Infection Control in Dental Anesthesiology: A Time for Preliminary Reconsideration of Current Practices

Abstract

Relegated to clinical afterthought, the topic of infection control has never taken center stage in our modern dental sedation and anesthesiology practices. Surgical and procedural masks, gloves, gowns, protective eyewear, and appropriate surgical attire have remained de rigueur in both fashion and custom for decades. However, the emergence of certain seminal events throughout health care history has driven mandated changes when practitioners, staff, patients, and the surrounding communities were exposed or put at risk of exposure to infectious disease. Hepatitis, human immunodeficiency virus, and now the global COVID-19 pandemic involving the novel coronavirus SARS-CoV-2, have forced us into rethinking our current practices. This review article will contextualize previous epidemics and their influence on infection control in dental settings, and it will explore the rapid evolution of current modifications to personal protective equipment and infection mitigation practices specific to sedation and anesthesia in dentistry.

At present, the world is facing a viral crisis in the most literal sense with the novel coronavirus, or specifically the SARS-CoV-2 virus (International Committee on Taxonomy of Viruses), and the resulting COVID-19 (World Health Organization, February 2020) pandemic affecting all levels of society around the world.¹ Of note, this newly emerging strain of Betacoronavirus is thought to be spread by aerosols or droplets per early investigations,² posing a substantial infection risk to all dental professionals, including providers of sedation and anesthesia for dentistry, and to surrounding communities. Notwithstanding the urgency of the current situation as of this writing, infection control while delivering sedation and anesthesia for dental and oral surgical procedures deserves an examination into current practices. Forthcoming modifications and wholesale change to infection control practices in dentistry are likely looming in light of the current pandemic, and this article will present the most contemporary issues and trends in infection control to consider implementing in clinical practice.

DENTAL PROFESSIONAL OCCUPATIONAL EXPOSURE

A recent article in the New York Times³ highlighted occupational exposure to the SARS-CoV-2 virus as high among dental professionals, using data sourced from the O*NET database from March 3, 2020. O*NET, a US Department of Labor, Employment, and Training Administration sponsor initiative, utilizes standardized and occupation-specific descriptors for occupations across the “entire US economy.” Dentists and associated clinical dental professionals rank near the top of the scale at high risk when comparing “exposure to diseases” versus “physical proximity to others.” Historically, professionals in dentistry have been vulnerable to a number of infectious diseases, including hepatitis B (HBV), hepatitis C, herpes simplex virus, Epstein-Barr–derived infectious mononucleosis, tuberculosis (TB), cytomegalovirus, rubella, gonorrhea, syphilis, influenza, and HIV.⁴ Dental literature from 1989⁵ cited 14% of general dentists and “nearly twice that number of oral and maxillofacial surgeons” testing positive for viral HBV markers. Accordingly, the American Dental Association (ADA) developed infection control guidelines that were supported by the US Centers for Disease Control and Prevention (CDC). The fallout from this era of HBV-transmission awareness was institutional regulations and national guidelines to have dental practitioners inoculated with the HBV vaccine once it became available in 1982. Unfortunately, it was predicted that despite the inherent risk for exposure and transmission, dentists would be reluctant to immunize themselves with the vaccine.⁵ From the time of the 1989 study, substantial delay within the professional dental community to vaccinate themselves against HBV existed despite the introduction of the vaccine 7 years earlier.

Improvements in other forms of infection control, such as the routine use of gloves and surgical masks, that were once met with resistance now became gradually accepted as the threat of HIV infection emerged in 1981. ADA recommendations from the Council on Dental Therapeutics⁶ stated that the first line of defense from pathogens was the regular use of barrier protection (ie, gloves, masks, and eye shields) in an era when such personal protective equipment (PPE) was not commonplace in dental practice. And perhaps most interestingly, a discussion from one of the contributors of a 1986 article⁴ published in the Journal of the American Dental Association mentioned that high-risk HIV-infected patients were viable for treatment in isolation rooms with extensive precautions that included stripping the “room bare, apart from the dental chair unit and light…cupboards and drawers are taped shut and covered with polythene sheeting, a moist glutaraldehyde ‘doormat' is placed across the threshold and before treatment begins the whole room and contents are swabbed with 2% glutaraldehyde solution.” Such extensive PPE coverage was suggested in the 1980s era of HIV infection, and elective procedures along with the reduction of blood-saliva aerosol generation with ultrasonic scaling or high-speed drill use were strongly discouraged during this time of uncertainty with suspected and confirmed HIV-positive patients.

