The key aspects of applying airborne precautions relate to:
• standard precautions, including respiratory hygiene and cough etiquette (see Section B1.6) • use of appropriate PPE (particularly correctly-fitted respirators)
• minimising exposure of other patients and staff members to the infectious agent.
Specialist procedural areas should refer to their discipline-specific guidelines for detailed advice on applying airborne precautions relevant to the field of practice.
Personal protective equipment
When there is a high probability of airborne transmission due to the infectious agent or procedure, sound scientific principles support the use of P2 respirators to prevent transmission (see also Table B1.6; page 52). Respirators are designed to help reduce the wearer’s respiratory exposure to airborne contaminants such as particles, gases or vapours. P2 respirators are appropriate for the majority of airborne precautions encountered in healthcare facilities. There is a range of respiratory protective equipment outlined in AS 1715:2009, which provide differing levels of protection dependant upon the nature of the microorganism, the mode of transmission and procedure being undertaken.
The need for PPE varies with the condition in question and the immune status of the healthcare worker. For example, staff members known to be immune to the relevant infectious agent are not required to wear a P2 respirator. For high-risk procedures such as bronchoscopy where the risk of droplet and airborne infection is high, a P2 respirator should be worn if the infectious status of the patient is unknown or unconfirmed.
P2 respirators – fit testing and checking
In order for a P2 respirator to offer the maximum desired protection it is essential that the wearer is properly fitted and trained in its safe use. A risk-management approach should be applied to ensure that staff working in high-risk areas are fit tested and are aware of how to perform a fit check.
Fit testing
The purpose of fit testing is to identify which size and style of P2 respirator is suitable for an individual, and to ensure that it is worn correctly. It also provides an opportunity to ensure healthcare workers are properly trained in the correct use of the mask.
Fit testing should be performed:
• at the commencement of employment for employees who will be working in clinical areas where there is a significant risk of exposure to infectious agents transmitted via the airborne route— assessment of the significance of risk will involve consideration of the location (e.g. risk is higher in an intensive care unit) and activities to be undertaken (e.g. a physiotherapist performing induced sputum is at risk of exposure to infectious aerosols);
• when there is a significant change in the wearer’s facial characteristics that could alter the facial seal of the respirator (e.g. significant change in body weight, facial surgery); and
• at regular intervals—AS1715:2009 recommends annual fit testing. Healthcare facilities should ensure that they have a respiratory protection program that regularly evaluates the risk to which healthcare workers are exposed and determines which employees are required to undertake fit testing.
Employers must ensure that their employees have the medical ability to wear a respirator. Medical evaluations are required for both positive pressure and negative pressure respirators.
There are two types of facial fit test—qualitative and quantitative. Qualitative fit tests are fast and simple but can be influenced by the wearer. Quantitative fit tests require the use of specialised equipment used by a trained operator. AS/NZS 1715:2009 outlines the method by which fit testing is conducted.
Fit checking
Healthcare workers must perform fit checks every time they put on a P2 respirator to ensure it is properly applied. No clinical activity should be undertaken until a satisfactory fit has been achieved. Fit checks ensure the respirator is sealed over the bridge of the nose and mouth and that there are no gaps between the respirator and face. Healthcare workers must be informed about how to perform a fit check.
The procedure for fit checking includes (see Figure B2.2): • placement of the respirator on the face
• placement of the headband or ties over the head and at the base of the neck
• compressing the respirator to ensure a seal across the face, cheeks and the bridge of the nose • checking the positive pressure seal of the respirator by gently exhaling. If air escapes,
the respirator needs to be adjusted
• checking the negative pressure seal of the respirator by gently inhaling. If the respirator is not drawn in towards the face, or air leaks around the face seal, readjust the respirator and repeat process, or check for defects in the respirator.
The manufacturer’s instructions for fit checking of individual brands and types of P2 respirator should be referred to at all times.
