View Full Version : hypothermia and survival post trauma
one of the pages at:
http://www.traumacare.no
sets down the basic principle of preventing hypothermia in order to prevent blood loss:
"Preventing hypothermia
Cold blood bleeds more due to platelet dysfunction. To stop bleeding, patients must be kept warm. We studied the in-field body temperature of 170 mine victims and found that post-injury hypothermia is a problem also in areas with a warm climate. Simple preventative in-field measures (removing wet clothing, cover with dry blankets, giving warm (40C) IV fluids) help prevent hypothermia when the prehospital evacuation times are high. Husum H, Olsen T, Murad M, Heng YV, Wisborg T, Gilbert M: Preventing hypothermia: a study of land mine victims in North Iraq and Cambodia. Prehosp Disast Med (submitted)."
This is rather surprising and comes into conflict with another school of thought. I'm thinking mainly of experience from river rescue where cold/hypothermia allowed prolonged periods of inadequate perfusion (heart is stopped or very slow) without neural deficit. The ultimate aim of the ABC's is to keep the brain alive, and hypothermia seems to help that. Additionally, when cold (but also when in shock) the vascular system constricts to force blood into the center of the body. For extremity wounds, hypothermia would seem a good idea. Likewise, it would increase tissue survival if the feeding vessles had been severed.
Just playing devils advocate here - discussion or thoughts?
-t
Tangent, There is very little conflict here.
Patients who have had a cardiac arrest and have their metabolism cooled significantly - ie immersed in very cold water have a potential for resus following a prolonged downtime.
Trauma patients who get cold become coagulopathic, are more likely to develop acute lung injury and are physiologically more unstable and diffcult to manage.
Different patient populations.
There is some debate in the second patient group over hypothermia and survival in view of some of the data from the Falklands war. But that data is limited and is probably only applicible to fit and healthy men, who have isolated penetrating extremtiy injuries, who survive the initial injury and have their bleeding controlled early - this isnt your average trauma patient - for them getting cold is a bad thing.
Craig
Craig,
thanks for the answer. Still, could you elaborate a bit on the physiology and "why" or "what's going on" for these 3 statements/terms:
1) coagulopathic, (new term to me - could you elaborate on what happens and how much cold really effects coagulation)
1a) would hypothermia be a good Tx for CHF or ischemic stroke, in the absence of drugs?
2) are more likely to develop acute lung injury (what is "acute lunk injury" and why would cold effect it?)
3) and are physiologically more unstable (how and why)
my thoughts were basically - ABC's purpose is to supply oxegenated blood to the brain, while cold is known to delay brain damage due to lack of oxegenated blood. It didn't seem like that much of a streach. Obviously shock throws a monkey wrench into this - but why...?
my understanding is that hydergine and/or piracetam are administered SOP for trauma in Europe for the same reason (protecting brain cells), yet I have not found a US MD, PA, nurse or paramedic that have ever heard of them here in the USA. I have seen them described as "miracle drugs" in these applications (drownding victims too).
from:
http://www.lef.org/protocols/prtcl-106.shtml
Protecting Brain CeLLS
To protect brain cells against oxygen deprivation or from permanent damage caused by head trauma, 10 mg of sublingual Hydergine should be immediately administered along with 10 mg of Hydergine tablets. Hydergine (ergoloid mesylates) is a potent antioxidant that facilitates oxygenation of brain cells. Although it is an FDA-approved drug to treat dementia, Hydergine is not always readily available in hospital formularies. Many Americans obtain Hydergine from European or Mexican pharmacies.
If piracetam is available, 4800 mg of piracetam should be administered to further protect against brain damage. Piracetam is a derivative of the amino acid gamma-aminobutyric acid (GABA), which increases neurotransmitter sensitivity in the brain. It is used in Europe to improve memory and learning. Many Americans obtain piracetam from European or Mexican pharmacies (or American compounding pharmacies). In 903 patients with head concussions of varying degrees of severity, treatment with piracetam and antiedema drugs resulted in swift disappearance of symptoms and a quick recovery of normal cerebral activity, plus a noticeable decrease in hospital stays (Cicerchia et al. 1985).
