Association between ultrasound-guided trigeminal nerve block and intraoperative hemodynamic responses during bimaxillary orthognathic surgery: a retrospective cohort study

Noxious stimuli during orthognathic surgery can induce marked hemodynamic fluctuations, which may increase surgical bleeding, impair surgical field visibility, and reduce operative precision. Ultrasound-guided trigeminal nerve block (USG-TNB) has been used as an adjunct to general anesthesia to attenuate responses to noxious stimuli during oral and maxillofacial surgery. Although USG-TNB may have analgesic and opioid-sparing effects, its association with intraoperative hemodynamic responses remains unclear. This study evaluated the association between USG-TNB and hemodynamic responses during bimaxillary orthognathic surgery. This nonrandomized, single-center, retrospective observational study included adult patients ( ≥ 18 years, American Society of Anesthesiologists Physical Status I–II) who underwent Le Fort I osteotomy combined with bilateral sagittal split ramus osteotomy between April 2024 and March 2025. Patients received either USG-TNB combined with local infiltration anesthesia or local infiltration anesthesia alone. The primary outcome was the incidence of a ≥ 20% increase in mean arterial pressure during maxillary osteotomy relative to the corresponding pre-osteotomy phase. Between-group comparisons were performed using bivariate analyses. Multivariable logistic regression was performed to evaluate the association between USG-TNB and the primary outcome after adjustment for anesthetic maintenance technique and the total volume of 1% lidocaine–epinephrine used for intraoral infiltration anesthesia. A total of 171 patients were included, comprising 95 patients in the USG-TNB group and 76 in the non-block group. Most demographic and perioperative variables did not differ significantly between the groups. A ≥ 20% increase in MAP during maxillary osteotomy occurred significantly less frequently in the USG-TNB group than in the non-block group (6.3% vs. 19.7%; p = 0.008; relative risk, 0.32 [95% CI, 0.13–0.79]). In multivariable logistic regression analysis, USG-TNB remained associated with lower odds of this outcome (adjusted OR, 0.258; 95% CI, 0.093–0.713; p = 0.009) after adjustment for potential confounders. No significant between-group differences were observed in systolic blood pressure or heart rate. No block-related complications were identified among the 95 patients who received USG-TNB. USG-TNB was associated with lower odds of a ≥ 20% increase in MAP during maxillary osteotomy after adjustment for anesthetic maintenance technique and lidocaine–epinephrine infiltration volume. The study was registered with the University Hospital Medical Information Network (UMIN) Clinical Trials Registry (Registration number UMIN000057867) on May 15, 2025.