key: cord-347262-q88g1561
authors: Schutzer‐Weissmann, J.; Magee, D.J.; Farquhar‐Smith, P.
title: Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection risk during elective peri‐operative care: a narrative review
date: 2020-07-11
journal: Anaesthesia
DOI: 10.1111/anae.15221
sha: 
doc_id: 347262
cord_uid: q88g1561

The protection of healthcare workers from the risk of nosocomial severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection is a paramount concern. SARS‐CoV‐2 is likely to remain endemic and measures to protect healthcare workers against nosocomial infection will need to be maintained. This review aims to inform the assessment and management of the risk of SARS‐CoV‐2 transmission to healthcare workers involved in elective peri‐operative care. In the absence of data specifically related to the risk of SARS‐CoV‐2 transmission in the peri‐operative setting, we explore the evidence‐base that exists regarding modes of viral transmission, historical evidence for the risk associated with aerosol‐generating procedures and contemporaneous data from the COVID‐19 pandemic. We identify a significant lack of data regarding the risk of transmission in the management of elective surgical patients, highlighting the urgent need for further research.

widely reported and is an issue of great concern to clinicians and policy-makers. Community surveillance in the UK suggests an increased incidence of SARS-CoV-2 infection among patient-facing healthcare workers [1] . Of confirmed COVID-19 cases in China, 3.8% were healthcare workers and higher proportions have been reported in Italy and Spain [2] . Up to 11 May 2020, 203 healthcare worker deaths had been reported in the UK [3] . Whilst none of these were anaesthetists or intensivists, 53/1718 (3.1%) healthcare workers performing or involved in tracheal intubation of patients with confirmed or suspected COVID-19 subsequently reported laboratory-confirmed SARS-CoV-2 infection [4] .

More than 20% of all severe acute respiratory syndrome (SARS) cases were healthcare workers [5] and nosocomial SARS infection was prominent among healthcare workers looking after patients who required respiratory support [6] . Following the SARS epidemic, the World Health Organization (WHO) published a list of aerosol-generating procedures [7] , a concept originally developed to protect against transmission of tuberculosis, an obligate airborne pathogen [8] . The WHO subsequently commissioned a systematic review of the evidence for the association between aerosol-generating procedures and nosocomial SARS coronavirus-1 (SARS-CoV-1) transmission [9] . This incorporated 10 retrospective observational studies, five case-control and five cohort studies. Given its genesis, the evidence is inevitably associative and imprecise. Nonetheless, there was a consistent and strong signal (pooled odds ratio 6.6) that tracheal intubation was associated with an increased risk of transmission of SARS-CoV-1 to healthcare workers.

Understandably, this has been given considerable weight by policy-makers during the current pandemic [10] [11] [12] .

The possibility that this increased risk may, in part, be due to airborne transmission has informed not only the use of personal protective equipment (PPE) but also procedural modifications of the peri-operative pathway. Guidance continues to evolve [13] and, although not all are explicitly advised in national or international guidelines, these have included: tracheal intubation and extubation in the operating theatre to avoid contamination of anaesthetic rooms; an 'aerosol clearance time' defined in terms of room ventilation during which no one should enter, and some suggest even leave, the room following an aerosol-generating procedure; avoiding manual (bag-mask) ventilation before tracheal intubation; and, by inference, avoiding intra-operative positive pressure ventilation via supraglottic airway devices. These may be associated with adverse consequences or resource cost, some of which are outlined in Table 1 .

This article is protected by copyright. All rights reserved Unlike SARS-CoV-1, SARS-CoV-2 is likely to become an endemic threat. Healthcare systems face the challenge of increasing activity to accommodate the backlog that has built up due to service disruption [14] whilst protecting patients and staff from nosocomial infection. However, there is limited evidence concerning transmission risk in the elective peri-operative setting. Here, we review the evidence from SARS and contemporaneous data from COVID-19 to inform assessment and management of the risk of SARS-CoV-2 transmission to healthcare workers involved in elective peri-operative care.

