Prognostic value of N-terminal B-type natriuretic peptide in patients at high risk of systemic inflammatory response syndrome/sepsis

Introduction

Patients undergoing major surgery are at high risk of postoperative sepsis. Early markers of septic complications would be useful for diagnosis and therapy of patients with sepsis. In contrast to the rather uniform results of studies dealing with other markers of sepsis such as C-reactive protein (CRP), the impact of raised n-terminal B-type natriuretic peptide (BNP) levels in the postoperative period is less clear. Furthermore, growing evidence supports the hypothesis that BNP could be an early predictor of sepsis in the ICU. We evaluated the time courses of BNP, CRP and APACHE II score and investigated their role as early markers of systemic inflammatory response syndrome (SIRS)/sepsis after major surgery.

Methods

Twenty-nine patients were prospectively included: 20 patients had major oncological surgery of the head and neck (Group 1). The second group included patients with manifest cardiovascular disease (n = 9) undergoing cardiac surgery. The APACHE II score and serum concentrations of BNP and CRP were determined before and daily after surgery. The American College of Chest Physicians Classification was used to diagnose SIRS, and organ system failure to define sepsis.

Results

Mean baseline levels of BNP were different in both groups (Group 1: 435.2 ± 906.1 ng/ml vs Group 2: 2,083.4 ± 3,694.9 ng/ml). The maximum values of BNP achieved at postoperative day 3 were significantly higher compared with the baseline levels. There was also a significant difference between both groups (Group 1: 1,500.0 ± 1,963.8 ng/ml vs 3,806.6 ± 3,822.0 ng/ml; P < 0.05; r² = 0.84). The APACHE II score was significantly higher at the maximum time point (day 3) for all patients (P < 0.05, r² = 0.45). However, the CRP levels were not significantly different within this period. Six patients developed SIRS. The average maximum BNP was 2,286.98 ± 2,943.58 ng/ml. Within this group, two patients died of severe sepsis and had significantly higher BNP levels as compared with the maximum postoperative values (P < 0.05).

Conclusion

Our results show that BNP levels are significantly higher in patients after undergoing major surgery at risk of SIRS/sepsis. We also observed significantly higher BNP levels in patients developing SIRS/sepsis. BNP may therefore be an appropriate prognostic marker indicating the early development of postoperative severe sepsis after major surgery.