Highlighting one prevalent pathogen can give us insight into the investigations of the level of exposure dental professionals encounter. Occupational exposure to Mycobacterium tuberculosis, commonly referred to as simply “tuberculosis” or “TB,” has a well-documented history in dentistry. Dense population growth and socioeconomic factors continue to contribute to the prevalence of TB infection, with statistics citing 8.7 million new or relapse infections and 1.4 million mortalities worldwide, with 85% of affected individuals in Asia and Africa. Transmission of this disease occurs as M tuberculosis becomes aerosolized from actively infected individuals via airborne particles termed “droplet nuclei” that are smaller than 50 μm in size.⁷ Sneezing, productive coughing, shouting, and speaking have been described as mechanisms capable of producing droplet nuclei by patients with active pulmonary infection. Host response largely determines the degree of M tuberculosis infection, with individuals recovering from active infection by mounting an adequate immune response to either eliminate infection completely or abate further infection while maintaining a level of live bacteria in organ systems without symptoms, or subclinical asymptomatic levels of noncontagious infection (ie, latent TB infection). Nearly every dental professional has experience with reactive tuberculin skin testing, or the common Mantoux or tine test, whereby a subcutaneous injection of tuberculin purified protein derivative is subsequently evaluated in 2–3 days for significant induration to determine exposure or previous exposure to M tuberculosis. A significant rate of false positives exists with bacille Calmette-Guérin vaccination or infection with non-TB mycobacterium, so overestimation of the amount of infection occurs. Petti,⁷ in his 2016 meta-analysis, listed various modes of TB transmission from patient to dentist, dentist to patient, and dental hygienist to patient in various clinical settings. However, the collected data were collated from 10-year-old or older reports, and currently minimal risk is experienced by dental health care workers when observing current CDC guidelines in relation to all health care workers. Notably, historical TB exposure to dental health care workers was attributed to lax infection control standards (surgical glove and surgical mask misuse) compared to later studies, which incorporated more stringent CDC infection control guidelines that included screening, testing, PPE, and environmental controls. Additionally, Petti⁷ stated that TB transmission through droplet nuclei produced via aerosol-generating procedures in dentistry was unlikely because the contamination occurs only during active sputum production and not through saliva or the minimal irrigation involved in ultrasonic scaling. At the time of this meta-analysis in 2016, the author suggested that wearing surgical masks during face-to-face patient medical history taking and N95 respirators during treatment of patients was not needed on a regular basis if standard precautions are followed and practiced.

The concern for effective infection control was not limited to clinical treatment, but extended to adjunct dental services and specialty care. During the emergence and spread of HIV in the early 1980s, dental auxiliary staff and dental laboratory technicians were believed to be at risk for HIV exposure from handling contaminated items such dental instruments or impressions. Initial guidance from the ADA Council on Prosthetic Services and Laboratory Relations Guidelines for Infection Control in the Dental Office and Commercial Dental Laboratory⁶ was released in 1985 along with revised guidelines from other agencies in an effort to improve infection control for all aspects of dental care. Specific guidance for dental specialties also emerged as details of practice were considered relative to the level of exposure and risk. Difficulties such as the loss of tactile sensation during endodontic instrumentation were encountered when glove-wearing mandates were introduced, whereas other specialties adopted standard precautions readily.

INFECTION CONTROL IN SEDATION AND ANESTHESIA DELIVERY

Providers of sedation and anesthesia for dentistry also encounter infection and disease transmission risks, particularly in traditional (ie, non–operating room) dental and oral surgery care settings. Much of the investigation and feasibility regarding sanitization of the instrumentation used in laryngoscopy, for example, was driven by documented reports of localized transmissible pathogen outbreaks, ongoing institutional regulations, and the aim to decrease surgical site infection risks. Since 1968, a 3-tiered level of decontamination has been in use to guide infection control procedures for various instrumentation depending on the type of tissue contact, otherwise known as the Spaulding classification. According to Spaulding, disinfection levels and techniques, stratified from low to high, were expected to be effective on bacteria, fungi, and enveloped/lipid or nonenveloped/nonlipid viruses.⁸ The level of processing required for instruments used in anesthesia care is placed at “high-level disinfection.”

For instance, laryngoscope blades, classified as semicritical by the CDC and Joint Commission, require high-level disinfection after each use because of their contact with mucous membranes or nonintact skin surfaces (Table 1). In the past, laryngoscope handles themselves were classified as noncritical, and therefore subject only to low-level disinfection unless substantial risk was identified in the anesthetic management of patients with infectious disease, including Ebola virus, or treatment involving patients with active prions, such as Creutzfeldt-Jakob disease.⁹ However, further studies into the efficacy of various sterilization chemicals and procedures have unveiled a number of pathogens resistant to typical high-level disinfection techniques. Several strains of nonenveloped norovirus, a leading cause of viral gastroenteritis, have been reported to have higher resistance to commonly used chlorine disinfectants,¹⁰ whereas some enveloped viruses, such as HIV, HBV, and influenza virus, are vulnerable to commercial disinfectants because of an easily compromised outer envelope. Therefore, in a 2019 Expert Guidance statement¹¹ from the Society for Healthcare Epidemiology of America (SHEA), subsequently adopted by the American Society of Anesthesiologists, both traditional and video laryngoscope reusable handles and blades should undergo high-level disinfection (at a minimum) or sterilization prior to use. High-level disinfection includes placement of instruments into a heat-automated washer-disinfector and/or liquid immersion into chemical sterilants, such as glutaraldehyde, glutaraldehyde with phenol, hydrogen peroxide with peracetic acid, or ortho-phthalaldehyde (Table 2).

