Use of cardiac index in pregnancy: Is it justified?

Systemic arterial response and ventriculo-arterial interaction during normal pregnancy

“…22 In nonpregnant subjects, Ea and E LV are standardised according to BSA; E a I and E LV I. Indexing of hemodynamic variables in pregnancy by use of BSA is debated. 23 However, the VAC index is the ratio between these two parameters, and is thus independent of BSA. Under normal resting conditions, when the interaction between the LV and arterial system are optimal, the E a I/E LV I ratio is usually close to unity (0.8-1.2).…”

Cardiac structure and function in normal pregnancy

“…Patient characteristics such as age, ethnicity, parity, body surface area (BSA), body mass index (BMI) and height have been shown to independently affect cardiac function and structure [6][7][8][9][10][11][12][13][14][15]. Cardiac output (CO) has been reported to decline with advancing age in nonpregnant individuals, and this has been confirmed in pregnancy [6][7][8].…”

“…Most studies concur that diastolic blood pressure (DBP) decreases during the first trimester, is stable or slightly reduced during the second trimester and increases during the third trimester [4,16,17,21,34]. MAP seems to parallel the changes of DBP [2,[5][6][7]12,13,[19][20][21]23,25,[29][30][31][32]35] (Table 1 and supplementary table S2, http://links.lww.com/COOG/ A1). Taking into account only the studies in which BP was measured following the National High Blood Pressure Education Program Working Group on High Blood Pressure in Pregnancy (NHBPEPWG) recommendations, agreement is found on the fact…”

“…1). There is a general agreement that CO increases during the first two trimesters, but there is considerable discrepancy regarding changes between the second and third trimester of pregnancy (supplementary table S1, http://links.lww.com/COOG/A1) [2,[4][5][6][7]12,13,[18][19][20][21][23][24][25][28][29][30][31]34,35,37,42]. CO decreases rapidly in the first 2 weeks after delivery, continuing to decrease until 24 weeks postpartum before stabilizing [4,5].…”

“…SV rises by about 20-30% in pregnancy, but there is significant disagreement about the time course of SV changes during pregnancy (supplementary table S2, http://links. lww.com/COOG/A1) [2,4,5,12,[16][17][18]20,21,23,25,[28][29][30][31][32][33][34][35]. SV can be calculated from the product of aortic Doppler flow velocity time integral and cross-sectional area (CSA) of the left ventricle outflow tract (LVOT), where slight differences in LVOT diameter will have a great impact on measurement error.…”