Prophylactic and Therapeutic Platelet Transfusion in the Setting of Antiplatelet Therapy
Platelet inhibitors are commonly used to prevent arterial thrombosis and coronary ischemia. Antiplatelet drugs are typically held before major surgery and resumed once the risk of perioperative bleeding has passed, although they may be continued. Aspirin is usually continued for isolated coronary artery bypass grafting, and patients requiring urgent or emergent cardiac surgery are frequently on dual therapy with aspirin plus a P2Y12 inhibitor such as clopidogrel, prasugrel, or ticagrelor at the time of presentation. These patients are challenging to manage, and residual antiplatelet effects are associated with perioperative bleeding and transfusion, so cautious delay is recommended, along with possible platelet function testing to guide operative timing.[38,55–57] The role of platelet function testing in patients on antiplatelet therapy has been recently reviewed in this journal. When surgery must proceed before the antiplatelet effect has passed, limited data suggest that platelet transfusion may help in a dose-dependent fashion. A single-center trial of platelet transfusion during emergency craniotomy for basal ganglia hemorrhage found that, among patients with an aspirin effect detectable by aggregometry, 1 to 2 units of previously frozen apheresis platelets were associated with lower postoperative hemorrhage and mortality. For clopidogrel and prasugrel, in vitro and ex vivo experiments suggest that 2 to 10 units of apheresis platelets may be necessary to reverse the antiplatelet effect, depending on the degree of inhibition. Ticagrelor appears to be practically irreversible within 24 h of administration-a laboratory finding supported by clinical case reports-but at 24 to 48 h after administration, adequate reversal might be achieved with at least 3 to 4 units of apheresis platelets. In the absence of clinical data, these doses and assumptions of efficacy must be received with caution.
In certain circumstances, platelet therapy may be contraindicated: one trial of 190 patients with intracranial hemorrhage on aspirin or other antiplatelet therapy randomized to receive platelet transfusions or standard care found a significantly increased composite rate of death or functional dependence in the platelet arm. These patients were managed without invasive interventions, and there was some baseline imbalance that may have affected the outcome, so the results should not be applied to patients undergoing open surgery.
Anesthesiology. 2021;134(3):471-479. © 2021 American Society of Anesthesiologists | Lippincott Williams & Wilkins