Aerosol-generating procedure

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An aerosol-generating procedure (AGP) is a medical or health-care procedure that a public health agency such as the World Health Organization or the United States Centers for Disease Control and Prevention (CDC) has designated as creating an increased risk of transmission of an aerosol borne contagious disease, [1] such as COVID-19. The presumption is that the risk of transmission of the contagious disease from a patient having an AGP performed on them is higher than for a patient who is not having an AGP performed upon them. This then informs decisions on infection control, such as what personal protective equipment (PPE) is required by a healthcare worker performing the medical procedure, or what PPE healthcare workers are allowed to use.

Designation of a procedure as an AGP may indicate a presumption that such a procedure causes the emission of more aerosols than a patient not undergoing the procedure. Such a position is at increasing odds with the scientific understanding of bioaerosol production and airborne transmission of respiratory infections. [2] [3] [4] [5] At times, healthcare workers concerned about their own risk of contracting airborne infections have been denied access to respirators outside the employment of AGPs. [6]

Medical procedures that have been designated as AGPs include positive-pressure mechanical ventilation including BiPAP and continuous positive airway pressure (CPAP), high-frequency ventilation, tracheal intubation, [7] airway suction, tracheostomy, chest physiotherapy, nebuliser treatment, sputum induction, bronchoscopy [8] and ultrasonic scaling and root planing. Different public health agencies have different lists of AGPs. [1] The term AGP became popular during the 2003 SARS epidemic, where small retrospective studies showed a higher rate of infection amongst healthcare workers in which the AGPs were performed.

COVID-19 pandemic

The COVID-19 pandemic [9] [1] has prompted research to measure the aerosols produced by patients during some AGPs including tracheal intubation and extubation, [10] [11] [12] gastroscopies, colonoscopies and trans-nasal endoscopies. [13] The AGPs studied generate less aerosols than a cough or even just breathing, [14] [10] [11] [12] so some AGPs may not increase the risk from aerosol-borne diseases such as COVID-19 significantly above that of a patient breathing or coughing normally. In a study that looked for viral RNA in air samples taken near patients with COVID-19, no correlation was found between finding viral RNA and mechanical ventilation, high flow nasal cannula, nebuliser treatment or non-invasive ventilation. [15] However data are still lacking for many AGPs. Conversely, fine and ultrafine aerosols constitute the majority of all detectable viral RNA in COVID-19 positive symptomatic and asymptomatic individuals during breathing, talking, and singing. [16]

Related Research Articles

<span class="mw-page-title-main">Tracheal intubation</span> Placement of a tube into the trachea

Tracheal intubation, usually simply referred to as intubation, is the placement of a flexible plastic tube into the trachea (windpipe) to maintain an open airway or to serve as a conduit through which to administer certain drugs. It is frequently performed in critically injured, ill, or anesthetized patients to facilitate ventilation of the lungs, including mechanical ventilation, and to prevent the possibility of asphyxiation or airway obstruction.

<span class="mw-page-title-main">Mechanical ventilation</span> Method to mechanically assist or replace spontaneous breathing

Mechanical ventilation or assisted ventilation is the medical term for using a machine called a ventilator to fully or partially provide artificial ventilation. Mechanical ventilation helps move air into and out of the lungs, with the main goal of helping the delivery of oxygen and removal of carbon dioxide. Mechanical ventilation is used for many reasons, including to protect the airway due to mechanical or neurologic cause, to ensure adequate oxygenation, or to remove excess carbon dioxide from the lungs. Various healthcare providers are involved with the use of mechanical ventilation and people who require ventilators are typically monitored in an intensive care unit.

<span class="mw-page-title-main">General anaesthesia</span> Medically induced loss of consciousness

General anaesthesia (UK) or general anesthesia (US) is a method of medically inducing loss of consciousness that renders a patient unarousable even with painful stimuli. This effect is achieved by administering either intravenous or inhalational general anaesthetic medications, which often act in combination with an analgesic and neuromuscular blocking agent. Spontaneous ventilation is often inadequate during the procedure and intervention is often necessary to protect the airway. General anaesthesia is generally performed in an operating theater to allow surgical procedures that would otherwise be intolerably painful for a patient, or in an intensive care unit or emergency department to facilitate endotracheal intubation and mechanical ventilation in critically ill patients. Depending on the procedure, general anaesthesia may be optional or required. Regardless of whether a patient may prefer to be unconscious or not, certain pain stimuli could result in involuntary responses from the patient that may make an operation extremely difficult. Thus, for many procedures, general anaesthesia is required from a practical perspective.

