-95 masks are in short supply, other approaches could be considered. The surgical team, including the nurses and surgeons, could vacate the operating room during airway management, including induction of anesthesia and emergence from anesthesia. Operating rooms normally have a slight positive pressure (see below) and higher air exchange, which will tend to disperse any aerosols relatively rapidly, although the time required will vary depending on the air exchange, how often operating room doors are opened, and other factors. The time required to remove airborne contaminants from an operating room can be estimated if the number of air exchanges per hour is known; typically, it takes approximately 7 total air exchanges to reduce contaminants by >99%. An operating room with 15 air exchanges per hour would require about 30 minutes to reduce the contaminants by 99.9%.63 Observing such wait times may not be actionable for a variety of reasons, but even shorter waiting times might reduce the risk. The American College of Surgeons has recommended routine N-95 masking for the surgical team during the SARS-CoV-2 pandemic, or if N-95 masks are in short supply, for the surgical team to vacate the operating room during periods of active airway management.46 Cautery or laser used during surgery could result in aerosolized particles, but unless performed in the respiratory tract, dispersion of infective SARS-CoV-2 viral particles may be unlikely. However, the use of N-95 masks by surgeons and the use of surgical smoke evacuation systems were advocated by the CDC64 and others65 as possible measures to minimize exposure to surgical smoke, before the SARS-CoV-2 pandemic. Discussion of the plan for respiratory precautions by the entire team would be a helpful addition to the preinduction “time out” (safety checklist).47
The conjunctiva is a possible route of infection by respiratory viruses.66–69 Therefore, eye protection is commonly advised during exposure to droplets or aerosols that may contain respiratory pathogens. A meta-analysis of observational studies suggested that eye protection helped to prevent infection by respiratory viruses.39 There is a paucity of information about exactly what eye protection should be used. The Occupational Safety and Health Administration (OSHA) describes the use of goggles or glasses with side protection in its standards for bloodborne pathogens.70 This standard would not be met by ordinary prescription eyeglasses which do not include side protection. Bischoff et al71 performed an interesting experiment concerning eye protection and masking in a small number of volunteers. They exposed the volunteers to aerosolized attenuated influenza virus under a variety of masking and eye protection conditions and measured the quantity of virus reaching the nasopharynx with quantitative reverse transcription polymerase chain reaction (RT-PCR). They showed that ocular exposure alone did result in measurable virus in the nasopharynx in 3 of 4 subjects. However, they were not able to show that wearing nonvented goggles improved the protection produced by wearing a surgical or N-95 mask alone, although the number of subjects may have been too small to measure the effect. Interestingly, in 1 of 5 subjects, influenza particles were found in the nasopharynx despite wearing a fit-tested N-95 mask and nonvented goggles.71
GOWNS AND “HAZARDOUS MATERIALS SUITS”
Gowns that cover part of the body or hazardous materials suits (also called coveralls or spacesuits) that cover the entire body have been widely utilized when caring for patients with known or suspected SARS-CoV-2 infection.6 The choice between a simple gown and a more elaborate hazardous materials suit appears to be based mainly on availability and local preferences. Gowns are also commonly used as part of a “standard” approach to patients who are under contact isolation due to a wide variety of other pathogens. Zamora et al72 demonstrated in a simulation study that a more elaborate approach with a hazardous material suit, hood, and PAPR provided greater protection from skin contamination than a less elaborate approach including a gown and N-95 mask but also found that the more elaborate approach was associated with a greater number of technical errors.73
Gowns are rated based on their permeability74; American National Standards Institute (ANSI)/Association for the Advancement of Medical Instrumentation (AAMI) protective barriers 70 (PB70) gown standards recognize 4 levels, ranging from minimal (level 1) to high risk (level 4).74 Level 1–3 gowns are tested for their permeability to water. Level 4 gowns are also tested for permeability to synthetic blood and to phiX174 bacteriophage, as a surrogate for Ebola and hepatitis B and C viruses.75 Level 4 gowns are ultrasonically welded and seam sealed to avoid the needle holes of conventional sewn garments. Repeated laundering of reusable gowns may cause the gowns to become more permeable.76 The role of gowns in protecting providers from infection with SARS-CoV-2 or other respiratory viruses is uncertain. There are no specific recommendations regarding types of gowns to be used for protection from respiratory viruses. Infection is presumed not to take place directly from contact between the virus and skin. However, virus particles on skin or clothing could be transferred to the respiratory tract by fingers. Therefore, it seems prudent to avoid SARS-CoV-2 contact with skin and clothing. On this basis, routinely wearing a gown during airway management or other aerosolizing procedure would appear to be a reasonable precaution.
