Unfortunately, the usefulness of BNP in this setting is not yet defined. While using BNP testing in the ICU, physicians must be aware of the low specificity for CHF, meaning left heart failure, in this setting. On the other hand, a given BNP level does not sufficiently reflect LVEF and cannot replace invasive monitoring in patients with sepsis. Thus, a thorough echocardiographic evaluation is preferable to BNP testing. A previous hypothesis that in patients with sepsis elevated BNP levels will identify the subgroup with acute ventricular dilatation and decreases in both LVEF and right ventricular ejection fraction, and thus a beneficial prognosis in contrast to those whose ventricles do not increase in size and preserve their function, cannot be confirmed by the available data. Here
Nevertheless, further studies are required to elucidate the full potential of both cardiac troponins and natriuretic peptides, especially NT-proBNP, to characterize the severity of disease and to prospectively assess the need for certain therapies in patients with severe sepsis and septic shock. The high prognostic impact of an early aggressive therapy including fluid resuscitation, transfusion of packed RBCs, and dobutamine in an attempt to achieve a central venous saturation of > 70% has been proven, whereas many other interventions have failed to improve prognosis in patients with sepsis.
It remains to be shown whether either cardiac troponins or natriuretic peptides will be able to identify patients who derive the highest benefit from aggressive therapy, and whether an approach combining the information coming from both of these biomarkers might be useful. Until now, the routine use of natriuretic peptides in patients with sepsis should be discouraged. However, we recommend the use of cardiac troponins as a part of the monitoring of patients with severe sepsis and septic shock with respect to predicting prognosis and impaired systolic left ventricular function. In contrast, in an analysis of 57 patients with severe sepsis, the N-terminal part of the prohormone, N-terminal-pro-ANP (NT-proANP), was not predictive of survival. However, it has been proposed that NT-proANP undergoes further fragmentation, and that immunoassays for NT-proANP might underestimate the true levels of NT-proANP secreted into the circulation.