EMS

Brought in by Ambulance, #3: My leg hurts! Well, here's your C-collar...

Case Scenario:
You are doing your second supervisor ride along and hoping that your white cloud of peace will disperse so you can see some St. Louis action. You are called emergently to MVC vs. two pedestrians. On arrival to the scene, you find one patient on the ground with an open fracture of his leg.  ABC’s are fine. The patient notes the car came around the corner and hit his leg. He remembers everything, and complains only of his leg hurting. A quick examination of his neck reveals no midline tenderness and no pain with range of motion. However, secondary to his distracting injury a C-collar was placed. As the ambulance drives away with the patient, you wonder what the evidence behind C-collar use is, and if it was really necessary to place a collar in this gentleman without any neck pain.



Current EBM evidence:
Most of the recommendations on c-collar use are based on opinion and tradition. The American Association of Neurological Surgeons and the Congress of Neurological Surgeons Joint Commission have made recommendations; however, most of these recommendations are based on Level III evidence. Unfortunately, there is a paucity of evidence for the implementation and continued use of C-spine collars. In fact, a Cochrane review in 2007 noted there wasn’t a single prospective RCT on c-collar use.

Currently, most of the validated evidence we have for spinal cord protection is in terms of imaging. Both the NEXUS criteria and the Canadian C-spine rules have been validated, and are used by the American Association of Neurological Surgeons and the Congress of Neurological Surgeons Joint Commission on their official recommendations on the management of acute spinal cord injury. The NEXUS criteria and the Canadian C-spine rules have been applied in the pre-hospital setting; those who will require imaging should therefore be placed in a cervical collar for C-spine stabilization.

Nexus Criteria:
No imaging if all of the following are true:
●No posterior midline cervical tenderness
●Normal level of alertness
●No evidence of intoxication
●No abnormal neurologic findings
●No painful distracting injuries

There has never been any control trial on patients examining if C-collars actually stabilize the spine. There have been a multitude of trials on volunteers and models, many of which have contradicting results. While some studies show that C-collars do stabilize the neck, others show that collars may actually increase neck movement. In a controversial study done by Hauswald et.al, un-immobilized patients in Malaysia had better neurological outcome than similar patients who were immobilized in New Mexico. While this study compared no immobilization to full spinal immobilization (and therefore flawed in the analysis), the overall philosophy that second injury due to transport is rare as the forces are weak compared to the force required to injure the spinal cord may still hold true.

While the evidence to support the use of C-collars is weak, there is an increasing amount of evidence noting potential risks and morbidity associated with C-collar use. While the goal of C- collars is to reduce movement of the cervical spine and protect the spinal cord, a few case studies have shown that forcing a neck into “anatomical position” can actually cause spinal cord injury, particularly in patients with ankylosing spondylitis. A study on cadavers noted that extrication collars caused an increased degree of separation between vertebrae when there is a dissociative injury.

In a systematic review done by Sparke et. al, there have been a few studies noting an increase of ICP pressure with the placement of C-collar. It is estimated that risk of increased ICP is 35.8%. It is thought that the increased ICP is secondary to pressure placed on the jugular veins (causing venous congestion); however there is no real knowledge of the etiology of the increased ICP. Sparke et. al also did a review of the risk of tissue ulcerations secondary to C-collar placement. A review of 14 studies showed the incidence of hospital acquired pressure ulcers from a C-collar range from 23.9-44%. While the review noted that the measurement of pressure from the C-collars was highly variable between studies, pressures from C-collars can be quite elevated (up to 150mmgHg). The review also notes that none of the studies examined in the review were randomized control trials.

The immobilization of the neck can cause increased difficulty in airway management and protection. It is often much more difficult to intubate a patient that has been placed in a C-collar. Patients who do not require intubation are at an increased risk of aspiration with vomiting.

