Audible Low-Battery Alarms on Pulse Oximeters
Hazard [Health Devices May-Jun 1990;9(5-6):200]
A member hospital reported that, on three separate occasions, a pulse
oximeter backup battery became depleted, rendering the pulse oximeter nonfunctional.
Because the pulse oximeter lacked an audible low-battery alarm and no one noticed the
visual low-battery indicator, the staff was not alerted to the depleted battery condition.
In at least one case, the AC power cord at the back of the unit was inadvertently
disconnected, leaving the unit running on battery power. Fortunately, no adverse effects
The pulse oximeter in these incidents, like many other pulse oximeters,
has a battery-in-use and low-battery indicator, but no audible low-battery alarm. Users
are expected to check these indicators routinely when any pulse oximeter is operating on
battery power to detect a low-battery condition. Failure to do so could result in battery
depletion, which would render the unit inoperable until it is connected to line power.
Clinical personnel must become familiar with pulse oximeters, which are
being relied on as critical care monitors more and more outside of the OR. (See our
evaluation of pulse oximeters in Health Devices 18(6):184-230, June 1989.) A
functioning pulse oximeter can provide safe and effective critical patient monitoring, but
not having an audible low-battery alarm in addition to the visual indicator(s) to warn of
a depleted battery places patients at unnecessary risk.
Pulse oximeters normally operate on AC power, but may be used (perhaps
inadvertently) on battery power. While an audible low-battery alarm does consume more
power and reduce remaining battery operation time, an audible low-battery alarm is an
important additional safety feature that is lacking on a majority of the pulse oximeters
on the market.
Since the late 1970s, ECRI has advocated the use of readily noticeable and
nondefeatable visual and audible alarms for all critical and life-support equipment and
monitors. (See "Critical Alarms: Patients at Risk," Health Devices
16(2):39-44, Feb 1987 and "Update: Critical and Remote Alarms," Health
Devices 18(12):426-7, Dec 1989.) But, ultimately, proper battery operation depends on
use and user care. Reliance on alarms should never supersede proper user training, device
application, and maintenance procedures.
- Placard a warning label on any pulse oximeters that lack an audible
low-battery alarm with the following:
oximeter has no audible low-battery alarm. Minimize use on battery power.
Verify power source with the battery-in-use light or AC power indicator.
When used on AC power, ensure that the AC power cord is properly
- Check pulse oximeters on battery operation routinely to be sure that the
batteries are not depleted.
Oximeters, Pulse [17-148]
Cause of Device-Related Incident
Device factor: Design/labeling error
User error: Inappropriate reliance on an automated feature
External factor: Power supply
Support system failure: Poor prepurchase evaluation
Mechanism of Injury or Death