Selective Immobilization: Current Research and Practice

Where did the protocols that are being followed come from, and how have they continued to develop?

EMS providers make clinical decisions regarding treatments they employ every day, and cervical spine immobilization is no different. Not every 20-year-old who twists his ankle falling on the stairs comes to the ED on a board, nor does every 65-year-old who has chest pain after a minor fender-bender. Clinical decision guidelines or protocols are the foundation of care in the prehospital setting. Several EMS systems are currently performing selective spinal immobilization. Where did the protocols that are being followed come from, and how have they continued to develop?

As with most other prehospital protocols, the guidelines for selective spinal immobilization are developed from emergency department and trauma surgery practice. In the prehospital arena, EMS providers must decide whether or not a patient should be immobilized using a long spineboard, cervical collar and cervical immobilization devices to prevent exacerbation of existing injuries during transport. For an ED physician, the question becomes whether or not to obtain x-rays of the cervical spine to evaluate for fracture or other unstable injury. For both, the question is whether the risks and costs of treatments and investigation outweigh the benefits of not filming or immobilizing and the inherent risk of missing a cervical spine fracture.

In the ED, the treatment risks include the unknown effects of doses of ionizing radiation, as well as prolonged stays in the ED and significantly increased costs. For EMS, the risks include aspiration, discomfort, injuries from bumpy rides on hard boards and anxiety from loss of physical control.

Over the last five years, ED treatment of patients with presumed cervical spine injuries has changed after completion of two different scientific studies of cervical spine x-ray procedures. Prior to completion of these studies, patient evaluation was done clinically by individual practitioners with no guidelines. Each provider made his own rules for ordering x-rays, given his length of time in practice, relationship with the patient, and patient history and physical exam. Two studies changed that. In July 2000, National Emergency X-Radiography Utilization Study (NEXUS) Group published the results of its validation study of clinical guidelines, and in October 2003, The Canadian C-Spine Rule for Radiography in Alert and Stable Trauma Patients was published.

NEXUS and the Canadian C-Spine Studies

The NEXUS study, highlighted in the accompanying article on page 99, was conducted at 21 university centers with patients whose emergency physicians believed needed to have x-rays due to concern for potential cervical spine injury, regardless of mechanism, injury pattern or mental status. By collecting a wide array of information about each patient who received x-rays and then reviewing the x-ray results, the authors were able to establish a set of clinical criteria that could be used as a guide for ordering x-rays in high-risk patients. The guidelines were then validated clinically in 34,069 prospective cases.

The NEXUS guidelines showed remarkable sensitivity in picking up cervical spine injuries in all patients who presented to the emergency department. Of the 818 cervical spine injuries diagnosed in the study population, all but eight would have been discovered using the clinical decision rule. This is a missed fracture rate of less than 1%. There were no adverse outcomes among the study population.

The Canadian cervical spine evaluation guideline was developed similarly at 10 emergency departments across Canada on 8,924 patients. The patient population studied was slightly different, with all patients enrolled having trauma to the head or neck, and all with a Glasgow Coma Score of 15. These guidelines highlighted concerning mechanisms, or head and neck trauma, as well as mechanisms that were low risk. This rule had 100% sensitivity for cervical spine fracture. No fractures were missed, but not everyone was filmed.

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