Hyperbaric Oxygen Brain Injury Treatment Trial

Inclusion Criteria:

* Age 16 years or older and 65 years or younger
* Present with severe TBI, defined as Glasgow Coma Scale (GCS) of 3 to 8.
* Marshall computerized tomography (CT) score \>1 in patients with a GCS of 7 or 8 or patients with an alcohol level \>200 mg/dl
* Ability to initiate the first hyperbaric oxygen treatment within 8 hours of admission in patients not requiring a craniotomy/craniectomy or any other major surgical procedure OR
* Ability to initiate the first hyperbaric oxygen treatment within 14 hours of admission in patients requiring a craniotomy/craniectomy or major surgical procedure

Exclusion Criteria:

* First hyperbaric oxygen treatment cannot be initiated within 24 hours of injury
* GCS of 3 with mid-position and non-reactive pupils bilaterally (4mm)
* Penetrating head injury
* Pregnant
* Pre-existing neurologic disease (e.g. TBI or stroke or neurodegenerative disorder) with confounding residual neurologic deficits
* Unstable acute spinal cord injury
* Fixed coagulopathy
* Severe hypoxia
* Cardiopulmonary resuscitation performed
* Coma suspected to de due to primarily non-TBI causes
* Any contraindications to the study intervention