Placement of a cervical collar increases the optic nerve sheath diameter in healthy adults Journal Article uri icon

abstract

  • 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.

publication date

  • 2018