Anticoagulation during extracorporeal circulation under conditions of an ongoing systemic inflammatory response syndrome: effects of heparin

Abstract

Objective: Open-heart surgery with cardiopulmonary bypass (CPB) causes changes in haemostasis. Artificial surfaces are bioincompatible and, thus, may initiate a reaction similar to an acute inflammation. In some patients, this ‘postperfusion syndrome’ (PPS), which includes changes in haemostasis, is the beginning of a systemic inflammatory response syndrome (SIRS). However, it is not clear whether the changes in coagulation represent a consequence or a main cause of the inflammatory reaction. Thus, the aim of our study was to investigate the cascade of coagulation and the effects of heparin under special circumstances of an ongoing SIRS. Methods: In a prospective evaluation using standardized operative procedures with CPB, we compared Group A (control group with normal postoperative course, n=20) with Group B (patients with postoperative SIRS, n=12). At six time points beginning before and ending two days after surgery, we measured platelet counts, leucocyte counts and plasma levels of fibrinogen, factor XII and antithrombin III (ATIII), in addition to standard coagulation tests (PTT, TT and ACT). Furthermore, we determined parameters of inflammation, such as C-reactive protein, PCT, IL-6, IL-8, IL-10 and TNF-alpha. Results: In Group B (SIRS), we found a reduced anticoagulation during CPB with significantly lower values for PTT (60±versus 160±11 s), ACT (270±33 versus 532±44 s) TT (40±3 versus 150±15 s) compared to the control Group A. Simultaneously, we found a significant increase of factor XII in the SIRS group (191±16 versus 10±2%). There were no significant differences concerning the preoperative ATIII levels and the intraoperative dosage of heparin; the intraoperative decrease of fibrinogen, ATIII and platelets was comparable in both groups. Furthermore, we could see that significant changes of inflammatory parameters in the SIRS group (increasing levels of TNF-α, Il-6, IL-8 and IL-10) occurred at least 30 min after the observed reduction of anticoagulatory effect. Conclusions: With our results, it could be demonstrated that the development of inflammatory complications after CPB is correlated to a significantly reduced intraoperative effect of heparin. As this reduction of anticoagulation significantly preceded the changes of inflammatory parameters in SIRS patients, we think that a hypercoagulatory state, especially in cases of ongoing inflammation, is an additional trigger of SIRS.