Global research trends and emerging themes of ketamine in perioperative neurocognitive disorders: a bibliometric analysis

Abstract

Within the contemporary perioperative neurocognitive disorder (PND) framework, postoperative neurocognitive outcomes include postoperative delirium, delayed neurocognitive recovery, and postoperative neurocognitive disorder. Interest in ketamine and its enantiomers has increased, but the clinical literature on perioperative neurocognitive outcomes remains heterogeneous. This study mapped the global research landscape, collaboration structure, thematic evolution, and recently intensified research themes at the intersection of ketamine and PNDs. Publications indexed in the Web of Science Core Collection (WoSCC) and Scopus were retrieved using a prespecified search strategy. English-language articles and reviews published from 2006 to 2025 were included. Records were integrated and deduplicated using a Python-based bibliographic consolidation workflow. VOSviewer 1.6.20 was used for collaboration, citation, and author-keyword analyses, whereas CiteSpace 6.4.R2 Advanced was used for keyword burst detection. A WoSCC-only sensitivity analysis assessed robustness to database composition. After database restrictions, 559 records remained (WoSCC, n  = 191; Scopus, n  = 368); removal of 127 cross-database duplicates yielded 432 unique publications with 13,085 citations. Of these, 283 publications (65.5%) were published during 2021–2025. China contributed the largest number of publications ( n  = 152), whereas the United States had the highest citation count (6,255) and country-level total link strength (66). The most frequent author keywords were delirium (77), postoperative delirium (74), ketamine (65), esketamine (57), and postoperative cognitive dysfunction (55). “Intraoperative ketamine” showed the strongest keyword burst (strength = 4.05; 2021–2023), while recent bursts extending through 2025 included mechanisms, dysfunction, ketamine, esketamine, reliability, and delayed neurocognitive recovery. The WoSCC-only sensitivity analysis showed broadly similar patterns, including a 9/10 overlap among the top keywords (Spearman's ρ  = 0.784). Research on ketamine and perioperative neurocognitive outcomes has expanded rapidly, particularly since 2020. Recent literature increasingly emphasizes esketamine, contemporary neurocognitive terminology, mechanistic questions, and delayed neurocognitive recovery. These bibliometric patterns represent research attention rather than evidence of clinical efficacy. Future studies should distinguish ketamine formulations and enantiomers, use standardized PND definitions and outcome windows, and prioritize adequately powered multicenter designs.