I’ve asked many pre-hospital providers that question, and I never receive a consistent response. It seems there is some confusion about when to give epi … confusion we should discuss.
In 1901 Parke-Davis introduced to the market a hormone called Adrenalin (epinephrine)[i], a potent vasoconstrictor used primarily to stop bleeding and to raise blood pressure in post-surgical shock. Generations later the synthetic version of this medication remains the undisputed champion of resuscitation drugs. You’ll find it on every crash cart and in every paramedic’s med-box in America, and rightly so. Given appropriately epi can start a dying heart, but first responders beware, there are times it can also stop it.
Studies indicate that epinephrine (epi) may actually do more harm than good in the treatment of cardiac arrest. According to the National Institute of Health, administration of epi during CPR can increase short-term survival, but the reduction of microvascular blood flow it produces within the heart may offset its benefits. Further, its detrimental effects have been shown to be greatest in patients found in ventricular fibrillation,[ii] a common form of cardiac arrest seen by pre-hospital providers. And the Merck Manual explains that the most common cause of ventricular fibrillation (VF) is inadequate blood flow to the heart muscle, as seen in heart attack.[iii] If this is true, it is supremely important that every pre-hospital care provider know exactly how to recognize a heart attack, and when to give epinephrine if that patient should arrest, like this one did…
The code …
“All right, we are at 1:45. Let’s pre-charge and check the rhythm at 2 minutes.”
Somewhere, right now, an EMS team is performing team-focused CPR. Defibrillation pads are in place, the airway is managed with capnography in place, and an IV or IO line has been established. Everything is going according to plan, but this seasoned team is about to make a critical error. Will you be able to spot it?
A coarse green line traces erratically across the ECG screen. Someone immediately announces, “All clear.” The team members clear and the shock is delivered. The body jumps, and without hesitation an astute team member resumes CPR – they achieve a 4 second peri-shock pause. Another team member attaches a syringe to the IV line. “Epi’s in,” she announces, rapidly pushing the plunger. She flushes the line with saline and then reaches for her next drug – assuming the rhythm is unchanged after the next pre-charge and ECG analysis.
A little history …
Before this 60-year-old patient coded, he had complained of “crushing” chest pain. He presented with all the signs of a heart attack, including shortness of breath, diaphoresis, and radiation that extended up to his neck and down his left arm. Here’s his 12-lead ECG:
So back to the code …
The epinephrine courses up the patient’s arm and enters his ailing heart. The left ventricle is pumping weakly, trying its best to limp along and increase ejection fraction, but with the next few chest compressions, tragedy occurs. The unneeded drug hits the heart like a hammer, plugging into beta-1 receptors and stimulating increased activity. Suddenly the oxygen starved myocardial tissues are forced to work even harder. Sodium channels open prematurely, myocardial cells depolarize at will, and within seconds, chaos breaks out again. VF returns and cardiac arrest resumes.
Two more minutes pass…
“Stop CPR,” the team leader announces, glancing at the ECG screen. “We’ve still got V-Fib. Shocking…..” Another 3-4 second peri-shock pause is achieved.
The code continues. Another shock, another drug. The team watches the rhythm change numerous times, but sadly, no pulse is ever produced. Ultimately the ECG rhythm degrades to a flat green line, and after thirty long minutes—eight more doses of epinephrine and sixteen additional rounds of CPR—the resuscitation effort is halted.
It would seem this team did a great job, but in reality they deviated from the ACLS algorithm. If they had waited until after the second defibrillation before giving epinephrine, they would have realized it was never indicated. It is important we all learn from this. We must understand that defibrillation within the first minute of collapse can produce survival rates close to 90%[i]. Therefore we should proceed with the assumption that the first defib will work. And in this case, it did.
Admittedly, there’s a lot of gray area in medicine, but the pre-hospital professional should never give a drug before its time. In cases where heart attack is the primary cause of VF, early epinephrine administration can be dangerous.
[ii] U.S. National Library of Medicine, National Institute of Health, Epinephrine for cardiac arrest: http://www.ncbi.nlm.nih.gov/pubmed/23196774
[iii] The Merck Manuals, Ventricular Fibrillation: https://www.merckmanuals.com/home/heart-and.../ventricular-fibrillation
[iv] National Center for Early Defibrillation, http://www.early-defib.org/