Batteries in Medical Devices: Small Sample Survey Summary
MedSun: Newsletter #84, May 2013
Survey Topic: Batteries in Medical Devices - Summary of Responses
Year Conducted: 2013
Batteries are an essential component of many electrically-powered medical devices such as automatic external defibrillators, infusion pumps, physiologic monitors, and ventilators. It is widely known that batteries contribute to device reliability and battery failures can play a significant role in medical device failures. Battery failures can lead to serious adverse events and deaths.
There are several types of batteries used in medical devices including standard alkaline, rechargeable, and custom made batteries for a specific device. As more medical devices are becoming computerized, compact, and mobile, the prevalence of battery use has increased. When faced with a medical emergency and power is not available, or is intermittent or unreliable, the effectiveness and reliability of back-up battery-powered medical devices used for patient care becomes essential.
The purpose of this survey is to enhance FDA’s understanding of how batteries are used, maintained, fail, and how FDA can work with device manufacturers to improve battery reliability. This information is intended to contribute to improved performance of these devices.
Survey respondents include nine health care professionals who are Biomedical and Clinical Engineers, Risk Managers, Nurses, Attorneys, and Purchasing Directors working in MedSun hospitals on the east coast, the mid-west, south, and southeast regions of the country. The information that follows is a summary of their responses to the survey questions.
The most common battery-powered medical devices used by the nine respondents are listed in Table 1. Of the devices listed, the respondents state that the most frequent problems are associated with large volume infusion pumps, telemetry boxes, pulse oximeters, thermometers, electric beds, monitors, and portable/mobile devices. Table 2 lists the most common battery-related problems reported by the respondents. Many of these problems, especially those related to large volume infusion pumps, may be attributed to staff practices. All nine respondents indicate that most problems with infusion pump batteries stem from the failure to plug in the pump or from under- or over-charging the pump by hospital staff resulting in premature depletion, loss of power and in some cases, fire.
Table 1. Most Common Battery-Powered Medical Devices Used by Respondents
*Devices with recurrent battery-related problems reported by respondents
|Diagnostic Devices||Infusion Pump Devices||Life Support Devices||Other Devices|
|*Physiological monitors||*Large Volume Pumps||Ventilators||*Portable lights|
|*Non-invasive blood pressure machines||Syringe Pumps||Defibrillators||*Portable X-rays|
|*Telemetry packs and boxes||Patient controlled anesthesia||Temporary external pacemakers||*Portable computer stations|
|Electrocardiograms|| ||Heart/lung machines||*Electric beds|
|*Pulse oximeters|| ||Anesthesia machines||Patient lifts|
|*Thermometers|| ||Intra-aortic balloon pumps||Sequential compression devices|
| || ||Aspirators|| |
| || ||Isolettes/warmers|| |
| || ||Feeding pumps|| |
| || ||Suction pumps|| |
| || ||Biphasic positive airway pressure machines|| |
Table 2. Battery-Related Problems Reported by Respondents
*Most frequently reported battery-related problems by respondents
|Battery-related problems||Reported Outcomes|
|*Failure to plug-in device when not in use||Premature depletion; loss of power|
|*Overcharging||Overheating; fire; explosion|
|*Undercharging||Premature depletion; loss of power|
|*Inaccessible plugs/outlets||Premature depletion; loss of power|
|Confusion with on/off button on pump||Premature depletion; loss of power|
|Loose connection between electrical cord and device||Premature depletion; loss of power|
|Incorrect replacement battery by staff||Leakage; increased hot temperature; ignites fire|
All nine respondents report that nursing staff is responsible for charging battery-powered medical devices on the units where they are used. However, staff either forgets to plug in the devices or outlets/plugs are not available when needed. Although all report providing ongoing training to reinforce the need for plugging in devices, staff often fail to do so even when outlets/plugs are available. This is particularly true after transport devices have been used to move patients from one location to another; staff does not remember to plug in the transport devices in the new locations. Two respondents attribute this problem to several factors, such as work pressures in the clinical area, constant transport of patients and devices between locations, and staff who tend to focus more on patient care tasks rather than charging the devices.