Table 1.

Instrument/Equipment Classification

Category	Definition	Instrumentation
Critical	Penetration of soft tissue, osseous contact, entry into bloodstream or other normally sterile tissue	Surgical instruments, periodontal scalers, scalpel blades, surgical dental burrs
Semicritical	Contacts mucous membranes or nonintact skin; will not penetrate soft tissues, contact osseous structures, or enter into or contact the bloodstream or other normally sterile tissue	Laryngoscope blades, laryngoscope handles, dental mouth mirrors, Magill forceps, amalgam condenser, reusable dental impression trays, dental handpieces*
Noncritical	Contacts intact skin	Radiographic head/collimator, noninvasive blood pressure cuff, facebow, pulse oximeter

^*Excluding dental burs used in tooth preparation, endodontic instrumentation, osseous recontouring, etc.

Table 2.

Sterilization and Disinfection Summary*

Process	Result	Method	Example	Instrument Type	Environmental or Clinical Surface
Sterilization	Destruction of all microorganisms, including bacterial spores	Heat-automated, high temperature	Steam, dry heat unsaturated chemical vapor	Heat-tolerant critical and semicritical	N/A
		Low temperature	Ethylene-oxide gas, plasma sterilization	Heat-sensitive critical and semicritical
		Liquid immersion in chemical sterilants	Glutaraldehyde with phenol, hydrogen peroxide, hydrogen peroxide with peracetic acid, peracetic acid	Heat-sensitive semicritical
High-level disinfection	Destroys all microorganisms, but not necessarily capable of killing bacterial spores	Heat-automated	Washer-disinfector	Heat-sensitive semicritical	N/A
		Liquid immersion in chemical sterilants or high-level disinfectants	Glutaraldehyde with phenol, hydrogen peroxide, hydrogen peroxide with peracetic acid, ortho-phthalaldehyde
Intermediate-level disinfection	Destruction of vegetative bacteria and majority of fungi and viruses Inactivates Mycobacterium bovis Not necessarily capable of killing bacterial spores	Liquid contact with disinfectant†	Chlorine-containing products, quaternary ammonium compounds with alcohol, phenolics, iodophors, EPA-registered chlorine products	Noncritical with visible blood	Clinical contact surfaces, blood spills on housekeeping surfaces
Low-level disinfection	Destruction of majority of vegetative bacteria, certain fungi, and viruses. Does not inactivate M bovis.	Liquid contact with disinfectant‡	Quaternary ammonium compounds, some phenolic, some iodophors	Noncritical without visible blood	Clinical contact surfaces, housekeeping surfaces

^*N/A indicates not applicable; EPA, US Environmental Protection Agency.

^†EPA-registered hospital disinfectant with label claim of tuberculocidal activity

^‡EPA-registered hospital disinfectant with no label claim of tuberculocidal activity. The Occupational Safety & Health Administration also requires label claims of HIV and hepatitis B potency for clinical contact surfaces

The ASA¹² indicated in its Statement on Standard Practice for Infection Prevention and Control Instruments for Tracheal Intubation that “all instruments used for intubation of the trachea should also be properly cleaned using standard methods for decontamination and high-level disinfection between each patient use and stored in a clean environment.” “Sterility,” as specifically stated in these 2015 recommendations, “is not required.” Prepackaged nasal and oral endotracheal tubes, when opened to check for cuff integrity, attach inflation syringes, or have stylets preinserted prior to use, can be reasonably stored for up to 48 hours, citing that the oropharynx is itself a nonsterile area. Infection control of anesthesia machines and supporting equipment is detailed in an ASA-endorsed guidance statement¹¹ issued by the SHEA. The 2019 SHEA Expert Guidance paper,¹¹ Infection Prevention in the Operating Room Anesthesia Work Area, expands on the ASA recommendations by discussing glove-wearing practices, the location of alcohol-based hand rub (ABHR) dispensers, barrier devices on anesthesia machines, cleaning and disinfecting anesthesia machines and related work areas, drug vial scrubbing, and even expiration times for drawn-up medications.

PPE RECOMMENDATIONS

PPE for both dentistry and anesthesia prior to the COVID-19 pandemic shared standards for hand hygiene, eye protection, and surgical mask wearing. Aside from hospital standards governing the use of headwear (surgical or bouffant caps), shoe covers, and surgical mask donning in an operating room setting, the expected levels of exposure and infection control were common to working in and around the oral cavity, nasopharyngeal area, and oropharyngeal area.

