Estimation of left ventricular filling pressure and cardiac index is important in the management of patients requiring right heart catheterization. Doppler echocardiography can provide a noninvasive measure of these parameters, but its accuracy in individual measurements, predicting hemodynamic subgroups, and in tracking serial changes in critically ill patients remains to be elucidated. Left ventricular filling pressure and cardiac index were assessed in 49 critically ill patients requiring right heart catheterization and Doppler echocardiographic studies. Two or more serial studies were performed in 18 of these subjects. Patients were placed into 1 of 4 hemodynamic subgroups for each technique based on the acquired hemodynamic parameters. Left ventricular filling pressure and cardiac index by Doppler echocardiography and right heart catheterization were similar (21 +/- 8 vs 20 +/- 8 mm Hg; 3.0 +/- 1.2 vs 2.9 +/- 1.2 L/min/m2, respectively) and correlated well with each other (left ventricular filling pressure, r = 0.88; cardiac index, r = 0.92). The Doppler technique accurately placed 73 of 76 studies into the correct hemodynamic subgroup. The noninvasive technique also reliably tracked serial hemodynamic measurements. We conclude that Doppler echocardiography accurately assesses left heart hemodynamics in critically ill patients. Since this technique can be readily acquired, it can be ideal for the rapid assessment of hemodynamic parameters in critically ill patients, especially when right heart catheterization is delayed or is problematic.