Additionally, once a C-collar has been placed, the patient may be more likely to undergo imaging to have his C-spine cleared. In a study done by Kim et. al., children who were placed in a C-collar were much more likely to undergo imaging to clear the c-spine (56.6 vs 13.4%) and were much more likely to be admitted to the hospital 41.6 vs 14.3%). This can have serious implications on the length of stay on the patient, as well as overall cost to the patient and the hospital.

While the evidence supporting C-collars is minimal, the potential consequence of movement causing additional spinal cord injury is so severe that much better evidence will be required before a change can occur. However, there is the potential to try and reduce the number of C-collars placed, especially on low-risk individuals. In a prospective study done by Rose et. al, it was found that physical exam (no neuro deficit and no midline tenderness or pain with range of motion) was over 99% sensitive with a 99% negative predictive value. In this study, all patients with GCS greater than or equal to 14 were attempted to be clinically cleared regardless of ethanol level or presence of distracting injuries. All patients received CT imaging of their spine, even if they were clinically cleared. Of the 464 patients with distracting injuries that were clinically cleared, only one was found to have C-spine fracture (C2 lateral mass). It should be noted that of the 544 patients without distracting injury that were cleared clinically, one was also found to have a C-spine injury (C6 lamina and C7 superior facet).

Take Home:
-No prospective randomized study on use of c-collars
-There are possible adverse outcomes with use of c-collars (eg increased ICP, pressure ulcers)
-There is evidence supporting clearing c-collar clinically, even with distracting injuries

References:
1. Walters BC, Hadley MN, Hurlbert RJ, Aarabi B, Dhall SS, Gelb DE, Harrigan MR, Rozelle CJ, Ryken TC, Theodore N; American Association of Neurological Surgeons; Congress of Neurological Surgeons. Guidelines for the management of acute cervical spine and spinal cord injuries: 2013 update. Neurosurgery. 2013 Aug;60 Suppl 1:82-91.
2. Sundstrøm T, Asbjørnsen H, Habiba S, Sunde GA, Wester K.. Prehospital Use of Cervical Collars in Trauma Patients: A Critical Review. J Neurotrauma. 2014 Mar 15;31(6):531-40.
3. Hauswald M, Ong G, Tandberg D, Omar Z. Out-of-hospital spinal immobilization: its effect on neurologic injury. Acad Emerg Med. 1998 Mar;5(3):214-9.
4. Ben-Galim P, Dreiangel N, Mattox KL, Reitman CA, Kalantar SB, Hipp JA. Extrication collars can result in abnormal separation between vertebrae in the presence of a dissociative injury. J Trauma. 2010 Aug;69(2):447-50.
5. Papadopoulos MC, Chakraborty A, Waldron G, Bell BA. Lesson of the week: exacerbating cervical spine injury by applying a hard collar. BMJ. 1999 Jul 17;319(7203):171-2.
6. Sparke A, Voss S, Benger J. The measurement of tissue interface pressures and changes in jugular venous parameters associated with cervical immobilisation devices: a systematic review. Scand J Trauma Resusc Emerg Med. 2013 Dec 3;21:81.
7. Leonard J, Mao J, Jaffe DM. Potential adverse effects of spinal immobilization in children. Prehosp. Emerg. Care 16, 513-518.
8. Rose MK, Rosal LM, Gonzalez RP, Rostas JW, Baker JA, Simmons JD, Frotan MA, Brevard SB. Clinical clearance of the cervical spine in patients with distracting injuries: It is time to dispel the myth. J Trauma Acute Care Surg. 2012 Aug;73(2):498-502.

Submitted by Melissa Kroll, PGY-2.
Faculty Reviewed by Phil Moy.

Brought In By Ambulance, #1: Vagal maneuvers in SVT

In this section, we will highlight EBM queries targeted to the prehospital care of patients.


