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so just to break down a couple of these
interventions a little bit more
epinephrine is a vasoconstrictor that's
why we use it in cardiac arrest as you
probably remember from pharmacology it's
a non-selective adrenergic drug meaning
it acts on the alpha and beta adrenergic
receptors all equally the great thing
about epinephrine is it increases
systemic vascular resistance so it
clamps down all the blood vessels below
the diaphragm and it cuts off blood flow
to organs we don't care about in cardiac
arrest like the liver and the kidney
what we care about in cardiac arrest is
the heart itself and the brain because
those are the two organs that are going
to determine our ultimate outcome in the
setting of arrest unfortunately even
though it makes a lot of sense to give a
medication that would optimize cardiac
and cerebral blood flow there's not
really great scientific evidence
supporting the use of epinephrine and
we'll talk a little bit more about what
there is so there's only one randomized
controlled trial on epinephrine that's
ever been done in the history of
medicine and it was just done a year or
two ago by a group down in Australia and
basically what they found is that when
epinephrine was given in place of
placebo for patients with out of
hospital cardiac arrest these patients
were much more likely to survive the
resuscitation itself or to get a pulse
back during the resuscitation and they
were much more likely to survive their
hospital transport and actually get
admitted to the hospital so they would
live through their ambulance ride live
through their time in the IDI and make
it up into an ICU setting unfortunately
there is no evidence that the group that
received epinephrine was more likely to
survive to hospital discharge so while
their short-term outcomes were a lot
better their long-term outcomes were
comparable one of the reasons for this
is that unfortunately the sample size of
the study ended up being smaller than
the investigators intended and they
weren't able to demonstrate a less
likely outcome like survival to hospital
discharge because they just didn't have
the sample size to do it so the bottom
line is we still don't really know
if epinephrine changes long-term
outcomes in cardiac arrests and if it
makes you many more likely to survive to
the end of your hospitalization or to
survive with a neurologically good
outcome now Abby's a bit of a
double-edged sword so on the pro side
for epi we know that it increases
vascular tone optimizes perfusion of the
heart in the brain and it improves
short-term survival which clearly is an
absolute prerequisite for long-term
survival so it seems like it would be a
pretty good idea however remember what I
told you causes cardiac arrest it's
mostly myocardial infarctions and other
forms of ischemic coronary disease so
when you give epi what does it do to the
heart
it increases rate it increases
contractility and ultimately it
increases myocardial oxygen demand which
can worsen ischemia epi also does reduce
reduce perfusion to other organs which
is problematic and we don't know what
effect if any it has on long-term
survival it might do no good it might
even be harmful in the long run we truly
don't know so hopefully we'll get more
scientific evidence regarding up a
nephron as time goes on but for right
now experts in the field believe that
the pros outweigh the cons and generally
it's considered the standard of care and
cardiac arrest so according to current
protocols epi is a mandatory
intervention you give one milligram of
it in one to 10,000 dilutions every
three to five minutes throughout the
cardiac arrest now there aren't many
drug doses you need to know cold but
this is one that you really should know
both for your exams and for your life
one milligram of epi one to 10,000
formulation repeated every three to five
minutes throughout the cardiac arrest
the other drug that was mentioned in our
arrest algorithm is amiodarone a mio as
you may know is a class three
anti-arrhythmic drug and it is indicated
for all cases of shock refractory v-fib
and v-tach but the current Heart
Association guidelines don't say you
definitely should give this drug because
it's awesome and saves lives they say
you can think about it so it's not
actually a mandatory intervention and
that's because there are two large-scale
studies of amiodarone that have
shown evidence of short-term survival
compared to placebo however there's no
evidence that amiodarone is superior to
other antiarrhythmics such as lidocaine
which was traditionally used in cardiac
arrest and there's no evidence that it
offers any benefit whatsoever for
long-term survival outcomes that means
that your patients will have had their
cardiac arrests detected quickly they
will have received rapid CPR that's high
in quality they will have had their
rhythm detected quickly and how to shock
administered so they've got a pretty
good chance of intact survival if we can
just get their heart restarted contrast
into patients we see in the IDI who
arrests at home or out in public places
who may or may not have a witnessed
arrest who may or may not receive rapid
CPR and rapid defibrillation these
patients often have a much higher degree
of cerebral injury a much higher degree
of cardiac injury from their cardiac
arrest event and they're less likely to
benefit from amiodarone so we have to be
a little bit circumspect in whether or
not we're going to use it in this
population of patients so the bottom
line with amiodarone is it's used very
commonly for refractory v-fib and v-tach
that's not responsive to epinephrine and
electricity the dose is 300 milligrams
which is double the normal loading dose
you would use for other indications and
you really should think about it in
cases where you suspect that the patient
might have a positive outcome if you can
reorganize their cardiac rhythm but may
be not useful to give it in patients who
are likely to have severe cerebral
anoxia and go on to have a bad outcome
no matter what you do so let's review
the algorithm one more time we're gonna
call for help and we're gonna start CPR
as quickly as we can we're gonna go
ahead and perform defibrillation and
fortunately for us we're very likely to
be able to get our hands on a
defibrillator out in public because
they've become so readily available in
public settings if the patient's in
v-fib or v-tach we're going to shock
them after the first shock we're gonna
perform five cycles of CPR or two
minutes by the clock at which point
we're going to give one milligram of F
Efrain after giving up a nephron we're
gonna again resume CPR for five cycles
or two full minutes at which point once
again we'll recheck the rhythm if it's
still shockable we'll perform another
defibrillation and then we will consider
the use of amiodarone because at this
point we would consider the patient to
be in shock refractory v-fib or v-tach
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