Emergency Department Implementation of the i-STAT Alinity Traumatic Brain Injury Whole Blood Test

The objective of this study is to identify determinants for implementing the i-STAT Alinity whole blood traumatic brain injury (TBI) test for its Food and Drug Administration (FDA)-indicated use and to evaluate other potential outcomes with clinical implications. The main questions it aims to answer are: 1. Determine the number of patients with non-elevated (i.e., below clinical cutoff) whole blood iSTAT Alinity tests who also receive CT scans. 2. What are the obstacles for using the i-STAT Alinity for its FDA-indicated use

Inclusion Criteria: 1. Aged 18 or older 2. Presenting to an enrolling ED with ED Arrival GCS of 13-15 following reported head blunt impact within 24 hours of injury 3. Meets Department of Defense (DoD) definition of mTBI: A traumatically induced physiological disruption of brain function as a result of an external force that is indicated by new onset or worsening of at least one of the following clinical signs immediately following the event: 1. Any alteration of mental status (e.g., feeling dazed, disoriented, or confused) 2. Any period of loss of or a decreased level of consciousness, observed or self-report (loss of consciousness 30 minutes or less, an alteration of consciousness up to 24 hours) 3. Any loss of memory for events immediately before or after the injury (post-traumatic amnesia up to 1-day post-injury) Exclusion Criteria: 1. Treating emergency department provider does not think a head CT scan is needed 2. Inability to obtain results for iSTAT Alinity TBI test within 24 hours of injury 3. Treating emergency department attending physician is not willing to participate 4. Pre-existing neurologic condition 5. Contraindication or inability to complete blood draw 6. Significant polytrauma that, in the opinion of the principal investigators, could impact peripheral GFAP levels or require a full body scan 7. History of penetrating TBI 8. History of neurosurgical intervention for previous TBI 9. Penetrating TBI for current injury 10. Any history of brain surgery 11. Any history of brain tumor 12. Patients on psychiatric hold