Aerosol production by suction apparatus and methods of containment

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The use of poorly-maintained suction equipment, or equipment which is not fitted with a bacteria-retentive filter to prevent dispersal of bacterial aerosols into the environment has been shown to be a potential source of infection. Rahman (1980) describes a case in which suction equipment contaminated with Mycobacterium fort&urn was used without a filter. The equipment required dismantling and contaminated parts were sterilized by low temperature steam and formaldehyde before reassembly. Where steps are taken to prevent the escape of aerosols by the use of filters the problem of aerosols remaining in the bottle above the liquid still presents a potential hazard. Not only can the ward atmosphere become contaminated, thus putting both staff and particularly patients at risk, but also the equipment becomes contaminated, putting engineering staff at a possible risk when the equipment requires servicing. The work reported here confirms the presence of an aerosol in the bottle and the ease with which it may escape into the atmosphere. The removal of uncapped bottles from suction equipment is also potentially hazardous for this reason. In addition, there is a constant danger of spillage of infected material during handling of uncapped containers. On many machines in current use, the filter is positioned so as to protect the pump mechanism alone, and occasionally no filter at all is fitted. In instances where a filter is provided to protect the pump alone it is still necessary to disinfect all pipework between the bottle lid and filter before the equipment is serviced. The dismantling and disinfection of any part of the equipment before servicing is costly in time, and the equipment may be out of use for a longer time than necessary. The extent of the problem became apparent when planned maintenance of suction equipment was undertaken centrally in the Hospital Sterilization and Disinfection Unit (HSDU) at Pinderfields General Hospital, Wakefield, West Yorkshire. The work reported here shows the ease with which aerosols travel throughout suction equipment and discusses how unsuitable equipment can be modified to remove the existing hazards to both patients and staff.