How much does Trendelenberg/Shock position actually work??

[Ridryder 911]

You are right fluid will go to least resistance and will follow flow of gravity. The difference is blood flow is controlled in the circulation by way of pressure gradient and valves. Even veins have controlled valves ( as anyone whom establishes IV's can attest) and when the valves are closed helps prevents back-flow ( as seen in patients with prolapsed valves with conditions of varicose veins and hemorrhoids). Remember as well, patients in hemodynamic compromise blood, will shunt into deep capillary systems (pale skin) and will be entrapped as well in that system. The reason for EJ may due to large amount entrapped blood in the thoracic area thus backwash into the veins.

I agree attempting to change the paradigm shifts will be difficult with old school medics and thinking. Hopefully, organizations such as ITLS and PHTLS will at least discuss the dilemma and confusion. Of course there are those that will refuse to accept anything other than what they were taught initially, such as hyperventilation of head injuries and the mythical fluid resuscitation of trauma patients.

R/r 911

[AnthonyM83]

Ahh, but if trendelenburg doesn't work on normotensive patients than why would it work for hypotensive patients? Also, in the study with 11 patients, 9 patients saw a decrease. At least 2/3rds of the hypotensive patients saw their blood pressure decrease.

In science, you can't assume because it won't work in one case, then it won't work in another case. You can suspect it, then come up with a study to prove it. Because 1 out of ever 100 assumptions will be wrong b/c there'll be an extra mechanism at work we didn't know about yet. And yes, in one study 2/3 saw BP dec, but in another it had (apparently) all 100% had BP inc.

So, something's going on, either different ways of measuring, different periods of time in Trendelenburg before remeasuring, etc. Point is, we don't seem to be sure which one is doing it right (or at least which one is more like the circumstances in the field on a real EMS call).

Now the problem that the study showed was that you do not have this increase in stroke volume with the supposive increase in venous return from the legs. If this is true AND the trendelenburg works, then a different mechanism exists for it to increase the blood pressure besides Starlings.

Isn't that what it's seeming like if BP did in fact go up? Could it be possible that stroke volume does affect BP, but BP doesn't significantly affect stroke volume (except maybe in extreme cases were BP is extraordinarily high or low)? Again, my point being that these 3 studies aren't exactly conclusive. And it's definitely not enough to convince my EMT partners, like one who argued he's SEEN it work (of course, he didn't test it, it could have gone up anyway without lifting the legs).

Additionally, there's Spock who just posted that they prep CABG pts in T-burg to get SBP inc by at least 20mmHg. If I'm going to be the odd-man out at work whose always coming in with new EMS ideas/research, it's gotta good.

Now let's throw in the cons. The blood is not going to just increase venous pressure at the heart, but also a the brain. Increase intracranial pressure might be worse for the patient in the long run by causing more damage. Researchers have seen an increase in difficulty breathing because the diaphram now has to lift the abdominal organs while decreasing intrathoracic pressure.

Now, there are some good points and that's what warrants more research into the topic.

[AnthonyM83]

Of course there are those that will refuse to accept anything other than what they were taught initially, such as hyperventilation of head injuries

PS Glad you told me about this one. I was just watching an EMT Refresher DVD course just for fun and they had one of those old "Emergency Medical Updates" clips discussing that. There I was absorbing it like it was new information. :-/

I believe they were saying injuries increase ICP as more blood tries to get to the area to feed it, but with O2 and even ventilations you feed it the oxygen it needs, thus reducing ICP. But I guess that's wrong. But apparently also giving O2 itself could increase ICP? Was that part of the O2 thread discussion..

[akroeze]

The only thing I have to contribute is that as of January 1st of this year the province of Ontario has removed elevation of feet from the BLS patient care standards.

[JPINFV]

In science, you can't assume because it won't work in one case, then it won't work in another case.

That happens all the time in stage 1 or stage 2 drug studies. Why do drug studies on healthy volunteers if you can't use the data collected to determine dosing (frequency of administration, amount per administration, and maximum dose) for sick patients?

