----- Original Message -----
From: "Mike Bjarkoy"
Subject: Lysis in the treatment of Cardiac Arrest
> OK - I know you are gonna say - 'Mike's lost it at last!' but here's a
thought...
> cardiac arrest is often dues to coronary thrombus/plaque rupture.
> There are other causes - the 4 H's and the 4 T's.
> Of these most can be identified and treated in the field.
Mike the four Hs and four Ts refer to the "treatable" causes of EMD (or
whatever it's called now). Many arrests are due to asystole, and some are
due to VF, the precise proportion depending, among other things, on time of
intervention. Of the four Hs and four Ts however, I believe that most of
these are untreatable:
Hypoxia - if someone arrests from end-stage hypoxia (respiratory failure)
it's unlikely that you will be able to recover them
Hypothermia - an unusual cause of EMD arrest; most will be asystole of VF
Hypo/hyperkalaemia - a rare and treatable cause of arrest
Hypovolaemia - usually something like an AAA - generally unsalvageable where
there is no output
Tension pneumothorax - a rare and treatable cause of EMD
Tamponade - mostly due to ventricular rupture - unsurvivable
Thromboembolism - very difficult to treat when there is no output
Toxins - arrhythmias due to poisoning with cardiotoxic drugs is very
difficult to treat
But most EMDs are none of the above, they are probably massive infarct with
marked ventricular hypokinesia, or else ventricular rupture, and none of
these are survivable. Most asystoles represent end-stage fine VF; most are
therefore unsurvivable.
So if one was to use thrombolytic agents, it would make sense to reserve
them for those patients who have resistant VF. Perhaps there might also be
an argument for the hypokinetic ventricle following massive infarct. There
seems no place for thrombolysis in asystole however. Finally these agents
require a "head of pressure" to allow coronary perfusion and thrombolysis,
and this is lacking during a cardiac arrest. Still I await studies with
interest...
Adrian Fogarty
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