Anesthetic efficacy of two administration regimens of obucaine hydrochloride gel for transnasal fiberoptic laryngoscopy: a single-center retrospective cohort study.

BACKGROUND: The primary objective of this study was to compare the comprehensive clinical tolerability and procedural performance, including intra-procedural pain, post-procedural pharyngeal discomfort, procedural efficiency, and safety, of nasal-only vs. combined nasopharyngeal anesthesia with obucaine hydrochloride gel for transnasal fiberoptic laryngoscopy (TFL). This study explicitly differentiated comprehensive clinical experience from pure analgesic efficacy, and made no a priori claim of superior anesthetic potency between the two regimens. METHODS: This single-center retrospective study enrolled patients undergoing first-time TFL between June and December 2025, who were assigned to either nasal-only anesthesia (Group A) or combined nasopharyngeal anesthesia (Group B). 1:1 propensity score matching (PSM) was conducted to balance baseline confounding variables. The primary outcome was the incidence of moderate-to-severe post-procedural pharyngeal discomfort assessed within 2 h of TFL, a composite endpoint reflecting holistic patient experience and procedural feasibility. We explicitly acknowledged that this endpoint includes functional impairments inherent to pharyngeal topicalization and may structurally favor the nasal-only regimen. This endpoint was not designed to measure pure analgesic efficacy. Secondary outcomes included examination duration, operator-assessed procedural difficulty visual analog scale (VAS) score, patient-reported pain VAS score, and adverse events. RESULTS: A total of 950 patients were initially enrolled (470 in Group A, 480 in Group B), and 420 patients per group were included in the final analysis following 1:1 PSM. Baseline characteristics were well-balanced between groups, with all p > 0.05 and standardized mean differences (SMD) < 0.1 for all covariates. Group A exhibited a significantly lower incidence of moderate-to-severe pharyngeal discomfort (28.33% vs. 52.14%, p < 0.001), shorter examination duration, and higher operator-assessed procedural smoothness VAS scores (reverse scoring: higher scores indicate lower procedural difficulty; all p < 0.001). After multivariable adjustment, no statistically significant difference in patient-reported pain VAS scores was observed between groups (p = 0.068), indicating comparable patient-reported pain intensity between the two regimens. Regarding safety, no systemic adverse events were observed in either group, and local adverse event rates were extremely low, with no statistically significant between-group difference detected in this cohort. No major safety signals were identified in this cohort. CONCLUSION: Among relatively healthy outpatients aged 18-60 years undergoing diagnostic-only TFL without anatomical abnormalities or concurrent therapeutic procedures, nasal-only administration of obucaine hydrochloride gel was associated with superior procedural tolerability and shorter objective examination time compared with the nasopharyngeal combined regimen. No significant between-group difference was observed in patient-reported pain intensity, and no major safety signals were detected in this cohort. No conclusion of safety equivalence can be drawn due to the limited sample size and follow-up duration. These findings provide real-world evidence to guide anesthesia regimen selection in this specific outpatient population, and generate hypotheses for future prospective, multicenter studies to confirm these results in broader clinical populations.