BNP and NT-proBNP levels were markedly elevated but only weakly correlated with pulmonary capillary wedge pressure (r=0.40 and r=0.32, respectively) in critically ill ICU patients.
Observational (n=40)
Effect estimate: r = 0.40 for BNP, r = 0.32 for NT-proBNP
OBJECTIVES: We examined whether B-type natriuretic peptides (BNP) can serve as noninvasive markers of pulmonary capillary wedge pressure (PCWP) in the setting of critical illness. BACKGROUND: The BNP and N-terminal pro-B-type natriuretic peptide (NT-proBNP) are highly correlated with left ventricular (LV) filling pressures in patients with depressed LV systolic function. However, their relationship to PCWP in a heterogeneous intensive care unit (ICU) population has not been established. METHODS: We prospectively studied 40 patients in the ICU requiring invasive hemodynamic monitoring. Hemodynamics were recorded simultaneously with blood sampling for BNP and NT-proBNP. RESULTS: The BNP (median 420 pg/ml) and NT-proBNP (median 3,304 pg/ml) levels were markedly elevated, but weakly correlated with PCWP (BNP, r = 0.40, NT-proBNP, r = 0.32) and other cardiac parameters. Peptide levels were approximately four-fold greater in patients with impaired (estimated glomerular filtration rate eGFR 60 ml/min) renal function, despite similar PCWP, cardiac index, and LV ejection fraction. In addition, both BNP and NT-proBNP showed stronger correlations with PCWP in patients with preserved (BNP, r = 0.58, NT-proBNP, r = 0.73) versus impaired renal function (BNP, r = 0.48, NT-proBNP, r = 0.34). Interaction terms between eGFR and BNP (p = 0.06) and NT-proBNP (p = 0.04) suggest that eGFR modulates the relationship of these peptides to filling pressures. CONCLUSIONS: The BNPs are markedly elevated, yet show only weak correlations to PCWP in ICU patients requiring invasive hemodynamic monitoring. Thus, a single value for BNP or NT-proBNP may not be a clinically useful noninvasive marker of filling pressures in the critically ill patient. This appears to be especially true in patients with impaired renal function.
“This study confirms what we know from clinical practice that a single value of BNP is often not useful unless we know the 'dry BNP' of the patient. An interesting study would be to determine whether serial BNPs track changes in filling pressures in critically ill patients with normal renal function.”
Forfia et al. (Fri,) conducted a observational in Critical illness (n=40). B-type natriuretic peptides (BNP and NT-proBNP) was evaluated on Correlation with pulmonary capillary wedge pressure (PCWP) (r = 0.40 for BNP, r = 0.32 for NT-proBNP). BNP and NT-proBNP levels were markedly elevated but only weakly correlated with pulmonary capillary wedge pressure (r=0.40 and r=0.32, respectively) in critically ill ICU patients.