Two different hypertonic (2400 mOsm/L) isochloremic dextran solutions (sodium acetate, HAD; and sodium lactate, HLD; in 0.9% NaCl + 6% dextran 70) were compared with HSD (2400 mOsm/L NaCl + 6% dextran 70) as initial treatment for severe uninterrupted arterial bleeding. The substitution of dextran 70 for lactated Ringer's solution as the maintenance isotonic infusion fluid was also analyzed. Experiments were performed in pentobarbital-anesthetized dogs. A recently developed model, pressure-driven hemorrhage (PDH), which mimics uninterrupted arterial bleeding, was employed. It was found that (1) the substitution of dextran 70 for lactated Ringer's as isotonic fluid makes no difference in hemodynamic terms; (2) isochloremic hypertonic solutions are similar in their hemodynamic resuscitative effect, representing an improvement over hypertonic NaCl in terms of cardiac output, O2delivery and O2consumption; (3) HAD proved superior to HLD in terms of O2consumption and correction of pH/base excess.