Effectiveness of Low-Volume Versus High-Volume Ropivacaine for Ultrasound-Guided Maxillary Nerve Block in Double-Jaw Surgery: A Randomized Non-inferiority Trial.

Background: Ultrasound-guided maxillary nerve block (UGMNB) is applied in oral and maxillofacial surgery to improve perioperative analgesia, decrease the risk of postoperative nausea and vomiting, and enhance recovery. However, the optimum volume of ropivacaine used for UGMNB is undetermined. Thus, it was hypothesized that in patients undergoing double-jaw surgery, low- and high-volume ropivacaine reduces perioperative pain with similar efficacy.

Methods: Adults undergoing double-jaw surgery were enrolled in a randomized non-inferiority trial to receive a bilateral single-injection UGMNB with 2 mL (low-volume [LV] group) or 5 mL (high-volume [HV] group) of 0.375% ropivacaine on each side. A visual analog scale (VAS) score for maxillary pain at 2 h postoperatively was taken as the primary outcome. VAS score for maxillary and mandibular pain at 2, 4, 6, 8, 12, 24, and 48 h postoperatively, hemodynamic changes intraoperatively, consumption of intraoperative opioids and sedatives, vasoactive medication use, extubation time, postoperative rescue analgesia, time to the first analgesia, postoperative nausea and vomiting and UGMNB-related complications within 48 h post-surgery were assessed as the secondary outcomes.

Results: Sixty-four adults were included. The maxillary pain score in the LV group was not inferior to that in the HV group at 2 h postoperatively, with a non-inferiority margin of 1 (mean difference - 0.1; 95% confidence interval [CI] - 0.6 to 0.8, P = 0.414 for non-inferiority). Maxillary and mandibular pain demonstrated no difference in the measured times between groups. The incidence of postoperative nausea was significantly higher in the LV group than that in the HV group at 6-24 h (12 (37.5%) vs. 5 (15.6%), P = 0.048). Moreover, no differences in intraoperative hemodynamic parameters, medications during anesthesia, time to extubation, rescue analgesia, time to the first analgesia, and postoperative vomiting were observed. Only one patient in the LV group was observed to have maxillary nerve block-related complications.

Conclusions: To conclude, the efficacy of UGMNB with 2 mL of 0.375% ropivacaine has the same efficacy as the 5 mL drug in reducing perioperative pain in patients undergoing double-jaw surgery.

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