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Infection Control Measures |
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In patients with a known infectious disease, many laboratories prefer to measure ventilatory function using a pneumotachograph or other electronic sensor, as these can be more easily cleaned and sterilised than conventional bellows or water-sealed spirometers.
Although the transmission of respiratory pathogens (e.g. Mycobacterium avium, M. tuberculosis and aspergillus species) via spirometers has not been fully established, the potential risks are difficult to disprove. During spirometry patients can generate flows up to 14 L/sec (840 L/min) which can easily mobilise saliva and create dense macro- and micro-aerosols by entrainment of the fluid lining the mucous membranes. These can then be deposited in the equipment. Unless such deposition is prevented or the equipment is rigorously cleaned and decontaminated, the chance of cross-infection exists.
Mouthpieces must be disposed of or cleaned and disinfected between patients because the greatest danger of cross-infection is via direct contact with bodily fluids.
Since it is usually impractical to effectively decontaminate the interior surfaces of a spirometer between patients, most lung function laboratories clean and disinfect their equipment periodically (weekly or monthly) or use a disposable, low-resistance micro-aerosol filter inserted between the subject and spirometer to prevent contamination. Filters also have the advantage of protecting sensors and the internal surfaces of the spirometer from damage and reduce the corroding effects of cleaning agents and disinfectants. The extent to which the use of filters can effectively obviate the need for cleaning and disinfection is unclear. The cost of filters may be offset by reduced cleaning and disinfection costs. Other laboratories use disposable mouthpieces containing a one-way valve to prevent inspiration from equipment, but this is only possible when performing solely expiratory spirometry. However, their effectiveness at reducing the risk of cross-infection does not appear to have been studied.
If disassembling the spirometer for cleaning, it is essential to:
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thoroughly dry the components before reassembling
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check the spirometer for correct operation
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adjust the calibration, if necessary.
Content Updated 28 March, 2008
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Last Updated ( Tuesday, 17 February 2009 )
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