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Why we capture a 12-lead ECG with the first set of vital signs

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February 14, 2012


EMS 12-Lead
by Tom Bouthillet

Why we capture a 12-lead ECG with the first set of vital signs

Too often, paramedics think of the 12-lead ECG as just one of the things to check off the list

By Tom Bouthillet

EMS is called to the residence of a 66-year-old female complaining of chest discomfort. The patient is found sitting in a kitchen chair. She is alert and oriented but highly anxious and diaphoretic. She appears acutely ill.

Paramedics assess her vital signs.

  • RR: 18
  • Pulse: 74
  • NIBP: 102/63
  • SpO2: 95

A 12-lead ECG is obtained.

Although this ECG meets the voltage criteria for left ventricular hypertrophy in the limb leads, it shows acute inferior STEMI.

ST-elevation is present in leads II, III and aVF along with reciprocal ST-depression in leads I and aVL. Remember that left ventricular hypertrophy is usually an anterior STEMI mimic.

A "Code STEMI" was called from the field. The patient was given four baby aspirin, a sublingual nitroglycerin spray and oxygen.

Less than 4 minutes later, the patient was in the back of the ambulance and another 12-lead ECG was captured.

As you can see, the ECG is now nondiagnostic for acute STEMI! This patient's reperfusion could have been seriously delayed. But, because the paramedics obtained a 12-lead ECG with the first set of vital signs, the patient was taken rapidly to the cardiac catheterization lab, where an acute 99 percent occlusion of the right coronary artery (RCA) was identified and stented.

The door-to-balloon time was less than 60 minutes.

Too often, paramedics think of the 12-lead ECG as just one of the things to check off the list. "I need to place the patient on oxygen, I need to start an IV, I need to give baby aspirin, I need to give nitroglycerin, I need to get a 12-lead ECG…"

In reality, early acquisition of a 12-lead ECG for all patients with signs and symptoms of ACS is critically important to the success of a prehospital 12-lead ECG program.

Why? Because the same drugs we give to restore balance between myocardial oxygen supply and demand can "clean up" or erase ischemic changes on the 12-lead ECG!

Sometimes the prehospital 12-lead ECG is the only evidence that a patient's chest pain was cardiac in origin! Imagine if this patient never received a prehospital 12-lead ECG and the cardiac biomarkers came back negative.

A patient with a high-risk lesion might have been discharged home. It's unlikely, but it could happen. What would you want for your mother or father?

Next month we'll talk about why we perform serial ECGs!

About the author


Tom Bouthillet is a Fire Captain/Paramedic with Hilton Head Island Fire & Rescue, Editor of the EMS 12-Lead blog, host of the Code STEMI web series at First Responders Network, a member of the Editoral Advisory Board of EMS World Magazine, and developer of the 12-Lead ECG Challenge smartphone app. He has taught nationally in the Critical Care Transport (CCEMT-P) program out of UMBC and his writings have been referenced in the American Heart Journal, the Journal of the American College of Cardiology: Cardiovascular Interventions and the EP Lab Digest. Contact Tom at tom.bouthillet@ems1.com.

