Serum measurement of N-terminal pro-brain peptide among septic patients

Introduction

Elevated serum N-terminal pro-brain natriuretic peptide (NT-proBNP) levels occur in severe sepsis or septic shock. Studies on the value of NT-proBNP testing among septic patients revealed conflicting results. The aim of the study was to investigate NT-proBNP among septic patients admitted to the ICU.

Methods

Serum NT-proBNP measurements were carried out in 10 consecutive patients (seven males/three females, age 66 ± 10.67 years) with sepsis within 6 hours of admission to the IXU. NT-proBNP was determined with a sandwich immunoassay on an Elecsys 2010 (Roche Diagnostics, Mannheim, Germany). Logarithmic transformation of data was required because of the skewed distributions of the NT-proBNP.

Results

Elevated levels of NT-proBNP were found in eight patients, while two were in the 'grey' zone (NT-proBNP < 400 pg/l). The median NT-proBNP level was 3,930 pg/ml (range, 307–16,800 pg/ml). Inhospital mortality was high, five patients died (50%). NT-proBNP showed a weak and inverse correlation with systolic blood pressure (r = -0.49, P < 0.05) and with body temperature (r = -0.57, P < 0.02), while no correlation was found for other analyzed parameters (age, diastolic blood pressure, body temperature, leucocytes, C-reactive protein, fibrinogen, lactates, procalcitonin). At admission, the mean log NT-proBNP levels were significantly higher in hospital nonsurvivors (3.66 ± 0.63 pg/ml) compared with survivors (3.36 ± 0.65 pg/ml), but without statistical significance (P < 0.54). Mean baseline levels of log NT-proBNP were different in septic patients with proved bacteriological infection than in patients without proved infection. Higher concentrations were found in proved infection (X ± SD) (3.66 ± 0.71 pg/ml) than in the bacteriological negative patients (3.24 ± 0.52 pg/ml), but were statistically insignificant (P < 0.32).

Conclusion

Our results showed that NT-proBNP levels can be elevated in critically ill patients presenting with sepsis. Values are higher in nonsurvivors than in survivors and in the patients with proved bacteriological infection, but with no statistical significance. More research is needed to accentuate the positive value of NT-proBNP in the ICU.