Comparison of cardiac output measured with echocardiographic volumes and aortic Doppler methods during mechanical ventilation

Objective: To compare two transesophageal echocardiographic methods of cardiac output and stroke volume measurement in mechanically ventilated patients. Design: Prospective clinical study. Setting: Operating room (group 1) and intensive care unit (group 11) in two university hospitals. Patients: Fifteen deeply anesthetized patients undergoing gynecological laparoscopy for sterility (group 1) and 40 patients with septic shock (group 11). Interventions: Transesophageal echocardiography with modification of hemodynamic conditions. Measurements and results: Left ventricular (LV) volumes, cardiac (CI) and stroke index (SI) were measured with two methods using either LV volumes or aortic Doppler. These values were significantly lower in group I compared to group II. Using ANOVA and paired t-tests, there were no significant differences between the two methods of measurement. Correlation between these methods was better in group II than in group 1, although not significantly so. In group I, bias for Cl measurements was low (0.05 l/min per m(2)), with a weak agreement in terms of the 95% confidence interval (-1.17; 1.06 l/min per m(2)) compared to the mean values obtained with both methods (1.3 l/min per m(2)). In group II, bias for Cl measurements was lower (0.2 l/min per m(2)). Agreement was weak, regarding 95% confidence intervals (-1.7; 1.3 l/min per m(2)) compared to the mean values (3 l/min per m(2) with the LV volumes method and 3.2 l/min per m(2) and with the Doppler method). Conclusions: Cardiac output and stroke volume can be measured from LV volumes in mechanically ventilated patients, yielding relevant information. However, the accuracy of LV volume measurements is not excellent compared to the aortic Doppler method. Thus, this latter technique should still be considered as the gold standard. Electronic Supplementary Material: Supplementary Material is available for this article if you access the article at http://dx.doi.org/l0.1007/ s00134-002-1582-1. A link in the frame on the left on that page takes you directly to the supplementary material.