Effect of different degrees of acute normovolemic hemodilution on mucous membrane of small intestine in rabbits

Abstract

Objective To investigate the effect of different degrees of acute normovolemic hemodilution (ANH) with 6% HES 200/0.5 on mucous membrane of small intestine in rabbits. Methods Thirty-two adult rabbits weighing 2.0-2.5 kg were randomly divided into 4 groups ( n = 8 each): Ⅰ control group underwent no ANH, and Ⅱ, Ⅲ, Ⅳ group underwent ANH with hematocrit (Hct) reduced to 24%, 18% and 12% respectively (group H1-3 ). The animals were anesthetized with 20% urethane 4 ml/kg, thracheostomized and mechanically ventilated (VT = 8 ml/kg, RR = 50 bpm). The body temperature was maintained at 36.5-37.6 ℃. Left carotid artery was cannulated for MAP monitoring and blood sampling. Right jugular vein was cannulated for CVP monitoring. Blood withdrawn from femoral artery was simultaneously replaced by iv infusion of equal volume of HES (200/0.5) until the target Hct was achieved. Blood samples were obtained from superior mesenteric vein (SMV)for determination of plasma concentrations of TNF-α before ANH(T0) and at 8 h after ANH (T1). Small intestinal mucosal tissues were obtained at T1 to observe the pathological changes by electron microscopy. Results Compared with those at T0, plasma concentrations of TNF-a in SMV were significantly increased at T1 in group H2 and H3 ( P ＜ 0.01 ), but no significant change was found in group H1 ( P ＞ 0.05). Compared with group C, plasma concentrations of TNF-α in SMV were significantly increased in group H2 and H3 ( P ＜ 0.01 ), but no significant change was found in group H1 ( P ＞ 0.05). No injury was found in mucous membrane of small intestine in group H1 . The injury to mucous membrane of small intestine was mild in group H2 and severe in group H3 . Conclusion ANH with 6% HES 200/0.5 does not affect mucous membrane of small intestine when Hct is reduced to 24% The injury to mucous membrane of small intestine occurs when Hct is reduced to≤ 18%. Key words: Hemodilution; Intestinal mucosa