Electrohysterogram-based sensor for non-invasive contraction monitoring with impr

DESCRIPTION (provided by applicant): The majority of obstetric deliveries in the US undergo continuous electronic uterine activity monitoring. Typically, an external tocodynamometer (strain gauge) is employed to provide the frequency and timing of uterine contractions. The reliability of this monitor depends on its proper positioning (which may be disturbed by patient movement), and the transmission of tension from the uterus to the sensor. In some patients, particularly the obese, the monitor may fail to d etect contractions consistently. In others the monitor requires frequent repositioning by the nursing staff. The alternative uterine activity monitor is an intrauterine pressure catheter (IUPC), which is placed through the cervical os in the adequately dil ated patient with ruptured membranes. While this monitor usually provides a more reliable signal, as well as quantitative information regarding intrauterine pressure, its invasive nature and increased risk of infection limit enthusiasm for its use. The obs tetric suite is subject to the obesity pandemic in the US, and these women have an increased risk for labor problems, infections and other complications. Existing non-invasive uterine activity monitoring, while preferable to reduce the infection risk, is p articularly unreliable in this population. The specific goal of the proposed research is to develop a reliable, non-invasive uterine activity monitor that is unaffected by obesity and requires less nursing intervention than the tocodynamometer. The end-pro duct will be a smart cable that connects an existing labor monitor to an electrode array and converts the electrical activity of the uterus (electrohysterogram or EHG) into tocodynamometer signals compatible with existing monitors. Preliminary results obta ined by our group indicate that the EHG can provide such a monitor, however these studies were conducted with 10 electrodes located across the maternal abdomen. We propose the following specific aims: Aim 1: Develop EHG signal processing and embedd ed software: Using retrospective data from our large database, signal processing algorithms to produce high quality contraction curves. A retrospective clinical interpretation study will be implemented to validate final signal processing system. Ai m 2: Build EHG system hardware with embedded software: A prototype EHG amplifier system will be designed to interface directly to existing maternal-fetal monitors. The amplifier signal will be processed to create uterine activity curves that will be displa yed in real-time and recorded for further analysis. Aim 3: Clinically evaluate the mini-array EHG uterine activity monitor: A 30-patient pilot study will be conducted to evaluate the reliability of the mini-array for monitoring contractions during active labor. The EHG uterine activity will be compared with that derived from the tocodynamometer and IUPC, and evaluated both electronically and by expert opinion. PUBLIC HEALTH RELEVANCE: The current method of non-invasive monitoring of uterine activit y fails frequently, particularly in the obese patient. When this occurs, often clinicians must use an invasive intra- uterine pressure catheter that is particularly problematic in these patients since they are already at increased risk for infections. The development of an alternative, non-invasive monitor of uterine activity that performs better in the obese patient and at least as well in the normal-weight patient, will reduce infectious complications by limiting the need for invasive monitoring while req uiring less nursing manipulation.