Postoperative Delirium Across the Perioperative Pathway: A Structured Narrative Review of Clinical Maturity and Implementation Priorities

Postoperative delirium (POD) is a highly prevalent but frequently underrecognized complication that disproportionately affects frail and older surgical patients. This structured narrative review aims to synthesize contemporary evidence on adult postoperative delirium across the perioperative pathway and to classify major preventive and therapeutic strategies according to clinical maturity, target population, and implementation readiness. A structured literature search of PubMed/MEDLINE, Scopus, Cochrane Central Register of Controlled Trials (CENTRAL) and Web of Science Core Collection was performed, supplemented by ClinicalTrials.gov, official ESAIC and ASA resources, reference-list screening, and selected seminal pre-2021 publications. Current evidence supports a multifactorial model in which baseline cognitive and physiological vulnerability interacts with inflammatory, pharmacological, hemodynamic, nociceptive, sleep-related, and environmental stressors. No single anesthetic technique, processed-EEG target, blood-pressure threshold, cerebral oximetry strategy, or pharmacological agent consistently prevents POD across surgical populations. Multicomponent non-pharmacological prevention has the most consistent support, whereas dexmedetomidine and other pharmacological approaches appear context-dependent, and biomarkers and metabolic targets remain investigational. Future progress will depend on standardized delirium ascertainment, better phenotyping, multimodal prediction and prevention strategies, and reliable implementation systems that identify vulnerability early and maintain effective preventive care across transitions.