Comments
The comments below are member-generated and do not necessarily reflect the opinions of EMS1.com or its staff.
Jake Bigelow Jake Bigelow Tuesday, February 14, 2012 3:57:11 PM I think it is important to note that there are still signs of ischemia present in the 2nd 12 lead. Al though it does not have a STEMI presentation, there are T wave changes present that do denote ischemia. A clued in provider should be able to pick up on those even if the first 12 lead was missed with basic patient presentation. Continue with the work in the ED and most likely continued evaluation this patient would end up with the same result... Cath lab. Now I do concur that the door to balloon time could be increased by missing the first 12 lead and that is not the BEST care we can provide. Point being, it is important, more than ever, for Paramedics to be completely clued in to proper 12 lead analysis and to ensure that we are doing, clinically, what is best for our patients, not just following a checklist. The difference between technician and clinician is not simply holding the title of Paramedic. It is the way we evaluate and treat our patients. I know plenty of technicians who are Paramedics and I know a few that are clinicians. It is up to the individual to become a clinician. If you repeat the top of your 12 lead as your interpretation and follow a checklist to provide care, we know what you are. Who knows where I am at. ;)
Justin Foster Justin Foster Tue Feb 14 16:26:20 PST 2012 We should all read this.
Justin Foster Justin Foster Tue Feb 14 16:31:57 PST 2012 Doesn't hurt to do more than one 12 lead
Vince DiGiulio Vince DiGiulio Tue Feb 14 20:10:15 PST 2012 I love your overall point, but it seems my experience with emergency department ACS care has been a bit less positive than yours. I know of places where that second prehospital ECG in isolation would be labelled "non-specific T-wave changes," serial ECGs may or (probably) may not be performed in the department, and the patient would end up admitted for UA vs. NSTEMI depending on the initial troponin, which is probably going to be normal if the patient's pain was recent in onset. Then 7 or 8 hours down the line, when a repeat trop finally gets drawn and analyzed in the middle of the night, everyone will realize that this is actually an acute occlusion and the patient may or may not get cathed the next day, depending on a whole bunch of factors. Maybe your experience has been different from mine, and it's not the main point of your comment, but I think that it's far from a given that a patient like this will end up in the cath lab, especially within a timeframe where he or she stands to benefit most from reperfusion.
Jake Bigelow Jake Bigelow Tue Feb 14 20:22:02 PST 2012 Vince DiGiulio You would hope that this patient's presentation would clue in some providers. There is an ischemic pattern but as you stated non specific T wave abnormalities seems like the more likely documented change so there is a possibility of a missed occlusion. My experience does say that any troponin bump greater than 0.02 is usually met with a call to the cardiologist. Again though, depending on this patient's onset, it may be normal. I guess the question is, should we be doing a 12 lead prior to any treatment that could result in re profusion? And taking it a bit deeper, what is the incidence of this actually happening on a regular basis? I'd be curious to know, but it would obviously be a hard thing to track. Good points though.
Jake Bigelow Jake Bigelow Tue Feb 14 20:25:36 PST 2012 Vince DiGiulio And to seal the deal on your point, I fly a significant number of "NSTEMI" patients from tertiary hospitals and en route often find myself speaking to the accepting physician with a sense of "to the cath lab and not to the floor" inflection. This is mostly due to the same points you brought up. All very interesting to say the least. Often it is because the trop was negative initially and by the time we get to the patient it has been 4+ hours with no repeat trop. We run one en route and find it extremely elevated.
Vince DiGiulio Vince DiGiulio Tue Feb 14 21:13:31 PST 2012 Jake Bigelow Interesting indeed; there's so much regional variation. Most of my experience is in suburban community hospitals, where the ACS patient either walks in with an obvious STEMI, which will get them quickly transferred to the local PCI center, or they don't, and get admitted to telemetry. Unfortunately, as demonstrated by Stephen Smith of 'Dr. Smith's ECG Blog,' my own personal series of cases, and it sounds like your experience, "STEMI" is probably a misnomer, as a good portion of ACS diagnosed as "NSTEMI" are actually the result of the same types of occlusions as STEMIs, just subtle or not picked up on the ECG. Thanks for sharing.
Bob Sullivan Bob Sullivan Tuesday, February 14, 2012 5:55:27 PM The opposite also applies. A Toronto study in the last PEC issue showed only 85% of STEMI's were caught on the first ECG. Their protocol is to do one at the patient's side, another in the truck before transport, and another before pulling into the hospital. If that hospital isn't a PCI center, they go to one that is.
