Overview of infection control during anesthetic care

INTRODUCTION — This topic addresses infection control to prevent risks to patients and providers during anesthetic care in operating rooms and other interventional procedural settings. Considerations for intraoperative anesthetic and airway management of patients with known or suspected coronavirus disease 2019 (COVID-19 or nCoV) are included in this topic.

Preoperative evaluation and risk assessment that may affect timing of surgical procedures is discussed in a separate topic. (See "COVID-19: Perioperative risk assessment, preoperative screening and testing, and timing of surgery after infection".)

GENERAL CONSIDERATIONS — Transmission of infection occurs via multiple vectors: contact, droplet, aerosol or airborne, and fluids (typically blood or mucous membranes). The distinction between droplet and airborne is based on size, with droplet being an aqueous body greater than 5 microns and aerosol being an aqueous body less than 5 microns. Droplets fall to earth quickly, while bodies smaller than 5 microns can remain in the air for much longer periods of time and be carried on air currents for hours. Standard surgical masks are effective against droplets, but an N95 mask or other respirator (eg, a powered air-purifying respirator [PAPR]) are much more effective against aerosols [1].

INFECTION RISKS FOR PATIENTS

Infection transmission from anesthesia provider to patient

Contact transmission: Hand hygiene, use of gloves, and standard OR attire — Standard precautions including hand hygiene and standard clean operating room (OR) attire (surgical masks, gloves, disposable caps, beard covers, shoe covers or designated shoes for OR use only) are used by anesthesia providers in all cases as a general precaution to prevent transmission of infection from provider to patient (or from patient to provider). (See "Infection prevention: Precautions for preventing transmission of infection", section on 'Standard precautions'.)

Fastidious hand hygiene is the single most important measure to reduce transmission of microorganisms from one person to another or from one site to another on the same patient. Hand hygiene (washing with soap and water or using alcohol-based gel) is necessary before donning (putting on) personal protective equipment (PPE), after removing gloves, after every contact with the patient, and before touching anesthesia equipment. (See "Infection prevention: Precautions for preventing transmission of infection", section on 'Hand hygiene'.)

Gloves should be worn by health care workers in situations in which exposure to blood or body secretions is possible; they provide a protective barrier for the health care worker as well as the patient. (See "Infection prevention: Precautions for preventing transmission of infection", section on 'Gloves'.)

Bacterial transmission from anesthesia providers' hands is a root cause of postoperative infections in as many as 16 percent of patients undergoing surgery, including gram-negative, hospital-acquired infection [2-4]. One study used fluorescent indicator dye to demonstrate that patient oral contents spread from the hands of the anesthesia provider to most nearby work surface areas in the OR within an hour of endotracheal intubation [5]. Double gloving with removal of the top set of gloves immediately after passing the endotracheal tube (ETT) reduced the spread of the indicator dye.

Droplet or aerosol transmission: Use of masks — A surgical mask worn by the anesthesia provider in the OR protects against droplets but protection against aerosols typically requires an N95 mask or powered air-purifying respirator (PAPR). Providers should not be in direct contact with patients (or colleagues) if they have an acutely symptomatic upper respiratory infection (URI), particularly if fever is present. (See "Infection prevention: Precautions for preventing transmission of infection".)

Catheter-related bloodstream infections — Catheter-related bloodstream infections (CRBSIs) can originate from peripheral intravenous (IV) or central venous catheters (CVCs). (See "Intravascular catheter-related infection: Epidemiology, pathogenesis, and microbiology".)

Prevention of central line infection — We use a checklist during CVC line insertion to ensure adherence to standard guidelines to prevent central line-associated bloodstream infections (CLABSIs) (table 1). During port access in the OR, as in other settings, we wear nonsterile gloves; however, using gloves does not obviate the need for hand hygiene. (See "Central venous catheters: Overview of complications and prevention in adults", section on 'Catheter-related infection'.)

Safe administration of intravenous fluids and medications — Safe vial access and injection practices are always necessary during administration of IV medications and fluids. (See "Routine care and maintenance of intravenous devices", section on 'Intraluminal specific strategies'.)