Three respondents have added outlets in patient rooms and storage areas. One of these also added power outlets attached on IV poles to improve accessibility for staff. This particular respondent also moved plugs from the head of patient beds to the side of the beds for easy access. For aesthetic reasons, this respondent has placed outlets in the cupboards in patients’ rooms, although these are cumbersome for some staff to use. Two respondents mention having to replace plugs worn out from use by so many battery-powered devices. One respondent meets with nursing staff to show the costs for replacing pump batteries when they are depleted (approximately $30.00 to $40.00 per pump each time), and notes that when staff understand the cost implications, the problem of not plugging in devices significantly decreases, thus preserving the life of the batteries.
All respondents express concerns about inappropriate battery charging. Three report that frequent over-charging results in deformed batteries, swelling, over-heating, fire, and explosion. Of these three respondents, two have stopped using third-party batteries because of the frequent swelling and over-heating. When a battery swells, it is difficult to remove it from the device.
Typically, undercharging occurs when the device is not plugged in long enough for the battery to completely recharge. This is particularly true of patient transport devices. Staff may charge the device for only 15 minutes when it may need to be charged for seven to eight hours. There is no message or other visual indicator specifying how long the device has been plugged in or if it is fully charged. Another respondent shares that when an infusion pump is not fully charged after transport and then is unplugged and used for transport again, batteries deplete, pump function is minimized and it may trigger several alarms. The alarms occur because the pump is trying to charge the battery and function at the same time. Not all devices have a “low battery” alarm, so when the battery is not fully charged error codes are displayed instead. Two respondents stated that pulse oximeters frequently show error codes as a result of undercharging. One suggestion to alert staff to the battery status, is to have the manufacturers add green, yellow and red LED lights on the devices that change color when the battery status changes.
Another issue affecting battery charging is staff using an incorrect battery for replacement. A respondent relates an incident when an incorrect battery was replaced in a Doppler. The Doppler worked fine initially, but the battery lost its rechargeable capabilities over time and didn’t work. The battery leaked and over-heated. While no patient adverse event occurred, the problem disrupted patient care. In another event, a respondent relates that a battery exploded after sitting idle on a shelf for months. In addition, batteries that are stored on a shelf or in a room and not used for months can swell or deplete. One respondent reports that batteries in some rental beds and infection controlled purified air devices may leak and explode after sitting idle for months. Some non-invasive blood pressure monitors have on/off switches on the front and back of the device. One on/off switch is for powering on the device and the other on/off switch is for charging the device. Staff is often confused about the light indicator on the device and whether it means the device is charged or powered on. Additionally when the battery gets low, there is no warning; it just shuts off.
In response to questions regarding labeling for battery-powered devices, six respondents say that labeling and the instructions for use (IFUs) are clear and contribute to proper use and maintenance of the devices, one respondent is not sure, and two believe the labeling is not adequate. The IFUs/manuals state to keep devices charged when not in use; however, in everyday practice it doesn’t help because the IFUs/manuals generally are not on the nursing unit with the device, and for reasons noted earlier (e.g., staff is too busy to remember to plug in devices, etc.), the IFUs are not followed. Some manufacturers provide a quick guide or shortened version of instructions that recommends keeping the device plugged in; however, the length of time needed for charging batteries is not always stated. All respondents add stickers or labels on the front of the device or attach laminated cards to remind staff to keep the device plugged in. However, sometimes the laminated cards fall off and staff throws them away. One respondent suggests that manufacturers add permanent bright orange labeling on devices to remind staff to charge the device, and another suggests that manufacturers eliminate the need for manual battery charging.
All nine respondents indicate that it would be very helpful if devices that have been shut off would alarm alerting staff that the devices should be plugged in. As stated previously, when some devices are not fully charged, they alarm frequently or error codes appear. After the devices are charged overnight, the error codes usually go away and they work fine. One respondent reports that one manufacturer’s infusion pump batteries frequently deplete because the pumps are not plugged in for charging or they may not be charging while plugged in. This particular respondent replaces an average of 30 to 40 batteries per week. When batteries in older pumps deplete, they can still be used with AC power.
