PP097. Cardiac output and systemic vascular resistance in normal pregnancy and in control non-pregnant women

Abstract

Changes in cardiac output (CO) and systemic vascular resistance (SVR) have been shown to precede the clinical onset of pregnancy complications, such as pre-eclampsia and fetal growth restriction. CO and SVR undergo major changes during normal pregnancy. However, assessment of these vascular parameters requires intensive training and expensive techniques, so currently can be performed only in specialised centres. The aim of this study was to investigate maternal cardiovascular function measured using an ultrasonic cardiac output monitor (USCOM), a simple non-invasive continuous wave Doppler device, in a cohort of pregnant women and non-pregnant controls. This was a cross sectional study including 185 women with normal singleton pregnancies at 11-40weeks of gestation and 49 non-pregnant controls. Stroke volume (SV), CO and SVR were measured using the USCOM device. All measurements were performed with the patients in supine position. All women with a gestational age of >20weeks were in a left lateral position by placing a wedge-shaped pillow under their right side to prevent vena cava compression. In a group of 25 pregnant women, each measurement was repeated three times to evaluate the reproducibility of this technique. Cardiac index (CI), SV index (SVI) and SVR index (SVRI) relate CO, SV and SVR to the body surface area. The data were normally distributed after logarithmic transformation. Comparisons between pregnant and non-pregnant women were performed using Studentt-test, Chi-Square test or multiple regression analysis, when adjustment for potential confounders was necessary. Data analysis was performed using SPSS 16.0. In the first trimester, all of the following vascular parameters were higher in pregnant women compared to non-pregnant controls: CO [median (IQR): 4.86 (4.45-5.57) vs 5.57 (4.76-6.52)L/min, P<0.001], CI [median (IQR): 2.69 (2.44-3.07) vs 3.25 (2.80-3.86)L/min/m(2), P<0.001], SV [median (IQR): 72.51 (68.10-80.18) vs 80.75 (74.50-99.74)mL/beat, P<0.001], SVI [median (IQR): 41.93 (37.53-46.57) vs 47.01 (43.85-53.79)mL/m(2)/beat, P<0.001]. Pregnant women had significantly lower SVR [median (IQR): 1458 (1261-1649) vs 1165 (1023-1406)sec/cm(-5), P<0.001] and SVRI [median (IQR): 2646 (2307-2963) vs 2006 (1179-2277)dynes-sec/cm(-5)/m(2), P<0.001] at 11-13weeks' gestation. Using USCOM, maternal cardiac function can be assessed in a simple, non-invasive and reproducible manner. This simple technique is likely to facilitate large scale studies of maternal cardiovascular function in pregnancy.