A Comparison between Low and High-dose of Hydroxyethylstarch Solution in Resuscitation for Shock induced by Ischemia/Reperfusion in Rabbits

The purpose of the study was to compare the effects of high and low dose of 6% hydroxyethyl starch solution (HES) on resuscitation for shock induced by intestinal ischemia/reperfusion (I/R) injury in rabbits. Thirty-two anesthetized rabbits were randomized into four groups of eight animals each, which was either treated with no fluid resuscitation as control, lactated Ringer's solution (LRS, 20ml/kg/h), LRS+HES (LRS 18ml/kg/h + HES 2ml/kg/h, low dose of HES) or only treated with HES (high dose of HES, 20ml/kg/h). These rabbits underwent the intestinal I/R injury developed by occluding superior mesenteric artery (SMA) with a noncrushing vascular clamp for 60min and then loosing the clamp for 240min. The fluid resuscitation began at the same time of reperfusion. Hemodynamic parameters including MAP, HR, aortic velocity (Qaorta, as CO) and SMA blood flow (Osma) were measured. Tissue oxygenation was assessed indirectly by measuring the tonometric parameters of gut, including difference between intestinal intramucosal PtCO2 and arterial PaCO2 (PCO2-gap), intestinal intramucosal pH (pHi), arterial lactate acid concentration and oxygen delivery (DO2). Mortality of the rabbits was calculated at the end. The results showed that hemodynamic parameters were significantly higher in group LRS+HES and HES than in group LRS and control (P<0.05). Low dose of HES was better than high dose of HES in restoring hemodynamic parameters (P<0.05). Low dose of HES could greatly decrease lactate and PCO2-gap, significantly improve pHi than other three groups (P<0.05), but high dose of HES did not do so, rather, which induced oral and nasal bleeding, even death of some animals. Low dose and high dose of HES significantly improved DO2 while LRS did not (P<0.05). Therefore low dose of HSE together with LRS was more effective than only high dose of HES or LRS in the resuscitation for shock induced by intestinal I/R injury in rabbits, because hemodynamic parameters increased suitably and tissue oxygenation was greatly improved.