Without further ado...
You respond to a call-out for "palpitations." You arrive on-scene to find a middle-age female patient who is awake, well-oriented, and talking to you in complete sentences. She is complaining of her heart "fluttering," and reports feeling somewhat short of breath and anxious. She reports a prior history of palpitations without a clear working diagnosis. Cardiac leads are placed, and the monitor shows a well-organized narrow-complex rhythm with rate in the 160s. Her BP is stable. Her skin appears warm and well-perfused. As the EMT's are working on establishing IV access, you wonder how effective vagal maneuvers are in terminating SVT.

Clinical Question:

Which vagal maneuver, if any, should be used to terminate SVT?

Literature:

In two studies, the authors found that the valsalva maneuver was more successful in terminating SVT than carotid massage or ice-to-face. In one case series, valsalva was able to terminate SVT in 54% of patients. These study authors also found that a right carotid massage was slightly more efficacious than a left carotid massage in terminating SVT (17% vs 5%). Attempting to provoke the diving reflex with ice had the same efficacy as the right carotid massage (17%)1.

A second study of prehospital treatment of SVT found that valsalva was more efficacious if the patient was supine, the maneuver was sustained for 15 seconds, and a pressure of 40mm Hg was obtained. The study again found that valsalva was more successful than carotid sinus massage and the ice-to-the face technique2.

In a third study, there was a trend toward valsalva being more effective than carotid sinus massage.  Valsalva had a success rate of 19.4% vs 10.5% for carotid sinus massage, though these figures did not reach statistical significance. When initial carotid massage did not resolve the SVT, valsalva was able to convert in 16.9% cases, versus 14% when carotid massage was used after failed valsalva.  Overall, the conversion rate was 27.7%3.

Valsalva maneuver is inherently safer than a carotid massage, as there is no risk of causing decreased carotid perfusion or dislodging clot. The most difficult part is ensuring full patient participation, especially in pediatric patients. One method that has been suggested to promote valsalva in pediatric patients is asking the child to blow through a straw. Several reports also suggest that valsalva maneuver is more efficacious than carotid massage in terminating SVT. There is also limited data to suggest that a right carotid massage is better than a left carotid massage. Given that Valsalva is safer and may be more efficacious, attempts at terminating SVT should begin with Valsalva.

Take home points:

- In available reports, valsalva maneuver appears to be the most efficacious of vagal maneuvers in terminating SVT. It may be effective anywhere from 20-50% of the time.

References:
1. Mehta D, Wafa S, Ward DE, Camm AJ. Relative efficacy of various physical manoeuvres in the termination of junctional tachycardia. Lancet. 1988;1(8596):1181.
2. Smith G, Morgans A, Boyel M. Use of the Valsalva manoeuvre in the prehospital setting: a review of the literature. Emerg Med J. 2009 Jan;26(1):8-10
3. Lim SH, Anantharaman V, Teo WS, Goh PP, Tan AT. Comparison of treatment of supraventricular tachycardia by Valsalva maneuver and carotid sinus massage. Ann Emerg Med. 1998 Jan;31(1):30-35

Contributed by Steven Hung, PGY-2

Rigid Backboard for Spinal Immobilization?

You are working a busy overnight shift when you see EMS bring in a “trauma packaged” patient – a young, healthy-appearing female, on a hard backboard and with a C-collar in place. Per their report, she was the restrained driver of a vehicle struck from behind at a low rate of speed while stopped at a red light. The patient denies LOC, but is endorsing pain in her neck and all the way down her back. She is complaining that the backboard is uncomfortable and making her back pain worse.

Clinical Question: 


What are the indications for prehospital rigid spine immobilization? Could it have been deferred in this patient?

Literature:


Despite the dogmatic and traditional use of rigid backboards for extrication and transport of patients with possible blunt traumatic injury of the spine, it is not an altogether benign intervention. The discomfort associated with bumpy ambulance rides while secured to a rigid board may worsen a patient’s initial presentation to the ED providers such that unnecessary spinal imaging is ordered. Prolonged transport times on rigid boards have been associated with pressure sore formation and respiratory compromise.

