Correlation Between Bedside Anatomical Indicators and Lifting Force and Glottic Exposure Under Different Video Laryngoscopy Techniques

This study is a single-center, prospective, observational study. A total of 196 adult patients scheduled for elective surgery under general anesthesia requiring orotracheal intubation will be enrolled. Preoperative bedside anatomical assessment will be performed by a standardized, blinded evaluator. The assessed indicators include mouth opening, thyromental distance, modified Mallampati classification, upper lip bite test, head circumference, and neck circumference. After standard anesthesia induction, video laryngoscopy will be performed by an experienced anesthesiologist. Two techniques will be evaluated in a fixed sequence: (1) Indirect epiglottis elevation (vallecula method): the blade tip is placed in the vallecula to indirectly elevate the epiglottis by lifting the tongue base. (2) Direct epiglottis elevation (subepiglottic method): the blade tip is advanced past the vallecula and placed directly under the laryngeal surface of the epiglottis to actively lift it. A resistive thin-film pressure sensor attached to the video laryngoscope blade will continuously record real-time force data, and the peak lifting force will be extracted for analysis. Glottic exposure will be evaluated using the Percentage of Glottic Opening (POGO) score. Between the two assessments, mask ventilation will be performed for at least 2 minutes to maintain SpO2 ≥ 98%. All procedures and data collection will adhere to the approved protocol by the Ethics Committee of the Second Hospital of Shanxi Medical University (Approval No. [2026] YX No. 172). Statistical analyses will be performed using SPSS 26.0 and R software, including Spearman rank correlation, Kruskal-Wallis test, and multiple linear regression with Bootstrap validation.