Considering the Fåhraeus effect and the blood volume regulation role of the microcirculation, we used a new method for calculating the blood volume change in microcirculation, macrocirculation as well as the whole circulation (
$\Delta V_{{\rm mic}}$
,
$\Delta V_{{\rm mac}}$
,
$\Delta V_{{\rm b}}$
), to compare fluid therapy effects of hypertonic saline dextran solution (HSD) and lactic Ringer’s solution at the early stage after burn–blast combined injury (BBI). The measurement of plasma viscosity was used in this calculation. The results showed that, with calculation of the blood volume change in microcirculation and macrocirculation, this method could more exactly and distinctly display the change and distribution of blood volume during the therapy. It confirms that HSD treatment can increase blood pressure and attenuate tissue edema, by significantly increasing total blood volume, recouping
$\Delta V_{{\rm mac}}$
. The study suggests that a desirable and practical clinical method for blood volume change can be developed based on the present study.
