The investigators are assessing the platelet function analysis of those who sustained significant head trauma while on aspirin or plavix and to assess if any qualitative difference is obtained if platelets are administered.

The platelet function analyzer VerifyNow® P2Y12 uses ADP as agonists to induce platelet activation and ascertain the level of platelet function impaired by these medications. VerifyNow® Aspirin Assay utilizes arachidonic acid as the agonist to measure platelet function specifically along this pathway. Our research question for this study is as follows:

Does the administration of desmopressin (DDAVP) and/or the transfusion of platelets in patients with head trauma reverse the platelet inhibition caused by Aspirin and/or Plavix? The investigators hypothesize that with the administration of platelets and/or DDAVP that there is a reversal of the inhibition.

Inclusion Criteria:

1. Age > 18yrs
2. Must be a trauma patient with blunt head trauma.
3. Must be on Aspirin and/or Plavix
4. Subject or Legally Authorized Representative (LAR) (per Heath and Safety Code, Sections 24170 to 24179.5) must sign study consent within 4 hours from the first blood draw. (If this criterion is not met the initial blood draw must be destroyed and NOT run for study results).

Exclusion Criteria:

1. Hemoglobin ≤ 10 GM/DL
2. Platelet Count ≤ 150 K/MCL
3. Pregnant Females
4. Subjects on Warfarin, Heparin or Enoxaparin