Experimental volume replacement through lower extremity veins

Hypovolemic shock was produced in anesthetized pigs by removal of 40% of blood volume over 10 minutes. Following blood loss, the inferior vena cava (IVC) was occluded below the renal veins to simulate the hemodynamics of emergency surgical treatment. Control animals were not treated. Experimental animals received intravenous lactated Ringer's solution equal to three times the blood loss given through catheters either in the IVC or the superior vena cava (SVC) to determine if lower extremity access would be efficacious in this model. To define the path taken by the resuscitation fluids, an additional group of animals received technetium-99m-labelled crystalloid through lower extremity catheters with continuous recording of isotope counts in the IVC and right atrium. The treated animals in all experimental groups had significant improvements in mean arterial pressure, cardiac output, and pH compared with controls. There was no significant difference in hemodynamic response in animals receiving volume replacement through the IVC compared with the SVC. When fluid was infused below a clamped IVC, the arrival of isotope in the right atrium was delayed only 1.5 seconds. We conclude that in a model simulating emergency control of potentially lethal hemorrhage, the beneficial effects of fluid resuscitation are unrelated to the site of venous access. Lower extremity veins provide a valuable site for volume replacement even with IVC occlusion. These findings should have direct application to resuscitation and surgical care of seriously injured patients.