●Medications – The metal caps covering the rubber stoppers of vials are dust protectors and offer no sterility. Rubber stoppers therefore must be disinfected with an alcohol wipe prior to piercing with a needle. Note that sterile injectable medications are used as soon as possible after preparation in the OR, with prompt disposal of medication syringes and vials at the end of each case or after their expiration date [3,6,7]. (See "Prevention of perioperative medication errors", section on 'Avoid multiuse vials'.)

●Fluids – Commercially available IV fluid bags should be used as soon as possible or within 24 hours after spiking the bag and connecting it IV tubing [8]. In one study, no bacterial growth was noted in samples drawn at the time of this preparation of IV solutions, nor 24 hours later after spiking open 1000 mL bags of either normal saline (n = 127) or 5% dextrose in water (n = 129) [9].

Role of the anesthesia provider in preventing surgical site infections — Prevention of surgical site infection (SSI) is discussed in detail in a separate topic. (See "Overview of control measures for prevention of surgical site infection in adults".)

PREVENTING INFECTION TRANSMISSION TO PROVIDERS — Anesthesiologists routinely care for patients known or suspected of harboring infectious pathogens [3,10]. The Centers for Disease Control and Prevention (CDC) categorize infectious agents by their transmission vector (ie, airborne transmission, contact or droplet exposure, or via needle stick injury). Standard precautions including fastidious hand hygiene and standard clean operating room (OR) attire (surgical masks, gloves, disposable caps, beard covers, shoe covers or designated shoes for OR use only) are used by anesthesia providers in all cases as a general precaution to prevent transmission of infection from patient to provider (or from provider to patient), whether active patient infection is suspected or documented. (See "Infection prevention: Precautions for preventing transmission of infection", section on 'Standard precautions'.)

Infectious agents transmitted by aerosol (eg, COVID-19) — For patients with known or suspected COVID-19 or other infectious diseases that are spread by aerosol (airborne droplet nuclei of 5 microns or smaller) such as tuberculosis, chickenpox, or measles, special precautions are taken as detailed below (see 'PPE for aerosol-generating procedures' below). The primary means of transmission of such agents is thought to be via aerosols generated when an infected person coughs, sneezes, or talks, and the secretions are inhaled by another person, or when those secretions make direct contact with mucosal membranes of another person. (See "COVID-19: Epidemiology, virology, and prevention", section on 'Route of person-to-person transmission'.)

Considerations during aerosol-generating procedures — Most COVID-19 guidelines have categorized all aspects of airway management as aerosol-generating procedures with potentially increased risk for viral transmission due to proximity to or contact with airway secretions, particularly if the patient coughs.

Relevant studies have yielded conflicting information regarding whether intubation, extubation, mask ventilation, and use of supraglottic airways generate high levels of aerosols [11-16]. Differing results could reflect differences in sampling and detection methodologies and OR ventilation. Notably, the National Health Service in the United Kingdom has removed mask ventilation, intubation, and extubation from its list of aerosol-generating procedures [17].

Whether use of noninvasive ventilation (NIV) or high-flow nasal oxygen (HFNO) generates high levels of aerosols is also unclear. A 2023 systematic review that included 12 studies in patients and 15 studies in healthy volunteers did not find associations between generation of pathogen-laden aerosols during use of NIV (odds ratio [OR] 0.38, 95% CI 0.03-4.63) or during use of HFNO (OR 0.73, 95% CI 0.15-3.55) compared with controls [18]. Although augmented respiratory activity caused by coughing, sneezing, or exertional breathing can generate high aerosol levels during use of NIV or HFNO, quiet breathing results in aerosol generation at levels similar to quiet breathing without these modalities [19].

Other aerosol-generating procedures include jet ventilation with an open airway, bronchoscopy and other interventional pulmonology procedures, tracheostomy, open suctioning of airways, upper endoscopy, and transesophageal echocardiography (TEE) [20-22]. (See "COVID-19: Infection prevention for persons with SARS-CoV-2 infection", section on 'Aerosol-generating procedures/treatments'.)

