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 Use—Requirements.

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.

“We’ve 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 adds.

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. “That’s 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). //