Reducing Post Operative Bleeding Following Cabg

The purpose of this study is to assess the efficacy of IV Tranexamic Acid and topical Tranexamic Acid to control post op bleeding following Coronary Artery Bypass Graft Surgery using Cardiopulmonary Bypass.

Coagulopathy is a common problem after open heart surgery using cardiopulmonary bypass (CPB). Some bleeding is significant enough to require early re-exploration to control hemorrhage in 2-4% of patients.(1,2) In adults, excessive post-operative bleeding occurs in association with repeat operations, emergency procedures, female gender, small body mass index, older age, peripheral vascular disease, renal insufficiency ( creatinine \> 1.8g/dL) , poor nutrition ( albumin \< 4g/dL) and in patients who have experienced prolonged CPB durations. (3,4)

Factors that contribute to coagulopathy after coronary artery bypass grafting (CABG) using CPB include thrombocytopenia, acquired platlet dysfunction, loss of clotting factors, free heparin and increased fibrinolysis. (5-7). Lemmer and Colleagues (8) found that extracorporeal circulation results in significant fibrinolysis, as reflected by increased concentrations of plasmin and fibrin degradation products (FDP), both of which have deleterious effects on platlet function. Fibrinolysis was found to be responsible for 25-45% of significant post-bypass bleeding. (9)

Many antifibrinolytic agents have been used to reduce post-bypass bleeding. These include ε- Aminocaproic Acid (10), Aprotinin (11) and Tranexamic Acid (TA) (12).

TA has been found to bind to lysine binding sites of plasmin and plasminogen. Saturation of these sites displaces plasminogen from the fibrin surface thus inhibiting fibrinolysis.(13). TA has been used both systemically and topically.

Due to the natural barrier properties of the pericardium, which prevents the free diffusion of substances, experimental studies have shown that the local application of different medications in to the pericardial cavity can lead to desirable therapeutic effects without significant systemic absorption. (14-16)

There has been a systemic review and meta-analysis study done looking at 8 trials (622 patients) using topical antifibrinolytic agents (aprotinin and tranexamic acid). No adverse effects were reported following usage of topical antifibrinolytics.(17)

Topical TA has also been successfully used in controlling bleeding in bladder, gynaecological, oral, \& oropharyngeal surgeries. (18-20)

There has been no authors thus far who have compared application of intravenous TA to combination of application of intravenous TA and topical TA.

This study is based on a hypothesis that the combination of intravenous (IV) TA and topical TA administration will significantly reduce the amount of post-op bleeding significantly following CABG using CPB.

Eligibility Criteria:
Inclusion Criteria:

* primary isolated CABG

Exclusion Criteria:

* patients who will have combined procedure
* redo-surgery
* bleeding diathesis (Haemophilia or platelet count ,100 x 109 L1)
* renal impairment (Creatinine \> 130umol/L)
* known allergy to TA
* recent (\< 7 days before surgery) intake of anti-platelets (eg Aspirin, Clopidogrel, Ticlid) or heparin administration within 48 hours of operation