Considerations for the use of TEE in patients with COVID-19 are discussed separately. (See "Transesophageal echocardiography: Indications, complications, and normal views", section on 'COVID-19 precautions' and "Overview of perioperative uses of ultrasound", section on 'Ultrasound use during the COVID-19 pandemic'.)

PPE for aerosol-generating procedures — In addition to meticulous hand hygiene and standard OR attire (gloves, disposable caps, beard covers, shoe covers or designated shoes for OR use only), recommendations of the Anesthesia Patient Safety Foundation (APSF) [23] and the American Society of Anesthesiologists (ASA) [24] for personal protective equipment (PPE) include an N95 or other respirator and eye protection during aerosol-generating procedures (figure 1).

●Respirator – We wear a properly fit-tested N95 mask (picture 1) or other respirator such as a powered air-purifying respirator (PAPR) offering a higher level of protection. A PAPR provides high-level respiratory protection, does not require fit testing, and can be repeatedly disinfected and reused [25]. Elastomeric respirators are reusable devices that can be used with high efficiency filters to provide a level of protection similar to PAPRs [26]. Elastomeric respirators avoid the limitations of vision that occur with the use of full head PAPRs and are quieter. However, they require strict cleaning protocols, and may cause difficulties with verbal communication or use of a stethoscope. (See "COVID-19: General approach to infection prevention in the health care setting", section on 'High-risk procedures (eg, aerosol-generating procedures)'.)

Options for extended use, reuse, and decontamination of N95 respirators when they are in short supply are discussed separately. (See "COVID-19: Infection prevention for persons with SARS-CoV-2 infection", section on 'When PPE is limited'.)

●Eye protection – As recommended by the CDC and the World Health Organization (WHO), we wear goggles and a full face shield covering the front and sides of the face or a hooded PAPR which provides comprehensive protection [27-29]. Standard eyeglasses do not provide sufficient protection against droplets. Some experts prefer a full-face shield since it provides eye protection and a double layer of protection for the nose and mouth, and also prevents contamination of the N95 mask or other respirator underneath it. Other experts prefer using both goggles (for airborne protection) and a face shield (for droplet protection of the eyes and face). (See "COVID-19: Infection prevention for persons with SARS-CoV-2 infection", section on 'Type of PPE'.)

Institutional protocols for use of PPE should be followed, with special attention to the appropriate sequence of putting on (donning) and taking off (doffing) PPE to avoid contamination (figure 2 and figure 3) [30]. These precautions are based on guidance from the CDC (refer to the CDC website [31]), and previous experience with other infectious agents (eg, severe acute respiratory syndrome [SARS-CoV] and Middle Eastern respiratory syndrome [MERS-CoV] viruses) [32]. (See "COVID-19: Infection prevention for persons with SARS-CoV-2 infection", section on 'Type of PPE' and "Infection prevention: Precautions for preventing transmission of infection", section on 'Airborne precautions'.)

For patients with known or suspected COVID-19, we avoid passive barrier devices such as boxes or drapes that do not use fans, air filters, or other features and were not intended to generate negative pressure. Concerns include the possibility that exposure of health care providers and patients to aerosolized airborne particles may actually be increased, and that barrier devices may make intubation more difficult have been cited [33-37].

Airway management

●Selection of airway device – Selection of an endotracheal tube (ETT) or a supraglottic airway (SGA) should be based primarily on patient and procedural factors as it would be in patients without an infection transmitted by aerosols (see "Airway management for induction of general anesthesia", section on 'Choice of airway device'). Risk of transmission may be increased during the processes of inserting and removing either an ETT or an SGA because of proximity to or contact with airway secretions, particularly if the patient coughs. Thus, high-level PPE is necessary during airway management. (See 'Considerations during aerosol-generating procedures' above.)

Goals during endotracheal intubation (or insertion of an SGA) are to secure the airway smoothly and rapidly, on the first attempt, and to reduce or eliminate aerosolization of respiratory secretions [38,39]. Other important considerations are use of disposable airway equipment whenever possible. Also, we use double gloves during intubation; we remove the outer gloves immediately after laryngoscopy. Once the ETT is placed in the trachea at the proper depth, inflate the cuff before connecting the breathing circuit. After giving a breath, ensure that there is no leak around the cuff.