<span class="mw-page-title-main">Respiratory syncytial virus</span> Species of virus

Respiratory syncytial virus (RSV), also called human respiratory syncytial virus (hRSV) and human orthopneumovirus, is a contagious virus that causes infections of the respiratory tract. It is a negative-sense, single-stranded RNA virus. Its name is derived from the large cells known as syncytia that form when infected cells fuse.

<span class="mw-page-title-main">Airway management</span> Medical procedure ensuring an unobstructed airway

Airway management includes a set of maneuvers and medical procedures performed to prevent and relieve airway obstruction. This ensures an open pathway for gas exchange between a patient's lungs and the atmosphere. This is accomplished by either clearing a previously obstructed airway; or by preventing airway obstruction in cases such as anaphylaxis, the obtunded patient, or medical sedation. Airway obstruction can be caused by the tongue, foreign objects, the tissues of the airway itself, and bodily fluids such as blood and gastric contents (aspiration).

In medicine, public health, and biology, transmission is the passing of a pathogen causing communicable disease from an infected host individual or group to a particular individual or group, regardless of whether the other individual was previously infected. The term strictly refers to the transmission of microorganisms directly from one individual to another by one or more of the following means:

<span class="mw-page-title-main">Surgical mask</span> Mouth and nose cover against bacterial aerosols

A surgical mask, also known by other names such as a medical face mask or procedure mask, is a personal protective equipment used by healthcare professionals that serves as a mechanical barrier that interferes with direct airflow in and out of respiratory orifices. This helps reduce airborne transmission of pathogens and other aerosolized contaminants between the wearer and nearby people via respiratory droplets ejected when sneezing, coughing, forceful expiration or unintentionally spitting when talking, etc. Surgical masks may be labeled as surgical, isolation, dental or medical procedure masks.

<span class="mw-page-title-main">Non-invasive ventilation</span> Breathing support administered through a face mask

Non-invasive ventilation (NIV) is the use of breathing support administered through a face mask, nasal mask, or a helmet. Air, usually with added oxygen, is given through the mask under positive pressure; generally the amount of pressure is alternated depending on whether someone is breathing in or out. It is termed "non-invasive" because it is delivered with a mask that is tightly fitted to the face or around the head, but without a need for tracheal intubation. While there are similarities with regard to the interface, NIV is not the same as continuous positive airway pressure (CPAP), which applies a single level of positive airway pressure throughout the whole respiratory cycle; CPAP does not deliver ventilation but is occasionally used in conditions also treated with NIV.

Ventilator-associated pneumonia (VAP) is a type of lung infection that occurs in people who are on mechanical ventilation breathing machines in hospitals. As such, VAP typically affects critically ill persons that are in an intensive care unit (ICU) and have been on a mechanical ventilator for at least 48 hours. VAP is a major source of increased illness and death. Persons with VAP have increased lengths of ICU hospitalization and have up to a 20–30% death rate. The diagnosis of VAP varies among hospitals and providers but usually requires a new infiltrate on chest x-ray plus two or more other factors. These factors include temperatures of >38 °C or <36 °C, a white blood cell count of >12 × 109/ml, purulent secretions from the airways in the lung, and/or reduction in gas exchange.

<span class="mw-page-title-main">Airborne transmission</span> Disease transmission by airborne particles

Airborne transmission or aerosol transmission is transmission of an infectious disease through small particles suspended in the air. Infectious diseases capable of airborne transmission include many of considerable importance both in human and veterinary medicine. The relevant infectious agent may be viruses, bacteria, or fungi, and they may be spread through breathing, talking, coughing, sneezing, raising of dust, spraying of liquids, flushing toilets, or any activities which generate aerosol particles or droplets.

<span class="mw-page-title-main">Heated humidified high-flow therapy</span> Respiratory support method

Heated humidified high-flow therapy, often simply called high flow therapy, is a type of respiratory support that delivers a flow of medical gas to a patient of up to 60 liters per minute and 100% oxygen through a large bore or high flow nasal cannula. Primarily studied in neonates, it has also been found effective in some adults to treat hypoxemia and work of breathing issues. The key components of it are a gas blender, heated humidifier, heated circuit, and cannula.

