Impact of Cardiac Surgery With a Minimal Invasive Extracorporeal Circuit οn Coagulation: Data From Point of Care Testing With Thromboelastometry and Impedance Aggregometry

Last update: 24th October 2019, Thessaloniki, Greece

Study protocol Objective Abnormal platelet function remains one of the main causes of severe bleeding during cardiac surgery, especially in the era of widespread evolution in antiplatelet therapy as standard of care in cardiac surgery patients. Additionally, conventional cardiopulmonary bypass is identified as a significant attributor to pathophysiologic derangement in coagulation and platelet dysfunction, induced by prolonged contact of blood with foreign surfaces, severe haemodilution, hypothermia and systemic inflammatory response. Minimally invasive extracorporeal circulation (MiECC) reflects the technological progress in cardiopulmonary circuits and offers improved perfusion conditions. The multiple electrode platelet aggregometry analysis can be a useful point-of-care diagnostic tool, assessing platelet receptors inhibition and aggregation, thus providing real-time information perioperatively. Our objective is to investigate the potential protective effect of MiECC on coagulation and platelet function and postoperative bleeding in a series of patients undergoing cardiac surgery.

Design This is a prospective cohort study. 57 adult patients presented for elective cardiac surgery were recruited in the study. Informed consent was obtained by all patients. Exclusion criteria were defined as follows: unwillingness to participate, preoperative platelet count ⩽150 × 109/mm3, age <18 or >79 years, emergency procedure, redo surgery, a known coagulation disorder and inaccurate documentation of preoperative antiplatelet medication.

Methods All patients were managed by the same surgical team and anaesthesiologist. They all received general anaesthesia in accordance with our institutional protocol. A dose of 15mg/kg tranexamic acid was given at induction of anaesthesia and after protamine administration. Surgery was performed under normothermia using a standard median sternotomy and MiECC modular (Type IV) circuit was used in all patients during CPB. An activated clotting time (ACT) value >300sec was aimed for patients undergoing CABG and an ACT>400sec for all other valve or complex surgery. Reversal of heparin was accomplished with protamine at a heparin-protamine titration ratio of 0.75.

Preoperatively demographics, comorbidities, use of anticoagulants, antiplatelet medication were collected and intraoperatively type of operation, duration of CPB, duration of aortic cross-clamp, and heparin and protamine doses were recorded. Fibrinogen levels (mg/dL) were measured before surgery (baseline) and after arrival in the ICU. Postoperative bleeding at 12 and 24 hours, as defined according to the universal definition of bleeding, was recorded, as well as intraoperative and 24-hour transfusion requirements (including blood products or coagulation factors concentrates) and major adverse events.