The application of point-of- care platelet function assay in guiding platelet transfusion in aspirin-users with intracranial haemorrhages

Abstract

Abstract:

Objectives:

To study the changes in platelet activities following platelet transfusion in aspirin users and identify factors associated with differential responses to platelet transfusion

Methods:

Patients admitted for intracranial haemorrhages who were on aspirin were recruited for this trial. We excluded patients that were on other anticoagulation or antiplatelet agents. Baseline aspirin response units (ARU) were measured using VerifyNow® and only aspirin responder were included. 4 units of platelet concentrate were transfused. ARU were then repeated at 4 hours, 24 hours and 48 hours from time of transfusion and their trend of platelet activity identified. The interval changes of the intracranial haemorrhage on CT scan and the patient’s outcome were set as secondary outcomes.

Results:

From February 2014 to April 2017, 26 patients were recruited into this prospective pilot study. 3 patients were excluded as platelet transfusion was deemed not necessary clinically, 2 patients were excluded as they were concomitantly on other antiplatelet or anticoagulation agents and 1 patient was excluded as he was an aspirin non-responder at baseline. 15 patients had definite head injury history. Only one patient required an emergency operation. At 4 hours after transfusion, 11 (55%) patients became aspirin non-responders after platelet transfusion. Overall, eight patients had persistently normalized platelet function, three delayed normalized, and four transiently normalized. Five (25%) patients had persistently abnormal platelet function. Factors that may affect platelet activity including platelet count on admission and baseline renal function were studied.

Conclusions:

Platelet activity was successfully normalized in more than half of the patients at four hours after platelet transfusion, but the duration of this effect varied. Whether we should give additional platelet transfusions to persistent aspirin responders based on the VerifyNow® result and if there are any differences in outcome in giving platelet transfusion based on their responder status on presentation would be the focus in future studies.