Usefulness of the Ultrasound Measurement of the Optic Nerve Sheath Diameter to Detect Intracranial Hypertension.

Abstract

Objectives: To determine the predictive value of the measurement of the diameter of the optic nerve sheath (ONSD) with ocular ultrasonography compared to invasive intracranial pressure (ICP) measurement for the detection of intracranial hypertension (ICH). Design: Prospective, observational study. Setting: Intensive Care Unit (ICU) of two tertiary university hospitals in Montevideo, Uruguay. Patients: We studied 56 adult patients of both sexes, over 18 years of age, who required sedation, mechanical ventilation, and invasive ICP monitoring (patients with severe, traumatic and non-traumatic AEI) with a Glascow Coma Score (GCS) equal to or less than 8 on admission to the ICU. Interventions: This was a study that utilized non-invasive (minimal risk) ultrasonography in patients admitted to the ICU. Measurements and main results: In our study, a logistic regression model was performed in which it was observed that the variable ONSD is statistically significant with a p value of 0.00803 (<0.05). This model estimates and predicts the probability that a patient will have an ICP greater than 20 mmHg. From the analysis of the cut-off points, it is observed that a value of 5.65 mm of ONSD maximizes the sensitivity (92.9%) of the method (a greater number of individuals with ICP > 20 mmHg are correctly identified). Conclusions: In sedated neurocritical patients, with structural Acute Brain Injury, the ONSD measurement strongly correlates with the ICP values measured invasively.