Hemodynamic assessment in managing the critically ill: is physician confidence warranted?

Prior to right-heart catheterization of 846 patients, 198 study physicians estimated values of pulmonary capillary wedge pressure (WP), cardiac index (Cl), and systemic vascular resistance index (VRI). The physicians also expressed their confidence in these estimates. Actual values of WP, Cl, and VRI as determined by catheterization enabled the authors to evaluate the quality of the physicians' judgments. The discrimination of the judgments was modest; areas under the ROC curves for WP, Cl, and VRI were 0.724, 0.681, and 0.656, respectively. Calculated using clinically relevant cutoff values, sensitivities were 64%, 50%, and 64%, and specificities were 71%, 75%, and 63%, respectively. Calibration of the estimates of WP, Cl, and VRI was also modest; physicians tended to overestimate low values and underestimate high values. Physicians were generally confident of their estimates, but there was no relation between confidence and accuracy. Experienced physicians were no more accurate than less experienced ones, although they were significantly more confident. The authors conclude that physicians should not use their levels of confidence in their subjective estimates of cardiac function in deciding whether to base therapy on these estimates.