RESUSCITATION AFTER UNCONTROLLED VENOUS HEMORRHAGE - DOES INCREASED RESUSCITATION VOLUME IMPROVE REGIONAL PERFUSION

Background: Recent studies have questioned the use of aggressive fluid resuscitation after uncontrolled arterial hemorrhage until the bleedi ng is controlled. However, it remains unknown whether resuscitation af ter hemorrhage from a venous origin (usually nonaccessible to surgical intervention) has any beneficial or deleterious effects on regional p erfusion. The aim of this study, therefore, was to determine whether i ncreased volume of fluid resuscitation after uncontrolled venous hemor rhage improves hemodynamic profile and regional perfusion in various t issues. Materials and Methods: After methoxyflurane anesthesia and mid line laparotomy, both lumbar veins in the rat were severed, which resu lted in lowering the mean arterial blood pressure to approximately 40 mm Hg. This pressure was maintained for 45 minutes by allowing further bleeding from the lumbar veins. The: abdominal incision was then clos ed in layers and the animals received either 0, 10, or 30 mL of lactat ed Ringer's solution intravenously over a period of 60 minutes. Cardia c output and regional blood flow were determined by radioactive micros pheres immediately or at 1.5 hours after the completion of resuscitati on, Results: Fluid resuscitation with 10 or 30 mL lactated Ringer's so lution increased mean arterial blood pressure and cardiac output immed iately after resuscitation compared with the nonresuscitated animals. At both time points, regional perfusion in the heart, kidney and intes tines remained significantly decreased compared with the sham values, irrespective of the volume of fluid resuscitation, Moreover, no furthe r improvements in hemodynamics or regional perfusion occurred when vol ume resuscitation was increased from 10 mL to 30 mL. Total hepatic blo od flow, however, increased with 10 mL lactated Ringer's solution comp ared with the other hemorrhage groups and the increase was evident eve n at 1.5 hours after resuscitation. Conclusions: Fluid resuscitation a fter uncontrolled venous bleeding transiently increased cardiac output and mean arterial blood pressure compared: with nonresuscitated anima ls. Moderate fluid administration, i.e., 10 mL, however, did increase total hepatic blood flow. In contrast, increasing the resuscitation vo lume to 30 mL did not improve hemodynamic parameters or regional perfu sion, Thus moderate instead of no resuscitation or larger volume of re suscitation is recommended in an uncontrolled model of venous hemorrha ge.