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The effects of recent aspirin ingestion on platelet function in cardiac surgical patients
N M Gibbs1, W M Weightman, N M Thackray
1Department of Anaesthesia, Sir Charles Gairdner Hospital, and PathCentre, Nedlands, Western Australia.
Objective:
To examine the effects of the preoperative aspirin-free interval on platelet function in cardiac surgical patients.
Design:
Prospective clinical investigation.
Setting:
University-affiliated teaching hospital.
Participants:
Patients undergoing elective coronary artery bypass graft surgery (n = 100).
Interventions:
The patients were divided into 3 groups based on the number of days since they last ingested aspirin: < or =2 days, 3 to 7 days, and >7 days. Preoperative platelet function was assessed in all patients using platelet aggregation responses to arachidonic acid, 5 microg/mL, and Platelet Function Analyser (PFA100) collagen/epinephrine closure times.
Measurements And Main Results:
Patients who ceased aspirin < or =2 days preoperatively had weaker platelet aggregation responses (18.5% +/- 7% maximum aggregation, mean +/- SD, n = 36) than patients who ceased aspirin 3 to 7 days preoperatively (68.8% +/- 29%, n = 48, p < 0.001) or >7 days preoperatively (68.3% +/- 28%, n = 16, p < 0.001). Similarly, patients who ceased aspirin < or =2 days preoperatively had longer PFA100 closure times (168 +/- 52 sec) than patients who ceased aspirin 3 to 7 days preoperatively (122 +/- 43 sec, p < 0.001) or >7 days preoperatively (128 +/- 42 sec, p < 0.01). The percentage of abnormal responses was also greatest in the aspirin < or =2 days group.
Conclusion:
Cardiac surgical patients who ingest aspirin < or =2 days preoperatively have greater impairment of platelet function than patients who have a longer preoperative aspirin-free interval.