The use of rigid spine immobilization by prehospital providers has become based largely on mechanism of injury and concern for possible spinal cord compromise, rather than being based on signs or symptoms of spinal injury itself. This is the opposite of how diagnosis of such injuries is handled once the patient arrives to the ED. As the validation studies of the NEXUS and Canadian C-spine rules have shown, the risk of a C-spine fracture in a patient with normal mental status and without clinical signs or symptoms of spinal cord injury or distracting injury is vanishingly small.

With this in mind, the National Association of EMS Physicians (NAEMSP) and the American College of Surgeons Committee on Trauma published a position paper in the journal Prehospital Emergency Care entitled “Indications for Prehospital Spinal Immobilization.” This paper (and the accompanying resource document) outlines who should and should not be immobilized based on best evidence.

To begin, patients must first be assessed for a mechanism of injury capable of causing spinal cord injury. This is somewhat open to interpretation by EMS providers, and can vary for different patient populations (i.e., a fall from standing would be a very low-risk mechanism for healthy young adult male but much higher risk in an elderly, frail female). The document specifically addresses penetrating wounds, based on evidence published in a paper in the Journal of Trauma in 2010. Basically, if a penetrating wound to the head, neck, or torso does not obviously affect the area of the spine and is not associated with evidence of spinal injury (including focal neurologic deficits), there is no need for rigid immobilization.

If the mechanism is determined to be a risk for spinal cord injury, the EMS provider must then perform a spinal assessment, which is largely derived from the NEXUS and Canadian rules for C-spine imaging. The spinal assessment is “positive” if there is any midline tenderness, palpable/visible midline deformity, or a new neurologic deficit. Immobilization must also be considered for those in which a spinal assessment is unreliable. This includes patients with altered mental status, who are intoxicated with alcohol or drugs, who have a painful distracting injury (by NAESMP criteria, a long bone fracture proximal to the wrists or ankles), or who are otherwise unable to fully participate in the exam due to a language barrier or due to age (i.e., pre-verbal pediatric patients).

If this assessment is negative, NAESMP recommends a C-collar should still be placed if the patient is over 65 (due to increased risk of C-spine injury in this population), but the patient does not require further spinal immobilization and can be transported in position of comfort. Obviously, a C-collar should be placed on any patient if there is midline tenderness in the C-spine.

Interestingly, a study from the Journal of Emergency Medicine published in 2013 reported data from a high-speed infrared motion analysis of healthy volunteers that showed those who extricated themselves with a C-collar in place had less spinal motion than those who were told to hold still while EMS crews attempted extrication themselves. Thus, if the patient is able to extricate themselves and able to ambulate, they should be allowed to do so. If their spinal assessment is positive, they can then be secured to the stretcher with seatbelts, which has been shown to be as effective at immobilizing the T- and L-spine as a rigid backboard. If the patient cannot self-extricate, they can be extricated using standard equipment and transported to the stretcher via a hard backboard. However, he or she should be logrolled off the backboard once reaching the stretcher to minimize time spent on the hard board. The safety of this approach is reinforced by data from other studies which have shown an extremely remote risk of significant (i.e., surgical) T- or L-spine injury in restrained persons in low-risk MVCs.

Take home: 


Remember that securing to the stretcher is an effective mode of spinal immobilization. Rigid backboards should probably be reserved for transfer of a nonambulatory patient from the scene to the stretcher, and should be removed as soon as possible.

References:

1) Prehosp Emerg Care. 2014;18(2):306-14.
2) J Trauma. 2010;68(1):115-20.
3) J Emerg Med. 2013;44(1):122-7.
4) Spine J. 2014. PMID 24486471 [EPub].
5) J Emerg Med. 2006;31(4):403-5.
6) Injury. 2006;36(4):519-25.


Kindly contributed by Sam Smith, PGY-3.