Topical Airway Lidocaine Spray Reduces the 95% Effective Dose of Sufentanil for Blunting Hemodynamic Response to Tracheal Intubation in Elderly Patients: A Biased-Coin Up-and-Down Sequential Allocation Trial

Purpose: Topical lidocaine is commonly used to blunt hemodynamic responses to laryngoscopy and intubation. In elderly patients, however, its specific effect on reducing the required dose of sufentanil during induction remains unquantified. We aimed to determine whether pre-intubation lidocaine spray lowers the 95% effective dose (ED 9 5 ) of sufentanil needed to attenuate this response. Patients and Methods: Eighty patients aged 65– 80 years undergoing elective surgery under general anesthesia with tracheal intubation were enrolled in this randomized, double-blind, dose-finding study. Prior to intubation, patients were randomly assigned to receive an oropharyngeal and laryngeal spray of either 2% lidocaine (Group A) or normal saline (Group B). The induction dose of sufentanil for each subsequent patient was adjusted based on the previous patient’s hemodynamic response, following a biased-coin up-and-down sequential allocation method with a step size of 0.05 μg·kg − 1 . A positive response was defined as MAP or HR remaining within 30% of baseline values within 3 min after intubation. The ED 95 and its 95% confidence interval (CI) were estimated using isotonic regression and bootstrapping methods. Extubation time, severity of coughing at emergence, postoperative sore throat (POST), and adverse events, were recorded. Results: The estimated ED 9 5 of sufentanil was 0.419 μg·kg − 1 (95% CI 0.348– 0.437) in Group A and 0.530 μg·kg − 1 (95% CI 0.400– 0.542) in Group B. Bootstrap analysis yielded a between-group difference (ΔED 9 5 ) of 0.111 μg·kg − 1 (95% CI 0.001– 0.188), indicating a statistically significant difference. Cough during emergence was more severe in Group B (P < 0.05). No statistically significant differences were observed between groups in extubation time, POST, or other adverse events. Conclusion: In elderly patients, topical airway lidocaine spray reduces the ED 9 5 of sufentanil to 0.419 μg·kg − 1 for blunting hemodynamic responses to tracheal intubation. This adjunctive intervention decreases sufentanil requirements and improves emergence quality by reducing the severity of coughing in this elderly population. Keywords: lidocaine, sufentanil, biased coin design, intubation, elderly patients