Miniaturized Transmitter To Be Used In Efforts To Save Babies

NASA's Ames Research Center, Moffett Field, CA, is developing the pill, which is about one-third-of-an-inch across and one-and-one-third-inches long, in cooperation with the Fetal Treatment Center at the University of California, San Francisco. Later, an even smaller pill will be developed that can be swallowed by astronauts so that NASA can track their vital signs during space travel.

"Nearly every time doctors operate on a fetus, the mother will later undergo pre-term labor that must be monitored," said Dr. Carsten Mundt, an electrical engineer on the Sensors 2000 team at Ames. "Pre-term labor is a serious problem that is difficult to predict and monitor with conventional equipment, and often leads to the death of the baby."

"But if you implant our pill, you can measure pressure changes in the uterus that result from contractions," Mundt said. "When doctors are able to monitor the magnitude and frequency of contractions, the physicians can identify the onset of pre-term labor early enough to prevent it from becoming life threatening to the fetus."

Earlier, pediatric surgeons at the Fetal Treatment Center pioneered a cesarean surgical approach to treat fetuses suffering from various birth defects including congenital diaphragmatic hernia. In this condition, a hole in the baby's diaphragm lets internal organs shift from inside the abdomen into the chest cavity, leaving insufficient room for lung development. Sixty to 75 percent of babies born with this condition perish. During some of these earlier surgeries, physicians implanted larger sensor-transmitters to monitor mothers and their fetuses.

Recently, Fetal Treatment Center surgeons changed their technique from cesarean to a less-intrusive endoscopic method during which they make small incisions and insert tube-like devices through the mother's abdominal wall.

Normally, an endoscope is used to see into the interior of a body or hollow organ. Endoscopic instruments are now also used more frequently in surgeries requiring smaller incisions.

"This minimally invasive method represents the future of fetal surgery," said Michael Harrison, M.D., founding director of the Fetal Treatment Center, who in 1981 performed the world's first corrective surgery on a fetus before birth.

"Because there are no commercially available sensor-transmitters small enough to fit through the tubes used in the new endoscopic surgery technique, scientists and engineers on our team developed the pill-shaped device so that it can pass through the tubes," said Ames team member Mike Skidmore. "Our first pill-shaped device can transmit temperatures as well as the pressure of uterine contractions."

Ames scientists are testing a prototype version of another pill that can measure and transmit pH, or acidity in the fetus, according to Dr. Chris Somps, a scientist on the Sensors 2000 team. "Plans also call for even smaller pills that will measure the electrical activity of the fetal heart," he said. "These pills will transmit fetal heart data, as well as measurements of the baby's body chemicals including ionic calcium, carbon dioxide and glucose."

"We would also like to use this technology to study what happens to astronauts during space travel," said Skidmore. "Not only could they swallow the smaller pill transmitters we plan to develop, but we have a conceptual design of small, flat transmitters that can be taped to the body like plastic bandages."

"There are many possible medical uses for this technology; pills could monitor intestinal pressure changes, or stomach acidity in ulcer patients," Mundt said. "The acid-base balance in the body is a basic measure of health."