Medical Construction & Design

JAN-FEB 2016

Medical Construction & Design (MCD) is the industry's leading source for news and information and reaches all disciplines involved in the healthcare construction and design process.

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instantaneous heating systems and ozonation. Systemic methods disinfect the entire system. These include thermal disinfection, hyperchlorination and copper-silver ionization. A combination of focal and systemic disinfection techniques eradicates existing bacteria and prevents recolonization. Thermal disinfection L egionella thrives in motionless water with ambient temperatures between 68 and 113 F. In a typical medical facility, storage tanks are set at 120 F. Once the water leaves the storage tank, its temperature decreases to the 68-113 F "danger zone" as it fl ows through the piping system. Thermal disinfection heats water above 140 degrees to in- hibit bacterial growth. Remote areas of the system, like faucets and showerheads, are fl ushed for 30 minutes. Skin can scald at 110 F or burn at 140 F. Mixing valves at outlets prevent injuries by reducing the water temperature below 110 F just before it exits the system. Insulation, automatic drains and recirculating loop distribution systems further regulate water temperatures. Water controls maintain fl ow Because Legionella grows in stagnant water, engineering controls must regulate water fl ow, as well as temperature. It is dif cult to know whether controls are capable of maintaining fl ow throughout the entire water piping system. The compo- nents that regulate fl ow are seldom visible. They are hidden above ceilings, in walls and inaccessible chases. Crucial components of diminishing risk of Legionella in hospitals BY CHARLIE HALL Prevention + Mitigation + Treatment W ith the recent reports of Legionella in the news, many hospital facility managers wonder if an outbreak could happen at their hospital. It can. Fourteen U.S. hospitals experienced Legionella outbreaks from 1981-96, proving it is quite possible. Legionella naturally exists in soil and water. But it also forms in man-made water storage systems and potable water systems. The following environments in healthcare facilities of er the ideal environment for Legionella growth: » Potable water system and outlets, including incoming service, water tanks, water softener, showers and faucets » Cooling tower and condenser water systems, including chillers, tower basin and sump » Evaporative air coolers, misters and humidifi ers The temperature and inactivity inherent to these systems foster bacterial growth. Then, their sprays, jets and mists aerosolize bacte- ria-laden water droplets. These are small enough (<5 micrometers) for patients to aspirate or inhale. Patients who smoke or are immu- nocompromised have diminished respiratory refl exes. This renders them less able to avoid aspirating the contaminated droplets. Patients who require intubation, ventilation assistance or respi- ratory therapy have an elevated risk. This care involves the use of aerosol generators such as humidifi ers or nebulizers. Neonates are particularly at risk due to their underdeveloped immune systems, intensive ventilation procedures and corticosteroid therapy. While aspirating the fi ne mist is the most common way to contract the bacteria, it's not the only way. Patients may osmose contaminated water either by drinking it or through contact with wounds. This happens when contaminated water travels through plumbing ele- ments and accumulates bacteria in biofi lms. Biofi lms easily adhere to rubber and plastic piping, connectors and fi xtures. The concentra- tion of Legionella can be three times higher on PEX, PVC or stainless steel piping. Similarly, rubber washers, hoses and fi ttings can house Legionella growth. Copper pipe is less likely to transmit Legionella bacteria because the ions in copper destroy biofi lm. Legionella mitigation approaches L egionella is resistant to standard disinfection techniques such as chlorination. Thus, hospitals face the challenge of evaluating alternative approaches. Disinfection techniques fall into two categories: focal and systemic. Focal disinfection methods target individual sections of a system. These techniques include ultraviolet light sterilization, + Vorclub/ 44 Medical Construction & Design | JA N UA RY/ F EBRUA RY 2016 | MCDM AG.COM

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