Isn't that what it's seeming like if BP did in fact go up? Could it be possible that stroke volume does affect BP, but BP doesn't significantly affect stroke volume (except maybe in extreme cases were BP is extraordinarily high or low)? Again, my point being that these 3 studies aren't exactly conclusive. And it's definitely not enough to convince my EMT partners, like one who argued he's SEEN it work (of course, he didn't test it, it could have gone up anyway without lifting the legs).

If trendelenburg doesn't increase cardiac output, but increases blood pressure then what mechanism does it do so by? Blood pressure is simply (warning: generalization, viscosity and concentration also affects a patient's blood pressure, but there is no reason for these to change because of patient positioning) a combination of the volume of the liquid and the volume of the container in the systematic arteries. Volume is added by the heart (stroke volume) at high pressure and leaves via the capillaries at low pressure. The volume of the container can change too depending on the patient (sympathetic and parasympathetic nervous system activation) and drugs given (nitro, epi).

While it is at least my understanding that, ignoring homeostasis (but if BP is a problem then the body is failing to self correct anyways), BP does not change a patient's stroke volume, but venous return (always low pressure) does.

Additionally, there's Spock who just posted that they prep CABG pts in T-burg to get SBP inc by at least 20mmHg. If I'm going to be the odd-man out at work whose always coming in with new EMS ideas/research, it's gotta good.

1. Is there any prehospital gurney that offers true trendelenburg (entire body tilt), or do all prehospital gurneys only lift the legs.

2. Spock, do you know if CVAs have been known to develop in patients while being prepped due to increased intracranial pressure?

[Richard B the EMT]

This seems to hint at the old adage that there are lies, damned lies, and statistics.

[AnthonyM83]

That happens all the time in stage 1 or stage 2 drug studies. Why do drug studies on healthy volunteers if you can't use the data collected to determine dosing (frequency of administration' date=' amount per administration, and maximum dose) for sick patients? [/quote'] Yes, but then they actually try the drug on sick patients to see if it works, before they say it works. Likewise, you have to eventually have studies showing hypotensive patients not having BP inc, first...not one showing increase and one showing decrease.

Good question...maybe it does it, because BP is usually taken in the arm and somehow increases the reasing there by backing up blood there? Something of that nature of blood pooling down and increasing pressure by weight/filling space? Maybe it's something else...but the fact we can't come up with an explanation doesn't validate the new theory...it only adds some support. Conclusive studies is what we need.

Additionally, there's Spock who just posted that they prep CABG pts in T-burg to get SBP inc by at least 20mmHg. If I'm going to be the odd-man out at work whose always coming in with new EMS ideas/research, it's gotta good.

As far as Trendelenburg gurney...I don't know. I know ours are far from it, though, especially when we have the portable O2 tank strapped to the head end, it gets in the way of lowering the patient's head to even a neutral tilt. The leg tilt is okaaay, but still better if you add padding to increase the tilt. I wonder what angles the studies were done at...I wonder what studies would say if done on Striker gurney beds with and without adding extra padding to elevate the feet.

[JPINFV]

^

What I was trying to get at with that last part is that most gurneys do not do a true trendelenburg (at least not the Fernos or Strykers that my company uses). Most (all?) just lift the legs instead of tilting the whole body.

[AnthonyM83]

Yeah, but they might still help some...and around here it really matters to the medics, because it can determine whether they get a bed or chair in the ER...if it's a bed, you find yourself waiting hours sometimes.

So we need to find out BEFORE calling it a myth.

[arctic_myst]

I would have to say that after talking to many of the medics I work with, they pretty much feel like the trendelenburg position is a waste of time and a hastle in the code and a few other emergency settings. However, it does work well with other problems like minor hypovolemia.

On the other side of this, what about someone who is telling you they are going to be sick and retching in the truck all the way to the ER. We told the receiving facility he was sick and felt like he was going to throw up. We picked him up for SVT. We gave 2 doses of adenosine before it worked. It brought his HR down, but we couldn't get his blood pressure up where we wanted it. So when we get to the ER, we tell them the exact deal. We can't get his blood pressure up, but, if you lay him back he WILL blow chunks. Long story short, they took a blood pressure, laid him back in trendelenburg's and he blew chunks....projectile style. It peaks my curiosity what effect the vagal response will have on a patient like that when their pressure is already low. Isn't that causing the potential for more problems?