Endothelial-related coagulation in cardiac surgery

The endothelium appears to play an important degrees in theregulation of intravascular coagulation. Thrombomodulin is oneof the anticoagulant substances that is expressed by endothelialcells. The influence of age and illness on the thrombomodulin-proteinC system was studied prospectively in 80 cardiac surgery patients.Patients > 70 yr old (n = 20) were compared with patients< 50 yr (n = 20) (group I), and patients undergoing a simplecardiac procedure (n = 20) were compared with patients scheduledfor complex surgery (n = 20) (group II). Thrombomodulin (normal<40 ng ml^–1 protein C and (free) protein S plasma concentrationswere measured by enzyme-linked immunosorbent assays (ELISA)after induction of anaesthesia (baseline values), during andafter cardiopulmonary bypass (CPB), at the end of surgery, 5h after CPB and on the first day after operation. Blood lossand use of homologous blood and blood products were significantlygreater in patients > 70 yr and in those undergoing complexsurgery. At baseline, thrombomodulin concentration was increasedin patients undergoing complex surgery (mean 52 (SD 9) ng ml^–1After bypass and after operation, thrombomodulin increased mostin patients > 70 yr (from 40 (8) to 78 (10) ng ml^–1and in those patients who underwent complex cardiac operations(from 52 (8) to 79 (10) ng ml^–1 (P < 0.05). Changesin protein C and protein S concentrations were similar in allgroups. On the first day after operation only, protein C concentrationswere reduced in patients > 70 yr and in patients who underwentcomplex cardiac surgery. Older patients and those who underwentcomplex cardiac surgery had greater changes in the thrombomodulin-proteinC system which may contribute to increased postoperative bloodloss.