"No one could have anticipated this outcome," says senior hospital epidemiologist Trish Perl, M.D., an associate professor of medicine and pathology at The Johns Hopkins University School of Medicine. "But, our experience underscores how advances in technology designed to improve health care may also have hidden risks to patients that can only be identified by paying close attention to what happens after the technology is put into practice."
In a case study reported in the latest edition of the journal Infection Control and Hospital Epidemiology online Jan. 6, a team of Hopkins patient safety experts describe how the introduction of a catheter valve newly marketed to the hospital in April 2004 coincided with a spike in potentially deadly bloodstream infections picked up by patients in the hospital's pediatric intensive care unit, or PICU, and other intensive care units.
Once the increased rate was confirmed, Hopkins experts launched an investigation that identified an intravenous catheter valve as the likely source of infection. No one at Hopkins died from the infections. Hopkins stopped using the valve and alerted the United States Food and Drug Administration, which approves use of medical devices, and the U.S. Centers for Disease Control and Prevention, which monitors infections in hospitals, the report noted.
"While new technology in health care is frequently beneficial or easier to use, it takes time and use to determine whether these devices are in fact safe," says Lisa Maragakis, M.D., the hospital epidemiologist who led the investigation. "It may be harder to clean and disinfect some new technologies, which can lead to potential complications," she adds. "New medical devices should be monitored after their introduction as closely as drug therapies because, as more hospitals are finding out, the 'bug' may be in the equipment itself."
The device, called the Alaris SmartSite Plus intravenous catheter valve, which like all catheter valves functions to allow the flow of fluids and medications into a patient's vein via plastic tubing, is considered superior to previous models because a positive pressure feature prevents the backflow of blood into the catheter. The valve also contains an enclosed needle plunger with a screw-top mechanism that allows for ready attachment to syringes for administering medications. Blood samples are also taken via such catheter valves.
As the Hopkins investigation and other inquiries were to show, the Alaris device and others like it have ridges in the screw-top mechanism that could potentially catch blood or other fluids and act as a source of infection. An opaque plastic cover did not allow hospital staff to see through it to ensure that fluids were effectively flushed through and cleaned out between procedures.
"Guarding against bloodstream infections is a daily battle in the hospital environment because patients are unusually susceptible to catching something hazardous, many are weak from their own illness with limited immune defenses, and they are also at increased exposure to other sick peoples' germs," says Maragakis, an assistant professor at Hopkins.
Patients undergoing intensive care are also at greater risk for picking up infections, Maragakis says, because these patients must have intravenous tubing put inside them, such as a central catheter, which provides an opening for dangerous bacteria to get inside the body.
For this reason, the infection control experts note, staff in the PICU, like other hospital units at Hopkins, routinely review best safety practices and policies to prevent hospital-acquired infections. This includes activities such as reviewing procedures on how best to maintain sterile or bacteria-free conditions around the patient by washing hands between procedures and maintaining barriers to prevent infection. Proper techniques for insertion and care of catheters are also important to prevent device-related infections.
This is why it came as quite a surprise to Perl and her team when they were called in to investigate the bloodstream infection cases in the PICU during just such a patient safety exercise to implement best practices for insertion and care of catheters.
According to statistics compiled quarterly by the hospital, bloodstream infections on the unit increased over the latter half of 2004. Infection rates increased from a low in the spring of slightly more than four days for every 1,000 days patients spent with catheters in the ICU, which is the relative norm, to a high of 17.3 days by the end of the summer. Infection rates stayed relatively high to the end of the year, at 11.9 days.
But, according to the infection control team, there was at first no clear "smoking gun" in this investigation. "The staff was already focused on best safety practices and following infection control procedures to the letter," says Maragakis.
By early 2005, analysis of blood specimens from infected patients showed that no single bacterium was responsible and that 26 percent of specimens were polymicrobial, containing more than one kind of bacterium. The norm for these kinds of infections was lower, at 8 percent. Having not found human error as the likely cause of infection, the Hopkins team was left with few remaining possibilities except that the likely source was mechanical.
Indeed, one of the infection control staff, Karen Bradley, R.N., B.S.N., had recently attended a national meeting of hospital colleagues where new catheter valve devices were reported to have caused an outbreak of bloodstream infections. According to the meeting report, the speculation was that the design of the new device prevented the full cleanout of fluids, allowing blood and other fluids to collect and serve as the source of infection.
Bradley found that in April 2004, the Hopkins PICU had, by coincidence, also introduced a new, albeit different, catheter device, the positive pressure mechanical valve from Alaris. Upon closer examination, Bradley and the other investigators noticed several similarities between the previously reported cases and Hopkins' new one. Alarmed by their findings, the Hopkins team immediately ordered a return to use of the previous valve, one that does not contain the positive-pressure feature, but also has no known risks for causing infection. Almost immediately after the switch, bloodstream infections on the PICU decreased to previous baseline levels. The improvement was so dramatic that by February 2005, the Hopkins team issued recommendations to discontinue use of the new valves throughout the hospital and for all staff to switch back to the older models.
This case marks the second time within a year that Hopkins experts have found risks of infection related to introduction of new medical devices. In December 2004, the Hopkins team reported in the Journal of the American Medical Association on the need for tighter controls surrounding use of a water-gun device for cleaning wounds, since less-strict handling of the device led to a series of bloodstream and wound infections in 11 patients.
Funding for the study was provided by Hopkins and the U.S. Centers Centers for Disease Control and Prevention. Other researchers involved in this investigation and study were Xiaoyan Song, M.D., M.S.; Claire Beers, R.N., M.S.N.; Marlene Miller, M.D., M.Sc.; and Sara Cosgrove, M.D., M.S.