Dynamics of heparin binding protein in cardiothoracic surgery using cardiopulmonary bypass – exploring its potential as a marker for postoperative infections.

Abstract Background Surgical trauma and cardiopulmonary bypass (CPB) cause an inflammatory response, difficult to differentiate from postoperative infections. Heparin-binding protein (HBP) is released from neutrophils and has been shown to predict infection-related organ dysfunction and disease progression to severe sepsis. The aim of this study was to investigate the pre-, intra- and postoperative dynamics of HBP in cardiac surgery using CPB, in order to explore the usefulness of HBP as a biomarker for postoperative infections. Methods and Results Thirty patients undergoing cardiac surgery with CPB were included, of which 15 underwent coronary artery bypass grafting (CABG) surgery and 15 underwent complex procedures with longer CPB time. A reference group of ten patients undergoing lung surgery without CPB was also included. HBP was measured at nine different time points during surgery. Our results showed that HBP levels were not affected by surgical trauma itself. An increase in HBP levels was observed immediately following heparin administration and further increased during CPB. Prior to protaminization, we measured higher peak in HBP-levels in the complex group 345.7 (287.8-472.6) ng/mL compared with the CABG group 152.7 (85.3-204.0) ng/mL, p <0.001. HBP decreased rapidly following end of CPB and simultaneous protamine administration. Delay of protamine administration revealed that protamine, and not the cessation of CPB is primarily responsible for the rapidly reduced HBP concentration. At the arrival to the ICU, the median HBP levels were 24.8 (15.6-38.1) ng/mL for CABG patients compared with 50.5 (36.5-104.6) ng/mL for complex surgery patients ( p =0.004). One day after surgery HBP levels in all three groups were below the proposed cutoff of 30 ng/mL previously found to predict development organ dysfunction during infection. There was a statistically significant correlation between CPB duration and peak HBP concentration (r=0.598, p =0.002). Conclusions HBP levels are elevated by administration of heparin and the use of CPB. However, at postoperative day one, HBP levels normalized regardless of surgical complexity, indicating that postoperative HBP measurement may be used as a screening tool for postoperative infections in cardiac surgery.