Literature Review: Broken Glass and C-Spine Immobilization

Sochor M, Althoff S, Bose D, et al. Glass intact assures safe cervical spine protocol. J Emerg Med, 2012 Dec 20 [e-pub ahead of print].

Abstract

Selective cervical spine immobilization performed by Emergency Medical Services (EMS) is being utilized with increasing frequency. These protocols, although very sensitive, still include subjective data such as “mild cervical discomfort.” The aim of this study is to create an objective clinical decision rule that would enhance the selective approach for cervical spine immobilization in patients aged 16–60 years.

Objective—It is hypothesized that, in a motor vehicle crash, the integrity of the involved vehicle’s glass window and air bag status is an excellent objective measure for the amount of energy a vehicle occupant has experienced during the crash. GLass intact Assures Safe Spine (GLASS) is an easy and objective method for evaluation of the need for prehospital cervical spine immobilization. Methods—A retrospective cohort study was performed with sample motor vehicle crash cases to evaluate the performance of the GLASS rule. The National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) was utilized to investigate tow-away motor vehicle crashes, including their glass damage characteristics and occupant injury outcomes, over an 11-year period (1998–2008). Sample occupant cases selected for this study were patients aged 16–60 years, who were belt-restrained front seat occupants involved in a crash with no air bag deployment and no glass damage before the crash.

Results—A total of 14,191 occupants involved in motor vehicle crashes were evaluated in this analysis. The results showed that the sensitivity of the GLASS rule was 95.20% (95% confidence interval [CI], 91.45%–98.95%), the specificity was 54.27% (95% CI, 53.44%–55.09%), and the negative predictive value was 99.92% (95% CI, 99.86%–99.98%). Conclusion—The GLASS rule presents the possibility of a novel, more objective tool for cervical spine clearance. Prospective evaluation is required to further evaluate the validity of this clinical decision rule.

Comment

Motor vehicle crashes are the most common indication for spinal immobilization; EMS systems are increasing the use of selective immobilization protocols. The two most studied are the National Emergency X-Radiography Utilization Study (NEXUS) and the Canadian C-Spine Rule. Neither of these uses the condition of the patient’s vehicle as one of the criteria.

The authors here used a large database of crash investigations conducted by NHTSA, whose NASS-CDS program collects detailed vehicle data (e.g., photographs, air bag deployment, fluid spills, broken glass) on about 5,000 vehicles a year. The authors specifically focused on easily determined, objective, yes/no criteria: broken glass and air bag deployment. Out of about 8,000 front-seat occupants who met the GLASS criteria, only six (three disc herniation, three fractures) had significant cervical spine injury.

We all know there is a correlation between the extent of vehicle damage and the extent of injury to the patient. The results of this study need prospective validation, and may then be a useful part of the puzzle in determining who is at risk for an unstable cervical spine injury.

Angelo Salvucci, Jr., MD, FACEP, is medical director for the Santa Barbara County and Ventura County (CA) EMS agencies and a member of the EMS World editorial advisory board.