Background: Ultrasonographic optic nerve sheath diameter (ONSD) is a satisfactory non-invasive intracranial pressure (ICP) monitoring test. Our aim was to evaluate ONSD as an objective screening tool to predict and diagnose ICP changes in sepsis associated encephalopathy (SAE).

Methods: Our prospective observational study was conducted on sepsis patients and after ICU admission the time to diagnose SAE was recorded and patients were divided into non-SAE group including conscious sepsis patients and SAE group including sepsis patients with acute onset of disturbed conscious level. ONSD was measured within 24h of ICU admission for all patients and then every other day for up to 10 consecutive days, until ICU discharge or death. The primary outcome was to compare ONSD measurements of both groups to find if there was a correlation between ONSD and SAE occurrence.

Results: Eighty-nine sepsis patients were divided into non-SAE group (n=45) and SAE group (n=44). ONSD showed a statistically significant difference at day 0 and a high
significant differences at day 2, 4, 6, 8, and 10. Day 2 ONSD had the best accuracy for
predicting SAE with a cutoff > 5.2mm (sensitivity of 93.2 %, specificity of 100 %),
statistically positive correlation with SOFA score (r=0.485, P