Nature and Preoperative Prediction of Difficult Non-Channeled Video-Laryngoscopic Tracheal Intubation in Otorhinolaryngological Surgery: A Retrospective Cohort Study of 1932 Adults.

Background/Objectives: Video laryngoscopy improves the glottic view, yet difficult intubation still occurs. Whether it reflects a poor view or arises despite an adequate one is rarely quantified in otorhinolaryngological surgery. We described this pattern and its preoperative predictors. Methods: In a single-center retrospective cohort of 1932 adults undergoing otorhinolaryngological surgery with non-channeled video laryngoscopy (2018-2021), difficult intubation was defined a priori as two or more laryngoscopic attempts (blade insertions), a lower bound on difficulty. The glottic view (Cormack-Lehane grade) and intubation time described the difficulty, and predictors were identified by logistic regression. An unweighted count of four anatomical bedside factors, selected on rationale (not data-driven significance) at pre-existing clinical thresholds, was the primary risk score; a five-factor version added a resident operator. Results: Difficult intubation occurred in 120 patients (6.2%; 95% CI 5.2-7.4). Most occurred despite an adequate view (64% at Cormack-Lehane grade I-II; 45% at grade I alone); the rate was 4.3% (95% CI 3.5-5.4) versus 29.3% (95% CI 22.5-37.1) for good versus poor views (odds ratio 9.2, 95% CI 6.0-14.0), and difficult intubations took about twice as long (median 90 versus 40 s). Independent predictors were shorter inter-incisor and thyromental distances and a resident operator. The four-factor count graded risk from 4.6% to 12.9% (odds ratio 1.63 per factor; apparent area under the curve 0.596, 95% CI 0.546-0.645, not corrected for optimism; positive predictive value 8.8% at one or more factors), and a five-factor count performed similarly (0.631). Within the good-view subgroup, difficulty appeared to relate more to operator inexperience than to anatomy (adjusted odds ratio 2.48 versus 1.13). Conclusions: Difficulty was far more likely with a poor view, but because a good view occurred in 92.4% of patients, most difficult intubations arose despite an adequate one. We hypothesize that difficulty then lies in tube delivery rather than visualization; because the analysis conditions on the view, this needs prospective testing. Discrimination was modest and the count exploratory; these single-center findings require external validation.