New research that will NOT help you.

There is a lot of discussion about different approaches to CPR these days: Cardiocerebral resuscitation, minimizing the peri-shock pause, "pit crew" CPR, etc. These are great topics, with some interesting research backing them up. This post isn't about those topics!
 

(CEMSMAC) who voted unanimously (5-0) to back the draft document - See more at: http://medicscribe.com/2013/02/in-praise-of-cemsmac/#sthash.2mwVR64E.dpuf

(CEMSMAC) who voted unanimously (5-0) to back the draft document - See more at: http://medicscribe.com/2013/02/in-praise-of-cemsmac/#sthash.2mwVR64E.dpuf

Instead, there were two recent publications that describe methods in CPR that I don't want to see anybody use in the foreseeable future. This is not a case of "needs to be tested in a large clinical trial," and it also isn't the case that "CEMSMAC voted unanimously to back the draft document," and we're still waiting for regional guidelines.

Now, perhaps one day, far in the future, there will be some evidence for the methods the authors are describing. But given the quality of these publications, I'm guessing that that day is still a ways off.

"Should we squeeze people's belly and legs during CPR?"
Even though MAST pants have gone the way of the dodo, and Trendelenburg position is going that way as well, the appeal of "auto-transfusion" persists.

To be fair, the look never went out of style! (YouTube)

A letter from a group of Chinese physicians was recently published in the American Journal of Emergency Medicine. The actual title of the letter is "Improvement of cardiopulmonary resuscitation by bending and pressing the lower extremities." In this letter (which does not contain any actual research), they make the modest claim that they have developed an "improved" CPR. 

This improved method? One picture is worth a thousand...

I think this could get this blog banned in my own hospital.

What the heck is that? The authors explain: 

Bending and pressing both lower extremities is based on the premise that bending and pressing the lower limbs during CPR will increase blood flow to the heart. As the patient's hemodynamic status improves, the blood flow to the coronary and cerebral arteries increases.

They go on to provide exactly zero references to support this idea, and no original evidence of their own. But they've got some great illustrations!

So, press at exactly 45°, because... Because why exactly? They don't explain, but they drop some pearls of wisdom like:

By reestablishing blood circulation, the hemodynamics of the [cardiac arrest] patient further improve, and ultra-early return of spontaneous circulation could be expected.

As a goal, it's hard to beat "ultra-early" ROSC. How about adverse effects though? 

If the steps are followed properly, there will be no further damage to the patient.

No further damage?

"The salutory effect of leg flinging during CPR"
 Not the actual title, but close enough. 

"Cardiac arrest: Vascular resuscitation by leg elevation" goes further than the paper above, and is written as a case report with a brief literature review. Like the paper above, it intends to describe a new technique to augment CPR, namely passive leg elevation (PLE). Given that PLE was recently shown to have some mild but indirect benefits, this a valid topic for a literature review.

The case report, however, raises a few questions, and the conclusion the author reaches are potentially dangerous. 

One late afternoon at a large gathering everyone stood up. Soon there were calls for help. A 40-year-old man was found on the floor. He was not breathing and was unresponsive. Two other doctors and I checked him serially but found no pulse. I checked his carotid for more than 30s without feeling any pulse. About 3 min had passed since the call for help, and I was about to start CPR when I remembered that some people were fasting that day.

I quickly lifted up his legs by putting my arm under his thighs. He was flaccid and his back came up off the ground, and the legs flew up into the air and then onto his abdomen.

The legs were placed on top of a chair pulled from nearby. He immediately became pink in color, opened his eyes, and started breathing. Asked if he was fasting, he answered yes. Water was brought and he drank. He lay supine with his legs up for 10 min, then he sat and stood. When paramedics arrived (at about 15 min), he felt fine and refused to go. When evaluated the next day, an ear infection was diagnosed and he was given antibiotics.

Just a fainting spell, right? We've all seen it. A moist, cool cloth on the forehead, a little air, and people perk up just fine on their own. 

Even Supergirl.

But instead of concluding that this was a simple faint, the author concludes that:

Amazing immediate and complete clinical improvement with leg raising was noted in a case of out of hospital cardiac arrest. 

Well, nothing's impossible. It may be the case that a patient who suffered a true cardiac arrest, after 3 minutes without CPR, completely recovered after having his legs propped up on a chair. But I doubt it.

The Bottom Line
As I said at the start, perhaps studies in the future will show I was all wrong in my impression of these papers. Maybe we'll find a benefit of leg-compression CPR, or even that the ABCs/CABs should be changed to the L-ABCs. 

