Improving Equipment Reliability Through Battery Management
The batteries that power an institutions sometimes thousands of medical devices are perhaps not the sexiest part of a biomedical engineers 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 failurethe result of a used-up batterythat sparked the battery-management program in the first place.
At Ottowa Hearts 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 Institutes cardiovascular devices division, involved an infusion pump in the facilitys 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, its 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 areaand 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 its 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 Zakutneys management program, and when you manage about 8,000 device fileswhich include 300500 batteries, most of them lead-acidconcern and confusion are two of your worst enemies. We are extremely busy, he comments. But we dont 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 batterys capacity is established by the manufacturer and indicates its ability to deliver a specified current over a specified period of timeso, 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. Thats 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 Institutes 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 havent 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 23 years. For a large hospital with hundreds of batteries, thats 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 youre 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 theres 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 Hearts Division of Cardiac Anesthesiology. When we converted to a lower-cost supplier, we didnt change manufacturers, he notes. We did look at another companys product, but we found that, relative to the manufacturer that we were using, it did not perform nearly as well. We havent 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. Were going to be doing that next, he says. We had two original objectives. One was to find out what exactly were putting in our medical devices. That was the real purpose of the research. Our second objective was to determine the dollar value of the programand its 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-sitewhich 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 its 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, youll 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 35 years.
Establishing Testing Protocols
To get information on how batteries are used in the real delivery of patient carehow long the devices they power actually have to run and how often they actually have to be drained more than the optimum amount, for exampleCleland 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 theyre parallel, what the drain on the battery from the equipment is, and what the equipments 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 nursings window of opportunity when it comes to equipment failure. Zakutneys 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 thats 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 Institutes cardiovascular devices division. Theres risk right there if you dont have some sort of battery-management program in place. There is a risk that you wont get the maximum life out of your devices if you dont have this kind of program. With our program, you can reduce the risk and have greater control of whats 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 batteriesis fine and good, but if you dont have a battery-management program in place, whos to say the batteries are good?
And, Zakutney points out, theres 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, thats a certain benchmark. Now, weve published our results on battery management, so the bar has been raised. Fortunately, a key philosophy of our program is treating batteries like medical devicesyou track them, tag them, and keep the information associated with them. Just by doing that, youre 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 Zakutneys to treat batteries like medical devices. When a new piece of equipment comes inor 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. Its 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 isnt time in the day all the time. People look at the thousands and thousands of devices theyre 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 510 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 useswhether you replace batteries or reuse the one in the device. The key, he stresses, is integrating the management process into the departments 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, youd repair it and then plug it in overnight to make sure its 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 doesnt 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, Clelands 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 dont measure new batteries, you cant be sure of what youre getting. That level of output capacity, he notes, would not have powered the defibrillators the batteries were intended to keep runningeven 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 Hearts battery-management program has spawned a level of success that really impresses James A. Robblee, BSc, MBA, MD, FRCP(C), chief of Ottawa Hearts Division of Cardiac Anesthesiology. Hes 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, its almost a seamless part of the job there. Its one of their functions, just like everything else theyre 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 whod 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 Hearts 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. Weve 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 theyre not confident it will be in good working order. But they know our devices are.
Russell Jackson is a contributing writer for 24×7.
1. Cleland MJ, Maloney JP, Rowe BH. The effects of lead sulfate on new sealed lead acid batteries. J Emer Med. 2000;18:305309.