Placement of a cervical collar increases the optic nerve sheath diameter in healthy adults.

INTRODUCTION: Blunt head trauma is a common cause of increased intracranial pressure (ICP). Ultrasound measurement of the optic nerve sheath diameter (OSND) is an accurate and non-invasive way to detect increased ICP. Blunt trauma patients are often immobilized in a rigid cervical spine collar. Our objective was to describe the changes in ONSD following the placement of a c-collar and determine if any changes were time-dependent. METHODS: We performed a prospective cohort study measuring the ONSD of healthy volunteers before and after placement of a c-collar. Two physicians obtained the measurements. Each eye was scanned twice using a standardized technique. This was done before c-collar placement, 5min after placement and 20min after placement. A mean of both eyes was calculated and analyzed using descriptive statistics. An intraclass correlation coefficient (ICC) was used to assess inter-rater reliability. RESULTS: Twenty study participants with a mean age of 37.1years old were enrolled. The mean baseline ONSD was 3.77mm (95% CI 3.48-4.07). The mean ONSD 5 min after the c-collar was placed was 4.47 (95% CI 4.17-4.78). The mean ONSD at 20min after c-collar placement was 4.53 (95% CI 4.13-4.92). These changes were statistically significant (p=0.003 and <0.001). Reliability was relatively strong overall (ICC=0.74; 95% CI: 0.65, 0.81). CONCLUSION: The placement of a cervical collar increased the ONSD at 5min and this change remained increased at 20min. Future study should assess whether similar results are found in patients with blunt head trauma.

Evaluation of the Storz CMAC®, Glidescope® GVL, AirTraq®, King LTS-D™, and direct laryngoscopy in a simulated difficult airway.

OBJECTIVE: The aim of this study was to compare first-attempt and overall success rates and success rates in relation to placement time among 5 different airway management devices: Storz CMAC, Glidescope GVL, AirTraq, King LTS-D, and direct laryngoscopy (DL). METHODS: Emergency medical technician basic (EMT-B), EMT-paramedics (EMT-P), and emergency medicine residents and staff physicians placed each of the 5 devices in a random order into an AirSim (TruCorp, Belfast, UK) part-task training manikin. The difficult airway scenario was created by fixing the manikin head to a stationary object and introducing simulated emesis into the hypopharynx. First-attempt and overall success and success in relation to placement time were compared. Provider feedback about device performance was also evaluated. RESULTS: Ninety-four providers (16 EMT-basics, 54 EMT-paramedics, and 24 emergency department doctors of medicine) consented to participation. First-attempt and overall success rates for DL, King LTS-D, GVL, and CMAC were not statistically different. Compared with DL, the AirTraq was 96% less likely to be placed successfully (odds ratio, 0.04; 95% confidence interval [CI], 0.01-0.14). When time was factored into the model, the odds of successful placement of the King LTS-D were higher compared with DL (hazard ratio [HR], 1.80; 95% CI, 1.34-2.42) and lower for GVL (HR, 0.59; 95% CI, 0.44-0.80) and AirTraq (HR, 0.228; 95% CI, 0.16-0.325). Providers ranked the CMAC first in terms of performance and preference for use in their practice setting. CONCLUSION: Overall success rates for DL, King-LTS-D, and both video laryngoscope systems were not different. When time was factored into the model, the King LTS-D was more likely to be placed successfully.