Effects of Infraorbital Nerve Block with Dexmedetomidine-Added Bupivacaine on Intraoperative Opioid Consumption and Postoperative Analgesia During Endoscopic Transsphenoidal Surgery: A Prospective, Randomized, Double-Blind Controlled Trial

Purpose: In endoscopic transsphenoidal surgery (ETSS) for pituitary adenoma, perioperative discomfort often requires opioid use under general anesthesia. Infraorbital nerve block (IONB), which targets nasal structures involved in ETSS-related pain, may improve analgesia. Combining dexmedetomidine with bupivacaine for IONB may further reduce intraoperative opioid requirements and improve recovery. Patients and Methods: In this prospective, randomized, double-blind study, total of 63 patients was randomized and undergoing ETSS received bilateral ultrasound-guided IONB and were assigned to dexmedetomidine + bupivacaine (2 mL of 0.5% bupivacaine with 5 µg dexmedetomidine per side), bupivacaine alone (2 mL of 0.5% per side), or control (2 mL of normal saline per side). 47 patients were included in the final analysis. The study aimed to evaluate the effects of IONB with dexmedetomidine-added bupivacaine on intra/postoperative analgesic requirements and postoperative pain scores. The study was registered on ClinicalTrials.gov (ID: NCT04785222) on 3 March 2021. Results: The dexmedetomidine + bupivacaine group required significantly less intraoperative fentanyl (1.80 ± 0.67 mcg/kg) than the bupivacaine (2.26 ± 0.78 mcg/kg) and control (2.83 ± 1.87 mcg/kg) groups (p < 0.001). Adjusted analysis showed a mean difference reduction of 1.12 mcg/kg in fentanyl use in the dexmedetomidine added group (p = 0.037). Regarding postoperative analgesic requirements, the time to first rescue fentanyl dose was significantly longer in the dexmedetomidine-added group (+33.9 minutes; p < 0.001), while the requirements for other postoperative analgesics were lower. Postoperative pain scores from the immediate postoperative up to 48 hours, and adverse events showed no significant differences. Hemodynamic parameters, hypotension and bradycardia, were comparable among groups. Conclusion: IONB with dexmedetomidine-added bupivacaine reduces intraoperative fentanyl use and prolong time for rescue opioid requirements during ETSS without increasing hemodynamic risk. Although postoperative pain scores were comparable among all groups, the intraoperative opioid-sparing effect support its role in multimodal analgesia for neurosurgical anesthesia.