Hand Hygiene

Clearly, the foundational work¹³ of both Ignaz Semmelweis and Oliver Wendell Holmes began the awareness of infection control beginning with hand cleanliness of clinicians. The ADA recommends that water and plain or antimicrobial soap be used for hand antisepsis. Alternatively, an ABHR can be used, but when hands are visibly soiled with dirt, blood, or bodily fluids, water and soap are preferred. The ASA-endorsed SHEA Expert Guidance statement¹¹ similarly outlines adherence to World Health Organization's “5 Moments for Hand Hygiene” (Table 3).¹³ It should be noted that the use of gloves, both clean and sterile, does not replace the need for recommended hand hygiene by either hand rubbing or handwashing. Accordingly, the World Health Organization recommends 2 methods for hand hygiene for nonsurgical procedures:

Table 3.

World Health Organization: Hand Hygiene

World Health Organization: 5 Moments Requiring Hand Hygiene
Before touching a patient Before clean/aseptic procedures After body fluid exposure/risk After touching a patient After touching patient surroundings

1. Hand-hygiene technique with an alcohol-based formulation (20–30 seconds in duration)

2. Hand-hygiene technique with soap and water (40–60 seconds in duration)

Details of the specific hand-hygiene procedures can be found at https://www.who.int/infection-prevention/campaigns/clean-hands/5moments/en/.

Specifically, in the current practice of sedation and anesthesiology in clinical treatment settings, the ASA-endorsed SHEA Expert Guidance statement¹¹ recommends that hand hygiene be performed prior to aseptic tasks such as insertion of peripheral or central venous catheters, drawing medications, or spiking intravenous fluid bags; before touching contents in an anesthesia workstation/cart; when hands become soiled or contaminated; and when leaving the operating room environment. ABHR dispensers should ideally be located inside the operating room, in the dental operatory, and in close proximity to anesthesia providers. Wearable ABHR dispensers have also been encouraged by the SHEA Expert Guidance statement.¹¹

Glove Wearing

A major area of deviation exists between the ADA infection control guidelines⁶ and the ASA-endorsed SHEA Expert Guidance statement¹¹ in the area of glove wearing. Whereas the ADA and standard precautions mandate single gloving for dental procedures, SHEA recommends the practice of double gloving during airway management. To reduce the risk of contamination of the anesthesia work area and related areas, the technique of wearing an additional layer of gloves that will be discarded immediately after airway manipulation is recommended when contamination is likely and there is insufficient time for hand hygiene between procedural steps. For instance, once intubation has been completed, the outer gloves should be discarded to reduce cross-contamination. Immediate availability of biohazard waste adjacent to patient care should also be considered in the preparation of airway instrumentation prior to anesthesia care. And, once inner glove removal has occurred, hand hygiene should be performed. There exist limited data on the efficacy of applying ABHR onto gloves in lieu of discarding gloves and performing hand hygiene; therefore, double gloving and subsequent hand hygiene are the only SHEA-recommended practices.

Other Components of Personal Protective Equipment

Although its recommendation is broad in nature, the ADA recommends “appropriate PPE,” such as mouth, nose, and eye protection, during “procedures that are likely to generate splashes or sprays of blood or other body fluids.” Further, the ADA refers to the 2007 CDC Guideline for Isolation Precautions¹⁴ for donning (wearing) and doffing (removal) of PPE while maintaining standard precautions. Aside from the exception of gloves, the CDC recommends wearing gowns “appropriate to the task, to protect skin and prevent soiling or contamination of clothing during procedures and patient care activities when contact with blood, body fluids, secretions, or excretions is anticipated.” Oropharyngeal and nasopharyngeal secretions with the possibility of contact with blood are an anticipated risk with airway instrumentation and manipulation, and therefore gowns are recommended when sedation and anesthesia is utilized for dentistry.

Likewise, the use of PPE to protect the wearer's at-risk mucous membranes (ie, the eyes, nose, and mouth) warrants appropriate selection of masks, goggles, and face shields. When aerosol-generating procedures such as endotracheal intubation, suctioning of the respiratory tract, dentistry with high-speed handpieces, and/or irrigation with water spray are anticipated on patients without suspected pathogens “for which respiratory protection is otherwise recommended,” the CDC recommends using a full-coverage face shield or a mask with goggles.

ANESTHESIA MACHINE AND EQUIPMENT INFECTION CONTROL

Because of the specific nature of dental anesthesiology practice, the ADA does not publish recommendations regarding infection control on anesthesia machines or workstations. ASA-endorsed SHEA Expert Guidance does not recommend disposable plastic draping or disposable covers to prevent contamination of anesthesia machines because of inadequate studies demonstrating benefit. However, the use of disposable barrier films or covers on anesthesia machines offers “plausible reduction in contamination and facilitation of cleaning and disinfection.”