All respondents suggest consistent, ongoing staff education and training in the proper use of devices, placing more emphasis on plugging in devices. One respondent proposes that new training material by itself will not change staff culture. Instead, the respondent suggests manufacturers design a product that will make it easier to detect the charge level of batteries, such as adding a feature to batteries similar to a gas gauge. Another suggestion is that manufacturers develop standard, easy to read indicators or symbols for batteries, i.e., battery time left, charging time, etc. Currently, where these do exist, they are different from one manufacturer to another.
The respondents did not report any battery-related deaths or injuries; however, one individual commented on potential for harm events that occur when the hospital loses power during storms. Infusion pumps and Uninterruptable Power Systems (UPS) replacement batteries are most troublesome when the power goes out and they don’t work. As a result, this respondent changes UPS batteries as frequently as the batteries in infusion pumps, which is a couple of changes every month. On one occasion when the hospital lost power during a storm, the emergency generator powered on after a five to six second delay. When the hospital power returned, the temperature settings on an infant warmer/isolette defaulted to the manufacturer setting and the isolette became too hot. The battery safety circuit had over-heated and the change in temperature was identified by one of the nurses. There was no harm to the patient. One respondent believes that not only high risk devices should always be plugged in unless they’re in transport, but also handheld devices such as pulse oximeters, telemetry boxes, and thermometers. Another respondent reports near misses with low or depleted batteries in temporary external pacemakers. Staff has no idea that the battery is low or depleted until it happens and only has two to five seconds to change the battery before a patient is compromised. This device performance can improve with an alarm. In addition, battery cells can go bad in a MRI conditional patient monitor even if the device is plugged in (the manufacturer is aware of this problem).
The percentage of battery-related service calls reported by the nine respondents, range from 8% to 50%. The biomedical/clinical engineers or hospital technicians are responsible for replacing batteries, especially if the battery case has to be opened. In one hospital, the Central Supply Department is responsible for replacing batteries in devices that are locked in code carts and the Respiratory Department is responsible for replacing batteries in respiratory equipment.
All nine respondents have preventive maintenance (PM) schedules for servicing and proactive replacement of batteries. One of the nine respondents only has PM schedules for devices that use a UPS. The PM schedules are based on the level of device risk and manufacturer recommendations and ranges from six months to five years. Respondents say some devices require battery replacement based on “hours of usage.” Two respondents follow the manufacturer’s recommendations for battery replacement. One of the two will replace the battery even if the battery is working. Another replaces batteries proactively based on device inspections, tracking, and service minutes. One other respondent indicates that when they conduct preventive maintenance, any device with a battery is tested to exercise the battery. In one respondent’s hospital, batteries in portable x-ray units are replaced by an outside vendor.
Most of the respondents, except one, track all battery-related service history calls and work orders electronically or they are in a manual log. Another individual also tracks codes for physical damage that occurs when the device is dropped on the floor, run into, or crushed. The processes and factors that all respondents consider before purchasing batteries are very similar. Table 3 lists the processes. Two respondents report they no longer purchase certain batteries for High Risk or Tier 2 devices because of frequent battery swelling. One of these two respondents describes a situation where a monitor caught fire and burned as a result of battery swelling. Another respondent purchases rechargeable batteries, although they are not always compatible with certain devices because they don’t always have the amps required for the device function, and yet another evaluates two manufacturers’ batteries before making a purchase. If a generic battery can be used, most will purchase an equivalent battery and add that it’s a performance as well as an economic issue. In one hospital, the biomedical engineers purchase rechargeable batteries and the hospital units purchase disposable batteries. In two other hospitals, respondents tell their corporate contract department what they want and the department finds the best price and purchases the batteries. If a custom battery is required, all respondents state they are locked into buying from the manufacturer, although they can be very expensive. One respondent states they will save a lot of money if they can use disposable AA batteries for their telemetry units, instead of rechargeable batteries.
