Improving Equipment Reliability Through Battery Management
The batteries that power an institution’s sometimes thousands of medical devices
are perhaps not the sexiest part of a biomedical engineer’s profession. But they are
an area where a fairly simple-to-implement program of measuring them and monitoring their
results can maximize battery life and maintain more dependable equipment. Indeed, one
facility that instituted such a program has seen solid savings with batteries actually
lasting, in many cases, twice as long as the manufacturers recommend. The facility also
enjoyed something that can be a rare commodity in hospital biomedical engineering
departments: relative peace of mind. According to those at the University of Ottawa Heart
Institute, Ottawa, Canada, there have been no repeats of the device failure—the
result of a used-up battery—that sparked the battery-management program in the first
place.
At Ottowa Heart’s battery-management-assessment station,
batteries are treated like medical devices and are labeled with inspection dates.
The incident that brought batteries to his attention, reports Timothy J. Zakutney,
MHSc, PEng, manager of biomedical engineering services for the Institute’s
cardiovascular devices division, involved an infusion pump in the facility’s
operating room (OR). The details do not mean much now, he points out, except that the
event led the Institute to conduct a study to look at whether there was anything his
department could do to improve its processes and avoid any such future “very, very
dangerous situations.” The result, he happily reports, has been exactly what he had
hoped for. And, he points out, it’s already been tested. “We had an incident
several months ago while we were renovating our cath lab,” he comments. “There
was a loss of power due to a construction mishap. We did a ‘postmortem’ and
determined that not one piece of battery-operated equipment in the [intensive care unit
(ICU)] failed. All the pumps and all the ventilators ran for the full hour it took us to
bring in power from an adjacent area—and none of them failed from being on battery
power.”
Of course, device manufacturers have tried to offer insight into the power in their
products, but the information is not particularly useful as presented, Zakutney points
out. The thermometer-like scale on the side of many of them is intended to graphically
display how much juice is available. “But does that mean it’s good or bad?”
he asks. “Does it mean that particular battery will last long enough for you or your
nurses or patients to get where they want to go? The lack of specificity creates quite a
bit of concern and confusion.” Treating batteries like devices is a key concept in
Zakutney’s management program, and when you manage about 8,000 device
files—which include 300–500 batteries, most of them lead-acid—concern and
confusion are two of your worst enemies. “We are extremely busy,” he comments.
“But we don’t have a huge amount of resources.”
Making a Plan
To start their battery-management program, Zakutney and colleague Mark J.
Cleland, senior biomedical engineering technologist at Ottawa Heart, melded the technical
description of battery capacity with the definition that means something to the nurses who
most often use the devices: “For how long will this device operate?” Officially,
Cleland explains, a battery’s capacity is established by the manufacturer and
indicates its ability to deliver a specified current over a specified period of
time—so, say, a 2 amp-hour battery should deliver 1 ampere of steady power for 2
hours, or 2 amps for 1 hour. “But when I talk to nursing about battery issues,”
he adds, “I frequently interchange ‘capacity’ with ‘run time.’
That’s the function of its capacity and of what kind of current drain the equipment
it powers makes on it.”
| Defining
the Costs and the Benefits |
| No hospital in North America
or anywhere in the world can afford to waste money on projects that seem, on paper, to
make sense but cannot have a price tag placed on them. That is the good thing about the
battery-management program at the University of Ottawa Heart Institute. There are
definable costs, sure. But there have also been definable benefits. “The battery analyzer we use costs about $3,000–$4,000
Canadian, and we have three,” reports Timothy J. Zakutney, MHSc, PEng, manager of
biomedical engineering services for the Institute’s cardiovascular devices division.
“We also have a software system and a data repository for all the work we do in the
system. Our total startup cost for the battery-analysis system was roughly
$10,000–$15,000 Canadian. We haven’t specifically quantified the cost savings,
but we have accepted that this is a good thing to do.” His department has also, he
adds, calculated some proxies for a specific return on investment, such as the fact that
tested batteries can be used for the actual length of active time they have remaining,
meaning many batteries last longer than what the vendors say. “Many infusion-pump
vendors suggest retiring the battery after one year,” he explains. “But our data
shows them lasting 2–3 years. For a large hospital with hundreds of batteries,
that’s significant.”
Also, he points out, a systemic battery-analysis and
battery-management program allows a facility to buy batteries from third parties and not
simply rely on the batteries that come with the equipment or that the same vendor also
sells. “Our program allows you to normalize your dealings with different battery
vendors,” Zakutney comments. “You can select based on price because you know the
quality you’re getting.” With one vendor, he explains, buying batteries direct
generally runs about $120 Canadian a pop. From a third party, equivalent batteries run
about $30 Canadian apiece. “We have batteries for a fleet of about 140 infusion
pumps,” he says, “so obviously there’s a benefit to sourcing batteries from
third parties.”
The facility could even change manufacturers, notes James A.
