16 Apr 09
Crystalloids versus colloids for goal-directed fluid therapy in major surgery
By L B Hiltebrand, O Kimberger, M Arnberger, S Brandt, A Kurz and G H Sigrudsson
Perioperative hypovolemia arises frequently and contributes to intestinal hypoperfusion and subsequent postoperative complications. Goal-directed fluid therapy (GDT) might reduce these complications. The aim of this study was to compare the effects of goal-directed administration of crystalloids and colloids on distribution of systemic, hepato-splanchnic and microcirculatory (small intestine) blood flow after major abdominal surgery in a clinically relevant pig model.
Methods
Twenty-seven pigs were anesthetized, mechanically ventilated and underwent open laparotomy. They were randomly assigned to one of the three following treatment groups: the restricted Ringer’s lactate group (R-RL, n=9) received 3 ml.kg-1.h-1 RL; the goal-directed RL group (GD-RL, n=9) received 3 ml.kg-1.h-1 RL and intermittent boluses of 250 ml RL and the goal-directed colloid group (GD-C, n=9) received 3 ml.kg-1.h-1 RL and boluses of 250 ml 6% hydroxyethyl starch (130/0.4). The two latter groups received a bolus infusion when mixed venous oxygen saturation (SvO2) was below 60% (lock out time 30 minutes). Regional blood flow was measured in the superior mesenteric artery and the celiac trunk. In the small bowel, microcirculatory blood flow was measured using laser Doppler flowmetry. Intestinal tissue oxygen tension was measured with intramural Clark-type electrodes.
Results
After 4 hours of treatment, arterial blood pressure, cardiac output, mesenteric artery flow and mixed oxygen saturation were significantly higher in groups GD-C and GD-RL than in group R-RL. Microcirculatory flow in the intestinal mucosa increased by 50% in GD-C but remained unchanged in the other two groups. Likewise, tissue oxygen tension in the intestine increased by 30% in GD-C but remained unchanged in GD-RL and decreased by 18% in the R-RL group. Mesenteric venous glucose concentrations were higher and lactate levels lower in group GD-C compared with the two crystalloid groups.
Conclusions
Goal-directed colloid administration markedly increased microcirculatory blood flow in the small intestine and intestinal tissue oxygen tension after abdominal surgery. In contrast, goal-directed crystalloid and restricted crystalloid administrations had no such effects. Additionally, mesenteric venous glucose and lactate concentrations suggest that intestinal cellular substrate levels were higher in the colloid-treated than in the crystalloid-treated animals. These results support the notion that perioperative goal-directed therapy with colloids might be beneficial during major abdominal surgery.