ROUTINE WEARING OF SURGICAL MASKS INSIDE THE HOSPITAL AND OPERATING ROOM COMPLEX
While there is a paucity of high-quality data demonstrating the effectiveness of standard surgical masks or cloth masks for preventing infection, our basic understanding of the spread of respiratory viruses and available evidence suggests that the routine wearing of standard surgical masks or cloth masks may reduce spread by capturing droplets that could otherwise be spread by coughing, sneezing, and talking.39,77–81 The CDC has recommended that health care providers, patients, and visitors wear surgical masks while inside of a health care facility during the SARS-CoV-2 pandemic.82 Standard surgical masks should be worn within the operating room complex, including anterooms, corridors, patient holding and recovery areas, break rooms, and other spaces where staff may congregate. Anesthesia providers should remember that they or their fellow workers may have unrecognized SARS-CoV-2 infection.83
IMPLICATIONS OF POSITIVE PRESSURE OPERATING ROOMS
Conventionally, operating rooms maintain slightly positive pressure compared to adjacent areas (eg, hallways).63,84,85 Airborne infectious isolation rooms used for patients infected with potentially airborne pathogens have slightly negative pressure. The risks presented in conventional positive pressure operating rooms by contaminated air flowing to the adjacent hallways due to the pressure differential can be minimized by keeping operating room doors closed as much as possible (especially during aerosol-generating procedures) and by avoiding congregating outside of operating room doors. Anterooms, when available, offer another way of helping to contain contaminated operating room air. It is possible to convert positive pressure operating rooms to negative pressure84,85; however, whether it is desirable to do so is unclear; negative pressure might result in increased surgical wound infection by drawing air from dirty to clean areas.
HAND HYGIENE AND SURFACE CLEANING OF THE ANESTHESIA WORK AREA
Because the SARS-CoV-2 virus persists on surfaces13,86,87 and may be transmitted by contact with contaminated surfaces (from surfaces to fingers to respiratory tract), cleaning of the anesthesia work area, which is also important for prevention of bacterial hospital-acquired infections,88,89 takes on additional importance. SARS-CoV-2 is readily inactivated by sodium hypochlorite, alcohol, or hydrogen peroxide,86 and some other hospital approved disinfectants.90 Hand hygiene is also critical for protecting providers and patients; hand gel dispensers should be placed in close proximity to anesthesia providers. Hand gel dispensers should not be withheld from the operating room due to misplaced concerns about fire safety.91 Personal, wearable gel dispensers have been shown to increase the frequency and efficacy of hand hygiene92–94b (Figure 2). Providers with dermatitis from frequent hand hygiene may consider applying gel to examination gloves.95
The anesthesia machine and supply cart are difficult to clean, especially with the limited time available between cases in a busy operating room. There is evidence that covering all or parts of the anesthesia machine may reduce the bioburden,96,97 and the use of plastic covers in operating rooms exposed to SARS-CoV-2 has been suggested.98 Consideration should be given to covering the computer keyboard, mouse, and computer touchscreens with single-use plastic covers. Another alternative consists of a purpose-made anesthesia machine cover, either full or partial, that includes a dedicated storage pocket for the airway suction88c (Figures 3–4). Contaminated covers should be disposed of with care to avoid cross-contamination.
The conventional anesthesia cart that is designed to hold supplies for several patients is problematic because of the common tendency to inadvertently contaminate the contents by reaching into the cart without first performing hand hygiene. Providers should only enter the cart drawers with clean hands,99 and it is logical to minimize entry into the cart during and immediately after aerosolizing procedures. A single patient case pack system, such as commonly used for surgical supplies, could be an attractive alternative to the traditional anesthesia cart. During lower intensity moments of anesthesia care, providers could use hospital antiseptic wipes to clean the high touch areas of the anesthesia machine (unless they have been covered with a plastic cover). Personal items such as cell phones, which may be highly contaminated,100 could be wiped with antiseptic wipes or covered with plastic bags.
