Hospital-acquired infections (HAIs) are a leading cause of death in the United States, killing more people than AIDS, breast cancer, and automobile accidents. In 2010 alone, HAIs contributed to more than 99,000 deaths—one death every 6 min—and costs of up to $57,000 per patient, with an increase in length of hospital stay of about 10 to 15 days.¹
The financial consequences of HAIs never have been higher. Reduced reimbursements, low patient-satisfaction scores, negative branding, and litigation impact the bottom line.
The Link Between HAIs and HVAC
Numerous studies have demonstrated HVAC systems are a viable reservoir for pathogenic and opportunistic bacteria and mold. Below is a partial list of microorganisms typically found on hospital evaporator coils and drain pans:
• E. coli.
These microorganisms have been linked to HAIs, especially in critical-care units. Airborne transmission is a proven route of infection for diseases such as tuberculosis, aspergillosis, and methicillin-resistant Staphylococcus aureus (MRSA). Pseudomonas aeruginosa commonly is found growing in wet drain pans and on coils and is known to be a cause of upper-respiratory infection and ventilator-associated pneumonia.
Ultraviolet-C (UVC) and Infection Control
The importance of good air quality in controlling and preventing airborne infections in health-care facilities cannot be overemphasized. Because the HVAC system is the largest reservoir of pathogens in a hospital, control at the source—coils and drain pans—is an effective means of reducing HAIs.
Ultraviolet germicidal irradiation (UVGI) targets the DNA of microorganisms, destroying their cells or making replication impossible. UVGI is a proven method of inactivating mold, bacteria, and viruses, reducing many airborne microorganisms.
Tips for Designing an Effective UVC System
Following are six tips for designing and delivering a UVC system to reduce HAIs in your facility:
• Talk it up. Your hospital-infection-prevention personnel most likely are focused on hand hygiene and surface decontamination to reduce infection. Sharing your knowledge of the role of HVAC and the efficacy of UVC in reducing HAIs with these professionals can be the key to implementing UVC as an effective infection-control strategy.
• Location, location, location. The best location for installed UVC is on the supply side of a HVAC system, downstream from the cooling coil and above the drain pan. This location provides more effective control than in-duct installation because the UVC attacks contaminants at the source to ensure simultaneous cleaning of surfaces and airborne microbes. The germicidal effect is immediate and continuous, as long as the lamps are kept on 24/7 with the fan running.
• Lamp performance. For optimum performance, a UVC device should be manufactured to deliver output of at least 9 microwatts per linear inch of glass measured from a distance of 1 m, tested at an air velocity of 400 fpm and a temperature of 50°F. This is critical to performance because UVC output declines over time, reaching a half-life after 9,000 hours of around-the-clock operation. Starting with the highest output ensures adequate performance throughout the service life of a device.
• The real story on watts. Sometimes, UVC lamps are marked with a label displaying input wattage. Judging the performance of a UVC device based on lamp input wattage is incorrect. UVC intensity or output—the important measure of performance—varies with not only input power, but a variety of other factors, such as lamp operating conditions, distance from the UVC source, power-supply type and design, and lamp design. Lamp input wattage is not a relevant factor in selecting UVC devices or predicting their performance.
• Evidence-based design. When deciding which UVC device to install, seek independent data to determine the efficacy of various systems for the application at hand. A series of test reports commissioned by the U.S. Environmental Protection Agency in conjunction with the National Homeland Security Research Center provides a benchmark for comparing the performance of various UVC devices. Peer-reviewed abstracts also can be a good source of validation of the impact on clinical and patient outcomes and the financial bottom line.
• Show me the money. When seeking funding for a UVC project, compare the expense of an effective infection-prevention-and-control program with the savings associated with shorter patient stays, a reduction in lost bed days, avoidance of readmission costs, and improved reimbursements. Well-designed systems have a reported payback of less than a year in terms of medical savings alone. Additional savings are achieved with reduced energy and labor, as well as improved operational efficiency. Look for vendors willing to work with you to validate the efficacy of UVC in your facility.
The Facility Manager’s Role
It is important for health-care facilities engineers to meet with infection-prevention personnel to not only raise awareness of the serious problem of HAIs, but do something about it.
If the goal is to reduce HAI rates, improve patient outcomes with shorter stays, and significantly reduce direct and indirect medical costs, facilities engineers and infection-prevention personnel need to work together to install UVC in their HVAC systems. It is a simple and cost-effective solution to a growing problem.
1) Cocanour, C.S., et al. (2005, Spring). Cost of a ventilator-associated pneumonia in a shock trauma intensive care unit. Surgical Infections, pp. 65-72.
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