Trauma professionals tend to focus on the two extremes of TBI: mild concussive injury because we see so much of it, and very severe injury that we have to work so hard to keep the patient alive. Today I’ll write about the one in the middle, diffuse axonal injury (DAI). People don’t talk about it nearly as much, and it seems kind of mysterious.
DAI is also known as a shear injury, because that’s what we think happens to the brain at the time of injury. Officially, it is diagnosed when a patient remains in a coma for more than 6 hours without a demonstrable mass lesion from bleeding seen on CT. It is seen in about 15% of trauma ICU patients with head injury. Essentially the substance of the brain moves around enough to disrupt a critical mass of axonal connections that results in prolonged unconsciousness. It then takes time to try to rebuild those connections and restore consciousness and some degree of cognition. Mechanisms which result in sudden acceleration or deceleration of the brain may cause this condition, and rotational forces which spin the head suddenly seem to be even worse.
CT scan of the head frequently shows no unusual findings. On occasion, small punctate hemorrhages may be seen. These are generally bad prognostic signs, because CT is so much less sensitive in showing these compared to MRI. Here are some key points about DAI:
If the head CT is negative,and all recreational drugs have worn off and the patient still doesn’t wake up, DAI is likely.
MRI can confirm the diagnosis, but is not good for giving a prognosis
Slow recovery of consciousness or failure to recover correlates with death
Hyperglycemia and the presence of a subdural also are highly correlated with mortality
Bottom line: The diagnosis of DAI can generally be made clinically with the assistance of head CT. MRI is not very useful, unless it is needed to confirm the diagnosis. It does not predict speed or degree of recovery so is otherwise not very useful. Supportive care, avoidance of complications and early therapy and rehab are the best treatments we have to offer.
Reference: Diffuse axonal injury in patients with head injuries: an epidemiologic and prognosis study of 124 cases. J Trauma 71(4):838-846, 2011.
Injury can be a bloody business, and trauma professionals take replacement of blood products for granted. Some patients object to this practice on religious grounds, and their health care providers often have a hard time understanding this. So why would someone refuse blood when the trauma team is convinced that it is the only thing that may save their life?
Jehovah’s Witnesses are the most common group encountered in the US that refuse transfusion. There are more than 20 million Witnesses worldwide, with over 7 million actively preaching. It is a Christian denomination that originated in Pennsylvania during the 1870s.
Witnesses believe that the bible prohibits taking any blood products, including red cells, white cells, platelets or plasma. It also includes the use of any dialysis or pump equipment that must be primed with blood. This is based on the belief that life is a gift from God and that it should not be sustained by receiving blood products. The status of certain prepared fractions such as albumin, factor concentrates, blood substitutes derived from hemoglobin, and albumin is not clear, and the majority of Witnesses will accept these products. Cell saver techniques may be acceptable if the shed blood is not stored but is immediately reinfused.
Why are Witnesses so adamant about refusing blood products? If a transfusion is accepted, that person has abandoned the basic doctrines of the religion, and essentially separates themselves from it. They may then be shunned by other believers.
So what can trauma professionals do to provide best care while abiding by our patient’s religious belief? In trauma care it gets tricky, because time is not on our side and non-blood products are not necessarily effective or available. Here are some tips:
Your first duty is to your patient. Provide the best, state of the art care you can until it is absolutely confirmed that they do not wish to receive blood products. In they are comatose, you must use blood if indicated until the patient has been definitively identified by a relative who can confirm their wishes with regard to blood. Mistaken identity does occur on occasion when there are multiple casualties, and withholding blood by mistake is a catastrophe.
Talk with the patient or their family. Find out exactly what they believe and what they will allow. And stick to it.
Aggressively reduce blood loss in the ED. We are not always as fastidious as we should be because of the universal availability of blood products. Use direct pressure or direct suture ligation for external bleeding. Splint to reduce fracture bleeding.
Aggressively use damage control surgery. Don’t go for a definitive laparotomy which may take hours. Pack well, close and re-establish normal physiology before doing all the final repairs.
Always watch the temperature. Pull out all the stops in terms of warming equipment. Keep the OR hot. Cover every bit of the patient possible with warming blankets. All fluids should be hot. Even the ventilator gases can be heated.
Think about inorganic and recombinant products such as Factor VIIa, tranexamic acid and Vitamin K. These are generally acceptable.
Consider angiography if appropriate, and call them early so their are no delays between ED and angio suite or OR and angio suite.
