Dexmedetomidine versus Subanaesthetic Ketamine for Opioid-sparing Anaesthesia During Lumbar Spine Surgery Under a Standardised Surgical Pleth Index-guided Analgesic Protocol: A Randomised Controlled Trial

Main Points• A standardised surgical pleth index (SPI)-guided analgesic protocol was used to facilitate predefined intraoperative opioid titration and to compare the opioid-sparing effects of dexmedetomidine and ketamine with those of saline.• Within a standardised SPI-guided analgesic protocol, both dexmedetomidine and ketamine significantly reduced intraoperative opioid requirements compared with saline.• Dexmedetomidine was associated with lower postoperative opioid consumption and favourable recovery outcomes compared with saline.• Postoperative pain scores differed significantly among the groups at all assessed time points, with dexmedetomidine demonstrating consistently lower pain scores than saline.