Cleaning and disinfecting anesthesia machines and anesthesia workstations between uses is recommended,¹¹ with suggested cleaning agents being US Environmental Protection Agency–approved hospital disinfectants compatible with equipment and surfaces as specified by manufacturers. A priority is given to high-touch surfaces, such as monitor touch screens, vaporizer controls, adjustable pressure-limiting valves, IV poles, infusion pumps, and ventilator controls. High priority is also given to monitoring devices and equipment in direct physical contact with patients, such as pulse oximeters, electrocardiogram leads, twitch-monitor leads, and reusable noninvasive blood pressure cuffs. Reusable laryngoscope handles that cannot be subject to high-level disinfection should not be used, according to SHEA. Examinations into using bactericidal wipes containing 70% alcohol and 2% chlorhexidine or coco alkyl dimethyl benzyl ammonium chloride eliminated common bacteria but did not effectively eliminate Clostridium difficile or norovirus.¹⁵

Laryngoscopes and Airway Instruments

As stated earlier, the ASA does not require sterilization for reusable laryngoscope blades or other instrumentation, but rather recommends high-level disinfection at the minimum. Storage of such items should be designated for repackaging as appropriate for semicritical items intended for high-level disinfection. Further recommendation from SHEA Expert Guidance states that strong consideration should be given to utilizing single-use direct or video laryngoscopes.

Intravenous Line Ports and Medication Vials

ASA-endorsed SHEA Expert Guidance recommends regular disinfection of intravenous line access ports and stopcocks with alcohol-based solutions prior to penetration by needles or needleless drug administration systems before each use. In systems that utilize sterile caps, isopropyl alcohol–containing caps should be affixed continuously until medications are administered or blood is drawn from the intravenous or arterial line. Ports should be continuously covered on stopcocks with sterile, isopropyl alcohol–containing caps as well. Although the use of alcohol wipes on injection ports remains a satisfactory infection control practice, it does require a 10–15-second drying time and may not be ideal in anesthesia practice, where urgent administration of medications may be necessary.

Where possible, single-dose vials for medications should be employed over multidose vials to reduce the risk of cross-contamination from multiple penetrations through the rubber stoppers. Any medication vial should be thoroughly wiped with at least 70% alcohol prior to vial access and medication withdrawal. Likewise, areas in which vials and equipment are stored, such as anesthesia workstations and carts, should be accessed only when anesthesia providers have performed adequate hand hygiene to reduce the bioburden on surfaces.

SHEA Expert Guidance recommends recapping of partially used syringes if needleless systems are utilized in medication administration. However, because of the obvious hazards of inadvertent needle-stick injury, SHEA does not recommend recapping of traditional syringes with needles and instead recommends direct disposal of sharps into appropriate sharps waste containers.

Dental Nitrous Oxide Units and Aerosolization of Pathogens

Based on limited and extrapolated data from studies examining aerosolization of pathogens from patients wearing various types of face masks, reasonable assumptions of the spread of infectious droplets and pathogens via the nitrous oxide–oxygen gas delivery systems used in dentistry can guide use, infection control, and disinfection of equipment. Studies using both simulation and human subjects demonstrate spread of aerosols from oxygen masks as far away as 0.4 m when fresh gas flows were at 4 L/min using Hudson-style or simple oxygen face masks.¹⁶ Investigations with a simulator using a human lung model indicated dispersal of potential infectious exhaled air at similar distances with a 12 breaths/min respiratory rate, a tidal volume of 500 mL, and 4 L/min oxygen flow through a simple mask.¹⁷ Although nasal hoods with scavenging systems and 1-way valves may provide improvements, data are limited in providing conclusive evidence.

UPDATED CONSIDERATIONS FOR TREATING PATIENTS WITH POSSIBLE HIGHLY COMMUNICABLE INFECTIOUS DISEASE

At this time (April 2020), the rampant spread of SARS-CoV-2 throughout the world has increased awareness of infection control in both emergent and elective dental surgeries, including those utilizing sedation and anesthesia. Particular emphasis on reducing occupational exposure to aerosolized pathogens has brought about innovative methods and equipment to provide sedation and anesthesia care for patients in numerous settings. Recent guidance from numerous professional organizations and regulatory bodies has suggested stricter infection control practices during airway manipulation and other perioperative, potentially aerosol-generating events. Although evidence is not conclusive, the primary modes of transmission of the SARS-CoV-2 virus are thought to be contact with contaminated environmental surfaces (fomites), droplet generation through coughing or sneezing, and aerosolization or formation of droplet nuclei.¹⁸

A directive from the journal Anesthesia & Analgesia by Dexter et al¹⁹ suggested the following for infection control while providing intubated general anesthesia in the operating room setting for SARS-CoV-2–infected patients:

1. Combined deep cleaning with surface disinfectants and ultraviolet light (UV-C) to attenuate residual environmental contamination of the work area and operating room.