Robblee, BSc, MBA, MD, FRCP(C), chief of Ottawa Heart’s Division of Cardiac
Anesthesiology. “When we converted to a lower-cost supplier, we didn’t change
manufacturers,” he notes. “We did look at another company’s product, but we
found that, relative to the manufacturer that we were using, it did not perform nearly as
well. We haven’t found a better-functioning product as yet, but our program
methodology does allow for that kind of approach.”
In the meantime, Zakutney notes, the benefits of the
battery-management program “certainly outweigh the costs.” Those costs, Robblee
adds, may actually be detailed in the very near future. “We’re going to be doing
that next,” he says. “We had two original objectives. One was to find out what
exactly we’re putting in our medical devices. That was the real purpose of the
research. Our second objective was to determine the dollar value of the program—and
it’s going to be considerable.” —RJ |
Rather than relying on manufacturers’ capacity determinations that do not apply
after the unit has been used and reused, he adds, Ottawa Heart measures capacity by
placing each battery on an analyzer. “Programs that simply replace batteries on
manufacturers’ guidelines or after a specified time fail to provide a quantitative
measure of the devices’ ability to perform,” he states. “As a result, some
good-quality batteries are discarded and poor-quality batteries continue to be used.”
Instead, his team focuses on the real-world life expectancy of the batteries it actually
has on-site—which means data on how the device the battery will power operates and is
used must be incorporated into the calculation of its power potential. “I compare a
battery to a ladder,” he explains. “The top represents a fully charged battery.
The remaining power can only scale the ladder so many times before you cut its life
expectancy, so we encourage staff to maintain batteries in a plus-charge state. If
it’s used, for example, in a transport situation, we ask them to plug it back in
right away. If you only use the top few rungs of the ladder, you’ll get maybe 1,500
cycles out of it, rather than the 200 to 300 you get if you run it down over and over,
extending its life from one year to as long as 3–5 years.”
Establishing Testing Protocols
To get information on how batteries are used in the real delivery of patient care—how
long the devices they power actually have to run and how often they actually have to be
drained more than the optimum amount, for example—Cleland and Zakutney talked to
medical directors and the other primary users of the equipment. “When they tell us
their demands,” he says, “we can start establishing our testing protocols to
ensure that the batteries are going to do what they ask of them.” The program also
takes into account how many batteries are employed in each device, whether they’re
parallel, what the drain on the battery from the equipment is, and what the
equipment’s end use will be. “We look at service manuals and at whether the
device being powered is for life support, therapy, or diagnosis,” he reports,
“and from that we establish a testing interval.”
The team also developed testing protocols around nursing’s window of opportunity
when it comes to equipment failure. Zakutney’s department had experience with
batteries in such poor condition that the time between the device indicating that it was
low on power and the time it stopped working was not long enough to have a replacement put
in place. He asked the nursing staff what their expectations were, and found they needed
at least 3 hours of operation time between batteries because some patients have to be
transferred to a cross-campus sister facility. “We looked at our data,” he
reports, “and found that a complete transfer takes 182 minutes, so that’s the
minimum value of run time we allow. We find we can achieve that if well-maintained
batteries are kept at at least 40% capacity.” That changes, of course, if the device
is being used for life support.
| Improved
Patient Care, Reduced Liability |
| There are probably a million
reasons not to add even a simple, cost-efficient program to the workload of any hospital
department. But there is a powerful reason to get on board with a battery-management
program: improved patient care and, perhaps, reduced liability. “Devices rely on batteries when the patient is in his or her most
critical stage, such as when he or she is being transported from an ambulance to an
emergency room or to surgery,” explains Timothy J. Zakutney, MHSc, PEng, manager of
biomedical engineering services for the University of Ottawa Heart Institute’s
cardiovascular devices division. “There’s risk right there if you don’t
have some sort of battery-management program in place. There is a risk that you won’t
get the maximum life out of your devices if you don’t have this kind of program. With
our program, you can reduce the risk and have greater control of what’s going on.
There are a lot of parameters to maintaining safe equipment, but you can make at least one
of them more constant.”
Indeed, notes Mark J. Cleland, senior biomedical engineering
technologist there, because the facility is, after all, a heart institute, patients are
often hooked to lines for antiarrhythmics and vasopressors. “The sudden cessation of
those meds can be catastrophic,” he says. “Removing and reinserting IV lines is
critical time. And the other option in a transport situation, bringing along extra
batteries—is fine and good, but if you don’t have a battery-management program
in place, who’s to say the batteries are good?”
And, Zakutney points out, there’s a legal term called
“due diligence” that refers to a level of investigation about the devices it
uses that an institution may be liable for carrying out. “If a vendor comes to you
and says you need to retire a certain battery after a year, that’s a certain
benchmark. Now, we’ve published our results on battery management, so the bar has
been raised. Fortunately, a key philosophy of our program is treating batteries like
medical devices—you track them, tag them, and keep the information associated with
them. Just by doing that, you’re probably meeting your due diligence requirement. As
minimal as our program is in terms of effort required, it can still be that
important.” —RS |
It is critical in a program like Zakutney’s to treat batteries like medical
devices. When a new piece of equipment comes in—or one is sent to biomedical
engineering for maintenance —the staff there logs the purchase date, if applicable;
the purchase order number; the cost of the device; and the serial number. “We have
the ability in our management-information system to monitor ‘parent-child’
relationships, so we keep track of which batteries are in which pieces of equipment,”
he comments. That is especially important, he adds, because many manufacturers do not
monitor the batteries that come in the devices they sell. “If a ventilator comes in,
for example, we analyze its batteries before the equipment is deployed,” he says.
