The prognostic role of cerebral ultrasound in hypoxic-ischemic encephalopathy: A systematic review.

OBJECTIVE

The role of cerebral ultrasound in prognostication after out-of-hospital cardiac arrest (OHCA) remains uncertain. This systematic review assessed the potential of cerebral ultrasound-derived measurements, i.e. cerebral blood flow velocities (CBFV), optic nerve sheath diameter (ONSD) and cerebrovascular reactivity (CVR), as tool for predicting neurological prognosis after OHCA.

METHODS

Following PRISMA Guidelines, we searched Medline, Scopus, Embase and the Cochrane Library through July 1, 2025. Studies investigating CBFV parameters (peak systolic, PSV or end diastolic velocity, EDV; resistance index, RI; pulsatility index, PI), as well as ONSD and CVR for neuroprognostication after OHCA were included. Unfavourable outcome (UO) was defined according to individual study criteria. Risk of bias and quality of evidence were assessed using the Newcastle-Ottawa Scale and GRADE.

RESULTS

Among 2849 articles, 14 met the inclusion criteria. Most studies were of low quality of evidence. CBFV findings were inconsistent: three studies found no predictive value, while two observed elevated RI within 12-24 h in patients with UO. One study reported persistently high PSV on days 5-7 correlated with UO. ONSD was associated with UO in five of six studies, with variable cutoffs values (between 5.3 and 7.2 mm). Two studies found that altered CVR was more frequently observed in patients with UO.

CONCLUSIONS

The role of cerebral ultrasound in prognostication after OHCA has been poorly described. Heterogeneous methodologies, timing of measurements, and lack of comparison with established prognostic tools currently limit its clinical applicability.