2. Placement of ABHR dispensers on IV poles to the left of the provider (if the anesthesia machine is positioned to the right of the anesthesia provider).

3. Double gloving as per the previous SHEA Expert Guidance recommendation, and immediate discarding of outer gloves after airway manipulation or instrumentation.

4. Placement of a wire basket lined with a zip-closure bag on an IV pole to the right of the provider (if the anesthesia machine is positioned to the right of the anesthesia provider)

   1. All contaminated instruments should be placed into this bag (laryngoscope handles and blades,Magill forceps)

5. Designate and maintain a “clean” and “dirty” area.

6. Wipe down all equipment and surfaces with disinfection wipes that contain a quaternary ammonium compound and alcohol using a “top-down” cleaning sequence.

7. Decolonize patients using preprocedural chlorhexidine wipes and 2 doses of nasal povidone iodine within 1 hour of procedure, and have the patient rinse with oral chlorhexidine.

8. Create a closed-lumen IV system and use hub/injection port disinfection.

9. Schedule long anesthesia personnel shifts with minimal handoffs to reduce use of surgical masks and SARS-CoV-2 exposure.

10. Perform one case in one operating room daily with terminal cleaning after each case, including UV-C or equivalent.

11. Avoid large pooled-patient postanesthesia care units to reduce contamination and community exposure. Instead, recover patients in the room where surgery occurred.

12. With the understanding that virtually every dental practice is not optimized for such recommendations, dentists, dentist anesthesiologists, and oral surgeons should make appropriate and reasonable modifications to the above recommendations when performing urgent or emergent procedures on infected, suspected, or asymptomatic patients. As more is discovered about this global pandemic and mitigation efforts continue to be developed, these recommendations are likely to remain dynamic until further research is completed.

PPE for Anesthesia Providers

The risk for infection with SARS-CoV-2 lies in the potential for asymptomatic and symptomatic individuals to transmit the virus via droplets and aerosols. Because of the assumed aerosolized nature of SARS-CoV-2 transmission, CDC recommendations for PPE include the use of N95 respirators, which offer a higher level of protection, instead of procedural masks (an elastic ear-loop mask intended for use in clean environments) or standard surgical masks (utilizing 2 straps and intended for use in sterile environments) when performing or present for an aerosol-generating procedure. The American Society for Testing Materials (ASTM) has also designated the levels of performance for procedural and surgical masks (Table 4).²⁰

Table 4.

ASTM Barrier Levels*

Characteristic	ASTM Level 1 Barrier	ASTM Level 2 Barrier	ASTM Level 3 Barrier
Bacterial filtration efficiency (Staphylococcus aureus), %	>95	>98	>98
Submicrometer particulate filtration efficiency at 0.1 μm, %	>95	>98	>98
Resistance to penetration by synthetic blood (minimum pressure for pass result), mm Hg	80	120	160

^*ASTM indicates American Society for Testing Materials.

According to the US Food and Drug Administration and the National Institutes of Occupational Safety and Health, the N95 designation indicates a mask that blocks at least 95% of very small (0.3 μm) test particles in controlled conditions.²¹ If powered air-purifying respirators are used, they must be cleaned and disinfected according to the specific manufacturer's instruction for reuse. N95 respirators must be “fit tested” in order for health care providers to be able to render care. The proper fit of an N95 respirator specifies a tight-fitting seal between the respirator and the wearer's skin so that no gaps exist and that it must capture more than 95% of the particles from the air that passes through it.²²

When low-resource conditions exist, as is common during the current COVID-19 pandemic, consideration of reuse and extended use of N95 PPE has been investigated. According to the CDC's and National Institutes of Occupational Safety and Health's Recommended Guidance for Extended Use and Limited Reuse of N95 Filtering Facepiece Respirators in Healthcare Settings,²³ extended use of an N95 mask can be considered if exposure of the respirator surface to possible contamination can be effectively limited. However, the CDC recommends the following regarding considerations for the reuse and extended use of N95 masks:

• Discard N95 respirators following use during aerosol-generating procedures.

• Discard N95 respirators contaminated with blood, respiratory or nasal secretions, or other bodily fluids from patients.

• Discard N95 respirators following close contact with, or exit from, the care area of any patient coinfected with an infectious disease requiring contact precautions.

• Consider the use of a cleanable face shield over an N95 respirator and/or other steps (eg, masking patients, use of engineering controls) to reduce surface contamination.

• Perform hand hygiene with soap and water or an alcohol-based hand sanitizer before and after touching or adjusting the respirator (if necessary, for comfort or to maintain fit).

• Discard any respirator that is obviously damaged or becomes hard to breathe through.

