Prehospital fluid resuscitation of traumatic injury is limited by difficulty in delivering large volumes of fluid in the field and time delays associated with gaining vascular access. We addressed these limitations in 14 anesthetized swine by evaluating a highly efficient volume expander, a near-saturated salt-dextran solution (SSD) administered through a new device, which gains vascular access via intraosseous (IO) infusion into the sternal bone marrow. After a steady-state baseline was achieved, all animals were hemorrhaged to 45 mm Hg for one hour. Half of the hemorrhaged animals were infused intraosseously with either normal saline (NS) or SSD until cardiac output was restored to the baseline value. No further infusion was given and animals were monitored for 2 hours. Both regimens were able to restore cardiac output to the baseline value, but only 1.3 pM 0.1 mL/kg of SSD was required vs. 31.6 pM 6.3 mL/kg for NS. In addition, cardiac output was better sustained after 2 hours with SSD than with NS. No deleterious effects of IO infusion of SSD were observed. From the improvement in cardiovascular variables and the lack of significant sternal or pulmonary pathologic perturbations, these data suggest that IO infusion of SSD can effectively treat hypovolemia and may allow field treatment when logistic considerations make conventional resuscitation impractical.