Objective: To compare the effects of high and low doses of 6% hydroxyethyl starch solution (HES) on resuscitation for shock induced by ischemia/reperfusion injury of the intestine in rabbits.
Methods: Thirty-two anesthetized rabbits were randomized into four groups of eight animals each. The animals in the control group received no fluid resuscitation, animals in group 2 received lactated Ringer's solution (LRS, 20 ml x kg(-1) x h(-1)), those in group 3 received LRS+HES (LRS 18 ml x kg(-1) x h(1)+HES 2 ml x kg(-1) x h(-1), low dosage of HES), and those in group 4 received HES only in high dosage of HES (20 ml x kg(-1) x h(-1)). All these rabbits underwent intestinal ischemia/reperfusion injury developed by occluding superior mesenteric artery (SMA) with a non-crushing vascular clamp for 60 minutes and then the clamp was loosened for 240 minutes. The fluid resuscitation began at the same time of reperfusion. Hemodynamic parameters including mean artery pressure, heart rate, aortic velocity (as cardiac output), and SMA blood flow were measured. Tissue oxygenation was assessed indirectly by measuring the tonometric parameters of the gut, including difference between partial pressure of carbon dioxide in intestinal intramucosal and partial pressure of carbon dioxide in arterial blood (Pt-aCO(2) gap), intestinal intramucosal pH (pHi), arterial blood lactate acid concentration and oxygen delivery. Mortality of the rabbits was counted at the end of the experiment.
Results: Hemodynamic parameters as measured in low and high doses of HES groups were significantly higher in values than LRS group (LRS) and control (all P<0.05). Low dose of HES was better in restoring hemodynamic parameters than high dose of HES (all P<0.05). Low dose of HES could greatly decrease lactate and Pt-aCO(2) gap, significantly improve pHi compared with other three groups (all P<0.05), but high dose of HES did not do so, and oral and nasal bleeding even death of some animals were seen. Low dose and high dose of HES significantly improved oxygen delivery while LRS did not (all P<0.05).
Conclusion: Low dose of HES together with LRS is more effective than only high dose of HES or LRS in the resuscitation for shock induced by ischemia/reperfusion injury of the intestine in rabbits, resulting in better hemodynamic parameters and tissue oxygenation.