Did the machine miss something big?

I'm going out on a limb here, since I don't have the cath report yet. But I'm getting it soon, so we will have some closure on this!

The case:
A 68 year old male called 911 for "10/10" chest pain, and took aspirin before EMS arrival. Nitroglycerin was given by the medic, but it dropped the BP. Some normal saline took care of that, and transport was expedited.

The first ECG:

Computer interpretation: "Widespread ST-T abnormality suggests myocardial injury/ischemia"

Literally seconds later, the monitor showed a burst of activity:

A repeat ECG then showed:

No further events enlivened transport to the tertiary-level, primary-PCI facility.

So what does the first ECG show?
This ECG suggests a proximal LAD occlusion in two different ways, and justifies cath-lab activation, in my view.

The first pattern is likely familiar to astute 12-lead ECG readers. There is widespread depression throughout the ECG (II, III, aVF, and V3-V6), and ST elevation in aVR. Such a pattern indicates either severe 3-vessel disease or severe occlusion of the left main artery.

The second indication of LAD occlusion is not as well-known. Note the upsloping pattern of ST depression in the precordial leads.  This is distinct from the horizontal or downsloping pattern that you often find with a posterior AMI.

For example, this posterior MI demonstrates horizontal ST depression:

Source

Another example of a posterior MI shows a downsloping pattern of the ST segment:

Source

By contrast, in our ECG we have a sharply upsloping ST segment. Furthermore, it terminates in a tall, fairly sharp, T-wave.

DeWinter "waves"
Back in 2008, de Winter and a few other authors described a ECG pattern that they had seen in 2% of anterior AMIs. Interesting, all of the patients with this pattern had occlusions of the LAD in the proximal region - a very serious blockage that could infarct a good chunk of myocardium.

[T]he ST segment showed a 1- to 3-mm upsloping ST-segment depression at the J point in leads V₁ to V₆ that continued into tall, positive symmetrical T waves. The QRS complexes were usually not widened or were only slightly widened, and in some there was a loss of precordial R-wave progression. In most patients there was a 1- to 2-mm ST-elevation in lead aVR

They offered 8 examples of the precordial ST-T pattern:

Interesting looking ST segments and T-waves! Comparing these examples to our patient, looking at a blow-up of the precordial leads:

Upsloping ST-segment depression? Check.
Tall, positive, symmetrical T waves? Check.
Loss of R-wave progression? Check.
Normal-width T-wave? Check.
ST-elevation in aVR? Check.

So even without the 20/20 hindsight that blogging affords me, I'm anticipating a proximal LAD occlusion.

The final ECG
It appears the ST segments have normalized - both the ST elevation in aVR, and the ST depressions in multiple leads have returned to baseline. Even though this spontaneous reperfusion is an encouraging development, the patient still requires emergent angiography in my opinion, given the high likelihood of a dangerous, unstable lesion.

The Bottom Line
There - you know what I know now. Do you see anything that points to an alternative diagnosis, another concomitant problem, or different management?

I'll dig up the final results, and and them in the comments in a few days.

Why do paramedics not want to treat pain in kids?

Forgive me for my provocative title.

Of course, most paramedics do want to treat pain in kids. It's been shown, however, that EMS (like many areas of medicine) doesn't do a great job treating it. Why is that?

Quantitative versus qualitative research

Studying many questions in EMS is relatively straightforward, as you can always look at the numbers.

Does prehospital CPAP prevent intubations? Just count how many people get tubed in the ED! Does use of a CPR-machine save lives? Well, count up how many patients get ROSC!

These sorts of studies, where we look at numerical comparisons, rates, and statistical differences are all quantitative - these rely on obtaining and comparing numbers. To answer this question (about what keeps medics from providing analgesia to pediatric patients), however, EMS researchers in Rochester NY used a qualitative method. 

So this study didn't involve measuring or testing, and collecting a bunch of numbers. Instead, the authors went out and, essentially, listened to what paramedics had to say on this topic!

PubMed link

How they did they do the study?
Getting a paramedic to open up and share their experiences is not exactly the hardest thing in the world...

Pictured: A whole book about medics talking.

 Far from just writing down a bunch of "war stories," however, the authors followed a few steps to ensure they obtained useful and credible information. 

They recruited medics from a variety of agencies in western NY state, with differing levels of experience, and varying levels of comfort dealing with kids. They also brought in a paramedic to actually conduct the interviews, figuring that this would be less intimidating than a physician or PhD. They also tried to figure out a useful way to guide the interviews, designing a set of provocative questions, but also planned to let the medics talk freely and widely on the topic.

So what did the medics say?

Some surprising things!

Now, this sort of research isn't designed to produce statistics or predictions, but I want to highlight some of the results that were felt by the authors to be new and significant, as well as direct quotations from the interviews.

The authors found that "the majority [of medics] viewed relieving pain as unimportant and not part of their job."

They also saw that the medics, in general, "were also concerned that the patients might have an unknown allergy to morphine ... [and had] a similar concern for causing respiratory depression"

Lastly, they found that paramedics "reported receiving generally no response or a negative response from hospital pediatric ED staff."

There are a number of other results and quotations in the article, but I think that these 3 selections convey the general point. Analgesia for pediatric patients is seen as fraught with risks, and is not emphasized as a priority.

As the medics see it, there are few ways to win, and many ways to lose!

