12 Lead ECG and the New Paramedic: Reducing the Germane Load.

What follows is hopefully the first in series of tips for new paramedics.

New EMS providers face a tremendous cognitive load when they attempt to look at the fine details of an ECG on a scene while listening to a patient and ensuring good scene management. I have witnessed many new paramedics apparently hypnotized by the ECG as they stare at a 12 lead mumbling to themselves and losing sight of what is going on with the patient and the rest of the responders.

My advice for new paramedics, when looking at an ECG on a conscious adult patient take a ten second look and then move on.

Look at the ECG and ask yourself the following:

• Is the rate less than 50?
• Is the rate greater than 130?
• Are there ST segment issues that are clearly ischemia or infarction?
• Are there giant T-waves or other changes that point to hyperkalemia?

If the answer to all of the above questions is no, then put the ECG down for now and move on to other things, the problem is not likely related to cardiac issues that you can quickly discern from an ECG.

A heart rate between 50 and 130 in an adult is not a rate related problem. It does not matter what the rhythm is, provided all the beats are perfusing, don’t waste time on the rhythm diagnosis initially if it takes you more than ten seconds.

Don’t spend time counting out small boxes, looking at axis, looking for zebras, and mumbling to yourself while marching out PR intervals and trying to remember the criteria for Sgarbossa’s criteria. Get every other thing taken care that needs to be done, starting IV’s, giving aspirin, pain management, talking to your patient and re-assuring them, thinking about your plan of action and getting them loaded on the gurney.

“What about if it is an AIVR rhythm at a rate of 55?”
It doesn’t matter, it is not the problem.

“What if it is an AV block at a rate of 52?”
It doesn’t matter, it is not the problem.

“What if it is atrial fibrillation at a rate of 120 – 130 beats per minute?”
What if it is? What are you going to do about it? It doesn’t matter, it is not the problem and it doesn’t need to be fixed, but it is possibly a symptom of something else like sepsis, dehydration, DKA, etc.

This is not to discouraging ECG expertise in any way. Experienced paramedics should strive to be experts at ECG interpretation. A new paramedic simply cannot be an ECG expert.

The ECG expert recognizes patterns unconsciously, they simply look at an ecg and because they have unconscious competence and pattern recognition they can tell what it is, at least most of the time.

After you have seen enough ECG’s you will simply recognize the patterns of things like LVH, LBBB, AV blocks, LAHB, atrial fibrillation, sodium channel blocker OD’s, etc with a cursory glance.  But it is important to understand the ECG expert gains this ability only after looking at thousands of ECG’s, counting out small boxes thousands of times, calculating the axis thousands of times and frankly being wrong numerous times in the past.

If you possess the knowledge to formulate a differential diagnosis that includes things an ecg can help rule in or rule out (TCA OD, channelopathies, Wellen’s syndrome, etc) then use the ECG right then and there. This is a much different mindset however than having a patient and you are not sure why they are ill so you do a 12 lead looking for clues. In the first scenario you are looking to confirm a hypothesis, in the second one you are simply ruling things out as the cause, or hoping to find a clue as to what is going on.

Once you have the patient comfortable and have all the needed interventions done then it is time to go over the ECG with a fine tooth comb and look for the subtle findings, count boxes, calculate axis and make sure you did not miss anything.