In the meantime, though, I think it's harmful for the authors to try and push these ideas so strongly. While lifting or squeezing the legs is not likely harmful in itself, it has the potential to distract rescuers from other tasks. And suggesting that people avoid CPR to prop up the legs runs contrary to the available evidence, and delays the known benefits of CPR.

Can you "GLASS" the patient to clear the c-spine?

It's hard to know what to write about, since there are so many valuable new studies being published each week. How can I choose?

Not filed under "valuable new studies": Leg-compression CPR

I just wrote about EMS and cervical spine trauma. However, a new study deserves attention for a few important reasons.

First, it describes a simple method of assessment.  Second, it "fits" with common sense. 

Lastly, one of the co-authors is a Bridgeport Hospital ER doc!

Dr Althoff (Note: does not usually dress like the Unabomber at work)

"Clearing" the spine by EMS
 There has been a lot of discussion about how to "clear" the potential cervical-spine injury in the field. Some people like the simplicity of the NEXUS criteria, while other think that the Canadian C-Spine Rule (CCR) is more sensitive, and thus safer. 

The use of these rules, though, can get complicated and confusing, with people arguing over how to define "intoxication" (when using NEXUS), or what is a "dangerous mechanism" (when using the CCR). Also, if the patient describes paresthesias, or insists that their neck is tender, despite an exceedingly minor mechanism, you may be obligated to immobilize.

Researchers at the University of Virginia decided to try a different approach - instead of examining the patient who has been in a MVC, how about just examining the car?

The stupidest clip-art I could find with Google Image

The "Glass Intact Assure Safe Cervical Spine Protocol" study
The researchers used a national database of MVCs that had been reported to police, where at least one of the vehicles had been towed from the scene. The vehicle had all received a complete, systematic survey for damage afterwards by the NASS investigators, using both crash-scene photos and reports collected by police, as well as direct inspection of the vehicles. In addition, federal researchers combed over medical records to determine whatever injuries the occupants had suffered.

The Virginia researchers then looked at a subset of the patients in the national database:

• Ages 16-60,
• Had been wearing setbelt,
• Airbags did not deploy, 
• All the car windows were intact

They called these the "GLass intact Assures Safe Spine," or GLASS, criteria. They then looked at how many "GLASS-negative" patients were subsequently found to have an unstable cervical spine fracture after the MVC. 

Well, it wasn't many. Out of 7639 drivers or passengers who met the "GLASS" criteria, only 6 had an unstable cervical spine fracture - that's 0.008%. Really, really infrequent.

Is this protocol ready to use?
Not quite yet, but it's promising. 

Keep in mind that this used a retrospective design, and a prospective design might look better or worse. And although there were very few injuries, they were serious. Here's a breakdown of those few, unlucky, patients with a spine injury after their minor (to us) MVC:

It's tough to draw any conclusions about these "potentially-missed" neck injuries You might be tempted to pay special attention to middle-aged females, but the (very, very) small sample really doesn't let us conclude much.

Nonetheless, the negative predictive value (or NPV) is astoundingly reassuring, with a confidence interval 99.86% to 99.98%. That's about identical to the NEXUS rule-out criteria, and much better than many other rules in emergency medicine (e.g. the PERC rule). 

Perhaps the biggest strength of the study is the number of MVCs studied. There is no way that the Virginia researchers could have investigated 14,000 MVCs on their own. Although you always have to worry about the quality of any one individual data-point in such studies, the mass of data enables us to identify important effects that would not be identified in smaller (although supposedly more high-quality) studies. 

The Bottom Line
The next time you pull up to an MVC, and you see all the car windows intact, you can check the results for yourself.

But you still better go ahead and talk to the patient and do a physical exam! 

Questions for one of the authors?
I've talked with Dr Althoff about this study on a number of occasions, EMS spinal care in general, and also future directions for research in this area. If you have questions about this study, or a related topic, send in a comment!

Morphine for MI - Benefit and risk

Should we be using morphine to treat chest pain? It seems like an odd question - we're supposed to treat pain, right? - but there some interesting wrinkles to this issue when it comes to heart problems; i.e. acute coronary syndrome (ACS).

At the outset, let me emphasize that the Sponsor Hospital Council guidelines suggest that morphine be used, up to 0.1 mg/kg IV, if chest pain of suspected cardiac origin is not relieved with 3 tabs/sprays of nitroglycerin. That hasn't changed!

The benefit of morphine in ACS
Angina and infarction hurt, and morphine can treat that. There are other supposed benefits (reducing ischemia, reducing "stress," blood pressure reduction), but these are mostly theoretical, and often can be accomplished with other agents.