According to the WHO, SARS-CoV-2 is predominantly transmitted by contact with infected respiratory fluids or exposure to infected respiratory droplets [15] . Environmental contamination is widespread [16, 17] and this can be mitigated by hand hygiene, gloves, aprons and environmental decontamination.

Exposure to infective droplets emitted by coughing may be mitigated by wearing a fluid-resistant surgical mask [18] . Airborne transmission is via aerosols, particles "that remain infectious when suspended in air over long distance and time" [19] and may, therefore, transmit infection further than the two-metre range of larger droplets [20, 21] . Aerosol deposition is also an important source of surface contamination [22] .

Airborne viral transmission is complex, uncertain and controversial [21] . Respiratory bioaerosols are generated by wind shear forces arising from the passage of air over infected mucosa in the respiratory tract. The number and size distribution of aerosols and their viral content vary according to the site and force of generation, environmental conditions and the degree of viral shedding at the site of aerosol generation. The infectivity of aerosols depends upon the aerosol viral load, where they deposit in the respiratory tract and tissue tropic factors (such as, in the case of SARS-CoV-2, cellular angiotensinconverting enzyme-2 (ACE-2) receptor expression) [23] .

Airborne viral spread has been demonstrated in animal models [24] and healthy human volunteers [25] and epidemiological studies suggest that this is a transmission route in other viruses [20, 26] . SARS-CoV-2 infects and replicates in both lower respiratory tract and nasopharynx [27] . Under experimental conditions, the persistence of viable SARS-CoV-2 in aerosols for up to 3 h has been demonstrated [28] .

SARS-CoV-2 ribonucleic acid (RNA) has been detected in air samples from clinical environments [22] .

Other studies were unable to detect SARS-CoV-2 in air samples but swabs from air outlets were positive [16] . It is important to note that presence of detectable SARS-CoV-2 RNA does not necessarily imply the presence of viable virus and there are no reports to date of viable SARS-CoV-2 isolated from air samples

This article is protected by copyright. All rights reserved collected in the clinical environment. There is no direct evidence of SARS-CoV-2 airborne transmission but there is epidemiological evidence that airborne SARS-CoV-1 transmission may have occurred, both in the community and in the healthcare environment.

For example, modelling of airflow dynamics correlated with the SARS-CoV-1 transmission dynamics in an apartment block, where spread by contact or respiratory droplet was unlikely [29] . Similarly, the transmission of SARS-CoV-1 to medical students who were not in direct contact with an infected patient correlated with airflow modelling [30] . In both cases, defective engineering created environmental conditions that may have contributed to these events (in the first, faulty drain seals allowing faecal aerosols to be drawn into the air conditioning; in the second, imbalance between ventilation inflow and outflow) and they are not necessarily representative of normal transmission dynamics [31, 32] .

Whilst the predominant route of SARS-CoV-2 transmission may be contact/droplet-mediated, environmental conditions -including those associated with aerosol-generating procedures -may promote 'opportunistic' airborne transmission [33] .

Aerosol-mediated airborne transmission has been a source of great anxiety among healthcare workers.

National guidelines recommend 'airborne precautions' [34] for those involved in aerosol-generating procedures but contact/droplet precautions for most other clinical activity [11, 12, 35] .

The WHO list of aerosol-generating procedures is based on epidemiological evidence of transmission to healthcare workers caring for SARS patients [30, [36] [37] [38] [39] [40] [41] [42] [43] [44] . This evidence is related to the risk of transmission whilst caring for patients with respiratory failure and critical appraisal of how this SARS data applies to the risk of SARS-CoV-2 transmission in the elective peri-operative environment is necessary. Table 2 summarises the raw data from the WHO-commissioned systematic review by Tran et al. [9] related to transmission risk associated with tracheal intubation. Tracheal intubation has been highlighted here because it is the most relevant aerosol-generating procedure in the context of elective peri-operative care. Other procedures, such as extubation, rely on this evidence by extension. Moreover, it is notable as an example of the methodology that tracheal intubation is a discrete and identifiable event and was common among SARS patients. It is therefore liable to proxy assumptions: for example, if the majority of SARS patients had developed appendicitis, such methodology might identify appendicectomy as an aerosol-generating procedure.

