A study on ultrasonographic measurement of optic nerve sheath diameter for detecting raised intracranial pressure in intensive care unit patients

Abstract

Introduction: Optic nerve sheath diameter (ONSD) using ocular ultrasound is increasingly used now a days as noninvasive means of detecting raised intracranial pressure. We conducted a cross‐sectional, observational study to assess its validity, optimal cutoff limit and inter‐observer variability in our ICU patients.

Methodology: The adult patients admitted to our ICU during six month interval (Jan 2014‐June 2014) were enrolled for the study. The exclusion criteria were patients breathing spontaneously, presence of hyperthyroidism, optic nerve tumor, neuritis, glaucoma and orbital fracture. The patients were divided into two groups. Group I – those having increased ICP clinically or as per radiological findings. Group II – patients having no features of raised ICP. A linear probe with a frequency 13‐7 MHz, Sonosite^TM USA, was used to measure ONSD by two blinded, experienced investigators. Mean of three readings was taken. The entire data was compiled and analyzed applying appropriate statistical tests.