Vitamin E administration has been shown to reverse free-radical damage induced by trauma and to reverse the effects of lipid peroxidation after trauma. The administration of vitamin E has also been shown to therapeutically protect against reduced T-cell membrane fluidity and suppressed T-cell functions (Liang et al. 1996). Additionally, in mice, a vitamin E-enriched diet has been shown to protect their brains against brain-circulatory injury (Rosenblum et al. 1996). Diabetic rats experience a delay in corneal healing when they are deficient in vitamin E (Hallberg et al. 1996). Trauma patients should consider supplementing with 800 IU daily of vitamin E along with 200 mg of gamma tocopherol and preferably at least 50 mg of palm-oil derived tocotrienols.
Protecting Against ParalysIS
In laboratory animals, the hormone pregnenolone has been shown to protect against paralysis from spinal cord injury (Cathala et al. 1975; Bloom et al. 2002). The immediate administration of 400 mg of pregnenolone, along with 800 IU of vitamin E, to a spinal-injured patient might be advisable. However, vitamin E can accelerate the bleeding process; therefore, vitamin E should not be used if there is excessive bleeding.
-t
>1) coagulopathic, (new term to me - could you elaborate on >what happens and how much cold really effects coagulation)
Coagulopathic means the clotting pathways are not working properly. Cold impairs platelet function, but also reduces the activity of the clotting factors in the blood.
>1a) would hypothermia be a good Tx for CHF or ischemic >stroke, in the absence of drugs?
CHF - no hypothermia wouldnt make any difference - the problem with heart failure is (in most cases) a mechanical one - and the treatment needs to aimed at altering the mechanics of pumping function of the heart - lowering body temperature wont help - and may make it worse because cold blood is harder to pump.
Stroke - in theory a good idea - but what research that has been done suggests that in stroke and head injury it dosnt help. However in Cardiac arrest mild cooling of a patient for the first few hours probably improves survival
>2) are more likely to develop acute lung injury (what >is "acute lunk injury" and why would cold effect it?)
Acute lung injury (or ARDS - adult respiratory distress syndrome) is complicated - essentially the blood vessels in the lung become leaky and the alveoli walls became swollen and inflammed (thats a gross simplification). Dont know why cold makes ALI worse - but it does
3) and are physiologically more unstable (how and why)
Its harder to main perfusion - BP and heart rate all over the place - the effect of cold is thought to be two fold - a direct effect on nerve conduction - slow it mostly and also slowing down enzymatic reactions - which in an acute stress response is vital
So you are right cold delays cellular injury - but it also has many undesirable physiological effects - the evidence at the moment (outside cardiac arrest) is that cooling people dosnt improve outcome.
As for the neuroprotective agents - piracetam is currently being used in a large trial - but there is no good evidence currently it improves outcomes - so we wait
There is lot of research going on looking at hypothermia and dozens of neuroprotective agents all around the world - so I think the jury is still out - but so far there is no magic bullet for severe brain injury despite what some organisations and web sites seem to say.
You have to keep coming back to this question: "Is there any evidence, from a randomised controlled trial, that treatment X improves the number of people who survive or have a meaningful recovery in condition/injury Y" . IF you ask that question everytime you read something that sounds good in a medical journal or on the internet you will rapidly sort out fact from fiction
Craig
great answers - thanks!
on number 1) - you never really addressed how much cold effected coagulation. Are we talking a little slower to clot or does not clot at all or....? The chemistry makes perfect sence.
on ergot for CVA's, etc. I punched in "hydergine AND stroke" to PubMed and it kicked out 8 articals. Some were controlled studies, and I'm quite sure I've seen others in the past. So I think they do in fact work. One study was inconclusive after 10 days, however, they felt it important enough to put the caviot in the abstract "at least at the dosage levels used in the study". This strongly suggests to me that they expected different results and their results were not in line with other studies. I haven't tracked down any of the studies yet.
you are right - it's a good disapline in evaluating information.
thanks,
-t
Tangent,
% activity at any given temperature is different for each coagulation factor. By the time you get below 28-29 degrees (from memory) there is essentially no activity - but the actual rate of decline from normal body temp varies.
