Quick Take: Risk factors and interventions for patients with TBI
Pre-hospital management of a traumatic brain injury: Saline, ketamine, TXA and finding the CO2 sweet spot
In a recent University of Washington Emergency Medicine Department (UWashEMS) Grand Rounds presentation, Andrew Latimer, MD, an emergency medicine physician and associate medical director of Airlift Northwest discussed pre-hospital management of traumatic brain injuries.
Top quotes on EMS management of TBI
Here are a few quotes from Dr. Latimer about prehospital treatment of traumatic brain injury:
“Fall back on airway breathing, ABCs and pay attention to these patients.”
“Don’t forget the low-tech stuff, elevate the head of the bed to 30 degrees. Using gravity to help decrease the intracranial pressure can help as much as these other interventions.”
“Half of all TBI injury patients who are going to die do so within the first 2 hours.”
Top takeaways on prehospital management of TBI
Here are the top 5 takeaways from the UWashEMS Grand Rounds presentation on pre-hospital management of TBIs.
1. Every head injury is different
There are many types of head injuries that can lead to long-term disability and mortality. Age, location and severity of injury, mechanism of injury and medical comorbidities will affect the type of TBI sustained.
A quick recap of the various TBIs EMS may encounter:
- Epidural hematoma. Blood between the dura and skull, often due to an arterial injury
- Subdural hematoma. Blood between the dura and the arachnoid, venous bleeding often seen in elderly patients
- Subarachnoid hemorrhage. Blood between the arachnoid and pia, can be spontaneous or traumatic
- Cerebral contusion. Bruising inside the brain tissue
- Diffuse axonal injury. Shearing between the brain’s grey and white matter, due to sudden deceleration/acceleration forces
2. Avoid hypoxia and hypotension
TBI patients who were hypoxic or hypotensive at any point had much worse outcomes than those who received enough oxygen in a 2017 study published in the Annals of Emergency Medicine. The study found that when patients were both hypoxic and hypotensive, their adjusted odds ratio was 6.1. This means that pre-hospital patients who had at least one SBP measurement less than 90 mmHg and at least one SpO2 below 90% were 6.1 times more likely to die. Hypoxia alone increased odds of mortality by 3 while hypotension alone increased odds by 2.5.
Ensuring that patients are adequately oxygenated and perfusing is crucial to patient care and this pre-hospital treatment will greatly affect their overall outcome.
3. Eucapnia is better than hypocapnia
Unless the patient is actively herniating, they will fare better with maintaining a normal CO2 rather than being hyperventilated. Brain vasculature is sensitive to arterial CO2, which means that as CO2 decreases, brain arterials will constrict, leading to decreased brain blood volume. Although this sounds good when you’re trying to decrease intracranial pressure, it also means that less oxygen will be delivered to the brain. This can then lead to rebound hypertension and increased brain swelling.
Hypercapnia can also be harmful, causing brain arterial dilation and increased intracranial pressure. Therefore, it’s important to hit the sweet spot where CO2 is normal.
4. Pay close attention to elderly and anticoagulated patients
As you age, your brain decreases in size, which means you have more room to move in the skull. Unfortunately, this also means you are more likely to have shearing of the bridging veins, leading to a subdural hematoma. Even a stumble could potentially cause a bleed. Patients on Warfarin, Aspirin and DOACs are also at higher risk for increased bleeding, therefore you should have a higher suspicion for brain bleeds in elderly and anticoagulated patients, even when the mechanism of injury is low impact.
5. Saline, ketamine and TXA in treating TBI
King County EMS in Seattle found no clear benefit when using hypertonic saline in the pre-hospital setting.
Ketamine may actually have some neuro-protective benefits and anti-epileptic effects. Previously, it was believed to increase intracranial pressure, but that study involved pediatric burn patients.
Moderate-to-severe TBI seems to benefit from TXA. High severity and low severity TBIs had no change in overall outcome.
Additional resources for EMS treatment of TBI
Learn more about prehospital TBI management with these resources: