Tag Archives: TBI

Head, Resuscitation

Best Of EAST 2023 #4: Whole Blood In Patients With Shock And TBI

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We know that even a brief shock episode in patients with severe TBI dramatically increases mortality. Therefore, standard practice is to ensure good oxygenation with supplemental O2 and an adequate airway ASAP and to guard against hypotension with crystalloids and blood if needed.

Many papers (and several abstracts in this bunch) have been written about the benefits of whole blood transfusion. The group at the University of Texas in Houston compiled a prospective database of their experience with emergency release blood product usage in patients with hemorrhagic shock.

They massaged this database, analyzing a subset of patients with severe TBI, defined as AIS Head of 3. They specifically looked at mortality and outcome  differences between those who received whole blood and those who received component therapy.

Here are the factoids:

  • A total of 564 patients met the TBI + shock criteria, and 341 (60%) received whole blood
  • Patients receiving whole blood  had higher ISS (34 vs. 29), lower blood pressure (104 vs. 118), and higher lactate (4.3 vs. 3.6), all indicators of more severe injury
  • Initial univariate analysis did not identify any mortality difference, but using a weighted multivariate model teased out decreases in overall mortality, death from the TBI, and blood product usage
  • Neither statistical model demonstrated any difference in discharge disposition of ventilator days

The authors concluded that whole blood transfusion in patients with both hemorrhagic shock and TBI was associated with decreased mortality and blood product utilization.

Bottom line: This is yet another study trying to tease out the benefits of giving whole blood. The results are intriguing and show an association between whole blood use and survival. But remember, this type of study does not establish causality. It’s not possible to rule out other variables that were not available or not considered that could be the cause of the difference.

In this type of study, it’s essential to look at the design. Was it possible to create the study to record a complete set of variables that the researchers thought might contribute to the outcomes? Or is it a retrospective analysis of someone else’s data that contains just a few of them? This study falls into the latter category, so we have fewer data elements to work with and the likelihood that others that are not present could contribute to the outcomes.

The details of the multivariate analysis are also important. The authors stated that weighted multivariate analyses were performed. It’s not possible to provide details in a standard abstract, but these will be important for the audience to understand.

Here are my questions and comments for the presenter/authors:

  • Tell us more about the database you used for the analysis. What was the purpose? How many data elements did you collect, and how are they related to your research questions?
  • How did you decide which variables to include in your multivariate analysis? And how did you determine the weights? These can have a significant effect on your results.
  • This is a preliminary proof of idea study. How should this be followed up to move from association to causation?

This is just one of many exciting studies trying to shed light on the forgotten benefits of whole blood in trauma. I’m looking forward to seeing the final manuscript!

Reference:  PATIENTS WITH BOTH TRAUMATIC BRAIN INJURY AND HEMORRHAGIC SHOCK BENEFIT FROM RESUSCITATION WITH WHOLE BLOOD. EAST 2023 Podium paper #2.

Trauma Center

What GCS Should Trigger Trauma Activation?

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For the most part, trauma centers are free to pick and choose their own trauma team activation trigger criteria. Typically, these are a mix of physiologic, anatomic, and mechanistic items. However, the American College of Surgeons Committee on Trauma mandates that either seven (Orange Book) or eight (Gray Book) specific criteria must present in every center’s highest-level activation list.

One of these mandatory criteria is a Glasgow Coma Scale (GCS) score of eight or less. The reason is that this level denotes a severe brain injury and as patients approach it they are less and less able to protect their own airway. Although this specific GCS is a minimum, centers are free to choose their own specific threshold as long as it is not any lower.

How does a center choose the “right” GCS? It seems straightforward, right? A mild TBI is defined as GCS from 13-15. These patients have only lost one or two points in their eye-opening, verbal, and motor scores and are relatively unlikely to have a significant lesion in their head or an airway issue.

At the other end of the spectrum is the severe TBI, with a GCS of 3-8. These are a chip shot, with the potential for severe injury and a frequently threatened airway. They demand rapid assessment and intervention, hence the required trauma activation.

But what about those patients with moderate TBI with a GCS from 9-12? They obviously have a higher risk for serious intracranial injury. And as the GCS declines, the patient’s ability to protect their airway decreases. At some point between those GCS scores, most clinicians hit their own internal trigger to provide a definitive airway.

So what do actual trauma centers choose as their threshold? I conducted an informal survey of my readers, asking them to provide their specific GCS threshold.

Here are the factoids:

  • A total of 147 trauma centers of all levels responded
  • They were located in the United States, Germany, Saudi Arabia, and Singapore
  • This chart shows the number of centers that selected a threshold less than or equal to the GCS on the horizontal axis:

 

  • Nearly a third of centers (30%) adhere strictly to the ACS criterion of 8
  • Another 22% use a threshold of 9, possibly to avoid any confusion from having a “less than or equal to” criterion
  • There is another bump on the curve at 13, with 20% using this threshold

Bottom line: A little more than half of centers use a GCS threshold of 8 or 9 as their TTA trigger. This meets the ACS criteria, but could potentially leave a few airways unprotected from time to time. Only about 5% of centers use the higher GCS levels with the exception of GCS 13. That seems to be another popular one.

Which one is right for you? GCS 8 will always work because it is the minimum requirement. My own personal threshold trends higher. I would rather be called to an activation and apply my own judgement rather than come running only when the patient needs to be intubated followed by a trip to the OR for craniotomy.

You will need to work with your emergency physicians, trauma surgeons, and neurosurgeons to determine their collective comfort levels. It comes down to a balance between safety and unnecessary intubation. Look at your own center’s experience and pick a threshold that achieves a proper balance of overall patient safety.

Philosophy

Stroke And Fall VS Fall And Bleed

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It’s like the old chicken and egg question. When dealing with head trauma and falls, which came first? Did the patient have a stroke and then fall down? Or did they fall and sustain some type of intracranial hemorrhage? And you may ask, does it make a difference? They are going to get a head scan anyway, right?

In my opinion, it makes a big difference! How often have you seen the following scenario? EMS is called to a house or nursing home for someone who has fallen. They notice some extremity weakness on one side and presume the patient is having a stroke. The emergency department is then notified that a stroke patient is inbound.

On arrival, the patient was rapidly assessed and whisked off to CT scan for a CT and angiogram, possibly with neurology present. My experience is that a majority of these scans is negative for CVA. And many are positive for some type of extra-axial hemorrhage like subdural or epidural blood from the real injury.

Unfortunately, something called anchoring bias is likely to occur in this situation. Everyone from the paramedics onward are moving along under the assumption that the patient has had a stroke. They stop considering the more common diagnosis of TBI and other potential injuries in the spine and torso. Even when the CT angiogram is found to be negative, it’s difficult for people to change gears. It then takes longer to address the subdural or epidural. The involved trauma professionals are less likely to activate the trauma team. And further evaluation of the chest, abdomen, and spine may be delayed or forgotten for a time.

Bottom line: In any case of a fall followed by neurological changes that could indicate stroke, always presume a serious TBI first! If EMS requests a stroke code, it should be changed to a trauma activation prior to patient arrival. This takes advantage of the odds (more in favor of TBI) and activates a team that is well versed in evaluating the entire patient. If no evidence of hemorrhagic stroke is present, the team will then order the brain CTA and involve the stroke team as necessary.

And for good measure, every one of these cases that does start as a stroke evaluation should be addressed by the trauma performance improvement process!

Head, Resuscitation

Best Of EAST #15: Prehospital TXA

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The world is divided into trauma centers that are TXA believers and those that are TXA nonbelievers. It all depends on how one interprets the CRASH-2 data and subsequent studies. Then came CRASH-3 with TXA use for patients with TBI. This large study found improved survival in patients with mild to moderate head injury when given “early.”

The group at Oregon Health Science University tried to better define this concept of “early.” They examined early vs later administration of TXA in patients with moderate to severe TBI. Note that this degree of head injury is a bit different than CRASH-3 (mild to moderate in CRASH-3 and moderate to severe in this one). This was a multicenter trial that included patients with GCS < 12 and who were hypotensive with SBP < 90. Patients received either a 1g bolus followed by a 1g infusion over 8 hours, or a 2 g bolus only. The authors subdivided these patients into early administration (<45 minutes after injury) or late (45 minutes to 2 hours after injury).

Here are the factoids:

  • There were 354 patients in the early administration group and 259 in the late group
  • All outcomes, including 1 month and 6 month mortality and the extended Glasgow outcome scale were not significantly different between early and late groups (exact numbers were not given)
  • There was no difference in secondary complications between the groups (again, exact numbers or complication types were not given)

The authors concluded that there was no difference in outcomes in early vs later administration of TXA in these head injured patients. They suggest that patients can be given TXA anytime within two hours without loss of benefit.

Bottom line: Essentially, this ends up as a noninferiority study. The biggest question with this type of study is, do you have enough subjects to detect a significant difference? Taken to an extreme, let’s say you have 5 patients who receive a drug who are compared to 5 who did not for some mystery condition. Three who did not get the drug die (60% mortality), but only two who get it do (40% mortality). In relative terms, there was 33% decrease in mortality with the drug. But in absolute terms, it was one patient. Would anyone see this as a significant result with such small numbers?

But now multiply by a thousand, and 300 die without the drug and only 200 die who were given it. The relative difference is the same, but the absolute difference is beginning to look large and significant.

So the smaller study won’t meet the test of significance but the larger one will. The key question in the TXA study here is, do they have enough patients enrolled to show there is no real difference between the groups? I love doing back of the napkin power analyses, and I admit I certainly don’t have all the numbers and probabilities needed for a precise calculation. But the groups sizes in this study (354 vs 259) seem a bit small to achieve significance unless there are large disparities in outcomes. 

I certainly recognize that it’s just not possible to put all the relevant information for a research project into a four paragraph abstract. One would need to be able to submit 12 slide PowerPoint decks. So I’m sure more info will be available as I take in the presentation next Friday.

Here are my questions for the authors and presenter:

  • The study is nicely designed as a randomized, double-blind trial, but how did you blind one vs two doses? Did everyone get an infusion of something, TXA vs saline?
  • Why did you select 45 minutes as the cutoff for early vs late administration? Was this arbitrary or is it based some data?
  • Show us the power analysis that demonstrates the total number of patients in the study is sufficient to show us true non-significance in your results.
  • And I’m sure you will show the actual survival and complications numbers (and type) in the presentation, since they were not available in the abstract.

Reference: THE EFFECTS OF TIMING OF PREHOSPITAL TRANEXAMIC ACID ON OUTCOMES AFTER TRAUMATIC BRAIN INJURY. EAST 35th ASA, oral abstract #40.

Head

Best Of EAST #10: (F)utility Of ICP Monitoring In Geriatric Patients?

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Patients with severe TBI are typically managed using staged protocols based on the Brain Trauma Foundation (BTF) guidelines for ICP monitoring. There have been a number of papers over the past six years that question the utility of ICP monitoring, at least using the procedures in the BTF guidelines.  Most of these studies do not specifically break out elderly patients.

The group at the Westchester Medical Center in NY used the TQIP database to review the impact of ICP monitoring for severe TBI in patients > 65 years old. They performed a four year database study on these patients with an isolated head injury (no other body regions with AIS > 2), initial GCS < 8, and a length of stay > 24 hours. The examined the presence or absence of an ICP monitor, AIS head score, GCS, and a number of outcome measures.

Here are the factoids:

  • A total of 4,433 patients met the above criteria, and 17% had an ICP monitor placed
  • After propensity matching for those with and without an ICP monitor, mortality was nearly identical in both groups at 49%
  • ICU length of stay, hospital length of stay, and ventilator days were significantly longer in the monitor group

The authors concluded that ICP monitoring in this elderly group of patients did not improve survival and increased length of time in the ICU, hospital, and on the ventilator. The recommend that the current guidelines be improved to recognize these facts.

Bottom line: This is a nice, simple study that sought to answer just a few nice, simple questions. The mortality results are convincingly equal between the groups with and without an ICP monitor. The lengths of stay and ventilator days are statistically significantly longer with p values < 0.001. However, the actual numbers are not provided. I have seen many studies where statistically different numbers are not clinically relevant.

There are a number of papers that have come to similar conclusion on other or broader groups of TBI patients. Although we have specific guidelines on who gets a monitor and what we do with the numbers, there is growing doubt that their use actually helps. Perhaps it is time for us to review the data and make appropriate revisions!

Here are my questions for the authors and presenter:

  • Tell us about your propensity score matching. This will help us understand how similar the patient groups really were, with the exception of their ICP monitors.
  • Please provide the actual numbers for your lengths of stay and ventilator days. We need to be sure these are clinically and/or financially significant.
  • Have the results of this work prompted you to rework your own practice guidelines for treatment of severe TBI? I’m always interested if the group feels strongly enough about their work that they would consider changing their practice based on it.

Reference: ROLE OF ICP MONITORING IN GERIATRIC TRAUMA PATIENTS. EAST 35th ASA, oral abstract #33.