S-ketamine plus dexmedetomidine vs. S-ketamine plus propofol for sedation–analgesia during positioning for spinal anesthesia in older adults undergoing lower extremity fracture surgery

Background Positioning for neuraxial anesthesia in geriatric lower extremity fracture surgery is painful and can destabilize hemodynamics. Sedation–analgesia must balance effective analgesia with respiratory safety and physiologic stability. Methods This single-center retrospective cohort study included patients aged ≥65 years undergoing lower extremity fracture surgery under spinal anesthesia who received S-ketamine plus dexmedetomidine (Group A, n = 48) or S-ketamine plus propofol (Group B, n = 46). Primary outcomes included a numerical rating scale (NRS) positioning pain score of 0–10 and an ordinal posture quality score measured at five stages (T1–T5). Repeated measures were analyzed using mixed-effects models (group, stage, group×stage; random: patient) with covariate adjustment. Stage-wise contrasts were Holm-corrected. Results A total of 100 records were screened, and 94 patients were analyzed. Group×stage interactions were significant for pain and posture quality. Group A had lower pain during the most noxious stages (T3–T5; adjusted differences −0.42 to −0.50) and higher odds of better posture quality (OR 2.30–2.70). Physiological differences were modest and stage-specific, with slightly higher SpO 2 and lower heart rate (HR)/mean arterial pressure (MAP) at T2–T3. Postoperative NRS differed only at 12 h. Adverse events were infrequent; delirium was identified from routine documentation without a standardized instrument (0/48 vs. 2/46). Conclusion In this retrospective cohort, dexmedetomidine-based sedation with S-ketamine was associated with improved comfort and cooperation during spinal positioning compared with propofol-based sedation, while adverse events were infrequent in both groups.