Ultraviolet light has been used for “terminal cleaning” of operating rooms and hospital patient rooms. Limitations of this approach include the problem of “shadowing.” The ultraviolet light must fall directly on the surface to be decontaminated, and objects in the shadows will not be decontaminated. Ultraviolet light can also be used to inactivate pathogens suspended in the air.101 Certain wavelengths of ultraviolet light may damage human skin and eyes; however, this problem can be managed by controlling the wavelength of the light and the intensity of the exposure.35 A recent study has shown that ultraviolet light at a wavelength of 222 nm inactivates coronaviruses in the air with minimal risk of human toxicity.102
Airway management has been associated with aerosolization of respiratory viruses and infection of anesthesia providers.17–19 Airway management may also spread pathogens to surfaces of the anesthesia work area and to airway equipment. There is evidence that double gloving for airway management and discarding the outer glove immediately afterward may reduce surface contamination of the anesthesia work area.103 Laryngoscopes are classified by the CDC as “semicritical” (in contact with mucous membranes) devices that require high-level decontamination (simply wiping a laryngoscope handle or blade with an antiseptic wipe is low-level, not high-level decontamination) or sterilization, including both the blade and the handle.104 In practice, it is common for conventional laryngoscope and videolaryngoscope handles to be wiped with antiseptic wipes rather than undergoing proper high-level decontamination or sterilization. Some videolaryngoscope handles cannot undergo high-level decontamination or sterilization (Supplemental Digital Content, Table 1, https://links.lww.com/AA/D186). Single-use conventional or videolaryngoscopes may offer a cost-effective alternative to performing high-level decontamination or sterilization of reusable conventional or videolaryngoscopes.
It is advisable to protect the anesthesia machine from contamination with aerosolized airway secretions by placing a high-efficiency particulate air (commonly known as HEPA) filter (or a filter with similar filtration capability, see below) on at least the exhalation side of the anesthesia circuit, at the “Y” of the circuit (protecting both inhalation and exhalation sides of the circuit), or both.105 HEPA filters are rated based on their filtering effectiveness for 0.3 μm particles, the size particle which passes through the filter most easily. A HEPA rating requires at least 99.97% filtration effectiveness based on the US Department of Energy standard,106 with a similar standard in the European Union. A HEPA filter does not act as a sieve in which particles smaller than the largest opening pass through. It consists of randomly arranged fibers that trap particles by a combination of diffusion, interception, and impaction.107 HEPA filtration effectiveness for particles smaller than 0.3 μm, such as influenza and coronaviruses (approximately 0.1 μm), exceeds that for 0.3 μm particles.108 A variety of different methods are being used to test breathing circuit filters, some of which are not standardized or recognized by regulatory agencies. Comparing filters tested with different testing methodologies can be problematic,109 especially if manufacturers do not provide complete specifications of the testing conditions. In addition to the HEPA standard, filters may be tested using the NIOSH N-95, N-99, N-100 standard that tests the penetration of very small sodium chloride particles (the same standard used for respirator masks),110 Viral Filtration Efficiency (known as VFE, which is not recognized as a standard testing method according to Rengasamy et al111), Bacterial Filtration Efficiency (BFE), or other testing methods. While some filters perform better than others,110 effective filtering of viral particles is clearly possible. For example, Heuer et al112 tested 3 different mechanical hydrophobic breathing circuit filters with monodispersed aerosol of H1N1 influenza A virus and found filtering efficiency of ≥99.9995%.
Hypothetically, opening the lumen of a double-lumen endotracheal tube could result in aerosolization of airway secretions. Although this has not been formally studied, it would be reasonable to place an anesthesia circuit filter on the unventilated lumen of the endotracheal tube.113 Opening the lumen of any endotracheal tube or supraglottic airway to the operating room atmosphere should be minimized as much as possible.
Several methods have been proposed for partially covering the patient’s head during airway management with plastic covers,114,115 covers connected to suction,116 or plastic boxes117 with the intention to prevent the spread of aerosolized airway secretions. However, the effectiveness of such devices and their impact on airway management are unknown. Plastic materials that have become contaminated during airway management would require careful handling during disposal or for reusable materials, decontamination. In addition, it is unclear whether such adjuncts might make intubation more difficult or complicate the management of a difficult airway. A simulation study of plastic intubation boxes found that intubation took longer, first attempts were less successful, and provider gown sleeves were frequently breached when boxes were used, raising questions of safety.118
A variety of recommendations have been made for airway management in patients with known or suspected SARS-CoV-2 infection, including the use of rapid sequence induction, avoidance of bag and mask ventilation, and the use of videolaryngoscopy in preference to standard laryngoscopy.119 While these recommendations may make sense, there is a paucity of evidence for reducing transmission of infection. We recommend that airway management for routine anesthesia care, for patients not known or suspected of being infected with SARS-CoV-2 virus, should be based on an individualized assessment of the patient’s airway.