Given the inconsistent support from supervisors and ED staff, there is every incentive to shove the issue off, and let the ED handle analgesia.

So, what can be done?

Paramedics are known for their aggressive attitudes in the field, and they don't shy away from challenges. Drilling needles into bone, cardioverting VT with a pulse, or even giving tPA in the ambulance - medics get into the field so that they can tackle the tough problems, not avoid them!

So it's not too hard to figure out where the medics acquired these perceptions about pediatric analgesia. They got these ideas from their supervisors, from their EMS educators, from their rotations in the ED, and in discussions with ED nurses and medical control doctors every day. I agree wholeheartedly with the authors when they conclude that

... the onus of responsibility to change the belief structure regarding pediatric pain management lies not with the paramedic, but with physicians, hospital staff, and paramedic supervisors.

The Bottom Line...

Medics, like all of us, like to engage in a modest amount of medically-appropriate bragging.

"Modest bragging" source

Whether it's sinking a tight ET tube, reversing a bad CHF with aggressive CPAP and nitro, or cardioverting VT in a patient's living room - it's all good material for illustrating your medical prowess. So why not with analgesia?

Perhaps in the future, we'll have quotations from medics that read a little different from those in this study. So, if medical control physicians all do our job right, we'll hear medics bragging about how many mg/kg of morphine they gave, or how quickly they medicated the kid with a femur fracture!

With that in mind, I made my own EMS meme. If we do our jobs right, maybe this will be less of a joke, and more of a reality in the future.

I can getz artsy on Cheezburger!

Should we increase the duration of CPR before "calling it?"

If you have worked in EMS for longer than one shift, you know how most codes will end up.

True story: During my tech/medic days, I got to tie a few toe tags myself.

This is old news - if EMS doesn't get a pulse back by the time the patient is moved onto the longboard, the prognosis is grim.

That's why the authors of the ACLS guidelines support appropriate field termination-of-resuscitation, writing in the 2010 Ethics portion of the ACLS guidelines:

Field termination reduces unnecessary transport to the hospital ... , reducing associated road hazards that put the provider, patient, and public at risk. In addition field termination reduces inadvertent paramedic exposure to potential biohazards and the higher cost of ED pronouncement. More importantly the quality of CPR is compromised during transport, and survival is linked to optimizing scene care rather than rushing to hospital.

They provide a suggested algorithim for field termination by paramedics, based on the most recent evidence:

The protocols for the Sponsor Hospital Council of Greater Bridgeport reflect this evidence. 

The relevant section, 3.16,  provides criteria for termination, which are, in part:

Most EMS systems around the country have similar protocols, and comfort with "calling it" onscene has been increasing in the EMS community.

And then this happens...

You can always trust what you read on Twitter!

Oh boy - are we going to go back to transporting them all to the ED?

So what's this new study?

Link

This study used data from a retrospective registry, collecting data from 435 hospitals over a 9-year period (2000-2008). They ended up with about 65,000 patients who had had a cardiac arrest while in the hospital.

First, they looked at how long patients received resuscitative efforts, and calculated the average duration of CPR at each hospital for patients who did not have ROSC. 

That last part is key - when the news reports talk about "how long patients got CPR," what they really mean is "the average duration of CPR at each hospital for nonsurvivors." Subtle, but important difference.

Next, they figured out a way (regression analysis) to make all the patients and hospitals "equal." For example, patients who came in to the hospital with CHF were clearly at higher risk of cardiac arrest than those who had cellulitis, so they figured out the difference, and calculated it in mix.

Last step - they looked at the "average" cardiac arrest patient at the hospitals with the longest average duration of resuscitation, and compared the survival rate with patients at the hospitals with the shortest average durations.

What did they find?

First, they found a some variation in how long hospitals would attempt to resuscitate patients. The hospitals that "coded" non-survivors for the shortest time did so for about 16 minutes, while those hospitals in the more persistent group ran resuscitations for an average of 25 minutes. These averages hide, of course, a lot of individual variation.

So how did the patients at the 16-minute hospitals (quartile 1 in the figure below) fare compared to those at the 25-minute (quartile 4) hospitals?

There was a 12% difference. 

Put another way, for every 100 patients that survived a code at the 16-minute hospital, the 25-minute hospitals (on average) would have 112 survivors.

So, does this apply to my patients in the field?

First, keep in mind that this study only looked at in-hospital cardiac arrest. Importantly, they excluded arrests that occurred in the ED, and EMS codes were not included either. We already know that in-hospital cardiac arrest patients are different from those in in the pre-hospital realm, so the results are not immediately applicable.

Second, the results are modest, and may be as small as only a 2% survival advantage if you look at the confidence intervals (95% CI) in the figure.

But probably the biggest reason to not let this study change your practice is that it wasn't comparing patients - it was comparing hospitals. And those hospitals were likely doing more than just doing CPR for longer periods of time. They may have been employing better CPR, getting people and resources to the patient faster, or using better post-resuscitation care. We don't know anything else about the hospitals except that they tended to do CPR for longer on the non-survivors!

The Bottom Line
Data from retrospective, registry trials like this is provocative, not least because it can generate statistical results from the large numbers of patients included. It's impossible, however, to explain those results, or show cause and effect. For that we need prospective trials. 

I don't see anything in the current study that could justify changing our current approach, so keep following the current protocols for termination, provide quality CPR, and if you do have a reason to transport while continuing resuscitative efforts, do so safely!