This article is protected by copyright. All rights reserved

The studies were limited by heterogeneous populations, poorly-defined and variable exposure, and recall bias. Across eight studies, there were 76 infections associated with tracheal intubation among a population of 2250 healthcare workers. The number of healthcare workers exposed to tracheal intubation is relatively small compared with those who were not, such as non-clinical staff. Across all studies, 22

patients transmitted SARS-CoV-1 to 99 healthcare workers. In the second-largest study, the 26 healthcare workers who developed SARS all looked after seven -and 23 looked after only four -of the 45 SARS patients whose tracheas were intubated [41] . In the largest case-control study caring for a "superspreading patient" (no definition offered in the paper) was associated with healthcare worker infection, and in multivariate analysis, this association was stronger than tracheal intubation [36] .

This evidence, therefore, rests on a small number of infections associated with a yet smaller number of highly infectious patients, among a heterogeneous population of healthcare workers, matched in some cases according to profession, in others by presence during rather than performance of the procedures under investigation. All identify other measures of proximity or contact with patients which are associated with increased transmission risk of a comparable order of magnitude to that of being involved in tracheal intubation.

The authors discuss the "difficulty in identifying the specific part of a given procedure, which may be complex and involve several manoeuvres, that imparts the greatest risk of transmission." They "acknowledge that the findings presented may have been influenced by direct and indirect contact transmission" and conclude that their "findings serve to highlight the lack of precision in the definition for aerosol generating procedures" [9] .

A recent systematic review led by Health Protection Scotland appraised the evidence base for the WHO list of aerosol-generating procedures [45] . They only identified four additional reports relating to transmission risk during tracheal intubation. Three are case reports and in each of these they found that "The multiple factors that could have led to infection transmission in this case make it very difficult, if not impossible to identify the most high risk elements." The other study that they singled out [42] was included in the WHO systematic review. Health Protection Scotland could only identify "weak evidence for an increased risk of respiratory infection transmission" from performing tracheal intubation.

This article is protected by copyright. All rights reserved There is a consistent and strong signal throughout these studies that involvement in tracheal intubation of SARS patients with respiratory failure was associated with an increased risk of viral transmission. In a recent international study, 10.7% healthcare workers involved in tracheal intubation during the COVID-19 pandemic reported lab-confirmed SARS-CoV-2 infection or hospitalisation or self-isolation due to COVID-19 symptoms [4] . How the risk of infection associated with tracheal intubation is mediated, however, is not clear.

The elective peri-operative environment is different from the acute settings from which this evidence is drawn. The preconditions and purpose of tracheal intubation for elective surgery are different from emergent/urgent tracheal intubation for respiratory failure. Pre-admission measures such as selfisolation, symptomatic screening and viral RNA testing prior to admission aim to reduce the risk that patients undergoing elective surgery are infected with SARS-CoV-2 and the risk of healthcare worker exposure to the virus in the elective peri-operative environment. However, it is important to note that these measures do not eliminate these risks. In order to provide effective and efficient protection to healthcare workers in this environment, it is imperative to consider how and why involvement in tracheal intubation and related airway procedures is associated with increased risk of viral transmission.

Coughing is the common denominator of a number of defined aerosol-generating procedures, including tracheal intubation, extubation and bronchoscopy. Indeed, the tuberculosis guidelines which introduced the term refers to 'cough-inducing and aerosol-generating procedures' [8] . The recent reiteration [46] that tracheal intubation is aerosol-generating was based on simulated tracheal intubation of a 'coughing' manikin [47] . Modelling studies confirm that the risk of airborne transmission depends upon cough frequency [48] . Air sampling demonstrates increased bio-aerosol concentrations during coughing on bronchoscope insertion [49] .

