Delayed awakening after out-of-hospital cardiac arrest: a scoping review of definitions, determinants, and prognostic implications.

Abstract

Delayed awakening in resuscitated out-of-hospital cardiac arrest (OHCA) patients complicates neuroprognostication and exposes to inappropriate and premature withdrawal of life-sustaining therapy (WLST) decisions. We synthesised evidence on definitions, determinants and outcomes of delayed awakening after OHCA. We searched Medline via PubMed, Embase, and Scopus, from inception to 22 February 2026. We included studies describing delayed awakening in resuscitated adult OHCAs, assessed risk of bias, and performed descriptive synthesis organised by definitions, determinants and outcomes. Nineteen studies (17 observational, 2 randomised trials; 5441 patients; all high-income countries) reported delayed awakening in 11-52% of patients. Eighteen of 19 studies predated the recommendations of International Liaison Committee on Resuscitation (ILCOR), and only two were conducted in settings without WLST. Nine distinct definitions varied in time threshold (48 h-7 days), reference point (post-resuscitation, post-rewarming, post-sedation withdrawal) and awakening criterion (Glasgow Coma Score, ability to follow commands, orientation, and Richmond Agitation-Sedation Scale). Therapeutic hypothermia, longer-acting sedatives, and prolonged sedation were the most consistent treatment-related determinants. Although delayed awakeners had worse outcomes, 51-94% achieved good neurological recovery at discharge across 4 cohorts, albeit with worse long-term quality of life. Delayed awakening after OHCA was predominantly influenced by treatment-associated variables and did not preclude meaningful neurological recovery. Nearly all existing evidence reflected outdated temperature management practices and was confounded by WLST-driven self-fulfilling prophecy bias, limiting conclusions regarding true outcomes. Standardised definitions and studies free of WLST-driven bias are urgently needed.