Crush and tourniquets

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O.K. I'll play.

In order to promote discussion, some thoughts on the
subject.

We know that the problems that ensue in crush are due to
diminished limb perfusion, usually due to venous
obstruction but possibly arterial as well.  The
consequence of this is obviously cellular anaerobic
metabolism, build up of cellular waste products esp
lactate, cellular swelling progressing to cellular death.
Resultant metabolic abnormalities coupled with this
include potassium, CK and myoglobin release.  So all this
sits in the limbs until the compressive force is released
and allowed back into the general circulation.

 From a long term management point of view the big issue
is the resultant renal failure secondary to rhabdomyolysis
coupled with the trauma to the limb and compartment
syndrome risks.  From the prehospital point of view the
issue is the sudden release of potassium and lactae into
the general circulation, coupled with the resultant
hypovolaemia from suddenely decreased
vascular resistance and its effect on the organs
principally the heart, which tends to react badly to
acidosis and large potasium loads, i.e. significant
arrhythmias.

We manage these prehospial then by giving adequate fluid
load to maintain adequate renal perfusion and protect from
effects of hypovolaemia.  The addition of sodium
bicarbonate to every second or third bag makes sense in an
attempt to maintain a urinary pH above 6.5 which decreases
the risks of renal failure caused by myoglobbin
preciptitation/casts/gel/gunk clogging up the renal
tubules/collecting system.  But what about the acidemia
and potassium load on the heart?
  
My approach to this is to ensure that I have defibrillator
pads attached to the patient prior to release (if
possible, access permiting) and that I have an ampoule of
calcium chloride ready to give at the first sign of ECG
changes looking like hyperkalaemia (i.e peaked T waves, no
p waves widening QRS etc).  Obviously not to be given in
the same line as the bicarb, limestone formation is
unlikely to help anyone.

If we consider that when people are pinned such that crush
injury is a factor, it is usually by the lower limbs and
usually bilateral then applying tourniquets to both limbs
(if possible, often not, or only one limb accessible) just
proir to patient release would seem to make theoretical
sense.  Then once patient released, releasing one
tourniquet would allow a measured release of acid and
potassium, the effect of this could judged on the basis of
ECG changes, if problem treat and wait until treatment
(i.e calcium, defibrillation, insulin/dextrose) has been
implemented and successful until subjecting heart to a
second insult before releasing the second tourniquet.  If
no effect upon releasing the first tourniquet, then
release the second and be ready to treat again.  This
would seem to be similar to the process of unclamping the
iliacs one at a time and monitoring the effects that
occurs in aortic surgery.

So my thoughts, but I have a question as well to add to
the discussion.

Would/do people give calcium prophlactically pre-release
or are people more inclined to have ready and treat on the
basis of clinical/ECG changes?

Looking forward to thers thoughts/discussion on this.

Cheers,
Stefan

Dr Stefan Mazur
Emergency Physician/Retrieval Fellow
Adelaide
Australia


On Mon, 18 Dec 2006 23:51:59 +0000
  "Mark Hellaby" <hellaby at hotmail.com> wrote:
> 
> 
> 
>  
> Much the talk so far has surrounded major bleeds and 
>snakes !  
> There has been nothing about the use of touniquets to 
>isolate a crushed limb from circulatory system prior to 
>release to allow rehydration, acid base analysis / 
>correction etc  and then following this a controlled 
>staged release in a managed environment....I would be 
>interested in peoples thoughts on this aspect of touniquet 
>use aswell regards
> 
> 
>    Mark Hellaby BSc (Hons), RODP 
> Think you're a film buff? Play the  Movie Mogul quiz 
> for a chance to win fantastic prizes  
> 
>  
> Click here to report this email as spam. 


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