Changes in blood volume and hematocrit during acute preoperative volume loading with 5% albumin or 6% hetastarch solutions in patients before radicalhysterectomy

Background. The impact of acute preoperative volume loading with colloids o n blood volume has not been investigated sufficiently. Methods: Before surgery, in 20 patients undergoing major gynecologic proced ures, volume loading was performed during anesthesia by infusing approximat ely 20 ml/kg of colloid at a rate of 90 ml/min (group I: 5% albumin solutio n; group II: 6% hetastarch solution; n = 10 each). Plasma volume (indocyani ne green dilution technique), erythrocyte volume (labeling erythrocytes wit h fluorescein), hematocrit, total protein, and hetastarch plasma concentrat ions (group II) were measured before and 30 min after the end of infusion. Results: More than 1,350 ml of colloid (approximately 50% of the baseline p lasma volume) were infused within 15 min. Thirty minutes after the infusion had been completed, blood volume was only 524 +/- 328 ml (group I) and 603 +/- 314 ml (group II) higher than before volume loading. The large vessel hematocrit (measured by centrifugation) dropped more than the whole body he matocrit, which was derived from double-label measurements of blood volume. Conclusions. The double-label measurements of blood volume performed showed that 30 min after the infusion of approximately 20 ml/kg of 5% albumin or 6% hetastarch solution (within 15 min), only mean 38 +/- 21% and 43 +/- 26% , respectively, of the volume applied remained in the intravascular space. Different, i.e., earlier or later, measuring points, different infusion vol umes, infusion rates, plasma substitutes, or possibly different tracers for plasma volume measurement might lead to different results concerning the k inetics of fluid or colloid extravasation.