“And we log all the assessment data in two places. It’s automatically entered on
the battery-analyzer system, and we also transcribe it into our general records.”
That does sound like a lot of work. And Zakutney notes that he hears that “there
just isn’t time in the day” all the time. “People look at the thousands and
thousands of devices they’re responsible for in a large hospital, with, say, 40%
using batteries, and they assume a battery-management program would add a lot to their
workload.” Instead, he suggests, hesitant biomedical engineers should think in terms
of “event time.” For example, think about how much time it adds when a pump
arrives to be repaired. With an automated program like the one at Ottawa Heart, the
management plan may tack an additional 5–10 minutes of staff time onto each battery
repair. “In the grand scheme of things, that is not a significant amount,” he
says. “And it could be less than that depending on the protocols your department
uses—whether you replace batteries or reuse the one in the device.” The key, he
stresses, is integrating the management process into the department’s day-to-day
activities.
And, he adds, once the program is operational, testing can be performed on batteries
that do not have to be put into service immediately. “You can amass a stock of
batteries that are relatively newly conditioned,” he explains. “Say a new pump
comes in. You can put in one of your tested and charged batteries so you know the
condition of the device, then put the battery that came with the device in line for
inspection later. Or, say, a broken pump comes up to biomedical engineering. Ordinarily,
you’d repair it and then plug it in overnight to make sure it’s fully charged
before it goes back down to the floor. Under our program, you could have a stockpile of
fully charged batteries so you could replace the one in the defective device right away.
That can dramatically reduce the downtime for, say, a pump being repaired.” His shop
rarely does that, he notes, preferring to keep batteries and devices together. But
facilities that opt for that tack can, over a year or so, “get a great handle on the
condition of all the batteries they have stocked up.” They can also pare the time
required to process the batteries’ information to 5 minutes or so apiece.
Cleland adds: “It doesn’t really add any significant amount of time to the
testing time, but it is an extra step. But the information you get from that extra step is
important.” In a test he conducted of battery capacity before coming to Ottawa Heart,
Cleland’s former employer purchased a number of batteries for a specific service.1
“We looked at 126,” he reports, “and 46 had less than 65% capacity, our
acceptance threshold for newly purchased batteries. The first point we learned from that
is if you don’t measure new batteries, you can’t be sure of what you’re
getting.” That level of output capacity, he notes, would not have powered the
defibrillators the batteries were intended to keep running—even though they were
brand new. That hospital contacted the manufacturer and discussed possible problems and
potential solutions. “We then reanalyzed the batteries,” he adds, “and saw
dramatic improvement in those that had failed their incoming inspection.”
Elevated Confidence and Patient Safety
Applying that lesson to Ottawa Heart’s battery-management program has spawned a level
of success that really impresses James A. Robblee, BSc, MBA, MD, FRCP(C), chief of Ottawa
Heart’s Division of Cardiac Anesthesiology. He’s the one who initially raised
the question of battery dependability after that incident where one failed during a
patient transport from the OR to the ICU. “Initially, the battery-management program
was the initiative of one of the biomedical engineers in our organization,” he says.
“But it has now become actually embedded within the functioning of the department.
From that point of view, it’s almost a seamless part of the job there. It’s one
of their functions, just like everything else they’re doing. There has been no
problem with buy-in whatsoever.”
And, he adds, nurses were “quite interested” in the program right from the
outset. “I asked around after the failure incident and found that possibly
undependable batteries are a regular occurrence,” he says. “Nurses named six
other patients who’d been potentially compromised as a result of problems with
infusion pumps that could have been tied to battery failure. And when we did the
patient-safety review that initiated the whole process, there was extensive feedback from
nursing. So they were instantly interested in the battery-management program.” It
has, he adds, raised awareness on their part and has added momentum to Ottawa Heart’s
whole patient-safety initiative.
Today, Zakutney notes, his department holds regular in-services for nursing that
include details on the battery-management program, and contributes to the critical-care
newsletter with reminders that equipment must be plugged in as often as possible.
“We’ve found staff have great confidence in our equipment,” he comments.
“Any rumors related to devices failing because of battery malfunction have been
eliminated. In fact, confidence in our equipment has risen to the point where, sometimes
when we get a pump from another hospital, nurses will refuse to use it because
they’re not confident it will be in good working order. But they know our devices
are.”
Russell Jackson is a contributing writer for 24x7.
Reference
1. Cleland MJ, Maloney JP, Rowe BH. The effects of lead sulfate on new sealed lead acid
batteries. J Emer Med. 2000;18:305–309.
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