<span class="mw-page-title-main">Wells curve</span> Science of medicine

The Wells curve is a diagram, developed by W. F. Wells in 1934, which describes what is expected to happen to small droplets once they have been exhaled into air. Coughing, sneezing, and other violent exhalations produce high numbers of respiratory droplets derived from saliva and/or respiratory mucus, with sizes ranging from about 1 μm to 2 mm. Wells' insight was that such droplets would have two distinct fates, depending on their sizes. The interplay of gravity and evaporation means that droplets larger than a humidity-determined threshold size would fall to the ground due to gravity, while droplets smaller than this size would quickly evaporate, leaving a dry residue that drifts in the air. Since droplets from an infected person may contain infectious bacteria or viruses, these processes influence transmission of respiratory diseases.

<span class="mw-page-title-main">Respiratory droplet</span> Type of particle formed by breathing

A respiratory droplet is a small aqueous droplet produced by exhalation, consisting of saliva or mucus and other matter derived from respiratory tract surfaces. Respiratory droplets are produced naturally as a result of breathing, speaking, sneezing, coughing, or vomiting, so they are always present in our breath, but speaking and coughing increase their number.

<span class="mw-page-title-main">Dental aerosol</span> Hazardous biological compound

A dental aerosol is an aerosol that is produced from dental instrument, dental handpieces, three-way syringes, and other high-speed instruments. These aerosols may remain suspended in the clinical environment. Dental aerosols can pose risks to the clinician, staff, and other patients. The heavier particles contained within the aerosols are likely to remain suspended in the air for relatively short period and settle quickly onto surfaces, however, the lighter particles may remain suspended for longer periods and may travel some distance from the source. These smaller particles are capable of becoming deposited in the lungs when inhaled and provide a route of diseases transmission. Different dental instruments produce varying quantities of aerosol, and therefore are likely to pose differing risks of dispersing microbes from the mouth. Air turbine dental handpieces generally produce more aerosol, with electric micromotor handpieces producing less, although this depends on the configuration of water coolant used by the handpiece.

<span class="mw-page-title-main">N95 respirator</span> Particulate respirator meeting the N95 standard

An N95 respirator is a disposable filtering facepiece respirator or reusable elastomeric filter that meets the U.S. National Institute for Occupational Safety and Health (NIOSH) N95 classification of air filtration, meaning that it filters at least 95% of airborne particles that have a mass median aerodynamic diameter of 0.3 micrometers under 42 CFR Part 84, effective July 10, 1995. This standard does not require that the respirator be resistant to oil; two other standards, R95 and P95, add that requirement. The N95 type is the most common filtering facepiece respirator. It is an example of a mechanical filter respirator, which provides protection against particulates but not against gases or vapors. An authentic N95 respirator is marked with the text "NIOSH" or the NIOSH logo, the filter class ("N95"), and, for most filtering facepiece respirators, a "TC" approval number of the form 84A-####, the approval number. All N95 respirators, regardless of type, must be listed on the NIOSH Certified Equipment List (CEL) or the NIOSH Trusted-Source page, and it must have headbands instead of ear loops.

<span class="mw-page-title-main">Workplace hazard controls for COVID-19</span> Prevention measures for COVID-19

Hazard controls for COVID-19 in workplaces are the application of occupational safety and health methodologies for hazard controls to the prevention of COVID-19. Vaccination is the most effective way to protect against severe illness or death from COVID-19. Multiple layers of controls are recommended, including measures such as remote work and flextime, increased ventilation, personal protective equipment (PPE) and face coverings, social distancing, and enhanced cleaning programs.

<span class="mw-page-title-main">Intubation granuloma</span> Medical condition

Intubation granuloma is a benign growth of granulation tissue in the larynx or trachea, which arises from tissue trauma due to endotracheal intubation. This medical condition is described as a common late complication of tracheal intubation, specifically caused by irritation to the mucosal tissue of the airway during insertion or removal of the patient's intubation tube.