After reconnection of the breathing circuit to the ETT or SGA, keep the viral filter on the ETT at all times (see 'Use of filters' below), including during any circuit disconnects (eg, transport, expiratory limb filter change). As an alternative, pause the ventilator and clamp the ETT before a disconnect. Use a closed suction system as necessary for tracheal suction, or for oral suction prior to extubation.

●Extubation – Risk during extubation is similar to intubation [12]. Efforts to avoid or minimize coughing at the time of extubation are warranted. Also, high-level PPE is necessary. (See 'Considerations during aerosol-generating procedures' above.)

Some experts suggest prophylaxis for coughing before extubation [40]. Options include intravenous (IV), topical, or intracuff lidocaine, low-dose opioids, and dexmedetomidine. (See "Extubation following anesthesia", section on 'Minimizing physiologic response to extubation'.)

After extubation, place a surgical mask over the patient’s face. For supplemental oxygen, apply a plastic mask attached to oxygen over the surgical mask, or nasal prongs under the surgical mask.

●Other airway management techniques – During mask ventilation, most clinicians aim for a tight seal and use low-pressure ventilation, although there is scant evidence to support the practice.

Considerations during low-risk procedures — Risks for transmission of infection during procedures that do not directly involve the respiratory tract and have little risk of aerosol generation have not been documented. We avoid unnecessary use of high-level PPE during procedures that do not involve the airway or other aerosol-generating procedures, because its use may impede communication and breathing, impair vision, degrade manual dexterity, and/or overheat the clinician, particularly use of a PAPR [41-43]. During low-risk procedures in patients with suspected COVID-19 or other infectious agent transmitted by aerosols, a surgical mask may be an acceptable alternative. However, an N95 respirator or PAPR should be used if a patient with known or suspected infection is coughing, even during low-risk procedures. (See "COVID-19: Infection prevention for persons with SARS-CoV-2 infection", section on 'Type of PPE'.)

Droplet transmission — Precautions against droplet transmission caused by sneezing and coughing, as well as during aerosolized treatments, are used when caring for patients infected with pathogens such as influenza. In addition to standard OR attire, providers should wear a face shield. Infected patients should wear a surgical mask. (See "Infection prevention: Precautions for preventing transmission of infection", section on 'Droplet precautions'.)

The anesthesia provider should also ensure that the anesthesia machine has high-quality filters placed on both the inspiratory and expiratory limbs for patients with active infection. (See 'Use of filters' below.)

Contact transmission — Precautions against contact transmission are necessary for patients with infections such as Clostridioides difficile (C. difficile). In addition to standard OR attire and fastidious hand hygiene that includes thorough hand washing (alcohol cleaning is not effective), a fluid-resistant gown is worn. Donning PPE occurs prior to room entry and removing occurs prior to leaving the room. (See "Infection prevention: Precautions for preventing transmission of infection", section on 'Contact precautions'.)

Sharp object injury — Risks for needlestick or sharp object injuries to OR personnel have been reduced due to advances in education, needle disposal, and engineering changes (eg, needleless devices, safety needles). Management after potential provider exposure to a bloodborne pathogen (eg, human immunodeficiency virus [HIV-1], hepatitis B virus [HBV], hepatitis C virus [HCV]) is discussed separately. (See "Prevention of hepatitis B virus and hepatitis C virus infection among health care providers" and "Management of health care personnel exposed to HIV".)

PREVENTION OF CONTAMINATION OF ANESTHESIA MACHINES AND EQUIPMENT

Standard measures to prevent contamination — Routine measures are always taken to prevent transmission of infection due to contamination of the anesthesia machine or other anesthesia equipment during use in subsequent patients [44]. These include:

Use of fresh disposable breathing circuit components — Fresh breathing circuit hoses and filters are always used for each patient to protect the internal components of the anesthesia machine from contamination by respiratory secretions from the previous patient.

