Platelet function assays fail to detect differences between transfusion of cold or room temperature platelets in traumatic brain injury patients

Abstract

Background: Traumatic brain injury (TBI) patients on antiplatelet medications lack definitive treatment for reversal of platelet inhibition and restoration of injury-induced platelet dysfunction. The use of platelet transfusions in this patient population remains controversial. Cold-stored platelets (CSPs) may be hemostatically superior to their room temperature platelet (RTP) counterparts for hemostatic resuscitation, but their impact on post-transfusion platelet function has yet to be assessed clinically. We aimed to evaluate the effect of CSP or RTP on post-transfusion platelet function in TBI patients on antiplatelet medications. We hypothesized that CSP would better restore platelet function based on the extensive in vitro data suggesting hemostatic superiority.

Methods: We performed a post hoc analysis of a randomized controlled trial comparing CSP and RTP in TBI patients on antiplatelet medications. Platelet hemostatic function was determined pretransfusion and posttransfusion using VerifyNow or thromboelastography with platelet mapping (TEG-PM). Clinical outcomes included 30-day mortality, need for neurosurgical intervention, and follow-up Rotterdam scores.

Results: Of the 94 patients with available data, 49 received CSP and 45 received RTP. Baseline characteristics and pre-transfusion assay measurements were similar between groups. Cold-stored platelet recipients had fewer neurosurgical procedures compared with RTP recipients (4.1% vs. 20.0%, p = 0.016). Room temperature platelet recipients showed a greater increase in TEG-PM kaolin maximum amplitude after transfusion compared with CSP recipients (2.4 mm vs. 0.6 mm, p = 0.004). No other differences were observed between RTP and CSP transfusions.

Conclusion: Despite a reduction in neurosurgical events, CSP did not significantly improve observed platelet function in TBI patients on antiplatelet medications. Our findings highlight the disconnect between platelet function assays and clinical results and suggest transfusion of CSP versus RTP has minimal effect on platelet hemostatic function. A definitive trial is needed to assess the efficacy of differentially stored products in the bleeding patient, with consideration placed on how platelet hemostatic function is assessed.

Level of evidence: Prognostic/epidemiologic; Level III.

Keywords: Platelet function assays; TBI; antiplatelet medications; cold-stored platelets; platelet transfusions.