Prediction of Difficult Airways in Elderly Patients Using Bedside Ultrasound: A Prospective Single-Blind Observational Study

Purpose Several ultrasound predictors have been shown to be useful for predicting difficult airways in adult patients. However, it remains uncertain whether these predictors can predict difficult airways with comparable accuracy in elderly patients. The primary objective of this study was to evaluate the predictive value of ultrasound predictors for difficult laryngoscopy and difficult intubation in elderly patients. Methods This was a prospective, single-blind observational study in which 242 elderly patients scheduled for elective surgery under general anaesthesia with endotracheal intubation were enrolled. During the preanaesthesia phase, demographic information, classical clinical predictors, and ultrasound predictors were collected. The ultrasound predictors included mandibular condylar translation distance (MCTD), tongue thickness (TT), tongue volume (TV), hyomental distance in the extended position (HMDe), and hyomental distance ratio (HMDR). After anaesthesia induction, laryngoscopic views were graded, and intubation difficulty was scored. The diagnostic value of each parameter for difficult laryngoscopy and difficult intubation was evaluated via receiver operating characteristic (ROC) curves. The primary outcome was difficult laryngoscopy, and the secondary outcome was difficult intubation. Results The final analysis included 226 elderly patients, 44 (19.5%) of whom experienced difficult laryngoscopy and 25 (11.1%) of whom experienced difficult intubation. There were significant differences between elderly patients with and without difficult laryngoscopy, as well as with and without difficult intubation in the following ultrasound predictors: MCTD, TT, HMDe, and HMDR. Compared with the other predictors, the mandibular condylar translation distance had the highest area under the receiver operating characteristic curve (AUC) for both difficult laryngoscopy (AUC 0.89; 95% CI: 0.84–0.94; P < 0.001) and difficult intubation (AUC 0.91; 95% CI: 0.86–0.97; P < 0.001). Conclusion Ultrasonic measurements of the mandibular condylar translation distance, the hyomental distance ratio, the hyomental distance in the extended position, and tongue thickness can be used to predict difficult laryngoscopy and difficult intubation in elderly patients. Notably, the mandibular condylar translation distance demonstrated the highest predictive value for difficult laryngoscopy and difficult intubation in elderly patients. Study registration Retrospectively registered at www.chictr.org.cn (ChiCTR2300076196), 27 September 2023.