Objectives To evaluate the ultrasonographic measurement of optic nerve sheath diameter (ONSD) as a predictor of intracranial hypertension as compared to the invasive measurement of intracranial pressure (ICP). Design Cross-sectional observational study. Setting Intensive Care Unit (ICU) of two tertiary university hospitals in Montevideo, Uruguay. Patients We included 56 adult patients, over 18 years of age, who required sedation, mechanical ventilation, and invasive ICP monitoring as a result of a severe acute neurologic injury (traumatic or non-traumatic) and had a Glascow Coma Score (GCS) equal to or less than 8 on admission to the ICU. Interventions Ultrasonographic measurement of ONSD to detect intracranial hypertension. 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 5.7 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 correlates with the invasive measurement of ICP. It was observed that with ONSD values less than 5.7 mm, the probability of being in the presence of ICP above 20 mmHg is very low, while for ONSD values greater than 5.7 mm, said probability clearly increases.

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.