Rigorous attention to patient safety and monitoring
for unexpected spikes in bloodstream infection rates at The
Johns Hopkins Hospital led a team of Hopkins specialists to
uncover an unintended, surprising safety problem with a new
device that was supposed to make patients safer and easier
"No one could have anticipated this outcome," said
senior hospital epidemiologist Trish Perl, an associate
pathology at the
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 edition of the journal
Infection Control and Hospital Epidemiology online
Jan. 6, a team of Johns 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 and other ICUs.
Once the increased rate was confirmed, Johns Hopkins
experts launched an investigation that identified an
intravenous catheter valve as the likely source of
infection. No one at Johns Hopkins died from the
infections. Hopkins stopped using the valve and alerted the
Food and Drug Administration, which approves use of medical
devices, and the Centers for Disease Control and
Prevention, which monitors infections in hospitals, the
Lisa Maragakis, the hospital epidemiologist who led
the investigation, said, "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. It may be harder to clean and disinfect some new
technologies, which can lead to potential complications.
"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," she said.
The device, called the Alaris SmartSite Plus
intravenous catheter valve — which functions, like
all catheter valves, 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 Johns 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
"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 people's germs," said Mar-agakis, an assistant
Patients undergoing intensive care are also at greater
risk for picking up infections, Maragakis said, because
these patients must have intravenous tubing, 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 hospital units at Johns Hopkins routinely review
best safety practices and policies to prevent
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 pediatric intensive care
unit during a patient safety exercise to implement best
practices for insertion and care of catheters.
According to statistics compiled quarterly,
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,"
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 team was left with few remaining
possibilities except that the likely source was
Indeed, one of the infection control staff, nurse
Karen Bradley, 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 Johns Hopkins
PICU had, by coincidence, 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 the
new one. Alarmed by their findings, the team immediately
ordered a return to use of the previous valve, one that
does not contain the positive-pressure feature but 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 Johns 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
Johns Hopkins experts have found risks of infection related
to introduction of new medical devices. In December 2004,
the 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 Johns Hopkins
and the CDC. Other researchers involved in this
investigation and study were Xiaoyan Song, Claire Beers,
Marlene Miller and Sara Cosgrove.