Oxygen monitors' safety value in births discounted

Use of fetal oxygen monitors during labor to determine if a baby is in distress does not reduce the rate of Caesarean deliveries or improve the health of infants, researchers reported today.

The Oxifirst instruments were introduced six years ago in the hope that, by supplementing information from fetal heart monitors, they would make vaginal deliveries safer and reduce the need for C-sections.

But a study of nearly 5,000 births showed no benefit, according to the report in The New England Journal of Medicine. The findings were so conclusive that the study was terminated early.

"What we were really hoping was that knowledge of a baby's oxygen saturation would be helpful," said Dr. Catherine Spong of the National Institute of Child Health and Human Development, one of the study's authors. "It was disappointing that that wasn't the case."

The institute sponsored the study, which was carried out at 14 university hospitals around the country under the auspices of the National Institutes of Health.

After the release of the findings, Oxifirst's manufacturer, Tyco International Ltd.'s Nellcor unit of Pleasanton, Calif., said it would no longer distribute the sensors needed for the monitors, effectively withdrawing it from the market.

The new results were "the nail in the coffin" for the device, said Dr. Thomas Garite of the University of California, Irvine, who was among the first obstetricians to study the device.

Oxifirst was conditionally approved by the Food and Drug Administration in 2000, but the $10,000 monitor was not widely adopted as physicians and hospitals waited for results from the current study.

The oxygen monitor was designed to be used with traditional electronic monitors, which track heart rate to determine if the fetus is experiencing stress or lacking oxygen.

The oxygen monitor works in much the same way as devices that are placed on a fingertip to measure blood oxygen levels through the skin. The Oxifirst sensor is manually inserted through the cervix and placed against the baby's cheek or forehead once the mother's water has broken.

The idea was that by keeping close tabs on the baby's oxygen level, doctors would know whether it was safe to continue with a vaginal delivery despite other signs of distress.

A team led by Dr. Steven Bloom of the University of Texas Southwestern Medical Center enrolled 5,341 first-time mothers. The sensor was inserted into all the mothers, but the readings from the sensor were made available to only half the attending physicians.

In 507 cases, the device was removed because of technical problems or at the request of the mother or doctor.

The information from the monitor apparently did not improve fetal care, the researchers found. Overall, just more than a quarter of the mothers in each group underwent Caesarean delivery, and the health of the infants in both groups was the same.

Although researchers had originally intended to enroll 10,000 women, they stopped the study early. "The results were conclusive at that point," Bloom said.

Garite, however, argued that the study should have focused on cases involving an abnormal fetal heart rate. Because the team included all pregnancies, "I would not have expected them to show benefit," he said.

Dr. Khalil Tabsh of the University of California, Los Angeles School of Medicine, which stopped using the devices based on earlier, small studies, conceded that they might help the occasional patient. "But why should we spend the money to use it on everybody when it is not cost-effective?" he said.

Material from The Associated Press is included in this report.