In contrast to the data obtained by Witthaut et al, Tung et al did not find a correlation between BNP level and cardiac index in 49 patients with different forms of shock who had a PAC in place. Interestingly, BNP level was also not correlated with PCWP, but a BNP level of < 350 pg/mL had a very high negative predictive value for the presence of cardiogenic shock. The two studies by McLean and associates revealed that among unselected patients in a mixed ICU (surgical/internal) the BNP level measured at ICU admission could identify those patients who had any cardiac abnormality, as assessed by transthoracic echocardiography, within 2 h after ICU admission. In both studies, patients with cardiac abnormalities had higher BNP levels than those without. However, the vast majority of patients in these two studies did not have sepsis, and thus the conclusions on the topic under discussion are limited. in detail
In a study that was restricted to patients with severe sepsis (n = 9) or septic shock (n = 25), BNP levels were markedly higher in patients with impaired systolic left ventricular function than in those with preserved systolic left ventricular function at days 1 to 4 during their ICU stay. In addition, at days 2 and 3 BNP levels were higher in nonsurvivors compared to survivors. A BNP cutoff value of > 190 pg/mL could differentiate survivors from nonsurvivors with a sensitivity of 70% and a specificity of 67%. A prognostic impact of BNP with respect to mortality was also found by Tung et al in evaluating BNP levels in 49 ICU patients with shock, mainly of noncardiac origin. In contrast, a very recent study analyzing 78 patients who had been admitted consecutively to a general ICU (with sepsis, 35 patients; without sepsis, 43 patients) revealed a trend toward higher BNP levels in survivors compared to nonsurvivors. When the analysis was restricted to the patients with sepsis, who had higher BNP levels than those without sepsis, the same trend was observed. Other studies, did not find any prognostic information of BNP levels in critically ill patients.
In the past few years, it has become obvious that previous studies in patients with CHF demonstrating a close relationship between BNP levels and left-sided filling pressures cannot be confirmed in critically ill patients.