Currently, minimal research exists on sterilization and reuse of N95 masks. Sterilization methods have been proposed that include decontamination by placing the mask at “some constant temperature between 65 and 80°C (149–176°F) with some relative humidity in the range of 50–85% for a duration of 30 minutes.”^24,25 Other sources cite the use of 1% hydrogen peroxide vapor in providing successful decontamination of commercially available N95 masks.²⁶

The CDC, as of this writing, offers no guidance on the care of patients that may fall under the category of being asymptomatic carriers. On April 1, 2020, the ASA issued a statement based on the recommendation of the National Institutes of Occupational Safety and Health and the US Food and Drug Administration Emergency Use Authorization to obtain and use personal respiratory protective devices during this uncertain time. Health care providers treating patients with known SARS-CoV-2 infection, persons under investigation for infection, and asymptomatic carriers of “unknown status in geographic areas with significant community transmission” are now being encouraged to obtain and use approved high-filtration respirators, even when clinical settings cannot assure supply.²⁷

The CDC also provides guidance on eye protection that parallels previous directives on PPE. Eye protection, such as goggles or disposable face shields that cover the front and sides of the face, is needed upon entry into the treatment area or patient room. Personal eyeglasses and contact lenses are not considered adequate eye protection. Gowns during aerosol-generating procedures are also to be donned upon entry into the patient room or treatment area.

The CDC has also issued specific guidance for the treatment of patients with known or suspected SARS-CoV-2 infection undergoing aerosol-generating procedures (Table 5),²⁸ which includes the following:

Table 5.

Aerosol-Generating Procedures

Aerosol-generating events

Coughing/sneezing

Noninvasive or positive pressure ventilation with inadequate seal

High-flow nasal oxygen

Delivery of nebulized/atomized medications via simple face mask

Cardiopulmonary resuscitation (prior to intubation)

Tracheal suction

Tracheal intubation

Procedures vulnerable to aerosol generation

Laryngoscopy

Tracheal intubation

Bronchoscopy/gastroscopy

Front-of-neck airway procedures (including tracheostomy, cricothyrotomy)

• The number of health care providers present during the procedure should be limited to only those essential for patient care and procedure support. Visitors should not be present for the procedure.

• Aerosol-generating procedures should ideally take place in airborne infection isolation rooms.

  • ○Airborne infection isolation rooms are single-patient rooms at negative pressure relative to surrounding areas with a minimum of 6 air changes per hour (12 air changes per hour is recommended for new construction or renovation).
  • ○Air from airborne infection isolation rooms should be exhausted directly to the outside or be filtered through a high-efficiency particulate air filter directly before recirculation.
  • ○Room doors should be kept closed except when entering or leaving the room, and entry and exit should be minimized.
  • ○Facilities should monitor and document the proper negative-pressure function of the room.

Preliminary Considerations for Dental Treatment Providers

Limited data exist on the current impact upon dental practice and on modifications for safe treatment of COVID-19 patients in typical dental settings. Initial investigations place dental professionals at high risk for infectious disease exposure because of face-to-face communication with patients; frequent exposure to saliva, blood, and other body fluids; and the handling of sharp instruments. The SARS-CoV-2 virus can be transmitted in dental settings through inhalation of airborne microorganisms that can remain suspended in the air for long periods, direct contact with bodily fluids, and occupational contact via aerosols generated by intraoral dental procedures and devices (turbine-driven handpieces, air-water sprayers, and suction).²⁹ Authors of the aforementioned study recommend PPE similar to CDC guidelines for treating patients with suspected or confirmed SARS-CoV-2 infection, with the addition of donning disposable working caps and disposable shoe covers along with protective gowns and “disposable isolation clothing.”

For mouth rinsing prior to dental procedures, 1% hydrogen peroxide or 0.2% povidone is recommended to reduce the salivary load of oral microbes. Rubber dam isolation and hand instrumentation is preferred, and antiretraction dental handpiece systems (antibackflow water irrigation) can considerably reduce the migration of oral bacteria and HBV into the handpiece and water supply lines.

Other recommendations against the use of oxygen delivery devices such as nebulizers, oxygen masks, and nasal continuous positive airway pressure systems can be carried over to nitrous oxide–oxygen inhalation systems that currently employ an open circuit with a simple scavenging system prone to leakage and aerosol promotion.³⁰

Airway Management, Controlled Ventilation, and Resuscitation Considerations

Previous experience with SARS-CoV and MERS-CoV coronavirus cases demonstrated susceptibility of health care workers to infection by patients when performing airway manipulation and instrumentation or being exposed to aerosolized pathogens via nebulizers, continuous positive airway pressure, bilevel positive airway pressure, or high-flow nasal oxygen therapy. The Anesthesia Patient Safety Foundation³¹ recommends avoiding awake fiber-optic intubation unless specifically indicated because atomized local anesthetic to topicalize the airway will aerosolize the virus. Video laryngoscopy is recommended. Preoxygenation and rapid sequence induction is recommended to avoid manual ventilation of the patient's lungs and aerosolization of pathogens.

