Function of various cellular blood components is altered under conditions of cardiopulmonary bypass (CPB) which can lead to activation of pro- and anticoagulant systems. In the present study, the effects of two different heart-lung-machine (HLM) concepts on the expression of surface markers on monocytes and platelets are compared.
In a prospective, randomized and single-blinded study sixty patients with elective coronary artery bypass surgery were recruited into three groups. A standard system (group 1) was compared with a modified HLM containing of a Deltastream pump, surface-modified tubing, and reduced priming volume (Optimized Mini-Circulation Cardiopulmonary Bypass System (OMCPB)) (group 2). In group 3 patients were operated on without extracorporeal circulation (OPCAB). Blood was collected at different time points before, during, and until 48 hours after surgical intervention. Platelets were incubated with either CD42b-FITC-/ CD62P-PE- or Factor Va-FITC-/ Tissue Factor-PE-labeled antibodies. EDTA-anticoagulated blood was incubated with CD11b-FITC- / CD18-PE- labelled antibodies. Samples were analysed applying flow cytometry.
CD42b-expression decreased significantly at the end of the observation period in group 1 disclosing significant differences to groups 2 and 3. Platelet Factor Va-expression was significantly elevated in group 1 during bypass compared to groups 2 and 3. Tissue Factor- and CD62P-expression showed no significant differences between groups. CD11b-expression on neutrophiles and monocytes increased significantly under bypass and until 30 minutes after bypass in groups 1 and 2 compared to group 3 with higher values in group 1.
Activation of Factor X through monocyte CD11b expression and Factor Va expression on platelet surfaces are synergistic conditions in thrombin generation under CPB. This procoagulant stimulus could be significantly reduced using OMCPB.
Dysfunction of cellular blood components has a major influence on clinical outcome after use of CPB through parameters like blood loss, systemic inflammation and micro-clot formation. Use of an optimized HLM may influence some of these factors.
Thomas Waldow, None.