RESUMO
To find the crystalloid and colloid mixture solution in proper ratio for acute hemodilution.Method:Fourty major surgical adult patients undergoing acute hemodilution were randomly divided into five groups (n=8). The average amounts of blood withdrawn were 20％-30％ of total blood volume. The general anesthesia was maitained,the blood was drawn through left radial artery, and in the meanwhile at the same volume one of the designed diluents was infused intravenously: Single crystalloid or colloid solution,mixture of crystalloid and colloid solution in proportion of 1:1:1:2 and 1:3. Result:Hemodynamics,ECG,SpO_2 P_EtCO_2 remained stable; Hb,Hct,PLC,Fg and blood viscosity decreased significantly following hemodilution in all groups. COP decreased significantly in single crystalloid, 1:1 and 1:2 groups, and remained unchanged in 1:3 and single colloid groups. Conclusion:The crystalloid and colliod mixture at ratio of 1:3 can be more safely applied to acute hemodilution.