Measuring plasma volume in women of reproductive age: a comparison study of hydroxyethyl starch to other methods

Methods for measuring plasma volume (PV) have rarely been validated or compared, and some are unsafe in certain populations (e.g., pregnancy). We aimed to develop and evaluate a PV method using hydroxyethyl starch (HES) that is safe in women of reproductive age and could be used in pregnancy. A convenience sample of healthy nonpregnant women (n=12) of reproductive age participated in a comparison study using two indicator dilution methods - HES and indocyanine green (ICG), and three estimations - Kaplan, Hurley, and Nadler equations. Baseline blood samples were collected; we injected ICG and HES separately, each followed by post-injection sampling. We compared HES PV to the other methods using Bland-Altman analysis. Participants had mean {+/-} SD age of 25.8{+/-}7.5 years and mean BMI of 21.7{+/-}1.7 kg/m2. Mean PV estimations for HES, ICG, Kaplan, Hurley, and Nadler methods were 2,046{+/-}392 mL, 2,765{+/-}820 mL, 2,443{+/-}464 mL, 2,407{+/-}301mL, and 2,373{+/-}406 mL, respectively. In each analysis, differences for 11/12 participants were within the Bland-Altman limits of agreement, {+/-}2 SD from each mean difference. In conclusion, PV measured by HES was >300 mL lower than other estimates, but had a narrow distribution within the expected range. Future studies should validate methods for PV measurement across populations, including pregnancy. HighlightsO_LIWhat is the central question of this study? How does plasma volume (PV) estimated using hydroxyethyl starch (HES) compare to estimates using other methods in healthy women of reproductive age? C_LIO_LIWhat is the main finding and its importance? In this comparison study of PV methods (HES, indocyanine green, and estimation equations), PV measured by HES was >300 mL lower than other estimates, but had a narrow distribution that was within the expected range. Future work is still needed to validate the HES method across populations. C_LI