Abstract:Objective To evaluate the effects of modified uhrafihration （MUF）on blood rheology in infants after open cardiac surgery. Methods According to admission number, 22 infants of body weight less than 10 kilograms with ventricular septal defect （VSD） and pulmonary hypertension （PH） were divided into control group （10 infants, the mantissa of their admission number was odd number） and experimental group （12 infants, the mantissa of their admission number was even number）. Cases in control group didn＇t undergo MUF at the end of cardiopulmonary bypass （CPB）, while cases in experimental group underwent MUF; the flow rate of MUF ranged from 10 ml/min · kg to 15 ml/min · kg. MUF lasting for 10-15 minutes. Blood samples were repeatedly collected as following time： before operation, at the end of CPB, 15 minutes after CPB or the end of MUF, 2, 24 h after operation. Blood sample of 2. 5 ml was collected from the radial artery with hepathrom test-tube. The changes of relative indexes of the blood rheology were observed by MDK-3200 completely automatic dual pathways blood rheology testing analysator at 37±1 C. Results Hemoglobin, hematocrit, red cell count, blood yielding stress, plasma viscosity, the whole blood viscosity at high shear rate, the whole blood viscosity at middle shear rate and low shear rate, the whole blood reduction viscosity at high shear rate and middle shear rate, the whole blood reduction viscosity at low shear rate and Casson viscosity in experimental group at the end of MUF were significantly higher than those in control group at 15 minutes after CPB （P〈0. 05）. There was no significant difference in red cell aggregation index and red cell deformity between two groups at each moment （P 〉 0.05 ）. Conclusion Hemoglobin, hematocrit and red cell count are significantly elevated through MUF after CPB. Whole blood viscosity in infants undergone open cardiac surgery after CPB with MUF is higher than those who didn＇t undergo MUF.