Table 3. Processes and Factors Considered When Purchasing Batteries
When asked how FDA can help respondents address medical device battery-related issues to reduce the occurrence of failures, some respondents indicate a need for better labeling and other related factors. Table 4 lists ways the respondents state that both FDA and manufacturers can help address battery-related issues. One respondent states that manufacturers should seek more input from users, particularly when designing large volume infusion pumps. Infusion pumps use battery technology to a considerable degree and can only be reset by biomedical/clinical engineers, which becomes a cost and labor issue.
|High risk or Tier 1 devices: custom made, proprietary, or a specialty battery purchased from the device manufacturer|
|Low risk or Tier 2 devices: rechargeable, third-party or generic batteries purchased from any company|
|Facility equipment needs|
|Quality of battery life|
Table 4. How FDA and Manufacturers can address medical device battery-related issues
|Education and training||FDA/MedSun provide potential for harm education and training, cognitive-based web training, focus groups, and case studies|
|Recalled batteries||FDA/MedSun provide access to recalls and alerts and note the specific battery used in recalled devices, and if the battery problem is associated with a root cause.|
|Performance data||FDA/MedSun track and present performance data, including device failures, on batteries from different battery manufacturers.|
|Labeling||Manufacturers provide stickers, posters and permanent labeling on devices to remind staff to plug in devices, time intervals to inspect devices, and servicing.|
|Warnings||Manufacturers provide visual indicators (lights) on infusion pumps for ‘low battery’ and ‘end of battery life’status.|
|Standards||Manufacturers provide standards for battery charging, replacement, service intervals, and disposal of batteries.|
|Battery technology||Manufacturers provide access to inside a battery compartment to check a cycle. Design devices that don’t require manual charging, and rechargeable instead of disposable batteries.|
|Battery testing||Manufacturers reclassify and provide testing information that is currently proprietary.|
The following is additional information provided by respondents to support this project:
- A battery was over-charged in an infusion pump because gas was entrapped in the chassis. The battery ignited and the infusion pump exploded.
- One respondent has numerous infusion pumps approaching end of life that need repair quite frequently. More than 25 batteries are replaced weekly and it takes one hour per pump making it the most timely and costly device. An engineering work station is used just for infusion pumps and in the future the facility may replace their current pumps.
- Glucose meter batteries don’t provide battery replacement information. If the manufacturer will give an estimate of time for replacement, the respondent can proactively evaluate battery life. Nurses will not have to count how many times they charge the batteries.
- In one hospital, more than 50% of the equipment is owned by specific departments. No one person has ownership to monitor batteries. One department is responsible for and provides battery boxes for recycling lead acid, rechargeable, and alkaline batteries. The Hazard Materials staff is responsible for all other batteries.
Special Studies and Surveys are two of many tools the FDA uses to evaluate the public health impact of the potential problems associated with the use of medical devices. Typically, small sample surveys are used to collect qualitative information on postmarket experiences of clinicians or facilities with medical device performance or use. Survey respondents are selected based on their experience with the topic device and their willingness to participate. Thus, these findings may not be generalized to all users of a device. The FDA continues to evaluate adverse event reports from its Medical Device Reporting program, the medical literature and other postmarket data sources as part of its ongoing monitoring of device performance. FDA scientific, medical, nursing and engineering staff is made aware of the survey results as needed. If FDA believes there is a significant risk of adverse events as noted from the survey, it will combine those results with data gained from the other sources. FDA will work with the manufacturers and health care professional organizations to make important information known to the clinical community. Additionally, FDA continues to work with manufacturers to ensure the development, testing and promulgation of methods for reducing the risk associated with these devices and to minimize the complications from adverse events that may occur in the course of normal usage. If the results of any survey raise serious concerns about the safety of these devices, FDA may convene an Ad Hoc group of clinical, scientific and regulatory experts to discuss further actions.
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