Monitoring of procalcitonin, IL-6 and brain natriuretic peptide for sepsis diagnosis in cardiac surgery

Introduction

Procalcitonin (PCT) and IL-6 are markers used in the evaluation of systemic inflammation (SIRS) and septic states. The purpose of this study is to analyse changes in plasma concentrations of PCT and IL-6 in patients undergoing cardiac surgery on-pump and assess its reliability in the early detection of postoperative infectious complications. In all patients the variation of brain natriuretic peptide (BNP) was also evaluated in order to stratify the clinical condition of patients.

Methods

We measured serum levels of PCT, IL-6 and BNP in adult patients undergoing myocardial revascularization and/or valve surgery performed in extracorporeal circulation. The measurements were performed on the day before the intervention (T0), at the end of surgery (T1) and then until the third and fourth postoperative day (T2 to T4). We also recorded the onset of cardiac, respiratory, neurological, renal and septic complications. The diagnosis of sepsis was confirmed retrospectively on the basis of clinical, radiological and microbiological data. All data are expressed as mean and standard deviation. The Kruskal-Wallis test was used to assess changes over time of variables. P < 0.05 was considered statistically significant.

Results

There have been enrolled 60 patients undergoing cardiac surgery in extracorporeal circulation. Among these, nine patients developed septic complications. The results of temporal changes and the significance are presented in Table 1.

Table 1 Results of temporal changes and significance

Conclusion

In patients who develop septic complications, changes in PCT occur earlier than changes in IL-6. Furthermore, BNP performs in the same fashion as PCT and correlates better than IL-6 with the clinical data of the infection status. In conclusion, monitoring PCT seems to be useful in early diagnosis of septic complications in patients undergoing cardiac surgery and more sensitive on the variations in IL-6. The combined study of variations in PCT and BNP could improve the diagnostic accuracy in these patients.