Aerosol generating procedures (AGPs) are a category of medical activities recognized for their potential to increase the risk of infectious disease transmission, particularly those spread through the air. Understanding these procedures became relevant during global respiratory virus outbreaks, where minimizing exposure to infectious particles was a primary concern for healthcare providers. The designation of a procedure as an AGP informs infection control decisions, ensuring that appropriate protective measures are in place to safeguard personnel and manage the risk of exposure to aerosol-borne pathogens like influenza or coronaviruses.
Defining Aerosol Generating Procedures
An AGP is a medical or patient care activity that artificially induces the rapid creation and spread of fine respiratory particles, known as aerosols, from a patient’s respiratory tract. The risk associated with these procedures comes from the volume and high concentration of potentially infectious material they generate. Aerosols are distinct from large respiratory droplets, which are generally defined as particles greater than five to ten micrometers in diameter. These larger droplets follow a ballistic path and fall rapidly to the ground within a short distance, typically less than two meters.
True aerosols are much smaller, often less than five micrometers in size, and can remain suspended in the air for extended periods. This ability to linger allows them to travel farther on air currents, increasing the potential for inhalation exposure throughout the room. The creation of these minute particles from deep within the lungs is what elevates the risk of airborne transmission for certain pathogens. Therefore, the designation of a procedure as an AGP is based on its propensity to create these highly mobile, respirable particles.
Common Examples in Clinical Settings
Several medical interventions are consistently identified as AGPs due to their capacity to generate infectious aerosols. One primary example is tracheal intubation and extubation, the process of inserting or removing a tube to secure an airway. Related procedures, such as open suctioning of the respiratory tract to clear secretions without a closed system, also fall into this category. The physical manipulation and resulting cough reflex during these actions release a high concentration of aerosols.
Other complex respiratory procedures classified as AGPs include bronchoscopy, where a scope is inserted into the lungs for examination or treatment. Non-invasive ventilation (NIV) methods, such as BiPAP or CPAP, are frequently listed, particularly when their closed circuits are broken or disturbed. Induced sputum collection, which involves stimulating a patient to produce a deep cough sample, is another recognized AGP. Furthermore, procedures associated with cardiopulmonary resuscitation (CPR), specifically manual ventilation before intubation, are managed as AGPs due to the forceful air movement involved.
Distinguishing AGPs from Routine Care
The difference between AGPs and routine patient care lies in the volume and velocity of aerosol generation. While natural actions like coughing, sneezing, or talking produce some aerosols, these emissions do not reach the sustained, high-volume release created by an AGP. Routine physical examination, administering oxygen through a standard nasal cannula, or simple vital sign checks are not classified as high-risk procedures. These activities are managed with standard droplet precautions for most infectious diseases.
Procedures like using closed-system respiratory suctioning, where the airway circuit remains sealed, do not qualify as AGPs. Nebulized medication treatments can be a source of confusion because they intentionally create a visible aerosol to deliver the drug. However, the particles generated are primarily medication and water, and the risk profile is considered lower than true AGPs, unless performed in an enclosed space. The determination is based on scientific evidence linking the specific procedure to an increased risk of infection transmission among healthcare workers.
Required Safety Measures and Environmental Controls
Mitigating the risk associated with AGPs requires a multi-layered approach involving personal protection and environmental engineering. Healthcare personnel performing or assisting with these high-risk procedures must wear specialized personal protective equipment (PPE). This includes high-level respiratory protection, such as an N95 respirator or a Powered Air-Purifying Respirator (PAPR), designed to filter out small aerosol particles.
Respiratory protection must be combined with a gown, gloves, and eye protection, such as a full face shield, to prevent contact with splashes and droplets. The procedure should ideally be performed in a specifically designed Airborne Infection Isolation Room (AIIR). These rooms maintain a negative pressure differential, ensuring air flows into the room but not out into the corridor, thereby containing infectious aerosols.
The ventilation systems in AIIRs are designed to rapidly clear the air through a high number of air changes per hour (ACH). Guidelines recommend that these rooms achieve a minimum of 12 ACH, with some older facilities requiring at least six ACH. This high turnover rate ensures that airborne contaminants are removed from the room, significantly reducing the environmental risk to subsequent occupants and staff. The door to the AIIR must remain closed during and after the AGP to allow the ventilation system to clear the air effectively.