The shortage of PPE has been a major problem in many facilities.120 The shortage has resulted from inadequate emergency stockpiles, overly centralized manufacturing, and overreliance by health care facilities and their suppliers on “just-in-time” inventory management.121 Compounding the difficulty, many facilities are now in financial straits from revenue that was lost when elective care was deliberately curtailed. More dramatic efforts to increase production of PPE in the United States and other severely affected nations are needed. Our health care systems should strive to acquire enough PPE that rationing should be the exception rather than the rule.81
THE “TEST AND STANDARD PRECAUTIONS” APPROACH
We recommend a set of respiratory precautions to be taken with all patients. As mentioned previously, this is analogous to “standard” precautions for bloodborne pathogens (such as HIV or hepatitis C viruses), which assume that all patients are potentially infected. An alternative approach is to test all patients with nasopharyngeal RT-PCR, hoping to identify patients who are infected, and utilize “standard” precautions (without increased respiratory precautions) for patients who are not infected. The testing approach is being taken by many facilities, including the facilities of the authors, but has a number of problems. First, the nasopharyngeal RT-PCR test for SARS-CoV-2 may be falsely negative. Because of the lack of a “gold standard” for diagnosis of infection, the rate of false negatives is difficult to determine but appears to be substantial.26–34 Second, testing requires time and is seldom performed on the day of the procedure; for example, in the authors’ facilities, testing is typically performed about 2 (S.S.) or 3 days (A.B., S.J.) in advance. Hypothetically, patients may become infected following testing but before the anesthetic. Third, this approach is not amenable to urgent or emergent procedures because the test requires time to perform. For these reasons, the authors recommend that the respiratory precautions as described in this article be applied to all patients, except for patients with known or suspected SARS-CoV-2 infection, in which case more elaborate precautions may be required.6–9
Table 2. -
Key Infection Prevention Precautions Before SARS-CoV-2 and During the SARS-CoV-2 Pandemic
|Surgical masks required for anesthesia care
||Respirator masks recommended for anesthesia care
|No masking required outside of procedure rooms
||Universal masking required inside of health care facility
|Hand hygiene primarily for protection from bacterial pathogens
||Hand hygiene for protection from respiratory viruses and bacterial pathogens
|Eye protection to protect from splashes
||Eye protection to avoid conjunctival contact with viruses in droplets and aerosols as well as splashes
Abbreviation: SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
For an unknown period of time, there will be substantial numbers of cases of SARS-CoV-2 infection, the prevalence depending on location. A negative test for SARS-CoV-2 infection and the absence of symptoms may not completely rule out infection with SARS-CoV-2. Our key recommendations are that anesthesia providers should wear surgical masks at all times when they are in contact with other people (including other providers) inside their facilities and respirator masks routinely while providing anesthesia care; be aware that not all providers can be fit for N-95 masks and that N-95 masks may not always provide adequate protection. Eye protection should also be worn, and hand hygiene should be performed frequently. These key recommendations have been summarized in Table 2. The surfaces of the anesthesia workplace should be kept as clean as possible, given the known difficulties and time constraints of cleaning anesthesia equipment between cases. Other recommendations to consider are found in Table 1. Shortages of supplies may continue to be very problematic. Health care facilities and government agencies should prioritize the production, distribution, and acquisition of the needed PPE, especially high-quality respirator masks. Continued research to better understand the SARS-CoV-2 virus is essential and will help us to refine our approach to protect ourselves and our patients. Whether routine precautions for respiratory viruses will be necessary for an indefinite time remains to be seen. The SARS-CoV-2 pandemic is not the first respiratory virus pandemic of the 21st century, and it will probably not be the last. A deadly influenza pandemic remains a constant threat.122 Heightened precautions against respiratory pathogens should be considered for incorporation into “standard” precautions. Anesthesia care for patients with a diagnosis of definite or suspected SARS-CoV-2 infection will typically require additional, more elaborate precautions, as previously described.6–9
Name: Andrew Bowdle, MD, PhD, FASE.
Contribution: This author helped with concept, first draft, revisions, and final approval of the manuscript.
Name: Srdjan Jelacic, MD, FASE.
Contribution: This author helped with concept, revisions, and final approval of the manuscript.
Name: Sonia Shishido, DO.
Contribution: This author helped with concept, revisions, and final approval of the manuscript.
Name: L. Silvia Munoz-Price, MD, PhD.
Contribution: This author helped with concept, revisions, and final approval of the manuscript.
This manuscript was handled by: Richard C. Prielipp, MD, MBA.
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