Revised Specification Has Pulse
on Oximeter Safety
A recent study from the Institute of Medicine, To Err Is Human,
reports that 100,000 accidents a year made by physicians or clinicians
results in 50,000 deaths. On p. 142, they actually cite pulse
oximetry as a major advance in reducing the number of anesthesia
adverse events, notes Sandy Weininger, Ph.D., U.S. Food and Drug
Administration, Rockville, Md.
Obtaining a pulse reading with a pulse oximeter finger ring
sensor is common in medicine. Accuracy and safety are major concerns
to users and manufacturers of the device. As well as reporting
the pulse and arterial hemoglobin saturation in med-speak, pulse
oximeters have multiple parts and are sometimes integrated with
larger systems that create additional concerns.
Members of the FDA, the medical, and manufacturing sectors in
ASTM Committee F29 on Anesthetic and Respiratory Equipment are
devoting painstaking attention to an expansive revision of ASTM
F 1415, Standard Specification for Pulse Oximeters and Pulse Oximeter
Testers. Redefined requirements for accuracy, safety, surface
temperature limits, and other performance issues have been added
to the specification based on demonstrated calculations or significant
scientific evidence. We go into extensive detail on what it means
to report accuracy. Accuracy is a very ambiguous term and there
have been lots of different ways of reporting accuracy over the
last 20-25 years of oximetry use, says Weininger. We are trying
to standardize on a particular definition.
At this juncture, the revisions are being reviewed within ASTM,
and additional participation or comments are welcomed. The current
draft has also been submitted to ISO as the starting point for
the development of ISO 9919: Pulse Oximeters for Medical UseRequirements.
The original ASTM Specification F 1415 for pulse oximeters was
released in 1992 by Subcommittee F29.03 on Ventilators and Ancillary
Devices. The current draft is based on IEC 60601, the IEC parent
of electromedical standards, explains Weininger. One of the
reasons for developing the standard was manufacturers would like
a single standard for pulse oximeter safety around the world.
There were several different standards, the ASTM standard, the
EN European Norm Standard, and ISO. This effort was put together
to try to harmonize all of those different versions. We should
be able to find consensus on what constitutes safety.
The revised specification proposes requirements for the safety
and performance of pulse oximeters including monitors, probes,
and cables, and also simulators used as pulse oximeter calibrators
or functional testers, whether new or overhauled. Eleven sections
describe requirements for operational accuracy, protection against
excessive temperatures or radiation, electric/mechanical/fire
hazards, and more, including an insightful 59-page appendix.
Weve done so much to add information to the annexes and appendices,
that some of the anesthesiologists are talking about using this
standard as a teaching tool in clinician teaching programs, he
The appendix covers evaluation and documentation of SpO2 accuracy
in humans, tracking calibration errors, functional testers, and
other considerations. For example, how does a hospital technician
judge how well an oximeter is working? People use functional
testers to determine whether the data they were getting is correct,
Weininger says. Thats not necessarily an appropriate use of
functional testers. The standard covers issues like that.
For further technical information, contact Sandy Weininger, Ph.D., US FDA Center for Devices & Radiological Health, Office
of Science & Technology (HFZ-141), 12720 Twinbrook, Parkway, Rockville,
MD 20857 (301/443-2536 x.134). Committee F29 meets May 8-12 at
ASTM Headquarters in West Conshohocken, Pa. For meeting or membership
information, contact F29 staff manager Teresa Cendrowska, ASTM (610/832-9718). //