February 25, 2000

Device that may reduce need for some C-sections nears approval

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Dr. Raymond DuBois

Device that may reduce need for some C-sections nears approval

A new fetal monitoring device being tested at Vanderbilt University Medical Center to help reduce the number of unnecessary cesarean sections because of questionable fetal heart rates has been recommended for approval by the U.S. Food and Drug Administration (FDA).

Dr. Frank H. Boehm, professor of Obstetrics and Gynecology and Nancy Townsend, a research nurse in Obstetrics/Gynecology spearheaded the nine-center study at VUMC and testified before the FDA advisory committee on Jan. 27.

The technique, fetal pulse oximetry, is used in cases of "nonreassuring fetal heart rate tracings" or decelerations in the fetus' heart rate that may or may not indicate decreased oxygen delivery or "hypoxia" in the fetus.

"This is helping revolutionize the way we take care of mothers during labor and delivery. About one-third of our patients have a tracing we're just not sure about. The uncertainty in the past has led to many unnecessary c-sections. Electronic fetal monitoring that was introduced thirty years ago measures fetal heart rate indirectly. This is direct," Boehm said.

"It's going to make a big difference in our ability to determine which baby is in trouble and which baby is not," he said.

When using routine electronic fetal heart rate monitoring, it can only be assumed that decelerations in heart rate or changes in heart rate variability are due to poor oxygen saturation, Boehm said. Approximately 5 to 10 percent of c-sections are performed due to fetal heart rate abnormalities. The new device helps doctors and nurses know which baby is truly suffering from hypoxia. The multi-center study showed that the c-section rate for non-reassuring heart rates was cut by half in the group that received fetal pulse oximetry.

Pulse oximetry is not new to medicine. It has been the standard of care in adult and pediatric intensive care units and operating rooms for more than a decade. The pulse oximeter, in adults and children, clips on the patient's finger. A red sensor light shines on the finger to read how much oxygen is in the bloodstream. It has been proven safe and effective over the past decade.

The new technology adapts pulse oximetry to a fetus. The sterile, single-use pliable device is inserted into the mother and rests next to the cheek or temple of the fetus during labor. It is simple to use and interpret.

An adult should have an oxygen saturation rate of 99 percent, but a fetus is adequately oxygenated when the level is greater than 30 percent, Townsend said.

VUMC became involved in a pilot study testing the new device in 1996. The promising results led to the multi-center study involving more than 1,000 patients nationwide and 110 patients at VUMC.

"The best thing about this device is that it takes away the uncertainty with fetal monitoring," Townsend said. "It is reassuring to mothers and to her nurses and physicians."