Cerebral oxygen monitoring during out-of-hospital cardiac arrest: A scoping review.

Background: Cerebral tissue oxygen saturation is not routinely monitored during out-of-hospital cardiac arrest (OHCA) but can be assessed using cerebral oxygen monitoring (COM). This non-invasive technique provides real-time measurements of brain oxygenation. The aim of this scoping review (ScR) was to map and describe published studies on the use of COM in OHCA in prehospital and emergency department (ED) settings. Methods: This review followed the JBI Manual for Evidence Synthesis and the Preferred Reporting Items for Systematic reviews and Meta-Analyses ScR (PRISMA-ScR) checklist. Peer-reviewed primary studies reporting the use of COM in OHCA patients in prehospital and/or ED settings were eligible. MEDLINE, Embase, CINAHL, Cochrane Library, and Web of Science were searched from inception to August 8th, 2025. Results: A total of 2166 records were screened, and 57 publications representing 51 studies were included. The studied populations were mainly adult males and included patients with non-traumatic causes of arrest. Most studies were small observational cohorts from Japan, conducted in the ED. Near-infrared spectroscopy (NIRS) was the predominant technology used. Studies commonly examined associations between COM values and return of spontaneous circulation (ROSC) or neurological outcomes. Few papers evaluated COM's impact on clinical decision-making or treatment. Conclusion: The evidence base is dominated by small, ED-based observational studies with limited geographical diversity. While many publications explored the association between COM values and ROSC or neurological outcomes, few reported outcomes data or investigated COM's role in influencing treatment. Future research should focus on methodological standardization, broader international representation, and the clinical utility of COM-guided interventions.