When patients with significant brain injuries present while taking drugs that interfere with clotting, we seem to have this burning desire to neutralize those drugs, right? Warfarin? Give PCC. Aspirin or clopidogrel? Well, not quite so easy. You can’t neutralize them, but can’t you just transfuse some working platelets?

That is the current practice among many clinicians, although there isn’t really much data to support it. A group at Iowa Methodist Hospital in Des Moines looked at using a commercial platelet reactivity test (PRT) to determine if platelets should be given in patients with moderate to severe TBI who were known or suspected to be taking an anti-platelet drug.

This was a retrospective study of 167 patients with a head Abbreviated Injury Scale score of 2 or higher. Patients had to have received at least 2 head CT scans in order to judge progression of any bleeds.

Here are the factoids:

• Nearly a third of patients (29%) were non-therapeutic on their anti-platelet medication, meaning that platelet function as judged by PRT was not abnormal
• No platelet transfusions were given to 92% of patients with non-therapeutic meds, and only 2 of these patients (4%) had clinical progression of their bleed
• Overall, using a selective platelet transfusion policy decreased platelet transfusions and their attendant costs by about half

Bottom line: So this is one of those “how we do it” studies. This means that the authors have been doing it this way for a while, and wanted to examine the results. It is not a comparison to their historical control, but it’s likely that their current usage is much lower than it used to be. Regardless, the results are impressive, and would seem to indicate that we are throwing a lot of platelets away based on a rumor that our patient is taking an anti-platelet medication.

Here are some questions for the authors to consider before their presentation:

• How did you define “clinically significant bleed” in the two patients that had them? Did they eventually get some platelets? Did it help?
• Have you looked at patients that did receive platelets for an abnormal PRT to see if their platelet function improves?
• Big picture question: What evidence is there that PRT results are meaningful? How do we know that abnormal PRT is associated with bleeding in head injured patients, or that normal PRT is not associated with it? In other words, is it a valid test?

Reference: EAST 2018 Podium abstract #4.