Hemodynamic and metabolic effects of resuscitation in an uncontrolled hemorrhage model of severe rat liver injury

Abstract

Purpose: The benefits of fluid resuscitation have become controversial for noncompressible uncontrolled hemorrhage. The effect of delayed access to definitive care is an additional confounding variable. Rural and military environments often entail delayed access to surgical care, and current recommendations are for ongoing fluid resuscitation to a normal blood pressure during transport. This approach has been proposed to increase survival time, at the expense of increased blood loss. This study was designed to evaluate the hemodynamic and metabolic response to resuscitation in a rat model of severe liver injury and uncontrolled hemorrhage over 4 hours. MethodsAll animals (N = 21, 275 ± 15 g), underwent a reproducible excision of the median hepatic lobe. The animals received either no resuscitation (NR) or 40°C lactated Ringer’s solution at 1 ml/min, starting at 2.5 minutes after the injury (LR). The end point of resuscitation was a return to the immediate preinjury mean arterial pressure (MAP). Total blood loss, MAP, survival time, fluid volume infused, serum lactate, arterial blood gasses, intra-abdominal pressure, and hematocrit were measured preinjury and at 4 hours or death. ResultsBlood loss was greater (p < 0.01) in the LR group (37.8 ± 13.5 ml/kg) than in the NR group (15.9 ± 5.9). Final Pao2 was lower (p < 0.01) in the LR group (55.0 ± 21.5 mm Hg) than in the NR group (92.2 ± 17). No differences were noted between groups in the amount of hepatic median lobe excised (60% ± 7%), overall survival time (86.3 ± 66.0 min), MAP nadir (35.2 ± 0.7 mm Hg at 1.9 ± 0.7 min postinjury), final pH (7.04 ± 0.14), final base excess (−16.5 ± 4.5 mmol/l), final intra-abdominal pressure (2.2 ± 1.4 mm Hg), and final serum lactate (6.8 ± 4.0 mmol/l). ConclusionsIn this model of uncontrolled hemorrhage from a solid organ, fluid resuscitation provided no survival or metabolic advantage, serving only to increase blood loss and decrease Pao2. Vigorous resuscitation may not provide benefit when significant injury and prolonged transport times are combined.