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Breaking News: RFID Tracks Spread of Disease in ED

SoRelle, Ruth MPH

doi: 10.1097/01.EEM.0000446050.11866.d1
Breaking News


Douglas W. Lowery-North, MD, an emergency physician at the Emory University School of Medicine, is likely to be wearing a mask when he approaches the nurses' station.

“I used to walk around with the mindset that patients are the hazardous sources of infectious disease. If I hear people coughing and sneezing, I'm more likely to wear a mask at the nurse's station than in patients' rooms,” said Dr. Lowery-North, the vice chair for clinical operations and the chief information officer in emergency medicine at Emory in Atlanta.

One reason for that seemingly odd precaution is that he probably spends more time interacting with nursing personnel than with the hacking, coughing patients in the waiting room. A recent study he and his colleagues did showed that staff-staff interactions were more numerous and longer than patient-patient interactions or patient-staff interactions. (PLoS One 2013 Aug. 21; The average number of contacts per shift totaled 2,084; 459 of those were patient-patient and 261 were patient-staff, but staff-staff were 1,466. Patient-patient contacts totaled 32 hours per shift; patient-staff, 22 hours, and staff-staff, 272 hours.

“As someone who is not an emergency physician, I might have thought staff spent a lot of time with other staff, but I did not expect it would be a whole order of magnitude more than they spent with patients,” said co-author Vicki Stover Hertzberg, an associate professor of biostatistics and bioinformatics in the Rollins School of Public Health at Emory.

She and Dr. Lowery-North undertook the study because they were interested in the intersection of technology and medicine. They used radio frequency identification tags (RFID) to measure interactions at one meter, the distance at which droplets containing influenza viruses can be easily transmitted. The study, she said, has implications for workflow, architectural design, and other elements of activity in a busy emergency department.

“The other thing that pushed us to do this study was the SARS [severe acute respiratory syndrome] outbreak in Toronto in 2003,” said Dr. Lowery-North. “A patient was held in the emergency department there for a long period of time waiting for a bed. The patient infected a number of staff, some of whom died from the virus. That lit a fire in my brain. Crowding is a huge problem, and this won't solve that. It may help us prevent the spread of diseases like this in the emergency department.”

Measuring the risk of infection in emergency departments is a popular theme. Caroline Quach, MD, MSc, a pediatric disease specialist at Montreal Children's Hospital and McGill University, and colleagues evaluated rates of new respiratory and gastrointestinal infections in long-term care facility residents 65 and older. (CMAJ 2012;184[4]:E232.) They randomly chose two patients for each patient who visited an emergency department, matching them by facility, age, and sex. They found that 21 of the 424 who visited the ED and 17 of the controls acquired new infections, and concluded that a visit to the ED was associated with more than a threefold increased risk of acute infection among elderly people.

“Looking overall at a population, it may seem that this is a small risk difference. However, when you look at it individually, the impacts on that person's health and people surrounding them are not negligible,” Dr. Quach wrote in an email to EMN. “Moreover, if viral respiratory and gastrointestinal infections can be transmitted in the ED, one can extrapolate this to other pathogens that are transmitted by the same route [mainly contact], such as MRSA, VRE, other multidrug resistant organisms, and C. difficile.”

Like Dr. Hertzberg, she sees her study as a guide to workflow and architectural needs. “In an ideal world, all patients would be seen quickly, observed in single-patient rooms, additional precautions when needed would be implemented, and environmental cleaning would be done regularly and as needed. If that were done, then transmission of infections in the ED would be minimal,” she noted, adding that the study shows the importance of compliance with infection prevention and control recommendations. Feasibility issues like the lack of individual ED rooms means that more fragile patients should be triaged quickly and disposed as soon as possible, she said.

The issues will become even more grave, said Dr. Lowery-North. “We had a potential MERS [Middle East respiratory syndrome-coronavirus] patient come through the emergency department recently. It takes a couple of day to know if any staff had picked that up. We are not always good at masking people. If one of the nurses had become infected, that person would have been shedding virus several days before symptoms. And the staff is spending a lot of time in a confined space with them.”

He said they are looking at how to identify locations in the emergency department that are hot spots for close proximity interactions; his study looked only at airborne routes of transmission and the RFID equipment was specially designed and deployed for interactions at 1 meter and greater. The ED waiting room, for example, is now configured with patients facing one another in a large circle or perhaps small tables where the patient and his family are exposed only to one another. Surfaces are another issue. Influenza virus can live 24 to 48 hours on steel and plastic. How do you clean those surfaces regularly enough to prevent spread of infection?

Dr. Hertzberg said a future study could use surveillance cameras in the waiting room to see who is coughing, sharing cell phones and touching each other and the surfaces. Dr. Lowery-North said video shows that people pass round clipboards and pens without decontaminating them, again raising the risk of infection transmission. “A lot of models of infection spread had relied on assumptions that people are exposed to infections in the same amount. These new studies with RFID show that people don't mix uniformly and that there are certain patterns of mixing,” he said. “We are not immune. The staff connections make us realize that. A nurse who has touched a sick patient who has a virus makes us realize we are likely to be exposed. It is important to realize when we are sitting at the nurses' station that it is not the safe zone we think it is.”

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