Surgery
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We tested the hypothesis that, after aortotomy, rapidly replacing three times the blood volume deficit with intravenous crystalloid will increase hemorrhage and decrease survival. Sixteen anesthetized Yorkshire swine underwent splenectomy and stainless steel wire placement in the infrarenal aorta and were instrumented with pulmonary artery and carotid artery catheters. ⋯ The volume of hemorrhage and the mortality rate were significantly increased (p less than 0.05) in the treatment group receiving lactated Ringer's solution relative to the control animals (2142 +/- 178 ml versus 783 +/- 85 ml, and eight of eight animals versus zero of eight animals, respectively). From these data we conclude that, in this model of uncontrolled arterial hemorrhage resulting from abdominal aortotomy, rapidly administering lactated Ringer's solution intravenously significantly increases hemorrhage and death.
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We addressed the impact on intracranial pressure (ICP) of posthemorrhage fluid resuscitation with a protocol in which additional fluid was infused to maintain a stable cardiac output after an initial bolus of fluid was infused. Anesthetized, mechanically ventilated mongrel dogs (n = 27) underwent a 30-minute interval of hemorrhagic shock (mean arterial pressure = 55 mm Hg) during which inflation of a subdural balloon maintained ICP at 15 mm Hg. After shock, animals were resuscitated with one of four randomly assigned fluids: (1) slightly hypotonic crystalloid (Na+, 125 mEq. ⋯ Cerebral blood flow, measured by the cerebral venous outflow method, increased immediately after resuscitation and then declined steadily over time in all groups. Fluids containing pentastarch maintained hemodynamic stability with minimal supplementation throughout most of the postresuscitation period, compared with crystalloid alone, which required substantial additional volume. If decreased intracranial compliance and hemorrhage are combined, ongoing resuscitation is associated with significantly increased ICP and significantly decreased cerebral blood flow, independent of the tonicity and oncotic pressure of the infused fluid.