Tag Archives: TBI

EAST 2017 #8: When Is “Mild TBI” Not So Mild?

Traumatic brain injury (TBI) is very common, with the majority falling into the “mild” category. This is usually defined as patients with injury to the head and a GCS of 13-15. These uncomplicated patients are frequently discharged from the emergency department, or undergo only a brief evaluation if admitted for other reasons.

The group at Shock Trauma focused on a less appreciated subset of mild TBI patients, those whose condition is a little more complicated. Specifically, these are patients with GCS 13-14 with positive findings on head CT leading to a calculated abbreviated injury score (head) of > 2, and some persistence of their symptoms while in the hospital. At many hospitals (including my own), these patients receive an inpatient TBI evaluation. But if they pass this initial screening, they are not consistently referred for any outpatient TBI followup.

Are these mild, complicated TBI patients (mcTBI) unique? Do they behave the same as the uncomplicated ones? The research group performed a prospective study on patients who sustained an mcTBI over a 4 month period.  They excluded patients with mental illness, dementia, and non-English speaking and homeless patients. They tried to contact patients up to three times after discharge to administer several standard tests and determine if they had any specific residual symptoms.

Here are the factoids:

  • Of the 142 patients with mcTBI during the study period, there was substantial attrition over time, with only 25 remaining at 6 months and 10 at one year
  • 64% of patients who responded at 6 months remained symptomatic. Depression, dizziness, and a feeling of impaired health were common.
  • 80% of patients still described symptoms at one year. The same complaints were most common, and some required changes in activities of daily living or assistive devices.

Bottom line: Although small and fraught with the usual problems in long-term tracking of urban trauma patients, this study is eye-opening. We too often dismiss “mild TBI” and being almost nothing, even in patients with positive findings on head CT. This work suggests that we are underestimating the needs of those patients. The authors used this data to design longer-term care processes for this subset of patients. Other centers should follow suit to make sure these patients’ post-injury needs are better met.

Questions and comments for the authors/presenters:

  • Describe the possible biases that patient selection and attrition may have had on the study
  • What type of TBI screening do you use in the hospital?
  • Given that a number of assessments were administered over the phone, I look forward to hearing some of the other details not listed in the abstract
  • Was there any correlation between specific CT findings and later symptoms?
  • Provide details of your long-term care programs for these patients
  • I enjoyed this thought provoking abstract!

Click here to go the the EAST 2017 page to see comments on other abstracts.

Related posts:

Reference: Mild TBI is not ‘mild’… survivors tell their complicated stories. Quick Shot #3, EAST 2017.

Managing Mild TBI Without A Neurosurgeon

TBI is a very common injury, and neurosurgeons are relatively rare resources for trauma centers. That mismatch can create significant problems for trauma programs. Reflexively, we consult neurosurgeons for a wide variety of neurotrauma, ranging from the very severe to the extremely mild.

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Can we intelligently and selectively utilize the skills of our neurosurgeons, and not jeopardize patient safety? Surgeons at Baystate Medical Center in Springfield MA reviewed their own experience managing mild TBI.

They defined a mild TBI as one with patient GCS of 13-15. However, their study included only patients with “GCS>14”, which I presume means all patients with GCS=15 (unless this is a typo). They allowed patients with normal GCS and intoxication, epidural (EDH) or subdural hematoma (SDH)<4mm, small subarachnoid hemorrhage (SAH), and non-displaced skull fracture (Fx). Any patient taking any type of anticoagulant or anti-platelet drug was excluded. They looked at need for neurosurgical consultation or intervention, readmission, and 30 day mortality.

This prospective study spanned 13 months. This lower volume center admitted 1341 patients, of which 77 were included in the study. Average age was 55, and average ISS was 16. A total of 97% presented for a followup visit (!).

Here are the factoids:

  • 47% had SAH, 43% SDH, 16% intraparenchymal hemorrhage (not mentioned in inclusion criteria), 14% Fx, and no EDH
  • Only one patient required neurosurgery consult, and none required intervention
  • There were no mortalities
  • Most (62%) were admitted to a ward bed, and the average length of stay for all patients was 3 days
  • Cost savings was estimated at about $16,000

Bottom line: Yes there is no magic in getting a neurosurgical consult for most mild TBI. The study is small, but telling. A carefully crafted practice guideline can dramatically decrease the (over)use of our neurosurgeons, saving both time and money.

In reviewing their guideline, I would recommend shaving even one more point off the GCS (>14), but stipulating that any central subarachnoid hemorrhage require consultation because of the possibility of an aneurysm being the culprit.

Check out the guideline in use at my hospital below. Also, look at the first related post, which is similar in idea to this one, but you can see the difference in management by surgeons vs neurosurgeons.

Related posts:

Reference: Mild traumatic brain injuries can be safely managed without neurosurgical consultation: the end of a neurosurgical “nonsult”? AAST 2016, Poster 51.

Which ICU For Neurotrauma Patients: Neuro-, Trauma-, or Med/Surg?

Different hospitals have different arrangements for taking care of critically injured patients. All Level I or II trauma centers have at least a mixed med/surg ICU, with most level I centers having a dedicated surgical unit. A few have specific trauma or neuro-critical care ICUs.

