USE OF CARDIAC INDEX IN PREGNANCY - IS IT JUSTIFIED

OBJECTIVE: The aim of this study was to test the hypothesis that stand ardization of cardiac output in pregnancy by correcting for body surfa ce area, and thus obtaining cardiac index, is justified. STUDY DESIGN: Cardiac output was determined by thoracic electrical bioimpedance mon itoring in 78 pregnant women; recordings were made at 1-month interval s from the first antenatal visit and a further two were made during th e sixth and twelfth weeks after delivery. In a separate group of 10 pr egnant women, cardiac output was determined by Doppler echocardiograph y at 5, 10, 14, 25, and 35 weeks and at 12 weeks post partum. RESULTS: Irrespective of gestational age, the correlation between cardiac outp ut and body surface area was poor, by either thoracic electrical bioim pedance monitoring (r = 0.15 to 0.39) or Doppler echocardiography (r = 0.00 to 0.29). Furthermore, strict proportionality between cardiac ou tput and body surface area was in general not the best way of describi ng the (poor) relation between these two. CONCLUSION: Standardization of cardiac output in pregnancy by correcting for body surface area to compare cardiac performance between individuals and between groups of individuals is not justified.