Ken Sawyer Ken Sawyer Wed Feb 15 08:53:18 PST 2012 I'm down with the serial EKG's, but isn't so many before transport self defeating as you are delaying transport to definitive treatment. I believe that time is muscle and regardless of your EKG, your pt's presenting S/S should guide you in your treatment (ie: O2, IV, ASA, NTG MS p the first EKG) time is muscle at least that's what they pounded into us back when I was in school and then throughout my EMS career. But I can see your point also.
Jason M. Rowland Jason M. Rowland Wednesday, February 15, 2012 5:40:23 AM The arbitrary administration of nitroglycerin, especially to a patient with inferior invovlement is highly dangerous. Despite the positive outcome of this scenario, if it is not hypothetical, a patient such as this could have decompensated rapidly and irreversibly upon receiving nitrogycerin. As right ventricular involvement frequently accompanies an inferior MI, drugs reducing preload should be given only with extreme caution. In the services with whom I am affiliated (something for yours to consider also) nitroglycerin would be contraindicated for this patient. I agree that 12 lead ECGs should be obtained early and often (leave the leads attached for automatic j point reevaluation for some monitors). But, presentations such as this are the precise reason why a 12 lead should be captured BEFORE nitroglycerin. At the very least, a V4R was indicated before NTG. Please don't let "the way we've always done it" interfere with the best interests of the patient. Not every chest pain needs nitroglycerin.
Shawn Green Shawn Green Thu Feb 16 04:33:07 PST 2012 That is what I was going to say exactly, good job.
Matt Hansen Matt Hansen Sat Feb 18 06:27:45 PST 2012 I agree that it can be very dangerous, but only if a medic fails to preload their patient. In extreme circumstances I have had it take 1-2 liters (even had a 3rd hanging) of fluid “NS/LR” to get a patient stabilized prior to giving NTG in this situation.
Manda Lin Manda Lin Sun Feb 19 15:26:53 PST 2012 In my agency NTG is a relative contraindication in an IWMI w/ RV STEMI; needless to say we are expected to use judgement prior to the admin of NTG in the presence of any STEMI, however the absolute contraindication is a SBP <90mmHg. Also, ALL vitals should be obtained & IV access should be established prior to NTG administration; you're not erring on the side of the pt's benefit when you give NTG w/o an IV, BP, or monitor. Several cases I've had... 1. FD gave NTG upon their arrival..NO BP, NO 12-Lead, NO IV. Luckily pt was fine. 2. Nursing Home gave 4 SL NTG's w/o ever obtaining a BP. Pt was in a slow junctional rhythm of 38, BP of 47/33, no radials, weak carotid, lethargic, pale, cool, diaphoretic. Took 2L NS to get her to 100/P & back into an RSR of 70. 3. Clinic MD gave NTG for angina pt...NO BP, NO 12-Lead. Pt has syncopal episode, he calls 911. Pt is lethargic w/ a BP of 60/42, HR of 220, SVT...poor thing got 50j to cardiovert him back into a sinus tach & then took a liter of NS to bring his pressure >100 which in turn brought his rate down to mid 90's upon turn over. We have lives in our hands, not manikins.
Eric Graham Chase Eric Graham Chase Wednesday, February 15, 2012 7:23:11 AM very true
Jim Daigle Jim Daigle Thursday, February 16, 2012 10:06:14 AM If this is a true inferior STEMI then why was NTG given?
Manda Lin Manda Lin Sun Feb 19 15:51:40 PST 2012 Not all IWMI's have RV involvement, & even if it is involved, the key to NTG is its great vasodilatory mechanism to dilate the vessels & reduce angina, which in turn reduces anxiety, which further decreases HR. In the end, treat the pt, not the monitor. If a STEMI is present, get serial 12's, trend vitals, & have a line in place & fluids ready. Everyone is different & reacts different. I've had big guys w/ 180's SBP drop to <100 w/ 1 SL NTG & small grannies w/ 110 SBP not budge or have it increase a few numerics after 2 doses. It's all about relative vs absolute, knowing your presenting factors, & how to fix what might go wrong. Being prepared for anything is how to handle any call, cardiac or not.
Jim Daigle Jim Daigle Thursday, February 16, 2012 10:07:32 AM I'm with you on this one Mr Rowland.
Erin E. Wojcik Erin E. Wojcik Thursday, February 16, 2012 2:55:52 PM This is the way we are taught in Northeast Wisconsin. We also are learning the V4R "cheat", and most protocols in the area require a 12 lead before giving NTG, anyway. Because of this outcomes have really taken a positive trend. I heard a report two weeks ago that for a patient experiencing a STEMI as assessed by paramedics in the field, the door to balloon time was 9 minutes. No that's not a typographical error. NINE MINUTES! In fact the patient was never fully handed off to ED staff. The paramedics, a hospital security guard, and a nurse accompanied the patient straight to Cath Lab. Green Bay doctors have really learned to trust the guys out in the field and with great results for patients.