Not sure where the reference to Ergot came from - but pure Ergot would by very very bad in Stroke - it causes forceful spasm of the blood vessels - not good.
Again as you know abstracts on pubmed tell only a fraction of the real story - >75% of published medical trials are rubbish - the trick is picking the ones that are of quality. My partner is a Critical care physician and she tells me these trials are crap - and there is no good evidence these agents are helpful - but I havent researched them myself. Im told there is NO neuroprotective drug that has shown a benefit when subjected to LARGE randomised controlled trials - intensive care specialists are desperate for a decent neuro-protective agent - but while promising in small studies and animal models they have not carried any benefit into large trials - or large trials havent been done. So while I think your enthusiasm for these agents is laudable - good evidence isnt there. Many of these small trials measure outcomes that are not important - you need to keep coming back to the question I posed before - does a treatment meaningfully improved function or survival - a 5 point improvement in a mental function score may be statistically significant and result in a positive trial result - but if both groups of patients are still bed bound with severe intellectual impairment - then that 5 point improvement is completely irrelevent and in no way supports the use of a new drug. - Do you see what Im getting at - you have to be extremely critical of the medical literature because so much of it is rubbish
Talking about hypothermia - in the JAMA about 2-3 weeks ago they had a meta-analysis looking at hypothermia in head injury - they sat firmly on the fence - said it might work - but more trials were needed and that it shouldnt be used outside research trials
Craig
> % activity at any given temperature is different for each coagulation factor. By the time you get below 28-29 degrees (from memory) there is essentially no activity - but the actual rate of decline from normal body temp varies.
would that be C or F?
> Not sure where the reference to Ergot came from - but pure Ergot would by very very bad in Stroke - it causes forceful spasm of the blood vessels - not good.
both hydergine and piracetam are Ergots.
I wouldn't put the "rubbish" % quite so high, however, I would put the "really useful" and "important paper" class of papers between 4% and 20% depending on the topic. That is of returned papers retrieved in a search. I do not subscribe to any medical journals (OK - one) and do not read any on a monthly basis. The only ones I have read from inception to pressent are JSOM and Trop Doct, both are highly useful. I've browsed and done broot force scans of others - WHO series and PAHO journals, Mil Med. I suspect what we are exposed to as to quality may be different due to our reading habits. - thoughts?
I do know what you mean though - there was one paper on the stability of epinepherine and the MD's that wrote it couldn't explain one "artifact" in their results, but I knew exectly where their mistake was - it was in the experimental technique. Every time they took a sample, they introduced O2 -> degredation of the drug... they took a lot of samples.
Thanks for the pointer to the JAMA artical.
Overall, great answers! - thanks!
-t
Hi again Tangent,
Celsius - the units everyone else in the world except the US uses !!
Ergot is a specfic drug
Ergots are a structural class --> important difference
I strongly disagree with you regarding the % quality - it is an absolute discrace, the number of really bad articles published in the medical literature - I would recommend Sacketts "Evidence Based Medicine", 2nd Ed - Oxford Uni press - I think - provides an excellent approach to picking out the good ones. I think we are talking at cross purposes to a point here - Im not talking about articles that I find interesting or have a positive result, Im talking about articles that are solid enough for me to change my practice - these are few and far between - a couple of small studies with bad design and 50 or 60 people isnt enough to change practice - its the major deliema of medicine - I spend several hours a week looking through relavent journals to my practice and bulk of it is crap.
Ive just read an article in last weeks Lancet on Asthma management - you read the abstract and it sounds great - you read the article and break down the methods and the data analysis and its absolute rubbish and its published in a major international journal - but you look at medline/pubmed and you would think it was a good article.
Craig
> Ergot is a specfic drug
Ergots are a structural class --> important difference
oops! - thanks!
> I think we are talking at cross purposes to a point here - Im not talking about articles that I find interesting or have a positive result, Im talking about articles that are solid enough for me to change my practice - these are few and far between
absolutly agree!
-t
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