Cardiovascular, colloid osmotic pressure, and hemostatic effects of 2 formulations of hydroxyethyl starch in healthy horses.

Abstract

BACKGROUND: Lower molecular weight and molar substitution formulations of hydroxyethyl starch (HES) solutions might maximize cardiovascular function and colloid osmotic pressure (COP) and minimize adverse effects on coagulation. HYPOTHESIS/OBJECTIVES: To compare effects of 1 low and 1 high molecular weight and molar substitution HES solution on cardiovascular variables, COP, and hemostasis in normal horses. ANIMALS: Eight healthy adult horses. METHODS: Randomized, crossover designed study: 10 mL/kg bolus of 6% HES (600/0.75) (hetastarch) (HS), 6% HES (130/0.4) tetrastarch (TS), and 0.9% NaCl (NS). Variables recorded included central venous pressure (CVP), noninvasive arterial blood pressure, packed cell volume (PCV), COP, and automated platelet analysis (CT). RESULTS: Central venous pressure was increased for 8 hours after all treatment (baseline = 8.4 &#xb1; 3.8; 8 hours = 10.3 &#xb1; 3.5 cm H2 O; P < .001). HS and TS produced an increase in systolic arterial pressure (HS = 109.1 &#xb1; 11.9; TS = 109.5 &#xb1; 10.9 mmHg) and mean arterial pressure (HS = 80.4 &#xb1; 13.0; TS = 82.3 &#xb1; 10.1 mmHg) compared to NS (SAP = 103.2 &#xb1; 13.2 [P = .023]; MAP = 74.2 &#xb1; 11.4 mmHg [P = .048]). PCV decreased transiently with HS (baseline = 37.1 &#xb1; 4.4%; 1.5 hours = 31.6 &#xb1; 3.9%) and TS (baseline = 38.4 &#xb1; 3.9%; 1.5 hours = 32.2 &#xb1; 3.3%), but not NS (P = .007). COP was greater with HS (1 hour; 24.0 &#xb1; 2.1 mmHg) and TS (8 hours; 25.9 &#xb1; 2.1 mmHg) than NS (1 hour = 20.8 &#xb1; 2.6; 8 hours = 22.9 &#xb1; 3.1 mmHg; P < .001). CT was greater at 8 (HS = 178.6 &#xb1; 36.9; TS = 121.9 &#xb1; 33.3; NS = 108.3 &#xb1; 23.6 seconds) and 24 hours (HS = 174.2 &#xb1; 41.7; TS = 100.8 &#xb1; 26.0; NS = 118.7 &#xb1; 38.7 seconds; P < .001) in horses receiving HS than TS or NS. CONCLUSION AND CLINICAL IMPORTANCE: Both TS and HS resulted in more effective volume expansion and arterial pressure support than NS. TS produced a more sustained effect on COP with shorter duration of adverse effects on platelet function than HS.