Leg injury and shock position

[tickle me doe face]

We're considering EMT books accurate sources of peer-reviewed scientific information now?

I bet there was a team of peers writing it, yes.

Since when are textbooks considered not accurate?

it wasn't an outdated edition or anything

 

[tickle me doe face]

Legs up will help improve vitals (too tired for more details) but trendellenburg will do zip.

what's the difference between legs up and trendellinberg, i think those sound alot alike

 

[JPINFV]

"Shock position" is just the legs while "trendelenburg" is technically an entire body tilt and generally can't be done on ambulance stretchers without a backboard.

 

[Aidey]

Peer reviewed and several EMTs and Paramedics each writing a couple of chapters are not the same thing. And they are considered not accurate since they continue to teach the automatic, unquestioning use of backboards, high flow O2, trendelenburg, lights and sirens, urban helicopter response, MAST pants...etc.

Spend some time searching those topics on Pubmed. I promise what you find will not be what your EMT book says.

 

[tickle me doe face]

"Shock position" is just the legs while "trendelenburg" is technically an entire body tilt and generally can't be done on ambulance stretchers without a backboard.

ok. but is there really a difference between the two, like physiologically?

 

[tickle me doe face]

Spend some time searching those topics on Pubmed. I promise what you find will not be what your EMT book says.

I;m finding this out quickly.

Why is there such a discrepancy?

Shouldn't science always agree with itself, no matter who, or where it is done?

Why does the science in my EMT book and class, not agree with the science in the rest of the world?

 

[McGoo]

ok. but is there really a difference between the two, like physiologically?

Yes there is. Trendellenburg raises the feet a few inches above the body and also creates a low point of the head. Legs up raises the feet and legs by the length of the femur, creating a larger head of pressure, without the drain of the head.

 

[tickle me doe face]

Yes there is. Trendellenburg raises the feet a few inches above the body and also creates a low point of the head. Legs up raises the feet and legs by the length of the femur, creating a larger head of pressure, without the drain of the head.

are we talking legs up like 90 degrees???

 

[Aprz]

 

[systemet]

ok. but is there really a difference between the two, like physiologically?

Both positions risk reducing vital capacity by allowing the viscera to compress the diaphragm, limiting lung expansion. I'm not sure if would be worse to be head down, or to have your hips flexed. I'm not feeling energetic enough to search Pubmed right now, but I wouldn't be suprised if someone's studied the difference. I'd assume this would be a bigger issue in the obese patient.

I think the amount of blood redistributed to the core by Trendelenburg versus modified-Trendelenberg, versus spine position is likely to be fairly trivial.

In the situation described, if the extremity hemorrhage is controlled, and there's no suspicion of abdominal / chest trauma, I'd be happy to administer a fairly large amount of crystalloid, provided there's no CHF / renal failure issues to be worried about.

 

[systemet]

I;m finding this out quickly.

Why is there such a discrepancy?

I'm not sure if you're trolling, but...

Most of the people writing EMS textbooks lack a scientific background. Most EMTs and Paramedics lack an understanding of research methodology, statistics, epidemology, and all the other things necessary to understand evidence-based medicine. As a result we're not critical consumers of information. We tend to believe what we believe because (i) some instructor told us, (ii) a senior medic told us, (iii) some random MD told us, or (iv) we read it in some textbook. We don't tend to demand to look at the source material and critically evaluate what we're being told. The textbooks reflect this.

Shouldn't science always agree with itself, no matter who, or where it is done?

In essence, yes. The underlying physiology of the human body doesn't change because a different researcher is evaluating the response to a given experimental therapy. The same way that pi remains a constant, and that the circumference of a circle is always going to be 2 * pi * r.

The problem with the human body is that it's a very complex system, and the responses aren't always easy to measure. Our understanding of this system changes with time, and as we gather more information what appears to be a beneficial or promising therapy often turns out to be harmful. For reference see any of the ACLS / CPR guideline changes.

It's also hard to study. There's ethical limitations on what we can do to human subjects. Animal data doesn't always transfer. A lot of experimental research is performed on small rodents, due to the expense and ethical concerns with working with large mammals.

A consequence is that treatments are often introduced on the basis of limited data that seems neutral or slightly positive. When newer data is produced that brings a practice into question it takes time for a therapy to be withdrawn. Some practices are common place today because they were used historically, but are now considered to be of questionable efficacy.

Why does the science in my EMT book and class, not agree with the science in the rest of the world?