Bottom line: Do what is right for your patient. Once you are aware of their beliefs, avoid the use of any prohibited products. Speak with them and their family to clarify exactly what you can and cannot do. This is essentially an informed consent discussion, so make sure they understand the consequences. Follow their wishes to the letter, and don’t let your own beliefs interfere with what they want.
For the most part, hypothermia is a bad thing for trauma patients. Its impact on bleeding and mortality has long been known. A paper just out now implicates it in surgical site infections as well. This fact has already been shown for some types of elective surgery (colorectal), but it appears to be a factor in trauma laparotomy as well.
A retrospective review of 524 patients who underwent a trauma lap looked at the correlation of surgical site infection (SSI) and the depth and duration of hypothermia. The mean low temp across all cases was 35.2° C (!). Nearly a third had at least one measurement below 35° C. About 36% of all patients developed an SSI.
Hypothermia is a common problem in these patients!
35 C was the nadir temp most predictive of developing an infection
Every degree below 35 C more than tripled the risk of SSI
Bottom line: Yet one more reason to avoid hypothermia in our trauma patients! This effort begins with prehospital providers doing their best to insulate and keep patients warm. The trauma team also has a responsibility to heat up the room and keep the patient covered as much as possible. Baseline temp should be obtained in all major trauma patients. And if they do end up in the operating room, anesthesia needs to monitor the temp closely and keep the surgeon apprised of any concerning drops.
Time for some philosophy again. A paper in Neurology released ahead of print confirms something I’m seeing more and more often. Specifically, hospitals can be bad for you, particularly if you are elderly.
The trauma population that we all see is aging with the overall population. Being older predisposes one to injuries that are more likely to require hospitalization. And unfortunately, being in the hospital can have adverse effects. I’m not just talking about the usual culprits such as medical errors or exposure to resistant bacteria.
The Chicago Health and Aging Project has been tracking a group of elders as they age, and has been making a number of interesting observations. Most recently, they have released information on a correlation between cognitive decline and hospitalization. They tracked nearly 1900 people, of whom 1335 ending up in the hospital for one reason or another (not just trauma). They found that there is a baseline rate of global cognitive decline with age (surprise!). Unfortunately, this rate of decline accelerated 2.4 times in the hospitalized group. Episodic memory scores declined 3.3 times faster, and executive function declined 1.7 times faster. And declines tended to be more pronounced in patients who had more severe illness, longer hospital stay, or advanced age.
There are some issues with the study. It is large, but it is a correlation study nonetheless. Are the effects due to something that happens in the hospital, or are they caused by something not evaluated by the study? It’s also not clear to me whether the declines noted are clinically significant in the daily lives of the people studied, or are just a number on some scale.
Bottom line: Some of the “benign” things that we do to patients in the hospital can have a big impact on their functional outcome. Always remember that they are more fragile than the young trauma patients we take care of. That extra fluid bolus, or dose of morphine, exposure to IV contrast, or noisy neighbor that keeps them from sleeping can make a real difference in how they do. Always consider that everything you do to them might kill them. Then seriously reconsider whether you really, really need to order it at all.
I’ve written about handoffs between EMS and the trauma team over the past two days. It’s a problem at many hospitals. So what to do?
Let’s learn from our experience in the OR. Best practice in the operating room mandates a specific time out process that involves everyone in the OR. Each participant in the operation has to stop, identify the patient, state what the proposed procedure and location is, verify that the site is marked properly, and that they have carried out their own specific responsibilities (e.g. infused the antibiotic).
Some trauma centers have initiated a similar process for their trauma team as well. Here’s how it works:
The patient is rolled into the resuscitation room by EMS personnel, but remains on the stretcher.
Any urgent cares continue, such as ventilation.
The trauma team leader is identified and the EMS lead gives a brief report while everyone in the room listens. The report consists of only mechanism, all identified injuries, vital signs (including pupils and GCS), any treatments provided. This should take no more than 30 seconds.
An opportunity for questions to be asked and answered is presented
The patient is moved onto the hospital bed and evaluation and treatment proceed as usual.
EMS personnel provide any additional information to the scribe, and may be available to answer any additional questions for a brief period of time.
Bottom line: This is an excellent way to improve the relationship between prehospital and trauma team while improving patient care. It should help increase the amount of clinically relevant information exchanged between care providers. Obviously, there will be certain cases where such a clean process is not possible (e.g. CPR in progress). I recommend that all trauma programs consider implementing this “Trauma Activation Time Out For EMS” concept.