Fluid treatment effects on tissue oxygen in dogs with hemorrhagic

Abstract

BACKGROUND: Enhancing plasma viscosity during fluid resuscitation results in vasodilation and improved microvascular perfusion in rodents subjected to hemorrhagic shock. We hypothesized that resuscitation with hyperviscous lactated Ringer's solution (hyperLRS) would result in improved tissue oxygenation and acid-base values in hemorrhaged dogs. METHODS: Twelve dogs were anesthetized and splenectomized. Vascular catheterization was performed, and tissue oxygen probes were placed in the jejunal serosa and skeletal muscle to assess macro- and microhemodynamic parameters. Baseline (BL) and posthemorrhage data were obtained. After 1 hour of hemorrhagic shock (mean arterial pressure [MAP] 30-40 mm Hg), treatment groups (n = 6) were administered bolus LRS or hyperLRS, and then received sufficient LRS to achieve and maintain an MAP between 60 mm Hg and 70 mm Hg. Data were obtained at 10, 30, 60, 120, and 180 minutes after fluid resuscitation. RESULTS: There were no significant differences between LRS or hyperLRS groups at BL or posthemorrhage. Blood and plasma viscosity were significantly increased by the administration of hyperLRS at all time points postresuscitation compared with LRS. Significantly more fluid was required to maintain MAP, and vascular hindrance was consistently lower in dogs administered hyperLRS versus LRS, suggesting viscosity-induced vasodilation. Central and mesenteric venous oxygen saturations were significantly decreased, whereas lactate and oxygen extraction ratios were significantly increased after hyperLRS administration compared with LRS. The tissue oxygen tension was similar in dogs administered hyperLRS or LRS. CONCLUSIONS: A hyperviscous balanced electrolyte solution did not improve hemodynamic parameters, tissue oxygen tension, or acid-base values despite evidence for viscosity-induced vasodilation.