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 periods: 20–27 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<.05). The systemic vascular resistance systemic vascular resistance means in each of the postpartum groups were significantly higher than the late second-trimester group means recorded at 20–27 weeks of gestation (P<.05).
CONCLUSION: The normative values reported in this investigation can be used to interpret and assess similarly tested patients with hypertensive or otherwise complicated pregnancy.
LEVEL OF EVIDENCE: III
Normative impedance cardiography hemodynamic data are provided for normotensive pregnancy and the first 2 days postpartum after a vaginal or cesarean delivery.
Divisions of Maternal-Fetal Medicine and Biostatistics, Department of Obstetrics and Gynecology, University of Mississippi Medical Center, Jackson, Mississippi.
The Division of Maternal-Fetal Medicine in the Department of OBGYN at the University of Mississippi Medical Center funded this study.
Corresponding author: James N. Martin Jr, MD, Professor OBGYN, Director MFM Division, Vice Chair, Research & Academic Development, Department of OBGYN-UMMC, 2500 N State Street, Jackson, MS 39216; e-mail: firstname.lastname@example.org.
Presented as poster at the 33rd Annual Meeting of the Society for Maternal-Fetal Medicine: The Pregnancy Meeting, February 11–16, 2013, San Francisco, California.
Financial Disclosure The authors did not report any potential conflicts of interest.