The value of Doppler echocardiography in cardiac output detection

In the present study simultaneous measurements of cardiac output by thermodilution method and Doppler echocardiography were obtained 105 times in five persons with congestive cardiomyopathy. A significant degree of correlation (r = 0.79) was verified between the values of cardiac output measured by the two methods. To estimate the accuracy of echocardiography for consecutive measurements of cardiac output, all of the patients were given a positive inotropic drug: 5 mg milrinone per os. After that the cardiac output was measured, first by thermodilution and immediately after that by the Doppler method, in successive time periods: 15 minutes after the drug, then 30, 45, 60 and 90 minutes later, and then 2, 3, 4 and 5 hours after the drug. The same procedure was repeated with all subjects after application of 10 mg milrinone per os. By statistical analysis of differences between the cardiac output measured by both methods, a low connection was found (r = 0.43). In addition, when the increase of cardiac output was registered, the Doppler method showed a decrease of cardiac output, both methods had similar directional changes, but the numeric data was not correct. This performed study demonstrated that the measurement of cardiac output by thermodilution and continuous Doppler echocardiography had good correlation. However, Doppler echocardiography cannot replace classic invasive methods in consecutive measurements and monitoring of cardiac output in seriously ill cardiac patients.