Use of filters

●Breathing circuit filters – There are three types of filters for the breathing circuit: mechanical filters, electrostatic filters, and heat and moisture exchange (HME) filters (picture 2) [45,46].

•Mechanical filters contain a sheet of thick hydrophobic filter material pleated to increase the surface area and decrease resistance to flow. They have a viral filtration efficiency (VFE) >99.99 percent that is not degraded by exposure to humidity. These filters may also provide some HME when placed at the airway. Most pleated filters have an internal volume of approximately 80 mL, and a minimum tidal volume requirement of 300 mL because of dead space ventilation.

•Electrostatic filters contain a thinner sheet of filter material that is less tightly woven, so that the resistance to flow is less for a given surface area. Electrostatic filters have an electrostatic charge that attracts and traps particles. The VFE of an electrostatic filter is generally ≤99.99 percent, and this tends to decline as the filter becomes wet (eg, when exposed to high humidity) [47].

•HME filters combine a heat and humidity exchanger and a filter (typically electrostatic-type) in one unit; thus, these are ideal for use in the breathing circuit after the Y-piece connector to provide both filtration and heat and humidity conservation. HME filters are 99.999 percent effective in removing bacterial, fungal, and viral agents. Notably, heat and humidity exchange devices without filters only provide heat and humidity exchange. These devices do not remove viral particles, and do not protect the anesthesia machine.

Many commercially available circuits come with an electrostatic filter on the inspiratory and expiratory limbs, and these are sufficient for routine cases, or for patients with active infections transmitted via droplet exposure. (See 'Droplet transmission' above.)

●Gas analyzer sampling line filters – A hydrophobic membrane filter is typically added to the gas analyzer sampling line to provide additional filtration. These filters are sieve filters, typically with a 0.2 or 0.22 micron pore size, which serve as water traps to prevent liquid and particles from entering the gas analyzer chamber. They may also trap viruses in the gas stream, because all filters are more efficient at trapping particles in a gas medium than in a liquid medium.

Considerations with COVID-19 or other agents spread by aerosol — For patients with known or suspected COVID-19 or other infectious diseases that are spread by aerosol (eg, tuberculosis, chickenpox, measles), the breathing circuit should contain two filters rated for the highest VFE (see 'Infectious agents transmitted by aerosol (eg, COVID-19)' above). HME filters have been shown to effectively filter out the severe acute respiratory syndrome 2 (SARS-CoV-2) virus even after prolonged mechanical ventilation in the intensive care unit (ICU) [48]. (See "COVID-19: Intensive care ventilation with anesthesia machines", section on 'Infection control'.)

●In adults, whom the tidal volume is greater than 300 mL, one HME filter is placed between the endotracheal tube (ETT) and the circuit, proximal to the gas sampling line (figure 4). This filter should be effective even in high humidity. A second filter is placed on the expiratory limb of the breathing circuit where it connects to the anesthesia machine. Furthermore, the gas sampling line should be connected to the breathing circuit on the side of the filter that is away from the patient (figure 4). Thus, filtering is accomplished for the patient, the gas sampling line and the breathing circuit. The patient inhales gas that is filtered once, and exhales gas that is filtered once before entering the gas analyzer sampling system and twice before entering the anesthesia machine.

●In children less than 20 kg, one filter should be placed on each limb of the breathing circuit, but a standard size filter should not be added between the patient and the breathing circuit due to added dead space [49]. A separate 0.2 micron filter should be added to the gas analyzer sampling line.

Decontamination of anesthesia machines and equipment

●Anesthesia machine – Surfaces of the anesthesia machine and other anesthesia equipment (eg, computer keyboards, touchscreen computer monitors, reusable components of equipment such as blood pressure cuffs, pulse oximeter probes, and wires from monitors to the patient, and the external surfaces of other large equipment such as transesophageal echocardiography [TEE] or other ultrasonography machines) can become contaminated with the patient’s respiratory secretions and may therefore provide a mechanism for disease transmission [50]. These surfaces should be wiped down with cleaning solutions approved for viral pathogens after each patient use. Note that hospitals do not permit operating room (OR) cleaning personnel to disinfect electronic devices; either anesthesia technicians should be assigned to complete this task, or providers can personally do this.

