Maternal Hemodynamics by Thoracic Impedance Cardiography for Normal Pregnancy and the Postpartum Period

OBJECTIVE:To establish normative impedance cardiography values for the second half of pregnancy and up to 48 hours postpartum after either vaginal or cesarean delivery. METHODS:A single-center prospective observational institutional review board-approved study of normotensive women (n=168) using thoracic impedance cardiography performed at specific times during gestation. Antepartum testing was performed at three time periods20–27 weeks, 28–33 weeks, and 34–40 weeks of gestation. Postpartum testing was undertaken after the immediate puerperium at 6–23 hours and 24–48 hours after vaginal or cesarean delivery. Data analysis was performed using STATA software; data are expressed as mean±standard deviation. RESULTS:All seven of the patient groups studied were comparable with regard to demographic features; 80% of the study participants were African American. Group means obtained between 20 and 40 weeks of gestation and postpartum after vaginal and cesarean delivery fell within the “normal range” of the hemodynamic graph that was developed to associate mean arterial pressure and systemic vascular resistance. The thoracic fluid content group means in both vaginal and cesarean delivery groups were higher than the antepartum patient groups. The thoracic fluid content mean after cesarean delivery at 48 hours is significantly higher than the mean value recorded between 20 and 27 weeks of gestation (P