<span class="mw-page-title-main">Source control (respiratory disease)</span> Strategy for reducing disease transmission

Source control is a strategy for reducing disease transmission by blocking respiratory secretions produced through breathing, speaking, coughing, sneezing or singing. Multiple source control techniques can be used in hospitals, but for the general public wearing personal protective equipment during epidemics or pandemics, respirators provide the greatest source control, followed by surgical masks, with cloth face masks recommended for use by the public only when there are shortages of both respirators and surgical masks.

William Firth Wells was an American scientist and sanitary engineer. In his early career, he pioneered techniques for the aquaculture of oysters and clams. He is best known for his work on airborne infections. Wells identified that tuberculosis could be transmitted through air via the nuclei of evaporated respiratory droplets, and developed the Wells curve to describe what happens to respiratory droplets after they have been expelled into the air.

<span class="mw-page-title-main">Transmission of COVID-19</span> Mechanisms that spread coronavirus disease 2019

The transmission of COVID-19 is the passing of coronavirus disease 2019 from person to person. COVID-19 is mainly transmitted when people breathe in air contaminated by droplets/aerosols and small airborne particles containing the virus. Infected people exhale those particles as they breathe, talk, cough, sneeze, or sing. Transmission is more likely the closer people are. However, infection can occur over longer distances, particularly indoors.

