BACKGROUNDStroke volume variation (SVV) is a robust indicator of fluid responsiveness during volume change. We compared the sensibility of SVV by Vigileo/Flotrac to central venous pressure (CVP) when volume changes in patients undergoing intraoperative acute normovolemic hemodilution (ANH) and acute hypervolemic hemodilution (AHH).

METHODSForty patients were randomly divided into an ANH group (n = 20) and an AHH group (n = 20). All patients received general anesthesia and were mechanically ventilated. Data were collected from 7 different time-points in the ANH group: baseline, after withdrawal of 5%, 10%, and 15% of the estimated blood volume (EBV) and after replacement with an equal volume of 6% hydroxyethyl starch 130/0.4 (HES) in 5% EBV increments to baseline. There were four time points in the AHH group: baseline, after 5%, 10%, and 15% expansion of the EBV with 6% HES. At each time-point, CVP, SVV and other hemodynamic parameters measurements were obtained.

RESULTSAfter removal of 10% and 15% EBV, SVV significantly increased from 10.9 ± 3.0 to 14.1 ± 3.4 and 10.9 ± 3.0 to 16.0 ± 3.3 (P < 0.01), and returned to a final value of 10.6 ± 3.4 after volume replacement. The CVP value was unchanged after removal and replacement of 15% of the EBV. There were no significant changes in SVV after 5%, 10% whereas there was a significant reduction after 15% (8.2 ± 1.7) expansion of the EBV compared with baseline (9.9 ± 1.8) (P = 0.033). However, there was a significant increase in CVP after 10% (10.3 ± 2.4), 15% (11.3 ± 2.2) expansion of the EBV compared with baseline (8.2 ± 2.7) (P < 0.01).

CONCLUSIONSVV is a more sensitive parameter for volume than CVP during hypovolemia, on the contrary CVP is more sensitive than SVV during hypervolemia.