Bleeding Complications Following Coronary Artery Bypass Grafting
Question 13.1 from the first paper of 2009 asks the candidate to come up with reasons for why their post-op CABG patient is bleeding to death, and to come up with a management strategy. Something similar occurs in Question 13 from the first paper of 2012. In addition to this, all those frequently repeated SAQs about the management of the haemodynamically unstable cardiac patient all involve the discussion of bleeding at some stage.
Post-cardiothoracic surgical bleeding complications
Sadly, bleeding complications are common enough to merit their own chapter. Excessive bleeding is usually due to one or more of the following factors:
- incomplete surgical hemostasis
- residual heparin effect after cardiopulmonary bypass
- platelet abnormalities (platelet dysfunction and thrombocytopenia – from bypass circuit consumption , antiplatelet agents etc)
- postoperative hypertension
- clotting factor depletion
- hemodilution (dilutional thrombocytopenia and coagulopathy)
Approach to haemorrhage in the immediate post-bypass period
So, your patient is bleeding into their pericardium. Why is the patient bleeding? There are two main categories for this; lets say one category is the surgeon's fault, and the other is the anaesthetist's fault.
Surgical causes of post-bypass haemorrhage
- Poor haemostasis with ooze
- Accidental vessel injury, unmasked by hypertension
- Coronary artery graft anastomosis failure
Medical causes of post-bypass haemorrhage:
- Hemodilution, with dilution of clotting factors
- Hypothermia, with clotting factor dysfunction
- Preoperative platelet inhibitor therapy
- Inadequate reversal of heparinization post bypass
One can safely say that in the ICU, apart from waking up the surgeons, nothing can be done about the first category. However, we can make moves on the medical causes.
- Measure the temperature
- Correct hypothermia
- Get a full set of coags, fibrinogen and ACT.
- Reverse the heparin with protamine
- Replace the missing clotting factors
- Get a full blood count and look at the platelets
- Transfuse platelets as needed
- Manage hypertension
- A high systolic BP will continue to blow the clots off the ends of the vessels. It is helpful to control this with some vasoactive agents. However, this is unlikely to be an issue in the context of hemodynamic collapse (as you are struggling to keep the blood pressure UP, not down.)
A normothermic patient with normal coagulation parameters should not be bleeding post-operatively if the surgical tasks have been completed to a satisfactory standard. Ergo, having gone through the abovelisted steps, one can ring the surgeon and ask them to get back into the chest. For them, an arterial bleed from a coronary artery graft is an easily reversible cause of haemodynamic collapse.