Abstract
Objective—To determine the effect of hydroxyethyl starch (HES) on colloid oncotic pressure (π) during fluid resuscitation of hypoproteinemic horses and to evaluate the clinical usefulness of direct and indirect methods for determination of π before and after infusion of a synthetic colloid.
Design—Prospective clinical study.
Animals—11 hypoproteinemic horses.
Procedure—Horses received IV infusions of 8 to 10 ml of a 6% solution of HES/kg (3.6 to 4.5 ml/lb) of body weight during fluid resuscitation. Blood samples were obtained for determination of plasma measured colloid oncotic pressure (πmeas) and plasma total protein and albumin (A) concentrations. Plasma globulin concentration (G) was calculated as the difference between plasma total protein and albumin concentrations. Calculated values for colloid oncotic pressure (πA + G) were determined by use of a predictive nomogram previously developed for horses.
Results—There was no significant difference between the means of πmeas and πA + G at the beginning of HES infusion. After HES infusion, the mean of πmeas was increased significantly from baseline for 6 hours. Mean plasma total protein and albumin concentrations and πA + G were decreased significantly from baseline for 24 hours. Differences between mean πmeas and πA + G after HES infusion were significant for 24 hours.
Conclusions and Clinical Relevance—There was good agreement between plasma πmeas and πA + G in blood samples obtained from hypoproteinemic horses immediately before infusion of HES. Use of a predictive nomogram did not, however, account for the oncotic effect of HES. Results of comparison of πmeas to πA + G after HES infusion suggest that a significant oncotic effect was maintained for 24 hours in the study horses. (J Am Vet Med Assoc 2001;218: 1130–1135)
