This guideline is to be read in conjunction with NSW Health policy directives PD2017_013 Infection Prevention and Control Policy and PD2018_009 Occupational Assessment, Screening and Vaccination Against Specified Infectious Diseases.
Sputum induction is a procedure used for patients who have trouble producing sputum spontaneously. The patient inhales nebulised hypertonic saline solution, which liquefies airway secretions, promotes coughing and allows expectoration of respiratory secretions. Sputum induction is simple and non-invasive, and if successful, often precludes the need for bronchoscopy.
The procedure produces coughing so it is likely that infectious droplets, if present, will be expelled into the room air. Strict airborne respiratory precautions should be observed whenever sputum induction is performed.
Sputum induction is used as an aid to the diagnosis of pulmonary tuberculosis (TB) in patients who are unable to spontaneously expectorate adequate sputum specimens. It may also be useful in the diagnosis of miliary tuberculosis and tuberculous pleural effusion
This procedure should only be performed by Physiotherapists and Registered Nurses who have been trained and accredited by their health care facility.
Assess the patient for the presence of asthma or any of the other conditions listed under Contraindications and Precautions above.
The following points should be explained to the patient prior to the procedure:
Document the procedure and any significant details in the patient's progress notes and the nursing care plan. Once a result becomes available document this in both the medical notes and on the result sheet in the front of the bed side charts for inpatients, or in the medical notes only for out-patients.
Place a sign on the door indicating when the room will be safe to enter
Adequate time must be allowed after the procedure for removal of at least 99% of airborne contaminants. This time period will vary; depending on the amount of air exhausted from the room, room air mixing, and the size of the room (see table 1).
Table 1 - Air changes per hour (ACH) and time required for removal efficiencies of 99.9% of airborne contaminants*
*This table can be used to estimate the time necessary to clear the air of airborne Mycobacterium tuberculosis after the patient leaves the area or when aerosol-producing procedures are complete.
A room with negative pressure should be used for sputum induction to prevent infectious particles from escaping to other areas of the facility. Air in rooms used for sputum induction should not be re-circulated unless it is via a well-maintained HEPA filtration unit. The air should be vented externally and external vents should not be in proximity to other patient areas (i.e. placement of vents needs to be done in consideration of the impact on the hospital population).
Type 5 (Respiratory isolation) rooms are rooms that are suitable for the isolation of patients with infections transmissible by the airborne route and which are designed to minimise the potential for these infections to be transmitted to other patients or staff. Appropriate personal protection should be utilised by individuals entering the room.
A Type 5 (respiratory isolation) room will comprise a single room with an en suite, but engineered such that the interior of the room can be made to be at a negative pressure with respect to the corridor with no, or minimal leakage of, air into the corridor.
With currently available technology and engineering practices, this means that an anteroom will usually be required. The anteroom should not be shared between rooms. The anteroom will not need to function as an absolute airlock. No air from the room should be recirculated into other areas within the facility (unless a HEPA filter is used).
Air change rates should be greater than or equal to twelve air change rates per hour with a minimum of two air changes per hour of outside air, whichever results in the greater air quantity, should be achievable when the filters have reached their maximum pressure drop.
Sputum induction rooms and local exhaust devices should be placed near patient care areas, where staff can monitor and assist patients as needed. The room should be located away from waiting rooms and other areas where patients or visitors are likely to enter and risk being exposure.
No air from respiratory isolation rooms should be reticulated via or to any other ventilation system. Air from these rooms should be exhausted directly outside of the building. The discharge points should be located as far as possible from air intakes, animals and persons. Alternatively, if external exhausting is not possible, air that is to be re-circulated should be directed through HEPA filters.
The maintenance of rooms used for sputum induction includes inspecting and replacing pre-filters and final HEPA filters. Many of these devices are equipped with filter gauges that indicate when filters are dirty and need replacement. Pre-filters (used to prolong the life of HEPA filters) need to be changed more often than final HEPA filters. Filters should be changed and disposed of in accordance with local requirements.
Recommendations on scheduled maintenance may vary with each manufacturer. A staff person or facility engineer should be assigned to monitor the maintenance of the sputum induction device. This person should be trained in the basic principles of the unit's operation, including recommended periodic checks.