For example!  (Source)

Okay, perhaps not bourbon, but there are others.

The risk of morphine in ACS
Of course, morphine causes (infrequently) respiratory depression, hypotension, or depressed mental status. These are true for any patient, not just those with ACS, and are generally avoidable with careful administration.

The patient with ACS may face specific risks with morphine though, leading to worse outcomes with their ischemia. This is a controversial area, and there is little good evidence. Nonetheless, breathless headlines like this came out after publication of a study in 2005 (PDF link).

"News" link

This study did not prove a cause & effect relationship with morphine - the study design could only show an association - but people have proposed 3 ways that morphine could potentially harm cardiac patients; 1) direct harm to the myocardum, 2) the side effects of orphine harm the myocardium, and 3) the "masking" of ischemic pain, such that it delays definitive therapy, such as angiography/angioplasty.

1. Does morphine directly harm the myocardium in ACS?
Some people are concerned that morphine, during an episode of ACS, may directly harm the ischemic heart. The authors of the "morphine increases death risk" study remark on the discussion section that "in animal studies, morphine has been demonstrated quite conclusively to actually increase myocardial infarction size." 

They cite, as "quite conclusive," a study from 1982, where rats where given a subcutaneous dose of morphine at 3 mg/kg. (That would be 210 mg for an adult human!) They then performed open-heart surgery, and tied-off a coronary artery - just blocked it off. When they looked at the hearts 2 days later, the rats who had morphine had MIs that involved 10% more myocardium than the morphine-free rats.

Rat open-heart surgery, w/ ligation of LAD. source

On the other hand, North Carolina researchers studied rats who underwent a limited period of coronary occlusion, and found that the morphine pre-treated rats had smaller infarct extent.

So it's an open question whether any of these animal studies represent great (or even mediocre) evidence that can guide our clinical management. It's not conclusive, that much is clear.

2. Do the adverse effects of morphine (hypotension, hypoxia) cause harm in ACS?
Perhaps morphine doesn't have a direct toxic effect on the myocardium, but the known adverse effects can certainly cause problems. Generally, though, these are not common if morphine is administered cautiously, and in practice hypotension or hypoxia are rare.

One study that has been cited as demonstrating the potential for hypotension in MI patients was conducted 1969. In The effect of morphine on blood pressure and cardiac output in patients with AMI the authors gave 15 mg morphine, intramuscularly, to 10 patients with an MI. They found a "slight tendency to development of orthostatic hypotension."

So if you give 15 mg IM of morphine, you might want to be ready to give them some fluids, or just not have them stand, but this doesn't seem persuasive as a severe adverse effect.

 3. Does morphine "mask" the ischemic pain, rather than treat it?
 This is really the most interesting question - should we avoid using opiod medications that could "mask" recurrent or continuing ischemic pain, so that we can make better decisions about further interventions?  I.e., does morphine delay angiography?

Spoiler alert: We have no idea. There is no evidence here, only opinion. 



Chest pain today = abdominal pain 50 years ago?
An analogy with abdominal pain is appealing. In the past physicians relied on the severity and evolution of abdominal pain to aid them in the decision to pursue surgery. If a patient's pain was "masked," the physicians had few means to understand the evolution of the disease. Nowadays, given the accuracy of blood tests and CT scans, most clinicians feel they may safely treat the abdominal pain prior to full evaluation of the patient.

A number of people would argue that we are still at the "pre-CT scan" point now for ACS. The argument is that, absent angiography, we have few means to establish the need for invasive treatment. Like the surgeons of ye olden days, we may be led to a "false sense of security" after morphine reduces the pain.

This is an important question since, in the UA/ACS patient, we use "recurrent ischemic pain" as one factor determining how urgently the patient is taken to angiography. Dr. Stephan Smith, of Dr. Smiths ECG Blog points out one case, for example, where he believes that the heavy-handed use of opiods contributed to a delay in angiography. 
  
But how much do we depend on the character or presence of recurrent/refractory pain, as opposed to other factors? We have the ability to check troponins, perform sequential (or even continuous) ECGs, and we can look "directly" at the myocardium with a bedside echo. We are not dependent on the unimpaired report of symptoms - technology has provided a few tools!

Two patients
Let's consider two extremes, two different patient presentations.

First, how should we consider a patient who adamantly denies any chest pain/pressure (or back pain, shoulder aches, or jaw discomfort...), but has an ECG that looks like this:
 

True story. Yeah, it was an RCA.

