Objective To evaluate the blood protective effect of ulinastatin through restraining fibrinoclase and protecting the function of platelet during open heart surgery performed with cardiopulmonary bypass ( CPB). 目的探讨乌司他丁(Ulinastatin)在体外循环心脏直视手术患者围体外循环(CPB)期通过抑制纤溶酶、保护血小板的功能达到血液保护的作用。