Oximeter postapproval trials go slowly.(14 Adverse Events Reported)

GAITHERSBURG, MD. -- Only one of the three postmarketing studies designed to address safety and efficacy issues related to the fetal pulse oximeter has been completed, and one is at a standstill.

At a meeting of the Food and Drug Administration's Ob.Gyn. Devices Panel, the FDA and the manufacturer of the device gave an update on the trials and 14 adverse event reports the agency has received since the device was approved in May 2000.

The device, known as OxiFirst and developed by Nellcor in Pleasanton, Calif., was approved as an adjunct to electronic fetal heart rate (FHR) monitoring in the presence of a nonreassuring heart rate pattern. It is indicated for use after membrane rupture in a singleton fetus in a vertex presentation. Gestational age should be over 36 weeks.

The study on which approval was based showed a significant reduction in the rate of cesarean sections performed for a nonreassuring fetal heart rate when the device was used with FHR monitoring, compared with FHR monitoring alone. The overall C-section rate was not affected, largely because of a higher rate of C-sections for dystocia in the oximeter group.

In September 2001, the American College of Obstetricians and Gynecologists said in a committee opinion that it could not endorse fetal pulse oximetry because of concerns that it would raise obstetrical care costs without improving outcomes.

The one study that has been completed is a prospective, nonrandomized, multicenter trial in 274 nulliparous patients monitored with both electronic fetal monitoring and fetal pulse oximetry. The researchers examined whether the nonreassuring FHR patterns used for entry into the original study identified patients at increased risk for dystocia.

Women were divided into two FHR classes: those with an intermittent "mildly nonreassuring" FHR pattern (class 1) and those with a persistent, progressive, moderate to severe nonreassuring FHR pattern (class 2). Of the 237 women in class 2, 22% had a C-section for dystocia vs. 8% of the 37 women in class 1, a significant difference. These results indicate that a significantly nonreassuring FHR "predicts Cesarean for dystocia among nulliparous patients with normally oxygenated ...