Category Archives: General

General

Hypothermia and Massive Transfusion

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Tuesday, I talked about a new notion of using profound hypothermia to save critically injured trauma patients. Since this concept is not yet ready for prime time, we still have to treat hypothermia as our enemy. Most trauma centers have established massive transfusion protocols that detail the use and ratios of specific blood components to avoid fatal anemia and coagulopathy. But do we pay enough attention to hypothermia?

A multicenter study was carried out that will be reported at the upcoming EAST meeting in January. They looked at patients who received massive transfusion (>= 10u PRBC in 24 hours) and looked at their lowest temperature during that 24 hour period. 

They found that as temperature decreased, shock parameters, coagulopathy, injury severity and transfusion requirements increased significantly. Specifically, if a temperature of <34C doubled mortality risk, and this effect was most pronounced in patients who received relatively less plasma.

Bottom line: Temperature is still very important, and hypothermia must be avoided at all costs. This is true in the ED and the OR. Allowing temperature to drop below 34C significantly increases mortality and is at least as important as giving enough FFP to correct coagulopathy from dilution.

Related post:

Reference: Hypothermia in massive transfusion: are we not paying enough attention to it? Poster 2, EAST 25th Annual Assembly, Jan 2012.

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Induced Hypothermic Arrest In Patients Bleeding To Death?

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Here’s an interesting note out of the University of Pittsburgh. They are preparing to engage in a study to look at the role of hypothermic arrest as a way to salvage trauma patients who are bleeding to death. Sometimes we encounter catastrophic injuries that are exceeding difficult to stop the bleeding. Some vascular injuries within the abdomen come to mind, particularly retrohepatic vena cava injuries.

So what would happen if you rapidly reinfused the patient with cold preservative instead of more blood? The idea is to stop the heart and induce profound hypothermia that would essentially put the brain and other key organs into suspended animation. This might provide a period of time to do the needed repairs, but not worry about the imminent danger of brain death.

Sam Tisherman, the principal investigator, terms this scenario EPR or “emergency preservation and resuscitation” instead of CPR. The desired temperature after cardiac arrest is 50 degrees F, or 10 degrees centigrade. Animal trials have shown promise.

Bottom line: It will be interesting to see how this goes. We’ve tried hypothermia for heart attacks, head injury, and a number of other clinical problems. Unfortunately after initial enthusiasm, they’ve generally not lived up to their billing. It seems counterintuitive to use a maneuver guaranteed to produce coagulopathy to save somebody who is bleeding. But sometimes this type of bold thinking results in life-saving breakthroughs.

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Percutaneous Tracheostomy Without The Bronchoscope

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It’s always nice to find an article that supports your biases. I’ve been doing percutaneous tracheostomy since the 1990’s, and have used a variety of kits and equipment. Some of these turned out to be rather barbaric, but the technique is now quite refined. 

A routine part of the procedure involved passing a bronchoscope during the procedure to ensure that the initial needle was placed at the proper level and in the tracheal midline. It was also rather frightening to watch the trachea collapse when the dilators were inserted.

I abandoned using the bronchoscope in this procedure about 10 years ago. It was an annoyance to get the bronchoscope cart and a respiratory therapist to help run it. And to find someone available to pass the scope while I did the trach. So I added a little extra dissection to the technique, directly visualizing the trachea at the desired location. From then on, I had no need to see the puncture from the inside because I could see it quite well from the outside!

An article in the Journal of Trauma this month shows that this technique works just as well without the scope. The authors looked at their own series of 243 procedures; 32% were done with the bronchoscope, 68% without. There were 16 complications overall, and the distribution between the bronch and no-bronch groups was equal.

Bottom line: In general, the bronchoscope is not needed in most percutaneous tracheostomy procedures. It adds complexity and expense. However, there are select cases where it can be helpful. Consider using it in patients in a Halo cervical immobilizer, the obese, or in patients with known difficult airway anatomy. And always do the more difficult ones in the OR, not the ICU.

Reference: Percutaneous tracheostomy: to bronch or not to bronch – that is the question. J Trauma 71(6):1553-1556, 2011.

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Technology: Real Time Cerebral Blood Flow Monitoring For TBI

Here’s a new toy that has recently received some funding from the US military. It allows real-time monitoring of cerebral blood flow. It may help identify flow problems from elevated intracranial pressure (ICP) or vasospasm early on, allowing prompt initiation of appropriate therapies to increase blood flow.

This device uses an array of ultrasound beams and locks onto the middle cerebral artery. It then continuously monitors blood flow and displays the result in real time. I predict that there will be a learning curve with this one, similar to near infrared monitoring of tissue perfusion. What’s a normal baseline? What kind of variation is considered “normal?” We’ll have to answer these questions before this tool is ready for prime time. Ultimately, it may allow noninvasive monitoring of ICP in the intensive care unit.

Credit: Physiosonics, Bellevue, WA.

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Blood Transfusion With Component Therapy

About 40 years ago, blood banks started moving away from keeping whole blood and began separating it into components (packed cells, platelets, plasma, etc.) for more targeted use. For most uses, this is just fine. But what about trauma?

Trauma patients bleed whole blood. Doesn’t it make sense to give whole blood back? Much of our experience with massive transfusion is derived from our colleagues in the military. Two decades ago, the norm was to give 4 units of packed red cells or so, then give two units of plasma, and every once in a while slip in a bag of platelets. Our military experience seems to indicate that this 4:2:1 ratio is not optimal, and that something like 1:1:1 is better.

If you think about it, whole blood is already 1:1:1. Splitting it into components and then giving them back seems to be a lot of extra work (and expense) to accomplish the same thing as just giving a unit of whole blood. Plus it triples the exposure to infectious agents and antigens, since the components will usually come from three separate donors. Note that the data in the table above is true for fresh whole blood (not practical in civilian life); banked whole blood will lose some coagulation activity.

Is it time to think about supplying whole blood to trauma centers? And actually looking at whether the outcomes are better or not?

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