ObjectiveTo study the effect of graded crystalloid fluid resuscitation on central hemodynamics and outcome after intra-abdominal hemorrhage.MethodsTen minutes after a 5-mm long laceration was produced in the infrarenal aorta, 32 pigs were randomized to receive either no fluid or Ringer's solution in the proportion 1:1, 2:1, or 3:1 to the expected amount of blood lost per hour (26 mL kg sup -1) over 2 hours. The hemodynamics were studied using arterial and pulmonary artery catheters and four blood flow probes placed over major blood vessels.ResultsDuring the first 40 minutes after the injury, the respective blood flow rates in the distal aorta were 39% (no fluid), 41% (1:1), 56% (2:1), and 56% (3:1) of the baseline flow. Fluid resuscitation increased cardiac output but had no effect on arterial pressure, oxygen consumption, pH, or base excess. Rebleeding occurred only with the 2:1 and 3:1 fluid programs. Survival was highest with the 1:1 and 2:1 programs.ConclusionsCrystalloid fluid therapy improved the hemodynamic status but increased the risk of rebleeding. Therefore, a moderate fluid program offered the best chance of survival.