Nick Desnoyer Nick Desnoyer Friday, February 17, 2012 12:51:27 AM I was taught, and I may be wrong here. That nitro with inferior MI is a relative contraindication, as long as you have an IV started with fluids ready.
Matt Hansen Matt Hansen Sat Feb 18 06:37:59 PST 2012 You are correct. It is only a relative contraindication and not an absolute. Patients must be preloaded with sometime very large amounts of fluid prior to NTG in an inferior. The reason that a lot of services call it a contraindication is that not everyone is a critical thinker. Just because there person standing next to you is wearing a paramedic patch docent mean that they will place as much forethought into patient care as you might, They just see a situation and react; all too often this results in a bad outcome. This is why a lot of skills are taken away or in this case you have a relative contraindication called an absolute.
Manda Lin Manda Lin Sun Feb 19 15:38:14 PST 2012 Matt Hansen: Sir, you are my Hero! I could not have stated what you just did, any better.
Nick Desnoyer Nick Desnoyer Tue Feb 21 22:30:44 PST 2012 Matt Hansen: Thank you very much for claifying.
Ken Grauer Ken Grauer Sunday, February 19, 2012 11:49:47 AM Lots of GREAT points by this case and the comments. Re the question about Why NTG for acute inferior? - the answer is that it worked (almost resolution of acute ST elevation). As Matt says - it's a relative contraindication RV MI - and a strong caution for inferior MI with full realization that sometimes "ya gotta be there" with clinical reasoning on potential for relative benefit from treatment vs potential for harm if there is relative hypovolemia which then leads to a marked decrease in BP - vs - whether anything truly need be done until rapid transport to the nearest ED (where IV NTG can be cautiously started and stopped if adverse effect ensues...). Having an IV and being aware and ready to administer fluids goes a long way. AND - as Jake says- the 2nd ECG is NOT normal. Instead we see big inferior Q waves - and clear ST coving (albeit not elevation) in III and aVF - with subtle but real (shapewise) reciprocal ST depression in I, II, aVL - as well as T inversion in II, III, aVF. In a patient with new-onset chest pain - one has to be aware that this may be a "transition" ECG (in between the stage of acute ST elevation and the stage of ST segments coming down and T waves inverting is a TRANSITION stage when there may be PSEUDONORMALIZATION - and this 2nd ECG is as good of an example of this as one will EVER see. In addition - the T in V1 is upright with a hint of T inversion (making me think that there may be associated RV MI... ) - and there is ST coving that definitely looks concerning (and which looks like it MAY be acute) in lead V4 - along with shallow T inversion in V4, V5, V6. None of this is what you see with LVH (in fact - perhaps this patient had repolarization changes of "strain" on her baseline - which further mask some of what we are seeing... ). FINAL POINT - It is because of this phenomenon of "pseudonormalization" (that in this case occurred NO MORE than 4 minutes later!) - that serial ECGs should be done WHEN clinically indicated. Again - its a balance - if the patient is stable - I honestly don't think in many (most) cases you truly gain anything by delaying transport doing multiple ECGs on the way to the hospital... whereas if something "changes" with the patient's clinical situation en route - then a follow-up ECG may be very helpful indeed, and could reduce ultimate door-to-balloon time.... There is NO one answer for all situations - and hopefully you are working in a situation that does allow you to apply judgement and collaborate/participate with the ED MD with whom you are in contact with. GREAT case Tom - THANKS for sharing!
Shea Coghlan-Peppard Shea Coghlan-Peppard Sunday, February 19, 2012 12:10:40 PM Your first paragraph had me concerned Jason, but you followed it up with in your second!
Byron Wanstall Byron Wanstall Monday, February 20, 2012 12:19:14 AM Is the nitro contraindication in this context due to the fact that an acute inferior MI can induce transient sinus brady via vagal enhancement? Aswell as myocardial dyskinesia due to ischemia and/or necrosis? Leading to decreased cardiac output and thus making a bad situation worse? Would anyone consider a thrombolytic agent here?
Di Peppler Di Peppler Mon Feb 20 03:01:58 PST 2012 erm, I'll get back to you on that one mate!
Antonio Flores Onrubia Antonio Flores Onrubia Monday, February 20, 2012 4:09:21 AM I agree with what Jason have said, it is highly dangerous to administer NTG to such a scenario... however the use of NTG will give a positive outcome if you'll stabilize the patient with NS fluid using large bore cannula prior to NTG administration.
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