Identifying the precursor to oxytocin-induced uterine tachysystole by monitoring with uterine EMG

Pretel, Inc., Chattanooga TN

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Abstract

Approximately 30% of all women in the US (over 1,200,000 annually) are exposed to IV oxytocin at some point during labor to increase the frequency and strength of uterine contractions. Oxytocin is classified as a high-alert medication requiring clinical vigilance. Oxytocin is generally safe, but adverse outcomes arise when contractions become too frequent, a condition called tachysystole. Tachysystole is associated with fetal distress resulting in emergency Cesarean delivery (RR 2), neonatal sepsis (RR 2.0), NICU admissions (RR 1.6) and depressed fetal outcomes (RR 1.5). To date, clinical vigilance alone has not sufficiently reduced these oxytocin-related clinical risks. There are marked variations of individual responses to oxytocin, with some patients contracting robustly at low doses, while others require high doses to express mild contractions. Without a reliable, non-invasive method to monitor the effects of oxytocin on the uterus, it remains difficult to effectively administer. The use of tocodynamometry (toco), the standard method of assessing contractions during labor, unfortunately results in 20% of patients experiencing tachysystole. This high rate is a serious gap in obstetrical practice. Electromyography offers an alternate method of assessing uterine contractions since bioelectrical signals are produced as the muscle contracts. Interestingly, it long been appreciated that uterine bioelectrical signals are also produced between contractions. These signals are the source of ?false positive contraction? reporting in commercial EMG-based systems. However, to date there have been no explanations of the source, importance, or meaning of these signals. In our preliminary uterine EMG studies, we found these ?between contractions? signals are prominent during oxytocin use. Furthermore, as the uterine contraction pattern approaches tachysystole, our analysis suggests that oxytocin-associated EMG signals last longer (2-3 minutes) and appear more frequently. In subjects that meet the clinical criteria of tachysystole, the oxytocin-associated signals are seen in all channels and persist even longer (3 to 10 minutes). In this Phase I SBIR project, we will show the feasibility of isolating the oxytocin-associated signals from raw data in real time (Aim 1). In Aim 2 we will use these signals to categorize the uterine contractions as 1) normal; 2) early oxytocin effects; 3) precursor to tachysystole; 4) tachysystole. Identifying the precursor to tachysystole will allow clinicians to know when additional oxytocin infusion is inadvisable and avoid tachysystole. This will close the gap in the practice of oxytocin management for induction of labor.