Lens model analysis of hemodynamic status in the critically ill.

The lens model recently has been extended to consider multiple outcomes and sequential use of clinical information. The authors have used this extended model 1) to describe the relationship between clinical information and physicians' assessments of hemodynamic status, 2) to describe the empirical relationship between clinical information and physiologic measures of hemodynamic status, and 3) to compare physicians' use of information with its empirical utility. Physicians prospectively provided estimates of cardiac index and pulmonary capillary wedge pressure for 440 intensive care unit patients prior to right heart catheterization. The correlation between physicians' estimates and measured hemodynamic status was lower than that between clinical information and hemodynamic status (0.42 versus 0.67). Only 7% of physicians' judgement was related to subsequent ancillary testing. Empirically, subsequent ancillary testing contributed 30% to the explanation of hemodynamic status. The lens model describes limitations of physician judgement in estimating left ventricular function and helps explain how patient features relate to measured hemodynamic status.