Objective:To study the correlation between the methods of partial CO2 rebreathing(RB)technique and thermodilution(TD)technique for cardiac output in order to provide the evidence of clinical application.Methods:Six healthy anesthetized and ventilated dog were enrolled in this study.Each animal was inserted with Swan-Ganz catheter

and was installed a partial CO2 rebreathing ventilator circuit(Novametrix Medical Systems Inc

NICO).Simultaneous measurement of CORB and COTD were performed:before and after cardiac output was varied by manipulating inotropic drugs(adrenine

dobutamine

verapamil);Paired t-test and regression statistics were used to compare the degree of agreement between concurrent measurement of TDco and RBco.Results:Paired t-test analysis revealed no significant difference between RBco and TDco measurement at base line(P>0.05).Regression analysis revealed an R value of 0.89 and the regression equation was as follows:CORB=0.78COTD+0.25;After manipulating inotropic drugs there was also a good agreement between RBco and Tdco

the correlation coefficient was 0.81

while the regression equation was CORB=0.91COTD+0.61.Conclusion:There is a high correlation between RBco and TDco measurement.Partial CO2 rebreathing measurement provids a new noninvasive circulation monitoring method for critical patients.