This patient was in serious denial, but after intensive interviewing (the Geneva conventions were observed!) he admitted to "chest congestion" that improved with NTG, and consented to cath.

Second, how should we proceed with a patient who describes "crushing" chest pain, with left arm radiation, an sensation of doom, etc., and looks like this...

... but whose ECG looks like this?

Stop looking, it's normal.

Yes, pain means something, but so do the troponins, the echo, and of course the ECG. 

In the end, it's worth pointing out that Dr Smith's "missed MI"  had an initial ECG that actually showed a STEMI, albeit an uncommon (but not rare) pattern. 


Bottom line: Still a recommended therapy!
This post contains more opinion than I usually like to write. There just isn't the level of evidence to help us. I think my observations are pretty mainstream, however. Talking with my colleagues, most of them tend to agree with the use of morphine in this situation. One emergency physician remarked "That's what morphine is for - to mask pain."

Despite the hypothesis-generating evidence provide by the CRUSADE trial, there is little other evidence that suggests that morphine is harmful, or that analgesia must be deferred while patients are in pain. Despite the inflammatory press coverage of the CRUSADE results, the AHA continues to recommend the use of morphine in ACS.


But hold the bourbon!


 

Gender, EMS, and STEMI - new study

Does our care of the patient change when the patient is a woman?

If you're like most EMS providers, your response is a strong "no." People who go into EMS generally share strong ideals, and are motivated to provide the best care possible to everyone who needs it. 

With that in mind, though, a recent study found results that are difficult to explain, and ought to prompt us to reflect on our practices. It's not proof, but it deserves discussion.

Is on-scene time longer for women with chest pain?
Time is muscle - you know the drill. With chest pain, and especially in a STEMI, we have the ability to save lives. This is what EMS is for; we identify the sick person, and we get them to the right place, fast.

Too fast! (jk - no injuries.)

With all the emphasis on reducing the door-to-ballon time, we have to identify any reasons that would delay definitive care. What if being female is one of those reasons? 

The authors of Gender differences in scene time, transport time, and total scene to hospital arrival time determined by the use of a prehospital electrocardiogram in patients with complaint of chest pain. (PDF link) looked at the EMS service in San Diego, and analyzed run-forms of chest-pain patients. They looked at two time periods, before & after EMS started obtaining prehospital ECGs. They then looked at the various time intervals, as well as the computer interpretations of STEMI (a required element in their system for field-activation of the cath lab).

They found over 21,000 patients who had been transported for chest pain. About half of the patients were men, but the women were, on average, significantly older (65 vs 59 years of age). Only 3% of the patients (in the later time period) had a STEMI, with most of those being men.

When they looked at the scene times and transport times for chest pain patients, nothing changed between the two time periods overall. In the second period, however, they found that patients with a "STEMI" interpretation on the ECG had shorter scene and transport times.

It gets more interesting, however, when they broke things down by gender. It seems that that women had longer scene times than men, both for those with and without a STEMI. Specifically, women with a STEMI, on average, had scene times about 3 minutes longer than men, while women with chest pain (but no STEMI) had scene times about a 1.5 minutes longer than men. Transport times were the same, roughly, for men and women.

Interpretation
This is a small, but provocative result, and it isn't clear what it demonstrates, let alone proves. 

Did paramedics feel less "urgency" with the female chest-pain patients? This seems unlikely, since the actual transport times were similar. Everyone got driven to the ED at the same speed.

The study design can't answer what accounted for the difference in scene time interval, unfortunately. The generally older age of the female patients could suggest that evaluation was more complex, and accordingly required more time. It's already well-known from other studies that women with ACS generally have more comorbid conditions (such as hypertension and diabetes) than men.And it's also hard to interview older patients quickly; some things are hard to rush.

Lastly, the difference is small in absolute terms. Although the authors suggest that the difference in scene time for STEMI could result in a 0.25% - 1.6% increased mortality, this is based on a questionable extrapolation.

How does this fit with prior studies?
It is still possible that there is bias in the care of female patients that was not captured in the data here. A prior EMS study showed that 7.5% fewer women than men got ECGs for chest pain (Is there gender bias in the prehospital management of patients with acute chest pain?). We don't know if this was the case in the current study, since the authors "assumed that all patients," men or women, got ECGs, since "it was the protocol." Some basic QA about ECG completion rates, by gender, would have strengthened the study.

Another study examined the differences in prehospital intervals  among men & women who ended up being diagnosed with an MI. The authors of Myocardial Infarction: Sex Differences in Symptoms Reported to Emergency Dispatch also found that women had longer on-scene times, by about 1 minute. When they took age into account, whoever, that difference disappeared. Hopefully the next San Diego EMS study will obtain the data to make these sorts of adjustments.

