Comparison of the effects of bolus vs. slow infusion of 7.5% NaCl/6% dextran-70 in a model of near-lethal uncontrolled hemorrhage

Bolus infusion of of 7.5% NaCl/6% dextran-70 (HSD-B) improves outcome from controlled hemorrhage. In contrast, HSD-B during uncontrolled hemorrhage in creases bleeding and short-term mortality. The purpose of this study was to compare the effects of bolus vs. slow infusion of HSD in a near-fatal vasc ular injury hemorrhage model. Sixteen (15-20 kg) swine with 4-mm aortic tea rs were hemorrhaged to a pulse pressure of 5 mmHg. An ultrasonic flow probe was placed proximal to the aortic tear for continuous blood flow (AF) meas urements. Group I (slow infusion; n = 8) was resuscitated with 8 mL/kg of H SD at 0.4 mL/kg/min. Group II (bolus infusion; n = 8) was resuscitated with 8 mL/kg of HSD at 1.33 mL/kg/min. In both groups, HSD infusion was followe d by administration of 30 mL/kg of shed blood at 3 mL/kg/min. Hemorrhage vo lume and 90-min mortality were greater in group II (79 +/- 11 mL/kg; 75%) c ompared with group I (43 +/- 9 mL/kg; 12.5%) (P-Hem < 0.001; P-Mort = 0.04) . Mean arterial pressure (MAP) and AF were greater in group II compared wit h group I during the first 15 min of resuscitation. In group I, MAP, AF, ca rdiac indices, and O-2 delivery gradually returned to baseline levels and w ere significantly greater than group II at 30 min and throughout the remain der of the protocol. In this model of near-lethal uncontrolled hemorrhage, slow infusion of HSD restored cardiodynamics while minimizing hemorrhage vo lume and mortality. Resuscitation regimens that cause early increases in bl ood flow and pressure may result in greater hemorrhage and mortality than t hose regimens that yield comparable flow and pressure increases late in res uscitation.