Tehran University of Medical Sciences Frontiers in Emergency Medicine 2717-3593 6 1 2021 11 03 e6 e6 Somayeh Mehrpour Department of Anesthesiology and Critical Care, Qom University of Medical Sciences, Qom, Iran Atabak Najafi Department of Anesthesiology and Critical Care, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran Arezoo Ahmadi Department of Anesthesiology and Critical Care, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran. Tayebeh Zarei Department of Anesthesiology and Critical Care, Hormozgan University of Medical Sciences, Bandar Abbas, Iran. Vasili Pleqi Department of Clinical Research, Mayo Clinic, Jacksonville, Florida, USA Kamal Basiri Prehospital and Hospital Emergency Research Center, Tehran University of Medical Sciences, Tehran, Iran. Khalil Komlakh Department of Neurosurgery, Imam Hossein Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran Hamed Abdollahi Department of Anesthesiology and Critical Care, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran Kaveh Hedayati Emami Department of Anesthesiology & Critical Care, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran 2021 09 28 2021 10 01 Objective: The purpose of this study was to quantitatively evaluate if the use of the optic nerve sheath diameter (ONSD) can be a suitable noninvasive surrogate approach for repeated invasive intracranial pressure (ICP) measures. Methods: The study used a sample of 22 adult patients with traumatic brain injury (TBI) from an in intensive care unit (ICU). ICP levels were measured using the gold standard and recorded in cmH20. ONSD was measured using ultrasonography with 5.6-5.7 MHz linear probe and recorded in millimeters. The data analysis was done using STATA software version 15. Results: The results showed a strong positive correlation between ICP and ONSD (r = 0.743, p = 0.001). The accuracy of the sonographic ONSD declined over time, starting from a high of 90.9% at the baseline and declining to a low of merely 20.0% after 48 hours. Conclusion: These findings indicate that the ONSD approach could be very useful alternative and noninvasive method for monitoring ICP.    https://fem.tums.ac.ir/index.php/fem/article/view/868 https://fem.tums.ac.ir/index.php/fem/article/download/868/375