Epinephrine and Amiodarone

00:01 So just to break down a couple of these interventions a little bit more.

00:05 Epinephrine is a vasoconstrictor, that's why we use it in cardiac arrest.

00:09 As you probably remember from pharmacology, it's a nonselective adrenergic drug.

00:14 Meaning, it acts on the alpha and beta adrenergic receptors all equally.

00:19 The great thing about epinephrine is it increases systemic vascular resistance.

00:24 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.

00:33 What we care about in cardiac arrest is the heart itself and the brain because those are the two organs that are gonna determine our ultimate outcome in the setting of arrest.

00:43 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 what there is.

00:57 Historically, epinephrine has been associated with increased rates of return of spontaneous circulation.

01:03 However, the effect of epinephrine on longer term survival was questionable.

01:09 A recent meta analysis suggested that epinephrine increases both rates of return of spontaneous circulation as well as survival.

01:16 However, increases in neurologically intact survival were not significant.

01:22 The utility of epinephrine for cardiac arrest remains a topic of study.

01:25 However, as of 2020, the American Heart Association continues to recommend use of epinephrine during resuscitation and cardiac arrest.

01:35 Now EPI is a bit double-edged sword.

01:37 So on the pro side for EPI, we know that it increases vascular tone, optimizes perfusion of the heart and the brain and it improves short term survival which clearly is an absolute prerequisite for a long-term survival. So it seems like it would be a pretty good idea.

01:53 However, remember what I told you causes cardiac arrest? It's mostly myocardial infarctions and other forms of ischemic coronary disease.

02:02 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.

02:15 EPI also does 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.

02:29 So hopefully, we'll get more scientific evidence regarding epinephrine as time goes on.

02:34 But for right now, experts in the field believe that the pros outweigh the cons and generally, it’s considered the standard of care in cardiac arrest.

02:41 So according to current protocols, EPI is a mandatory intervention.

02:46 You give one milligram of it in 1 to 10.000 dilution every 3 to 5 minutes throughout the cardiac arrest.

02:53 Now, there aren’t many drugs doses you need to know cold, but this is one that you really should know both for your exams and for your life.

03:00 One milligram of EPI, 1 to 10.000 formulation repeated every 3 to 5 minutes throughout the cardiac arrest.

03:08 The other drug that was mentioned in our arrest algorithm is amiodarone.

03:13 Amio as you may know is a class three antiarrhythmic 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 'cause its 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.

03:43 However, there's no evidence that amiodarone is superior to other anti-arrhythmics 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.

03:58 The American Heart Association now recommends that amiodarone and lidocaine are equivalent, and they state that either can be administered for a refractory unlockable rhythm in cardiac arrest.

04:09 That means, that your patients will have had their cardiac arrest detected quickly, they will have received rapid CPR that’s high in quality, they will have had their rhythm detected quickly and had a shock administered.

04:23 So they’ve got a pretty good chance of intact survival if we can just get their heart restarted.

04:29 Contrast to the patients we see in the ED, who arrest 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.

04:40 These patients often have a much higher degree of cerebral injury, a much higher degree cardiac injury from their cardiac arrest event and they’re less likely to benefit from amiodarone.

04:51 So we have to be a little bit circumspect in whether or not we’re gonna use it in this population of patients.

04:58 So the bottom line with the amiodarone is it’s used very commonly for refractory V-fib and V-tach that’s not responsive to epinephrine and electricity.

05:08 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 maybe 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.

05:34 So let's review the algorithm one more time.

05:37 We're gonna call for help and we're gonna start CPR as quickly as we can.

05:41 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.

05:52 If the patient's in V-fib or V-tach, we're gonna shock them.

05:55 After the first shock, we're gonna perform five cycles of CPR or two minutes by the clock at which point we’re gonna give one milligram of epinephrine.

06:05 After giving epinephrine, we're gonna again, resume CPR for five cycles or two full minutes at which point once again, we’ll recheck the rhythm.

06:16 If the rhythm is still shockable, will perform another defibrillation.

06:20 Then we'll consider the use of amiodarone or lidocaine, because at this point we would consider the patient to be in shock, refractory V-Fib or V-Tec.