High-level disinfection or sterilization is necessary for reusable laryngoscopes, video-laryngoscopes, flexible intubating bronchoscopes, and TEE probes after each patient use.

The disposable components of the breathing circuit are changed before use on another patient, as noted above (see 'Use of fresh disposable breathing circuit components' above). If overt contamination of the breathing system or internal components of the anesthesia machine is suspected (eg, due to failure to use filters, incorrectly placed filters, sampling of contaminated gas that is returned to the breathing system, or spillage of pulmonary edema fluid into the circuit), the specific manufacturer’s recommendations for terminal cleaning of that anesthesia machine model must be followed. Some models require internal sterilization or a prolonged period of decontamination. Links to specific manufacturers’ recommendations can be found here. For further information on cleaning of anesthesia equipment, refer to guidance from the Anesthesia Patient Safety Foundation (APSF) and American Society of Anesthesiologists (ASA).

After use in patients with COVID-19 infection, the gas sampling tubing that connects to the anesthesia breathing circuit should also be changed [51].

●Operating room – For patients with airborne infection such as COVID-19, the room should remain temporarily closed after the patient has left the OR, until enough air exchanges to remove aerosolized pathogens have occurred according to institutional guidelines. Many hospitals have implemented enhanced environmental cleaning and disinfection protocols for ORs and other rooms in which COVID-19 patients have received care. However, contaminated surfaces are no longer thought to be a major route of transmission. Thus, the Centers for Disease Control and Prevention (CDC) recommends routine cleaning and disinfection. Details are discussed in a separate topic [52]. (See "COVID-19: Infection prevention for persons with SARS-CoV-2 infection", section on 'Environmental disinfection'.)

For organisms spread by contact transmission such as Clostridioides difficile (C. difficile), disposable equipment that can be discarded after use is ideal (eg, disposable blood pressure cuffs). Nondisposable equipment is properly disinfected prior to use on another patient. A product containing bleach must be used to clean equipment and surfaces in the OR after use for a patient with C. difficile. Details are discussed separately. (See "Infection prevention: Precautions for preventing transmission of infection", section on 'Contact precautions'.)

PRECAUTIONS DURING PATIENT TRANSPORT — Selected patients with active infectious diseases that are transmitted via aerosols or droplets (eg, COVID-19, influenza) should wear a surgical mask when they are transported to and from the operating room (OR), or to other in-hospital locations. During transport of intubated patients, a high-quality heat and moisture exchanging (HME) filter should be inserted between the self-inflating (Ambu) bag and the patient.

Clinicians who have had direct contact with patients with active infections should not touch environmental surfaces such as elevator buttons during transport; this should be done by a security officer or another helper with clean hands.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Infection control".)

SUMMARY AND RECOMMENDATIONS

●Prevention of infection risks for patients

•Standard precautions to prevent transmission of infection – Standard precautions used by anesthesia providers to prevent transmission of infection from provider to patient (or from patient to provider) include fastidious hand hygiene and standard clean operating room (OR) attire (surgical masks, gloves, disposable caps, beard covers, and shoe covers or designated shoes for OR use only). (See "Infection prevention: Precautions for preventing transmission of infection", section on 'Standard precautions' and 'Infection transmission from anesthesia provider to patient' above.)

•Prevention of catheter-related bloodstream infections

-Prevention of central line infection – We use a checklist during central venous catheter insertion to ensure adherence to standard guidelines (table 1). (See "Central venous catheters: Overview of complications and prevention in adults", section on 'Catheter-related infection'.)

-Safe administration of intravenous (IV) medications – Safe vial access and injection practices includes use as soon as possible after preparation, with prompt disposal of medication syringes and vials at the end of each case. IV fluids should be used as soon as possible or within 24 hours after spiking the bag and connecting it to IV tubing. (See 'Safe administration of intravenous fluids and medications' above.)

•Role of the anesthesia provider in preventing surgical site infection (SSI) – Anesthesia providers manage certain aspects of standard precautions to reduce SSI risk including administration of appropriately timed antibiotic prophylaxis, maintaining normothermia (avoiding temperature decreases <35.5°C), and avoiding hyperglycemia. (See "Overview of control measures for prevention of surgical site infection in adults".)

