Thursday, November 6, 2014

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, 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

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.

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