Early outcome prediction in resuscitated postcardiac arrest individuals is still difficult. Transorbital sonography (TOS) can be used to estimate the brain edema, induced by hypoxic ischemic encephalopathy, indirectly by measuring the optic nerve sheath diameter (ONSD). This study aimed to evaluate the prognostic efficacy of this simple, safe, and reproducible approach.

We prospectively recruited unconscious individuals (Glasgow Coma Scale less than 6) after successful resuscitation. TOS ONSD measurements were taken initially on admission, 6 hours later, and 24 hours postcardiac arrest. Established prognostic parameters such as computed tomography brain to detect brain edema and fundus examination for papilledema were performed. The Cerebral Performance Category (CPC) score was used to determine the outcome.

ONSD measurements were significantly higher in the group of individuals with computed tomography showing brain edema. Patients were subdivided into 2 groups according to the neurological outcome: Group A included 19 (34.5%) patients with favorable outcome (CPC score 1–2) and Group B included 36 (65.4%) patients who had unfavorable outcome (CPC score 3–5). On day 0, nonsurvivors had significantly greater ONSD values (P < 0.001). A cut-off value of 5.8 mm exhibited 81% specificity and 94.1% sensitivity for predicting mortality.

ONSD data collected through TOS with a cut-off value of 5.8 mm can reliably predict outcomes in patients with hypoxic ischemic encephalopathy. In comparison with other known markers, the major advantages include early prognosis, within the first 24 hours, being a safer and easier technique that avoids the risks of critical patients transfer.