Wednesday, July 30, 2008
Small Device Allows Extended Monitoring for Nearly 24 Hours
Doctors at the University of Maryland Center for Advanced Fetal Care are testing a new fetal monitor that may provide valuable information about changes in an unborn baby’s heartbeat and movement over an extended period of time. The device, about the size of an iPod, measures the electrical impulse of the fetus’ heartbeat on the mother’s skin, detected with electrodes similar to an electrocardiogram (EKG). The system then uses special software to separate the maternal and fetal heartbeats. The monitor can collect data on fetal heartbeat and uterine activity for nearly 24 hours, much longer than ultrasound, which is generally used for a maximum of two hours.
"This device, called the Monica AN24, allows us to see changes in uterine contractions and fetal heartbeat and movement throughout the day and night, rather than just a snapshot of what’s going on at one particular time," explains Ahmet Baschat, M.D., a maternal-fetal medicine specialist at the University of Maryland Medical Center. "Ultrasound-based monitoring is limited because you can use it only for a short period, and, if the baby moves out of optimal position, the sound waves can’t bounce back and won’t provide the information we need."
By collecting data for an extended period, researchers want to see if they can spot earlier signs that the fetus is at risk or the patient may go into preterm labor. The device may be helpful for mothers who have medical conditions such as diabetes or autoimmune diseases. It may also provide crucial information in patients with poor fetal growth or problems with the placenta, which may require early medical intervention.
"With some high-risk conditions, the baby’s health may decline over time, which you may not pick up if you’re only monitoring for an hour or so with ultrasound," says Dr. Baschat, who is also an associate professor of obstetrics, gynecology and reproductive sciences at the University of Maryland School of Medicine.
The new device also appears to be extremely safe, since it simply monitors what is already occurring. During a monitoring session, four or five patches are placed on the mother’s belly. These patches contain the electrodes that pick up the fetal and maternal heartbeats, just like an EKG for heart monitoring. The electrodes are connected by wires to the small monitor that stores the data.
With ultrasound, a technician uses a wand to send sound waves, which are energy, into the uterus. The bounce-back of those waves is used to monitor the baby. However, doctors do not know if there are any effects of long-term exposure to ultrasound energy.
The Monica system provides an accurate measurement of the fetal heart rate and the strength of uterine contraction compared to ultrasound-based systems, which provide only an approximation. The new device also gives maternal-fetal medicine specialists a significant amount of data on fetal health, which they can analyze to look for changes or early signs of problems.
"Right now, we do not know if there’s a benefit to having all this information, but it’s one of the things we are hoping to find out. We want to know how we can use this data to help women with high-risk pregnancies to deliver healthy babies," says Dr. Baschat.
Currently, researchers at the University of Maryland Center for Advanced Fetal Care are using the device for women with high-risk pregnancies who are in the hospital with conditions such as pre-term labor and preeclampsia. The team also uses it during patient appointments at their clinic. However, because the device is lightweight and portable, developers hope the monitor can be used outside the hospital, to provide information about fetal movement and heart rate under real world conditions. Mobile technology could send the information to the hospital through wireless or Bluetooth systems.
The University of Maryland Medical Center team has been using the device for several months and plans to test it on 200 patients. The Medical Center is the only academic hospital in the United States testing the system.
The University of Maryland Center for Advanced Fetal Care is a leader in patient care and research in perinatology, the care of the unborn child. The specialists in high-risk pregnancies provide state-of-the-art care for diagnosing and treating complex pregnancies, including multiples like twins and triplets, genetic conditions and problems of fetal development. Treatments include transfusions, gene therapy, shunts and fetal laser surgery for conditions such as twin-to-twin transfusion syndrome, a complex disorder involving an unequal blood exchange between identical twins. Researchers at the Center for Advanced Fetal Care have a wide range of interests, such as examining biomarkers in a mother’s blood in the first weeks of pregnancy as a possible predictor for subsequent preeclampsia.