●Prevention of infection risks for anesthesia providers

•Infectious agents spread by aerosol (eg, COVID-19, tuberculosis, chickenpox, measles)

-Aerosol-generating procedures – Airway management is an aerosol-generating procedure with risk for viral transmission due to contact with or proximity to airway secretions, particularly if the patient coughs. Other aerosol-generating procedures include jet ventilation with an open airway, bronchoscopy, tracheostomy, open suctioning of airways, upper endoscopy, and transesophageal echocardiography. (See 'Considerations during aerosol-generating procedures' above.)

-Personal protective equipment (PPE) during aerosolizing procedures – In addition to meticulous hand hygiene and standard OR attire, PPE should include a N95 mask or powered air-purifying respirator (PAPR), eye protection, and a fluid-resistant gown. (See 'PPE for aerosol-generating procedures' above and "Infection prevention: Precautions for preventing transmission of infection", section on 'Airborne precautions'.)

-Airway management – Endotracheal intubation is used to secure the airway during general anesthesia, ideally smoothly and rapidly, on the first attempt, with minimal aerosolization of respiratory secretions. During extubation, coughing is avoided or minimized. After extubation, a surgical mask is placed over the patient's face. (See 'Airway management' above.)

-Low-risk procedures – We avoid unnecessary use of high-level PPE during procedures that do not generate aerosols since it may impede communication and breathing, impair vision, degrade manual dexterity, and/or overheat the clinician. However, when caring for a patient with known or suspected infection who is coughing, an N95 respirator or PAPR should be used. (See 'Considerations during low-risk procedures' above.)

•Droplet transmission – In addition to standard OR attire, providers should wear a face shield when caring for patients with infections such as influenza. Infected patients should wear a surgical mask. (See "Infection prevention: Precautions for preventing transmission of infection", section on 'Droplet precautions'.)

•Contact transmission – In addition to standard OR attire and fastidious hand hygiene that includes thorough hand washing (alcohol cleaning is not effective), a fluid-resistant gown is worn for patients with infections such as Clostridioides difficile (C. difficile). Disposable equipment is used when feasible. (See "Infection prevention: Precautions for preventing transmission of infection", section on 'Contact precautions'.)

•Sharp object injury – (See "Prevention of hepatitis B virus and hepatitis C virus infection among health care providers" and "Management of health care personnel exposed to HIV".)

●Prevention of contamination of anesthesia machine and equipment

•Standard prevention measures – Fresh disposable breathing circuit components and a mechanical, electrostatic, or heat and moisture exchange (HME) filter (picture 2) are always used. (See 'Standard measures to prevent contamination' above.)

•Considerations for patients with COVID-19 – The breathing circuit should contain two filters rated for the highest viral filtration efficiency (VFE). One is a HME filter placed between the endotracheal tube (ETT) and the circuit, proximal to the gas sampling line (figure 4). A second filter is placed on the expiratory limb of the breathing circuit where it connects to the anesthesia machine. The gas sampling line should be connected to the breathing circuit on the side of the filter that is away from the patient (figure 4). The gas sampling tubing should be changed after use. (See 'Considerations with COVID-19 or other agents spread by aerosol' above.)

●Decontamination of anesthesia machine and equipment – Surfaces of the anesthesia machine and other anesthesia equipment are wiped down after each patient use with cleaning solutions approved for viral pathogens. High-level disinfection or sterilization is necessary for reusable equipment such as laryngoscopes, video-laryngoscopes, flexible intubating bronchoscopes, and transesophageal echocardiography (TEE) probes. (See 'Decontamination of anesthesia machines and equipment' above.)

●Precautions during patient transport – Selected patients with active infections transmitted via aerosols or droplets (eg, COVID-19, influenza) should wear a surgical mask during transport to and from the OR. For intubated patients, a high-quality HME filter should be inserted between the self-inflating (Ambu) bag and the patient. (See 'Precautions during patient transport' above.)