Predictive value of ultrasound-measured tongue base thickness for upper airway obstruction during monitored anesthesia care: a single-center prospective observational study.

PURPOSE: Monitored anesthesia care (MAC) is increasingly used for various procedures, but sedation-related upper airway obstruction may lead to hypoxemia or conversion to general anesthesia. This study evaluated whether preoperative tongue base thickness (TT), measured using ultrasonography, can predict upper airway obstruction during MAC.

METHODS

In this single-center prospective observational study, adult patients undergoing transcatheter aortic valve implantation or endovascular aortic repair under MAC were enrolled. TT was measured preoperatively using submental ultrasonography. Upper airway obstruction was defined as disappearance of the capnogram that reappeared after jaw elevation. Receiver operating characteristic (ROC) curve analysis was performed to determine the optimal TT cutoff and diagnostic performance. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and likelihood ratios were calculated. The STOP-BANG score and composite criteria combining TT and STOP-BANG were also evaluated.

RESULTS

Data from 42 patients were analyzed, and upper airway obstruction occurred in 21 (50.0%). The median TT was 59.8 mm in the non-obstruction group and 61.0 mm in the obstruction group (p = 0.466). The ROC analysis identified a TT cut-off value of 58 mm (area under the curve = 0.566). For TT ≥ 58 mm, sensitivity, specificity, PPV, and NPV were 76.2%, 42.9%, 57.1%, and 64.3%, respectively (LR + 1.33, LR - 0.56). Combining TT with the STOP-BANG score did not improve predictive performance.

CONCLUSION

Preoperative TT measurement showed limited diagnostic performance for predicting airway obstruction during MAC, and its combination with the STOP-BANG score did not significantly improve predictive performance.