Background and purpose: The early prediction of hypoxic encephalopathy after cardiac arrest is challenging. Measurement of the optic nerve sheath diameter (ONSD) by using sonography is a straightforward, noninvasive technique to detect an increased intracranial pressure, which can even be conducted at the bedside. However, it remains unknown whether or not sonographic ONSD measurement is valuable as a prognostic indicator of hypoxic encephalopathy.
Methods: Seventeen patients after cardiac arrest were retrospectively enrolled in this study. ONSD measurements 3 mm behind the papilla were recorded. A Glasgow Outcome Scale score of 4 or above was considered to indicate a favorable prognosis.
Results: The mean ONSD associated with a favorable prognosis was 5.0 mm (4.4-6.1 mm). The ONSD associated with a poor prognosis was 6.1 mm (5.4-7.2 mm). ONSD less than or equal to 5.4 mm was an indicator of a favorable prognosis, with a sensitivity of 83%, specificity of 73%, positive likelihood ratio of 3.1, and negative likelihood ratio of .23.
Conclusions: Sonographic ONSD measurement is a simple, rapid technique to assess the neurological prognosis after cardiac arrest.
Keywords: Ultrasonography; cardiac arrest; hypoxic encephalopathy; optic nerve sheath diameter; prognosis.
Copyright © 2015 by the American Society of Neuroimaging.