Effects of 6% Hydroxyethyl Starch and 3% Modified Fluid Gelatin on Intravascular Volume and Coagulation During Intraoperative Hemodilution

In the perioperative period, artificial colloids are most often infused in doses of 500-1000 mL intravenously. This randomized study compared the effects on intravascular volume and coagulation of approximate 2000 mL of two isooncotic artificial colloids: 6% hydroxyethyl starch (HES; MW 200,000; substitution ratio 0.40-0.55) and 3% modified fluid gelatin (GEL). We hypothesized more pronounced hypocoagulation with HES and a weaker intravascular volume effect of GEL. Forty-two patients, scheduled for primary total hip replacement, were allocated randomly to receive HES or GEL during acute normovolemic hemodilution and subsequent further intraoperative hemodilution. Blood samples were taken before and after 500 mL and 1000 mL of acute normovolemic hemodilution; intraoperatively after 20 mL/kg of artificial colloid and at the end of colloid infusion; on arrival in the recovery room; and 3 h later. We quantified: 1) coagulation variables; 2) blood loss; 3) hemodynamic stability; 4) necessary infusion volume; 5) interstitial extravasation, calculated from plasma volumes measured using albumin marked with technetium-99m and iodine-125, respectively; 6) percentage volume effect at the end of the study as well as hematocrit, total serum protein, and colloid osmotic pressure. Intraoperative volume therapy was guided by radial systolic pressure and systolic pressure variation, mixed venous hemoglobin saturation in the pulmonary artery, and pulmonary capillary occlusion pressure. The following differences (HES vs GEL, P < 0.05) were found: 382 vs 725 mL extravasation; 76% vs 56% intravascular volume expansion 7 h after the median point of artificial colloid infusion; 27% vs 29% hematocrit and 35 vs 45 g/L total serum protein on arrival in recovery; 4 vs 0 abnormal bleeding times (>900 s); 3437 vs 2778 mL blood loss. This study quantifies a poorer volume effect of GEL and a higher blood loss with HES. The higher blood loss was significant with one-tailed testing only. These observations warrant extra GEL infusion to avoid hemoreconcentration and caution with large dose HES. (Anesth Analg 1995;81:1235-42)