Coughing is not a procedure but its exclusion from discussions of aerosol-generating procedures may also reflect the misconception that it does not produce aerosols, which originates from early studies that were technically insensitive to smaller particles [50] . Any respiratory activity, including breathing, produces aerosols and more recent studies have demonstrated that coughing produces large numbers of both droplets and aerosols [51, 52] . The dichotomy between droplets that deposit within a short distance and aerosols that travel further may be an over-simplification [53, 54] .

This article is protected by copyright. All rights reserved H1N1 avian influenza viral titres in air samples taken during tracheal intubation were not significantly higher than background levels in intensive care units [55] although this study may have been underpowered to detect this difference [45] . Another study found no link between influenza aerosols in sampled air and aerosol-generating procedures [56] . In Canada, use of muscle relaxants for tracheal intubation was increased during the second SARS outbreak which may have contributed to the decrease in healthcare worker infections [57] and support the notion that coughing is the prime aerosol (and/or droplet) generator.

The studies upon which the WHO list of aerosol-generating procedures is based do not provide any direct evidence that tracheal intubation itself increases the risk of SARS transmission. Rather, this data implies that proximity and time in proximity to desaturation after induction of anaesthesia can be minimised by effective pre-oxygenation [74, 75] and measures which facilitate apnoeic oxygenation (for example, maintaining airway patency, minimising air entrainment via mask leak and head-up position [76] ).

Recent guidance supports the judicious use of supraglottic airway devices [13] . Some have advocated against the use of supraglottic airway devices in favour of cuffed tracheal tubes on the basis that there may be a lower risk of an aerosol leak during positive pressure ventilation [77] . There is evidence that, when used appropriately, this is not the case. The mean oropharyngeal leak pressure of the i-gel® (Intersurgical, Wokingham, UK) is 25 cmH 2 O in non-paralysed patients and 28 cmH 2 O in paralysed patients [78] . The leak fraction with i-gel® was no higher when ventilating with peak pressures below 25 cmH 2 O compared with cuffed tracheal tube [79] . Several tests of leak have been shown to be sensitive and reliable in clinical settings [80] . The risk of aerosol generation may be greater on insertion or removal where poor seal or coughing may facilitate generation and dispersal of aerosols. Therefore, perhaps more important than leak fraction is the primary failure rate where supraglottic airway devices do not achieve an adequate seal on insertion. For i-gel® this has been estimated to be 4-7% [81] but in this regard, supraglottic airway devices with an inflatable cuff may be more reliable [82] .

An 'aerosol clearance time' -waiting for a period of time for room ventilation defined in terms of air changes -has been recommended [83, 84] . UK national guidance from Public Health England advocates (as 'pragmatic') 20 minutes in a room with 10 to 12 air changes per hour following an aerosol-generating procedure [85] . This corresponds to approximately four air changes and a clearance of 96-98%. This is similar to the three to five air changes recommended by the Australian and New Zealand College of

This article is protected by copyright. All rights reserved

Anaesthetists [86] . There is evidence to support this where there has been extensive aerosol generation, e.g. intensive care rooms [55] or bronchoscopy suites [49] .

If aerosols are generated by associated respiratory activities rather than the act of tracheal intubation or extubation itself, requiring an aerosol clearance time following these procedures but not in other situations, for example in a recovery ward where patients are breathing and coughing, may seem logically inconsistent: in both environments, patients generate potentially infectious aerosols by breathing and coughing. There are, however, arguments for maintaining aerosol clearance times in the elective perioperative environment. Foremost is the precautionary principle: there is epidemiological evidence that tracheal intubation and other airway manoeuvres are consistently associated with an increased viral transmission risk and there may be elements of these procedures which increase risk that we do not appreciate.

