BOF: Clotting (Anticoagulation)

A 78 year old man presents with a troponin positive acute myocardial infarction without ECG criteria for primary angioplasty.. He is treated with 300mg aspirin, 300mg clopidogrel and a first dose of 80mg enoxaparin (1mg/kg body weight). He has normal renal function. Two hours later he collapses. A CT scan reveals a large subarachnoid haemorrhage with intracerebral extension. He is reviewed urgently by the neurosurgeons who wish to proceed to invasive intracranial pressure monitoring and possible evacuation of the haematoma. He is given a pool of platelets to compensate for aspirin and clopidogrel-induced platelet dysfunction. Which ONE of the following additional interventions is MOST appropriate to reduce further bleeding and cover any invasive procedures?

a) 10mg intravenous Vitamin K

b) Fresh Frozen Plasma (15ml/kg)

c) Protamine sulphate

d) Prothrombin complex concentrate

e) Tranexamic acid is useful to control severe bleeding

Answer:

c) Protamine sulphate

Explanation:

FFP would be antagonised by the effect of enoxaparin. Vitamin K antagonists are not implicated in this bleed. Cryoprecipitate is indicated to replace fibrinogen. DDAVP and tranexamic acid could augment platelet function but may be associated with thrombosis (he has had a non-ST elevation infarct by troponin and ECG changes). Recombinant VIIa and prothrombin complex concentrate are relatively contraindicated with recent myocardial infarction. Protamine sulphate is effective in partially reversing the effect of low molecular weight heparin but rapidly loses effectiveness with time following the dose (up to 60% activity antagonised at fifteen minutes post LMWH administration). Aspirin and clopidogrel will have impaired the function of circulating platelets for up to two weeks and a platelet transfusion may for a short period provide functional platelets.

Reference:

Reversal of anticoagulation is subject to local variation in practice and availability of blood products and pharmacological agents. Click the link for an example from the United States which has access to novel agents for one example of 'best care'.