Sternomental displacement and neck circumference: a new look for the neck as a difficult airway predictor in obese surgical patients—a cohort study

Abstract Background Sternomental displacement (SMDD) is a surrogate indicator for cervical spine (C-spine) mobility. SMDD revealed good potential to predict difficult airway, but its validity in obese patients not evident. Therefore, this study assessed the performance of with neck circumference (NC) predicting airway surgical patients. The involved 135 adult body mass index (BMI) ≥ 35 kg/m 2 scheduled elective surgeries under general anesthesia endotracheal tubes (ETT) inserted using Macintosh laryngoscopes. was SMDD, NC, and modified Mallampati test (MMT). Difficult laryngoscopy view (DLV) defined as Cormack–Lehane (C-L) grade 3. accuracy DLV set primary endpoint, while compared that MMT, NC/SMDD ratio secondary endpoint. Results cases were 28 (20.7%), mean BMI 41.1 ± 3.3 . < 5cm NC > 43 cm could an area receiver operating characteristic curve (AUROC) 0.97 0.83 respectively. had negative correlation ( r = − 0.6; 95% CI 0.7 0.4; p 0.0001). best prediction (AUROC 0.98 at cut-off value 7.8). Conclusions In patients, ratios are excellent predictors when values 7.8, Trial registration ClinicalTrials.gov, NCT04524546. Registered August 2020.