Healthcare workers who have facial hair (including a 1–2 day beard growth) must be aware that an adequate seal cannot be guaranteed between the P2 respirator and the wearer’s face.
figure B2 .2: Process for putting on a P2 respirator
Source: Courtesy of DHS Victoria www.health.vic.gov.au/environment/downloads/fitting_mask.pdf. Wearing a P2 respirator
Considerations when using a P2 respirator include (DoHA 2006):
• if a good facial seal cannot be achieved (e.g. the intended wearer has a beard or long moustache), an alternative respirator such as a powered air-purifying respirator (PAPR) should be used
• respirators should not be touched while being worn • respirators should be changed when they become moist
recommendation
22 Personal protective equipment to prevent airborne transmission Grade
Wear a correctly fitted P2 respirator when entering the patient-care area when an airborne-
transmissible infectious agent is known or suspected to be present. D
Patient placement
When patients have a confirmed or suspected airborne-transmissible condition or if nebulisation is to be performed, it is important to place them in an area that can be contained (e.g. placing them in a single room and, providing it is tolerated, asking them to wear a surgical mask while not in a single room, until advised to remove it by attending staff). It is important that the door to the room remains closed and that, where possible, only staff or visitors who are immune to the specific infectious agent enter the room. Non-immune staff should be provided with appropriate PPE. While there is a paucity of evidence to confirm their effectiveness, the use of correctly serviced/ maintained negative pressure rooms may reduce the transmission of airborne infection within healthcare settings (Siegel et al 2007).
Visitors should be restricted and screened by nursing staff, with visitors’ names recorded either in a log book or in the case notes.
recommendation
23 Placement of patients requiring airborne precautions Grade
Patients on airborne precautions should be placed in a negative pressure room or in a room from which the air does not circulate to other areas.
Exceptions to this should be justified by risk assessment.
GPP
transfer of patients
If transfer of the patient outside the negative pressure room is necessary, asking the patient to wear a correctly fitted surgical mask while they are being transferred and to follow respiratory hygiene and cough etiquette, as well as covering any skin lesions associated with the condition (e.g. chickenpox [varicella]) will reduce the risk of cross-transmission. Children should wear a correctly fitting mask when they are outside an isolation room. The child’s oxygen saturation should be monitored. risk-management case study
M. tuberculosis among immunocompromised patients attending outpatient services
An investigation into the healthcare-associated transmission of M. tuberculosis followed reports of two epidemiologically linked patients (Patient 1 and Patient 2) with haematologic malignancies and active pulmonary TB. Subsequently it was found that four oncology patients had spent more than an hour in the same room as Patient 1. Patient 1’s pulmonary TB was not diagnosed for 3 months as clinical findings were attributed to lower respiratory tract infection from other infectious agents or adverse effects of oncology treatments. Patient 1 was not placed on airborne precautions during this period. The investigation found that delayed TB diagnosis in Patients 1 and 2 ultimately resulted in the transmission of M. tuberculosis to 19 patients and staff at three hospitals and a residential facility.
eliminating risks In this situation, it is not possible to eliminate risk, so it must be managed.
Identifying risks In this case, the risk has been identified as cross-transmission of M. tuberculosis from a single
patient attending a number of outpatient facilities.
analysing risks The sources of risk are a failure to consider the possibility of tuberculosis and delays in
screening and diagnostic tests. These resulted in a lack of transmission-based precautions applied to Patient 1, a source of risk to subsequent patients.
evaluating risks The balance of likelihood and consequences identify this as a ‘very high risk’ situation requiring
immediate response.
treating risks Immediate measures may include avoidance of potential exposures in outpatient settings,
implementation of airborne precautions and treatment of febrile, coughing patients with pulmonary TB. State/territory TB services would also need to be notified, as they would assist in the development of a management plan. Longer-term measures could include implementation of baseline TB screening for immunocompromised patients and protocols to assist with earlier diagnosis of active disease. Further measures would include increasing awareness of tuberculosis generally, educating staff about identifying the high-risk patients for a particular facility, and development of specific protocols, such as ‘cough protocols’.
monitoring Ongoing surveillance would assist in reducing the risk of subsequent outbreaks. Retrospective
review and screening of other contacts and laboratory typing of M. tuberculosis isolates to identify unrecognised, linked transmission could also inform future actions.
Measles (rubeola) control in general practice
The case study in Section A2.2 (see page 30) outlines a risk assessment approach to airborne precautions in the primary care setting.