In any breathing circuit, such as in bag-valve-mask resuscitators and closed and semiclosed breathing circuits, the Anesthesia Patient Safety Foundation recommends the placement of a high-quality heat and moisture–exchanging filter rated to remove at least 99.97% of airborne particles 0.3 μm or greater between the face mask and breathing circuit or between the face mask and reservoir bag.³² Although studies are extremely limited at this time to indicate best practices, caution should be exercised in disconnecting any breathing circuit where forced fresh gas flows are present, and prudent practice would include clamping of the endotracheal tube with nonserrated forceps, discontinuing fresh gas flows and controlled ventilations into the circuit from the ventilator, and ensuring minimal disconnections when manipulating the breathing circuits (suctioning, transport, or ventilator change). Consideration should also be given to placing a heat and moisture–exchanging filter onto the endotracheal or nasotracheal tube prior to intubation to minimize aerosolized pathogens from reaching health care providers in the immediate vicinity of patient care. End-tidal carbon dioxide sampling should also be placed distal to the heat and moisture–exchanging filter, and if this is not possible, a viral filter should be placed on the sampling line. Additional filters are recommended to be placed on the expiratory limb of the anesthesia breathing circuit to protect the sterility of the anesthesia machine itself. Finally, each breathing circuit should be discarded and replaced for each patient.³³

CONCLUSIONS

At the present time, imminent spread of the COVID-19 respiratory virus (SARS-CoV-2) has reached global concern. Much like the resurgence of TB and spread of HIV in the latter half of the 20th century brought about wholesale change in the infection control procedures in dentistry, the current pandemic will undoubtedly affect major aspects of dentistry, including not only infection control but also operatory design and disinfection, patient evaluation, and PPE availability and innovation. Currently there is no immunization or effective treatment in existence for this novel coronavirus, and it may be quite a long time before mitigation is seen. Beyond that, reasonable and prudent measures should be incorporated into the practice of sedation and anesthesia for dentistry to reduce exposure, risk, and transmission to both dental professionals and patient communities. The current investigations into the COVID-19 pandemic indicate that affected individuals incubate the SARS-CoV-2 virus for a prolonged 14-day period prior to showing any symptoms and may indeed be highly contagious during this incubation period. Conceivably, improvements in standard precautions for treating asymptomatic carriers may shift to include protection against aerosolized pathogens, much in the same manner as gloves, masks, and eye protection were introduced decades earlier with the spread of other communicable diseases.

CONTINUING EDUCATION QUESTIONS

This continuing education (CE) program is designed for dentists who desire to advance their understanding of pain and anxiety control in clinical practice. After reading the designated article, the participant should be able to evaluate and utilize the information appropriately in providing patient care.

The American Dental Society of Anesthesiology (ADSA) is accredited by the American Dental Association and Academy of General Dentistry to sponsor CE for dentists and will award CE credit for each article completed. You must answer 3 of the 4 questions correctly to receive credit.

Submit your answers online at www.adsahome.org. Click on “On Demand CE.”

CE questions must be completed within 3 months and prior to the next issue.

1. Society for Healthcare Epidemiology of America Expert Guidance recommends which of the following immediately after airway manipulation or instrumentation?

   1. Application of an alcohol-based hand rub onto gloved hands to prevent cross-contamination

   2. Direct application of glutaraldehyde-containing solutions to all anesthesia work surfaces, exposed airway devices (endotracheal tubes), and syringes used in treatment

   3. Discarding of the outer layer of gloves when employing a “double-glove” technique of personal protective equipment wearing

   4. Vigorous suction with a saliva ejector, Yankauer-type suction, or orogastric tube to reduce salivary and gastric secretions prior to oral surgery or dental procedures

2. What is the recommended length of time to wait after wiping the tops of medication vials with an alcohol wipe prior to penetration with a syringe?

   1. 0–5 seconds

   2. 10–15 seconds

   3. 25–30 seconds

   4. No wait time needed

3. National Institutes of Occupational Safety and Health–approved N95 masks can be used whenever an aerosol-generating procedure is anticipated only after:

   1. A patient has tested positive for a SARS-CoV-2 viral infection

   2. Confirmation that a patient has exhibited clear signs and symptoms of tuberculosis or SARS-like infection

   3. Negative-pressure rooms have been established and will be used as patient treatment areas

   4. The wearer has been “fit tested” to ensure no gaps exist between the face and mask edge

4. In-line high-efficiency particulate air filters or a heat and moisture–exchanging filter should be placed:

   1. Between the junction of the patient mask and the bag-valve-mask outlet

   2. Only on the expiratory limb of an anesthesia circuit

   3. Only on the inspiratory limb of the anesthesia circuit

   4. When a patient is suspected of having a respiratory communicable disease