Current UK guidelines do not recommend airborne precautions for healthcare workers where aerosolgenerating procedures are not taking place, for example in recovery wards, outpatient suites or general practice consultation rooms [11] . Other international authorities, however, advise airborne precautions for all healthcare workers coming into close proximity to an 'open' airway and not just after aerosolgenerating procedures [87] and this would include healthcare workers in recovery wards and many outpatient and community healthcare environments. This guidance is supported by the evidence presented here which emphasises the importance of proximity to patients' airways over the procedure itself. A further example of this might be a recent study of 44 anaesthetists who performed awake spinal anaesthesia (not an aerosol-generating procedure) on 49 SARS-CoV-2 positive patients which found that only 1/37 (2.7%) who used aerosol precaution PPE subsequently tested positive for SARS-CoV-2 compared to 4/7 (57.1%) who used droplet precaution PPE [88] . This may have implications for other regional anaesthetic techniques, a subject which has been recently reviewed by Uppal et al. [89] .

The focus on aerosol-generating procedures may also risk neglecting other practices to reduce transmission that are equally important. These control measures include frequent handwashing [90] , double-gloving during tracheal intubation [91] , surface cleaning of anaesthetic machines, monitors and other equipment in the immediate vicinity after tracheal intubation [92] and patient use of fluid-resistant surgical mask following extubation [93] . Basic infection control practices are often poorly observed [94] .

Sampling studies consistently identify extensive surface contamination warranting greater emphasis on this element of infection control [16, 17] . Evidence-based guidance [92] includes simple, inexpensive

This article is protected by copyright. All rights reserved measures such as placing alcohol-gel dispensers near anaesthetists which have been shown to dramatically increase hand decontamination [95] . Strict adherence to standard infection control precautions and frequent, thorough surface cleaning may reduce contact transmission [96] .

One product of the SARS experience was the concept of the aerosol-generating procedure. This epidemiological evidence, graded as very low quality, provides useful guidance in the management of symptomatic acutely unwell patients. In the elective peri-operative and other healthcare settings, however, restricting airborne precautions to healthcare workers undertaking aerosol-generating procedures may under-estimate risks to those who are in close proximity to patients but not involved in these procedures. The emphasis on aerosol-generating procedures also potentially risks neglecting the primary barriers to COVID-19 transmission of contact precautions and hand washing.

The limitations of this review reflect the limitations of the data. There is very limited evidence related to the risk of SARS-CoV-2 transmission in the elective peri-operative environment. The mechanism of infection transmission and the factors that influence it is inferred from physical studies of aerosol generation and behaviour and clinical studies of other viruses in other settings. As anaesthetists, our understanding of the complexities of aerodynamics and virology is necessarily limited and highlights the need for multidisciplinary research in this area. 

Coronavirus (COVID-19) Infection Survey pilot: 28

Rapid Risk Assessment -Coronavirus Disease 2019 COVID-19 in the EU/EEA and the UK -Eighth Update

At least 23 nationalities among NHS staff killed by covid

Risks to healthcare workers following tracheal intubation of patients with COVID-19: a prospective international multicentre cohort study

Summary of probable SARS cases with onset of illness from 1

Critically Ill Patients with Severe Acute Respiratory Syndrome

Infection Prevention and Control of Epidemic-and Pandemic-Prone Acute Respiratory Diseases in Health Care

Guidelines for preventing the transmission of Mycobacterium tuberculosis in health-care facilities

Aerosol Generating Procedures and Risk of Transmission of Acute Respiratory Infections to Healthcare Workers: A Systematic Review

Consensus guidelines for managing the airway in patients with COVID-19

COVID-19: infection prevention and control (IPC)

European Centre for Disease Control Prevention and Contol. Infection Prevention and Control and Accepted Article This article is protected by copyright. All rights reserved Preparedness for COVID-19 in Healthcare Settings -Third Update

Use of supraglottic airways during the COVID-19 pandemic -ICM Anaesthesia COVID-19

Elective surgery cancellations due to the COVID-19 pandemic: global predictive modelling to inform surgical recovery plans