I'm going to suggest that the people writing your EMT textbook were probably largely ignorant of the science. I imagine the people teaching your EMT course probably are too. That's not to say they're not good people.

Are you being taught physiology by a physiologist? Pharamacology by a pharmacologist? Is a board-certified emergency physician teaching you emergency treatment?

There's also a limit to how much information you can put into a short course without academic prerequisites. In some cases you're being taught procedures and therapies without what you might consider is an adequate scientific background.

 

[Akulahawk]

Both positions risk reducing vital capacity by allowing the viscera to compress the diaphragm, limiting lung expansion. I'm not sure if would be worse to be head down, or to have your hips flexed. I'm not feeling energetic enough to search Pubmed right now, but I wouldn't be suprised if someone's studied the difference. I'd assume this would be a bigger issue in the obese patient.

I think the amount of blood redistributed to the core by Trendelenburg versus modified-Trendelenberg, versus spine position is likely to be fairly trivial.

In the situation described, if the extremity hemorrhage is controlled, and there's no suspicion of abdominal / chest trauma, I'd be happy to administer a fairly large amount of crystalloid, provided there's no CHF / renal failure issues to be worried about.

If the hemorrhage is controlled... I would probably stick with small amounts of crystalloid, judiciously administered so as to not pop clots. From what I've read, any effect you get from Trendelenburg or Modified Trendelenburg in terms of BP improvement is transient, and not much better, if at all, than supine positioning. With a Modified Trendelenburg, you may see some gravity induced autotransfusion of about 3-500 mL of blood to the central circulation though. That autotransfusion effect will disappear as soon as the legs are lowered back to supine, which limits it's practical use to showing if someone needs more fluid.

In the urban prehospital environment, it's going to be of little use.

 

[systemet]

If the hemorrhage is controlled... I would probably stick with small amounts of crystalloid, judiciously administered so as to not pop clots

I think I'd be less worried about this, if it's an isolated extremity injury.

With a Modified Trendelenburg, you may see some gravity induced autotransfusion of about 3-500 mL of blood to the central circulation though. That autotransfusion effect will disappear as soon as the legs are lowered back to supine, which limits it's practical use to showing if someone needs more fluid.

Is it that much? Because I think only about 500 ml of blood redistributes to the core when you go from standing to supine.

In the urban prehospital environment, it's going to be of little use.

Agreed.

 

[systemet]

This reference suggests that the redistribution of blood volume with a 15 degree full Trendelenburg versus supine is around 2% (of around 5.5 L, so about 110ml). When you read the article it seems like there's a lot of intersubject variability, e.g. changes in lower compartment blood volume of - 7.3% to + 0.2%, and it's just 10 subjects.

[This is also in healthy volunteers. I'd expect a hypovolemic trauma patient to already have substantial redistribution of blood from the extremities to the core, suggesting a lesser benefit. But that's just an opinion.]


Bivins HG, Knopp R, dos Santos PA. Blood volume distribution in the Trendelenburg position. Ann Emerg Med. 1985 Jul;14(7):641-3.

 

[Stingray91]

My book says the shock position is no longer recommended basically because the abdomen organs can be pushed up toward the diaphragm, making breathing more difficult, and increasing pressure inside the skull in pts with a head injury and of course, defiantly contraindicated in a pt. with suspected spinal injury. But the trendelenburg and shock are good to use for a pt who just suffered a simple faint.:deadhorse:

 

[medichopeful]

Why does the science in my EMT book and class, not agree with the science in the rest of the world?

Because it's such an entry-level class that they literally teach the bare minimum.

 

[Meursault]

I was hoping this thread would die quietly after a few people confirmed the textbook answers, this being the NREMT forum. Eh, into the fray.

I;m finding this out quickly.

Shouldn't science always agree with itself, no matter who, or where it is done?

Science is not a substance one extracts by doing research and then sprinkles on textbooks. Science is a set of methods/ontological framework for describing and interpreting the real world. Part of that involves learning to deal with conflicting research findings and opinions that conflict with each other or with research findings. In the case of your textbook, its opinion probably conflicts with the existing evidence because it was never based on any evidence at all, just a plausible idea.

 

[Meursault]

And I just checked my email and found an article in EMS World that cites the same handful of studies we've all been talking about:
http://www.emsworld.com/features/article.jsp?id=17918&siteSection=5

The author equivocates a bit, but so did some of the study authors.