Source: Kwan I, Bunn F, Roberts I. Spinal immobilisation for trauma patients. Cochrane Database Syst Rev. 2001;2001(2):CD002803.
Study Population: Trauma patients with potential spinal cord injuries
Efficacy Endpoints: Mortality, neurological disability, spinal stability
Harm Endpoints: Pressure ulcers, discomfort/pain, airway compromise
Narrative: Spinal immobilization or spinal motion restriction after blunt trauma is a routine practice and standard care in most settings due to fear of movement causing or worsening spinal cord injury. This is ingrained in guidelines for trauma management. Immobilization is typically performed with backboards, cervical collars, sandbags, straps, and vacuum mattresses. The aim of these interventions is to restrict mobility in order to prevent secondary spinal cord injury during extrication and transport. However, the benefits of this approach are unclear while harms are common. Cervical collars have been shown to have several deleterious effects. Studies have shown that cervical collars may increase ICP1 and that these increases may in fact be worse in the setting of underlying elevated ICP.2 Additionally, cervical collars may reduce mouth opening and complicate airway mechanics which may impede rapid airway management.3, 4 Collars may also increase the risk of aspiration,5 conceal wounds or cause local pressure injury,6 resulting inpatient discomfort.
The Cochrane systematic review discussed here7 searched multiple electronic databases for randomized controlled trials studying the effects of spinal immobilization. No studies of sufficient quality were found, and the authors were unable to make firm conclusions about the effect of immobilization on mortality, neurologic injury, spinal stability, or adverse effects.
Caveats: This Cochrane systematic review restricted the inclusion criteria to randomized trials. Given that no such trials exist, the authors conclude that there is insufficient evidence for or against spinal immobilization in obtunded blunt trauma patients. However, absence of trial data points out that further research is needed. In the meantime, lower level studies are the only sources to help answer the question.
In the absence of trial data, common sense and general principles of causal inference are important. For instance, the moment at which irreversible traumatic cord damage occurs is overwhelmingly the moment of impact. This seems true anecdotally and intuitively, as any massive energy transfer capable of compromising spinal column integrity will rarely be trumped by, or simply a set up for, a comparatively minor movement during patient care. In rare cases such events have been reported, though it is difficult to know how often. Since these events are indistinguishable from cases in which impact causes ischemia, compression, or hemorrhage that leads to deterioration in the period during patient care and transport. Regardless, it is apparent that the overwhelming majority of blunt trauma patients do not have spinal instability and thus can only be harmed by immobilization.
While a complete literature review is beyond the scope of this summary it is notable that validated criteria for spine injury clearance are widely and safely applied both in the emergency department and the prehospital setting,8 and a recent trend favors spinal motion restriction without boards or collars.9, 10 Limited studies have detected no increases in cord injury following implementation of any such protocols.9 Though some professional societies including the Society for Academic Emergency Medicine (SAEM) do recommend cervical collars in the setting of blunt trauma, the position paper cited by SAEM does not provide any evidence of efficacy of cervical collars or rationale for their presumed benefit.11
As enumerated in a letter to the editor in response to a 2006 summary of this Cochrane review, one non-peer reviewed estimate of NNT for spinal immobilization to prevent secondary neurologic injury was reported to be between 625 and 3333.12 This was calculated based on three case series’ published 32 to 64 years ago,13, 14, 15 and assumes all episodes of deterioration were both directly caused by movement during transport and were preventable by immobilization. This claim, however, is critically limited by the now antiquated manner in which these cases were managed on presentation—in many cases no cervical spine imaging was performed despite major trauma or a clear spinal injury threat. The workup of severe trauma in the modern emergency department universally includes high-quality CT imaging in such cases, which seems almost certain to have identified causes of neurologic compromise early in the hospital course of these patients. Conversely, harms of spinal immobilization have not been estimated or quantified in this fashion, though one review suggests morbidity and mortality likely trumps any benefits.16
The weakness of supporting evidence, known harms, and burdens of immobilization have resulted in calls to discontinue the practice. Yet it remains intuitively possible that immobilization may provide a benefit in some cases. Perhaps subgroups more likely to see that benefit can be identified and targeted (e.g. patients with neurological deficits or those with gross anatomical deformity of the spine10), relieving systems and individuals of the harms and devotion of resources associated with widespread, routine immobilization. Well-designed large trials are needed to answer these questions. Based on the existing evidence, we have assigned a color recommendation of Yellow (Unclear if benefits) to this intervention.
The original manuscript was published in Academic Emergency Medicine as part of the partnership between TheNNT.com and AEM.
Author: Olivia Serigano, MD; Matthew Riscinti, MD
Supervising Editors: Shahriar Zehtabchi, MD
Published/Updated: October 15, 2020
The title bar is color-coded with our overall recommendation.