Inaccuracy of cardiac output by thermodilution during acute tricuspid regurgitation.

We have been comparing cardiac output measured with a novel Doppler pulmonary artery catheter to that measured by thermodilution and aortic electromagnetometry in cardiac surgical patients. We report here our observation of a nearly twofold increase in thermodilution cardiac output after the acute intraoperative onset of tricuspid regurgitation that was not confirmed by the novel catheter or direct measurement of aortic blood flow. We conclude that in some patients, acute tricuspid regurgitation may lessen the reliability of thermodilution cardiac output.