Background: Normal saline (NS) and lactated Ringer's solution (LR) continue to be used interchangeably for the resuscitation of hemorrhagic shock in some institutions. We hypothesized that, aside from hyperchloremic acidosis, NS resuscitation would be similar to that of LR in a swine model of uncontrolled hemorrhage.
Methods: Twenty swine weighing a mean of 37 kg underwent invasive line placement, midline celiotomy, and splenectomy. After a 15-minute stabilization period, we recorded a baseline mean arterial pressure (MAP) and created a grade V liver injury. The animals bled freely for 30 minutes after which we measured blood loss. We blindly randomized the swine to receive NS (10 animals) versus LR (10 animals) to achieve and maintain the baseline MAP for 90 minutes postinjury. Laboratory values were obtained at baseline and upon completion of the 2-hour study period.
Results: Initial blood loss was 25 mL/kg in the NS group and 22 mL/kg in the LR group (p = 0.54). Animals required 256.3 +/- 145.4 mL/kg of fluid in the NS group as compared with 125.7 +/- 67.3 mL/kg in the LR group (p = 0.04). The urine output was higher in the NS group (46.6 +/- 39.5 mL/kg versus 18.9 +/- 12.9 mL/kg, p = 0.04). Upon study completion, the NS group had a significant hyperchloremia (119 +/- 1.9 mEq/L versus 105 +/- 2.9 mEq/L, p < 0.01) with acidosis (7.28 +/- 0.12 versus 7.45 +/- 0.06, p < 0.01) in comparison to the LR group. In addition, resuscitation with NS resulted in significantly lower fibrinogen levels (99 +/- 21 mg/dL versus 123 +/- 20 mg/dL, p = 0.02). The serum lactate was 4.7 +/- 2.2 in the LR group and 1.7 +/- 1.7 in the NS swine (p < 0.01) at the end of the study.
Conclusions: Resuscitation of uncontrolled hemorrhagic shock with NS requires significantly greater volume and is associated with greater urine output, hyperchloremic acidosis, and dilutional coagulopathy as compared with LR. Resuscitation with LR results in an elevation of the lactate level that is not associated with acidosis. Lactated Ringer's solution is superior to NS for the resuscitation of uncontrolled hemorrhagic shock in swine.