Airway Stenosis and Tracheostomy Cannula Type as Determinants of Pharyngeal Residue in Traumatic Brain Injury Patients Using Speaking Valves

Background/Objectives: Dysphagia is common in tracheostomized patients with traumatic brain injury (TBI) and may be influenced by airway pathology and tracheostomy-related factors. This study investigated whether tracheostomy cannula type is independently associated with swallowing function and pharyngeal residue after accounting for airway stenosis and clinical variables. Methods: This retrospective observational study included 80 tracheostomized TBI patients using a speaking valve. Participants were grouped according to cannula type (non-fenestrated vs. fenestrated). Swallowing function was evaluated using Fiberoptic Endoscopic Evaluation of Swallowing (FEES), and pharyngeal residue severity was assessed using the Yale Pharyngeal Residue Severity Rating Scale (YPRSRS). Airway stenosis severity was graded using the Cotton–Meyer classification. Multivariable ordinal logistic regression analyses were performed to identify independent predictors of pharyngeal residue. Results: Higher pharyngeal residue scores were observed in the fenestrated cannula group under selected conditions, particularly for 5 mL liquid (p = 0.039) and 5 mL semi-solid boluses (p = 0.004) in the vallecular region, and for 5 mL semi-solid boluses in the pyriform sinuses (p < 0.001). Airway stenosis grade was strongly associated with increased pharyngeal residue and reduced SpO2 levels (p < 0.001). In multivariable analyses, airway stenosis emerged as the factor most consistently associated with pharyngeal residue severity (e.g., OR = 4.909, 95% CI: 1.646–14.646, p = 0.004), whereas cannula type was not independently associated with most outcomes. Condition-specific associations were identified between fenestrated cannula use and pharyngeal residue in two models (vallecular residue for 5 mL semi-solid: OR = 0.354, 95% CI: 0.143–0.876, p = 0.025; pyriform sinus residue for 10 mL liquid: OR = 0.190, 95% CI: 0.073–0.495, p = 0.001); however, the direction of these associations differed from unadjusted comparisons, indicating prominent confounding by stenosis severity. Conclusions: FEES-estimated airway stenosis appeared to be the factor most consistently associated with pharyngeal residue severity in tracheostomized TBI patients, whereas the effect of cannula type appeared to be limited. Comprehensive airway assessment may therefore be important in dysphagia management.