Modes of Transmission of Virus Causing COVID-19: Implications for IPC Precaution Recommendations

Surface environmental, and personal protective equipment contamination by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from a symptomatic patient

Aerosol and surface distribution of severe acute respiratory syndrome coronavirus 2 in hospital wards

The role of community-wide wearing of face mask for control of coronavirus disease 2019 (COVID-19) epidemic due to SARS-CoV-2

Infection Prevention and Control of Epidemic-and Pandemic-Prone Acute Respiratory Infections in Health Care

Recognition of aerosol transmission of infectious agents: A commentary

Airborne transmission and precautions: Facts and myths

Aerodynamic analysis of SARS-CoV-2 in two Wuhan hospitals

Multiorgan and Renal Tropism of SARS-CoV-2

Mode of parainfluenza virus transmission determines the dynamics of primary infection and protection from reinfection

Airborne transmission of respiratory Accepted Article This article is protected by copyright. All rights reserved infection with coxsackievirus A type 21

Viral infections in workers in hospital and research laboratory settings: a comparative review of infection modes and respective biosafety aspects

Virological assessment of hospitalized patients with COVID-2019

Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1

Evidence of airborne transmission of the severe acute respiratory syndrome virus

Cluster of SARS among medical students exposed to single patient, Hong Kong

Epidemiology: Dimensions of superspreading

A pandemic in times of global tourism: superspreading and exportation of COVID-19 cases from a ski area in Austria

Airborne Transmission of Communicable Infection -The Elusive Pathway

Personal protective equipment during the coronavirus disease (COVID) 2019 pandemic -a narrative review

Infection Control: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)

Which preventive measures might protect health care workers from SARS?

Investigation of the influencing factors on severe acute respiratory syndrome among health care workers

Factors associated with transmission of severe acute respiratory syndrome among health-care workers in Singapore. Epidemiology and Infection Accepted Article This article is protected by copyright

Risk factors for SARS infection among hospital healthcare workers in Beijing: A case control study

A case-control study on the risk factors of severe acute respiratory syndromes among health care workers. Chung-Hua Liu Hsing Ping Hsueh

Risk factors for SARS transmission from patients requiring intubation: A multicentre investigation in Toronto

Transmission of severe acute respiratory syndrome during intubation and mechanical ventilation

SARS among Critical Care Nurses

Illness in intensive care staff after brief exposure to severe acute respiratory syndrome

Assessing the evidence base for medical procedures which create a higher risk of respiratory infection transmission from patient to healthcare worker

COVID-19 and risks posed to personnel during endotracheal intubation

Exposure to a surrogate measure of contamination from simulated patients by Emergency Department personnel wearing Personal Protective Equipment

Toward understanding the risk of secondary airborne infection: emission of respirable pathogens

Evaluation of bioaerosol exposures during hospital bronchoscopy examinations

Droplet fate in indoor environments, or can we prevent the spread of infection?

Exhaled droplets due to talking and coughing

Size distribution and sites of origin of droplets expelled from the human respiratory tract during expiratory activities

Airborne transmission of severe acute respiratory syndrome coronavirus-2 to healthcare workers: a narrative review

Turbulent Gas Clouds and Respiratory Pathogen Emissions: Potential Implications for Reducing Transmission of COVID-19

Influenza aerosols in UK hospitals during the H1N1 (2009) pandemic -the risk of aerosol generation during medical procedures

Exposure to influenza virus aerosols in the hospital setting: Is routine patient care an aerosol generating procedure

Intubation of SARS patients: Infection and perspectives of healthcare workers

Exposure to influenza virus aerosols during routine patient care

Aerosol transmission of influenza A virus: a review of new studies

Dispersion and exposure to a cough-generated aerosol in a simulated medical examination room

Health and Social Care Committee. Oral evidence: Management of the Coronavirus Outbreak

Epidemiological research priorities for public health control of the ongoing global novel coronavirus (2019-nCoV) outbreak

