Objective: The aim of the article is to suggest a practical approach to the cardiac output (CO) measurement with combined use of echocardiography and thermodilution in patients with various valve disorders. Design: Prospective observational study. Setting: 20-bed general intensive care unit in the university hospital. Material and Methods: 27 mechanically ventilated patients with no significant aortic valve disease were included. Patients were measured twice using simultaneously transesophageal echocardiography (TEE) and pulmonary artery catheter (PAC) for CO. Results: Continuous doppler measurements were taken in the left ventricular outflow tract (LVOT) at the level of the aortic valve.CO was calculated bymultiplying velocity-time integral (VTI) with aortic valve area (AVA) and heart rate. Simultaneous PAC measurements were taken averaging the results of the three 10 cc boluses of iced saline. The difference between the methods expressed as mean ± 2 SD was 0.5 ± 1.1 l/min in the first group of patients (N = 8) with no or the 1st degree tricuspid regurgitration (TR), r = 0.96. A mean difference of 0.8 ± 2.0 l/min was found in the second group (N = 9) with the 2nd degree TR, r = 0.92. The difference was 1.9 ± 2.3 l/min in the third group (N = 10) with the 3rd degree TR, r = 0.69. Only in the third group the statistic bias was different from zero (T = 6.83, P < 0.0001). Conclusions: The presence of significant aortic valve disease on echocardiographic investigation impairs validity of CO measurement in LVOT. In those cases thermodilution may become the method of choice. On the other hand a high degree of TR is associated with an underestimation of CO measurement by thermodilution. Echocardiography is more accurate modality for CO assessment in those patients.

        Key words: tricuspid regurgitation – cardiac output – echocardiography – doppler-ultrasonography – pulmonary artery catheter – thermodilution