In general, severely injured trauma patients do better when taken care of by trauma teams who have sufficient experience (volume). What about patients with severe traumatic brain injury (TBI)? Does the experience and volume of patients receiving care in the ICU make a difference?

A group of 12 trauma centers with varying ICU arrangements pooled their outcome data to see if the type of ICU makes a difference. All patients admitted with GCS<14 with CT evidence of TBI were evaluated if they were admitted to an ICU.

Here are the factoids:

  • 2951 patients from the 12 centers met inclusion criteria
  • Type of ICU, age, and ISS were independent predictors of death
  • Patients admitted to a trauma ICU had the best probability of survival, and stayed high across all ISS scores
  • Those admitted to med/surg ICUs had higher probabilities of death, especially with higher ISS (> 38 or so)
  • Survival for isolated TBI patients in a neuro ICU was similar to a trauma ICU in patients with lower ISS (< 32)

AAST2016-Oral21

Bottom line: This is a fascinating study, but it is giving us just a glimpse of the complete picture. What’s the difference between a med/surg ICU vs a trauma ICU. How much head trauma does a neuro ICU have to see? What kind of nurses work in them? What types of critical care physicians? 

These questions are not answered in the abstract. And they may not be answered during the presentation at the meeting. But they are extremely important, and must be resolved in the next iteration of this study. Hopefully, there will be one!

Reference: Neuro-, trauma-, or med/surg-ICU: does it matter where polytrauma patients with TBI are admitted? Secondary analysis of the AAST-MITC decompressive craniectomy study. AAST 2016, paper #21.

EAST 2016: How Long Does VTE Risk Last In TBI?

Most trauma patients
are considered to be at some risk for deep venous thrombosis (DVT) and/or
venous thromboembolism (VTE) during their hospital stay. Trauma professionals
go to great lengths to screen for, prophylax against, and treat these problems.
One of the tougher questions is, how long do we need to worry about it? For
fractures, we know that the risk can persist for months. But what about head
injury?

A group at Brigham
and Women’s Hospital did a large database study looking at the VTE risk in adults
who sustained significant head injury, with only minor injuries to other body
regions. They tried to tease out the risk factors using multivariate regression
models.

Here are the
factoids:

  • Patients were only included if their AIS Head
    was >3, and all other AIS were <3
  • Of the over 50,000 patients in the study,
    overall incidence of VTE was 1.3% during the hospital stay, and 2.8% overall
    within 1 year
    of injury
  • Risk factors for VTE after discharge included
    age > 64 (3x), discharge to a skilled nursing facility (3x), and prolonged
    hospital length of stay
    (2x)
image

Incidence of VTE over time

Bottom line: View this paper as a glimpse of a potential unexpected
issue. The risk of VTE persists for quite some time after head injury (and
probably in most other risky injuries like spine and pelvic fractures. The
three risk factors identified seem to identify a group of more seriously
injured patients who do not return to their baseline soon after injury. We may
need to consider a longer period of screening in select patients, but I believe
further work needs to be done to help figure out exactly who they are.

Reference: How long should we fear? Long-term risk of
venous thromboembolism in patients with traumatic brain injury. EAST 2016 Oral
abstract #28.

EAST 2016: Brain Hypoxia In TBI With Aeromedical Evacuation

I’m sure that most of you have noticed that I very rarely write about animal studies. The problem I have is that the effects generally found are not dramatic, and results seldom carry over to humans the way we think they should. 

But for this paper, I’ve made an exception. It uses a swine model to study the effect of air transport at altitude on TBI. As you may know, most aeromedical transport in the US is via helicopter. 

However, some patients in more rural areas must travel longer distances to get high level trauma care, and may need to fly in fixed wing aircraft. U.S. military transports overseas use fixed wing almost exclusively. 

Medical helicopters typically fly at only 1000-3000 feet above the ground, and the change in air pressure (and hence PaO2) is small. However, fixed wing aircraft fly at much higher altitudes, and the effective cabin altitude may rise to about 8000 feet. This is why your ears “pop” so many times as you ascend. You’ve essentially just climbed Mt. St. Helens in Washington state. The amount of oxygen in cabin air also decreases with altitude.

So what happens to a patient with severe TBI when exposed to these fluctuations in pressure and oxygen levels? A group at the Naval Research Center looked at this issue in anesthetized swine that received a TBI from a percussion device. They received standard TBI and injury-specific care (for pigs?) for two hours, then underwent flight simulation using a hypobaric chamber set to a cabin altitude of 8000 feet for four hours. 

Here are the factoids:

  • Six study pigs underwent the 2 hours at sea level followed by 4 hours at altitude. Six control pigs stayed at sea level after their injury.
  • Mean arterial pressure in the pigs at altitude decreased somewhat, but not significantly.
  • Intracranial pressure (ICP) increased significantly in the TBI group(!)
  • As a result, cerebral perfusion pressure (CPP) dropped in the study group (highly significant result).

Bottom line: Aeromedical transport at typical cabin altitudes significantly increases ICP and decreases CPP in an injured pig model. Although the groups are small, this information is startling and deserves rapid confirmation. This information may have a significant impact on the way we fly patients with head injuries. In particular, this is important for military aeromedical evacuation.

Reference: Brain hypoxia is exacerbated in hypobaria during aeromedical evacuation in swine with TBI. EAST 2016 Oral abstract #2, resident research competition.