Epidemiology, transmission dynamics and control of SARS: The 2002-2003 epidemic

Accepted Article This article is protected by copyright. All rights reserved

Estimating the generation interval for coronavirus disease (COVID-19) based on symptom onset data

Covid-19: four fifths of cases are asymptomatic, China figures indicate

The relative transmissibility of asymptomatic COVID-19 infections among close contacts

SARS and MERS: Recent insights into emerging coronaviruses

Symptom Screening at Illness Onset of Health Care Personnel with SARS-CoV-2 Infection in King County

Screening of healthcare workers for SARS-CoV-2 highlights the role of asymptomatic carriage in COVID-19 transmission. eLife 2020. Epub 11 May

Detection of SARS-CoV-2 in different types of clinical specimens

COVID-19-guidance/Personal-protective-equipment-Public-Health-England-and-COVID-19-Montgomery-in-reverse

Medications to reduce emergence coughing after general anaesthesia with tracheal intubation: a systematic review and network meta-analysis

Exhaled air dispersion during bag-mask ventilation and sputum suctioning-Implications for infection control

Preoxygenation techniques: Comparison of three minutes and four breaths

Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults

Peri-operative management of the obese surgical patient

Anaesthesia and caring for patients during the COVID-19 outbreak

Comparison of oropharyngeal leak pressure and clinical performance of LMA ProSeal TM and i-gel® in adults: Meta-analysis and systematic review

Comparison of the i-gel with the cuffed tracheal tube during pressure-controlled ventilation

Comparison of four methods for assessing airway sealing pressure with the laryngeal mask airway in adult patients

Greif R. i-gel TM supraglottic airway in clinical practice: a prospective observational multicentre study

Success rate of airway devices insertion: Laryngeal mask airway versus supraglottic gel device

Consensus statement: Safe Airway Society principles of airway management and tracheal intubation specific to the COVID-19 adult patient group

Personal protective equipment (PPE) for both anesthesiologists and other airway managers: principles and practice during the COVID-19 pandemic

infection-preventionand-control/reducing-the-risk-of-transmission-of-covid-19-in-the-hospital-setting

Australian and New Zealand College of Anaesthetists and the Faculty of Pain Medicine. ANZCA statement on personal protection equipment during the SARS-CoV-2 pandemic

Evaluating the national PPE guidance for NHS healthcare workers during the COVID-19 pandemic

Accepted Article This article is protected by copyright. All rights reserved

Spinal anaesthesia for patients with coronavirus disease 2019 and possible transmission rates in anaesthetists: retrospective, single-centre, observational cohort study

Neuraxial anaesthesia and peripheral nerve blocks during the COVID-19 pandemic: a literature review and practice recommendations

Physical interventions to interrupt or reduce the spread of respiratory viruses: Systematic review

Anaesthesia and COVID-19: infection control

Perioperative COVID-19 defense: an evidence-based approach for optimization of infection control and operating room management

Minimising droplet and virus spread during and after tracheal extubation

Frequency of hand decontamination of intraoperative providers and reduction of postoperative healthcare-associated infections: A randomized clinical trial of a novel hand hygiene system

The effect of improving basic preventive measures in the peri-operative arena on staphylococcus aureus transmission and surgical site infections: A randomized clinical trial

This article is protected by copyright. All rights reserved

 Table 2 Summary of the raw data incorporated by Tran et al. [9] of evidence relating aerosol-generating procedures to SARS-CoV-1 infection among healthcare workers.*p < 0.05; OR, odds ration; RR, relative risk; NA, not available; ECG, electrocardiograph Ma et al. [40] This study is based on the same dataset used by Liu et al. [39] . The exposure definition used is different: it reports a risk estimate for exposure to a composite of four procedures (intubation, tracheotomy, airway care, and cardiac resuscitation). To avoid duplication and false comparison, its data is not presented here.

Healthcare workers exposed to confirmed SARS-CoV- Wong et al. [30] Not applicable to tracheal intubation but reports a cohort of medical students exposed to a single inpatient; 16