Cause of Device-Related Incident
Device factors; External factors; Support system failures; User errors

Clinical Specialty or Hospital Department
Anesthesia; CCU / ICU / NICU; Clinical/Biomedical Engineering; Emergency Medicine; Nursing; Obstetrics and Gynecology; OR / Surgery; Pulmonary / Respiratory Therapy

Device Factors
Design / labeling error

Document Type
Hazard Reports

External Factors
Power supply (including piped medical gases)

Mechanism of Injury or Death
Monitoring failure

Support System Failures
Poor prepurchase evaluation

Tampering and/or Sabotage
*Not stated

User Errors
Inappropriate reliance on an automated feature

Oximeters, Pulse [17-148]

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 were reported.

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.


  1. Placard a warning label on any pulse oximeters that lack an audible low-battery alarm with the following: This pulse 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 connected.
  2. 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

Monitoring failure

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