References

  1. 1 2 3 Klompas, Michael; Baker, Meghan; Rhee, Chanu (2021-02-01). "What Is an Aerosol-Generating Procedure?". JAMA Surgery. 156 (2): 113–114. doi: 10.1001/jamasurg.2020.6643 . ISSN   2168-6254. PMID   33320188.
  2. ↑ Zayas, Gustavo; Chiang, Ming; Wong, Eric; MacDonald, Fred; F Lange, Carlos; Senthilselvan, Ambikaipakan; King, Malcolm (21 March 2012). ""Cough aerosol in healthy participants: fundamental knowledge to optimize droplet-spread infectious respiratory disease management"". BMC Pulmonary Medicine. 12. doi: 10.1186/1471-2466-12-11 . PMC   3331822 . PMID   22436202. Small size droplets (< 1 μm) predominated the total number of droplets expelled when coughing
  3. ↑ Stadnytskyi, Valentyn; Bax, Christina E.; Bax, Adriaan; Anfinrud, Philip (May 13, 2020). ""The airborne lifetime of small speech droplets and their potential importance in SARS-CoV-2 transmission"". Proceedings of the National Academy of Sciences. 117 (22): 11875–11877. Bibcode:2020PNAS..11711875S. doi: 10.1073/pnas.2006874117 . PMC   7275719 . PMID   32404416. These observations confirm that there is a substantial probability that normal speaking causes airborne virus transmission in confined environments.
  4. ↑ Bourouiba, Lydia (October 6, 2020). "The Fluid Dynamics of Disease Transmission". Annual Review of Fluid Mechanics. 53: 473–508. doi:10.1146/annurev-fluid-060220-113712 . Retrieved 21 March 2024.
  5. ↑ Wang, Chia C.; Prather, Kimberly A; Sznitman, Josué; Jimenez, Jose L; Lakdawala, Seema S.; Tufekci, Zeynep; Marr, Linsey C. (27 Aug 2021). "Airborne transmission of respiratory viruses". Science. 373 (6558). doi:10.1126/science.abd9149. PMC   8721651 . PMID   34446582. Given the lack of evidence for droplet and fomite transmission and the increasingly strong evidence for aerosols in transmitting numerous respiratory viruses, we must acknowledge that airborne transmission is much more prevalent than previously recognized.
  6. ↑ MacIntyre, C Raina; Veness, Benjamin; Ananda-Rajah, Michelle (June 16, 2021). ""At last, health, aged care and quarantine workers get the right masks to protect against airborne coronavirus"". The Conversation . Retrieved 21 March 2024. The existing guidelines said health providers working around COVID-19 patients should wear a surgical mask. It restricted use of the more protective P2 or N95 masks, which stop airborne particles getting through, to very limited scenarios. These involved "aerosol-generating procedures", such as inserting a breathing tube.
  7. ↑ El-Boghdadly, K.; Wong, D. J. N.; Owen, R.; Neuman, M. D.; Pocock, S.; Carlisle, J. B.; Johnstone, C.; Andruszkiewicz, P.; Baker, P. A.; Biccard, B. M.; Bryson, G. L. (2020-06-09). "Risks to healthcare workers following tracheal intubation of patients with COVID-19: a prospective international multicentre cohort study". Anaesthesia. 75 (11): 1437–1447. doi: 10.1111/anae.15170 . ISSN   1365-2044. PMC   7300828 . PMID   32516833.
  8. ↑ Tran K, Cimon K, Severn M, Pessoa-Silva CL, Conly J (April 2012). "Aerosol generating procedures and risk of transmission of acute respiratory infections to healthcare workers: a systematic review". PLOS ONE. 7 (4): e35797. Bibcode:2012PLoSO...735797T. doi: 10.1371/journal.pone.0035797 . PMC   3338532 . PMID   22563403.
  9. ↑ Wilson, Nick; Corbett, Stephen; Tovey, Euan (2020). "Airborne transmission of covid-19". BMJ. BMJ 2020;370:m3206. 370: m3206. doi: 10.1136/bmj.m3206 . PMID   32819961. S2CID   221178291. Archived from the original on 2020-08-21.
  10. 1 2 Brown, J.; Gregson, F. K. A.; Shrimpton, A.; Cook, T. M.; Bzdek, B. R.; Reid, J. P.; Pickering, A. E. (2021). "A quantitative evaluation of aerosol generation during tracheal intubation and extubation". Anaesthesia. 76 (2): 174–181. doi: 10.1111/anae.15292 . ISSN   0003-2409. PMC   7675579 . PMID   33022093.
  11. 1 2 Dhillon, R. S.; Rowin, W. A.; Humphries, R. S.; Kevin, K.; Ward, J. D.; Phan, T. D.; Nguyen, L. V.; Wynne, D. D.; Scott, D. A.; the Clinical Aerosolisation Study Group; Yule, A. (2021). "Aerosolisation during tracheal intubation and extubation in an operating theatre setting". Anaesthesia. 76 (2): 182–188. doi:10.1111/anae.15301. ISSN   0003-2409. PMC   7675280 . PMID   33047327.
  12. 1 2 Shrimpton, A. J.; Brown, J. M.; Gregson, F. K. A.; Cook, T. M.; Scott, D. A.; McGain, F.; Humphries, R. S.; Dhillon, R. S.; Bzdek, B. R.; Hamilton, F.; Reid, J. P. (2021-08-26). "A quantitative evaluation of aerosol generation during manual facemask ventilation". medRxiv   10.1101/2021.08.23.21262441v1 .
  13. ↑ Phillips, Frank; Crowley, Jane; Warburton, Samantha; Gordon, George S.D.; Parra-Blanco, Adolfo (June 2022). "Aerosol and droplet generation in upper and lower gastrointestinal endoscopy: whole procedure and event-based analysis". Gastrointestinal Endoscopy. 96 (4): 603–611.e0. doi: 10.1016/j.gie.2022.05.018 . PMC   9386278 . PMID   35659608. S2CID   249324970.
  14. ↑ Nestor, C. C.; Wang, S.; Irwin, M. G. (2021). "Are tracheal intubation and extubation aerosol-generating procedures?". Anaesthesia. 76 (2): 151–155. doi:10.1111/anae.15328. ISSN   0003-2409. PMC   7753480 . PMID   33274761.
  15. ↑ Thuresson, Sara (2022). "Airborne SARS-CoV-2 in hospitals – effects of aerosol-generating procedures, HEPA-filtration units, patient viral load and physical distance". Clinical Infectious Diseases. 75 (1): e89–e96. doi: 10.1093/cid/ciac161 . PMC   9383519 . PMID   35226740.
  16. ↑ Coleman, Kristen K; Wen Tay, Douglas Jie; Sen Tan, Kai; Xiang Ong, Sean Wei; Than, The Son; Koh, Ming Hui; Chin, Yi Qing; Nasir, Haziq; Mak, Tze Minn; Jang Hann Chu, Justin; Milton, Donald K; Chow, Vincent T K; Tambyah, Paul Anantharajah; Chen, Mark; Tham, Kwok Wai (15 May 2022). "Viral Load of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in Respiratory Aerosols Emitted by Patients With Coronavirus Disease 2019 (COVID-19) While Breathing, Talking, and Singing". Clinical Infectious Diseases. 74 (10): 1722–1728. doi:10.1093/cid/ciab691. PMC   8436389 . PMID   34358292 . Retrieved March 20, 2024.
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