Electrical intervention (EI) uses bipolar, constant-current (1-20 mA), square-wave pulses in 20% duty cycles. Women in active preterm labor have an electrode catheter placed into the posterior fornix of the vaginal canal. The EI current is given up to 80 minutes while monitoring tocodynamometric (toco) contractions and adjunct electrohysterographic (EHG) activity while continuously monitoring maternal vital signs, fetal heart rate and electrocardiogram (fECG). The study includes a pre-EI control period (C1); the EI period, when a 10-second current burst is delivered only during a contraction; and a post-EI control period (C2). The whole study will take a maximum of two hours.
The uterine toco contraction frequency and adjunct EHG electrical activity are analyzed for changes caused by EI. Changes in maternal vital signs, fetal heart rate and fECG will determine EI side-effects.