The Bottom Line
Like all studies that are able to "dredge" through a large data-base of run-forms, we end up with more questions than answers. The large number of patients enables researchers to find some statistical results, but the interpretation gets muddy.

Moving forward, the key will probably be in QA; making sure that all the appropriate patients get ECGs, that transport is expedited in STEMI, and that feedback is obtained from the ED and cardiology. I'm hoping that future, and better, studies will demonstrate that EMS is taking acre of everyone to the same high standards. 

In order to protect the c-spine, should we stop helping?

There have been some interesting recent evolutions in long-held beliefs about managing the possible cervical-spine fracture, however, and a recent study adds an interesting development.
The Study
The new study, Cervical Spine Motion during Extrication, makes an interesting contribution to the research, uses intriguing methods, and is very relevant to EMS. 

It is usual practice for EMS to go through great efforts to maintain cervical spine immobilization after an MVC. The patient will often have both a cervical collar and a "short board," or KED, applied. The EMS crew will then go through elaborate efforts to move the patient onto a long board right from the car seat, avoiding any active participation by the patient.

The ideal

The somewhat messy reality

This is a lot of effort, but the hope is that, by avoiding motion of the cervical spine, there will be no further, or "secondary," trauma to the spine. The actual risk of secondary injury is controversial, but immobilization is the current usual practice. 

Well, a natural question to ask is: Does it work? Do these multiple devices and great physical efforts avoid motion of the cervical spine? 

Well, this question has been approached in a number of ways in the past, but Missouri researchers took a new approach. They used a simulated extrication scenario, and tracked motion of the cervical spine using video motion capture, the technique used to, among there things, render Tom Hanks into a cartoon character.

Looks kind of creepy to me, but Hanks can get away with anything.

Note the little dots on Tom's head, hands, and shoulders. By tracking the movement of these points, a computer can compare degrees of flexion, etc., of the neck.

For the simulated extrication scenarion, they used a mock-up of a Corolla that had been in a bad head-on MVC. They recreated the postions of all the posts with PVC, replaced the surfaces with chicken wire, and replaced the seatback with Plexiglass. This way, they could record the extrication from all angles.

The participants were all paramedics with more than 5 years of experience - some of them also played the victim, along with some non-EMS people.

The victims exited the vehicle in 4 different ways:

1. They were instructed to get out on their own, and walk over to the backboard and lie down.
2. They first had a cervical collar placed, but still had to get out on their own.
3. Collar was placed, and then the EMTs proceeded to maneuver the patient onto the board while "holding c-spine," instructing the victim to not offer assistance.
4. A collar was placed, as well as a KED, before being moved onto the board.

(For what it's worth, method #4 is what I was taught by the good folks at SOLO in Conway, New Hampshire, when I first got my wilderness EMT. It took me awhile before I felt comfortable with method #3, that everyone in the "real world" was using!)

So how much neck motion did they see? A lot! 
 

Looking at the graphs, you can see how much motion, in each plane, they observed with each extrication method. 

Now here's the weird thing: method #2 (c-collar and "get out on your own") showed significantly less cervical motion than both methods #1 and #4! 

For example, take a look at "Graph C" from just above:

In other words, "Here's a collar, now please step out of the vehicle" produced less neck motion than "Don't move! We'll do all the moving for you."

Interpretation
The results are seemingly paradoxical, but it squares with some of my experience. Placing the KED and moving the patient to the backboard always seemed to go smoothly if the patient was slender, short, and driving a large car. 

Smaller car, bigger person - it doesn't go so smoothly...

E.g. Try putting a KED on Klump.

Also, it's worth highlighting the change in protocols that a few EMS agencies have already rolled out, actually prior to the publication of this study.

For example, in the last year,  Xenia FD in Ohio, as well as New Haven, CT, have started using method #2 for certain lower-risk trauma. A number of other agencies are said to be following suit. 

And although it's not a prehospital policy, Bridgeport Hospital is now encouraging nurses and EMTs to remove backboards as soon as patients arrive in the ED - no doctor involved! This shift in practice was prompted both by the risk to patients that backboards pose, and the scant evidence that supports their use once the patient has arrived at the hospital.

And you get your board back right away!

This study suggests that those policies may not be as risky as previously imagined, and may, in fact, be more conservative than the "usual practice!"

The Bottom Line
This study adds to the growing body of research that suggest that our approach to spinal care may be quite different in the near future!

(In the meantime, of course, please stick to your local protocols and guidelines.)