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!

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.)

Bradycardia - Traumatic etiology?

When the patient has bradycardia, you run through a short differential. Electrolytes, MI, drugs,.... trauma? How does that work?

The patient
A trauma alert was rolled into room 5 at the 'Port. A 45 year-old male, restrained driver in a roll-over, who had been ambulatory on EMS arrival. He was mildly intoxicated, denied any significant medical problems. His vitals were normal both prehospital and in the ED. (The trauma alert was due to mechanism, not his condition.) 

His exam was notable for a rather large laceration to his scalp, with a correspondingly large blood clot at the head of the backboard.

"He probably smells my dog!"

The bleeding was controlled, and the evaluation continued. 

While we were getting the chest x-ray, however, we noted that his heart rate, which had intially been around 70-80, started slowing down. 60, 50, 40, down to the 30s! 

His blood pressure, which had also been normal, plunged down to a systolic BP of around 50 mmHg. His ECG showed this:

An old ECG was entirely normal. Interestingly, the patient, in a supine position the whole time, denied any symptoms whatsoever, and was moderately amused by our concern.

Discussion
So what happened to his heart? 

Well, we should worry first about ischemia- or infarction-related bradycardia. An inferior MI is notorious for causing 1° and 2° AV blocks, most of which resolve on their own. These bradycardias manifest with a narrow QRS, since the block involves the AV node, but not the bundle of His, etc. They usually get better in a few days, on their own.

By contrast, anterior MIs may involve an infarct of part of the ventricular conduction pathways. The patient will have a wide QRS and a high-grade 2° or 3° AV block. These are bad, and need permanent pacemakers!

Although you should think of hyperkalemia when you see bradycardia, there was little else to suggest it. He denied any medications, so digoxin, beta-blockers, and calcium-channel blockers seemed unlikely, especially given how quickly the rhythm had developed after normal prehospital vital signs.

Perhsps I should be clearer about how the bleeding from the scalp was controlled. Since the wound was large, and the bleeding brisk, a number of staples were rapidly placed.

NOT an approved wound closure technique. (credit)

Let's take a closer look at the ECG. Like I said before., he gradually slowed down to 34. 

Sinus activity is almost extinguished - I can only find 2 P-waves, preceding beats #1 and #3. The QRS is narrow, suggesting a junctional rhythm, albeit much slower than you would expect (usual junctional rate is 40-60). You can't really call it complete heart block, since there is so little atrial activity; instead, it's just called AV dissociation.

Putting all this together, it appears he had a cardioinhibatory/reflex syncopal episode; i.e. he fainted. The placement of the staples likely triggered a strong vagal reflex, which inhibited both the sinus node (almost no P-waves) and the AV node (junctional bradycardia). 

Fortunately he was already supine when it occurred!

Inappropriate stapling technique.

The treatment
He got atropine 0.5 mg IV, and a liter of NS on a pressure bag. His heart rate corrected quickly, coming up to about 80, but his blood pressure took a few more minutes to come up! He was admitted, and did not have any more bradycardic episodes. 

Bottom line
 No harm, no foul, as they say. But I do think we're going to be more enthusiastic about using lidocaine in the trauma bay, however!