A Pilot Study of Preoperative Submandibular POCUS to Predict Difficult Mask Ventilation

Multiple assessment tools are available to evaluate for difficult mask ventilation. Obstructive sleep apnea (OSA) is a known risk factor. In this observational study, patients were screened using the STOP-BANG questionnaire. Submandibular point of care ultrasound (POCUS) was performed to determine the correlation between ultrasound findings and difficult mask ventilation.

POCUS was performed to measure tongue thickness (TT), geniohyoid muscle thickness (GMT), distance between lingual arteries (DLA), lateral pharyngeal wall thickness (LPW), hyomental distance (HMD), and oral cavity height (OCH). The results were analyzed to determine the correlation with difficult mask ventilation scores.

TT, GMT, DLA, and HMD were larger in those with STOP-BANG scores ≥ 3. OCH was larger for those with STOP-BANG score ≥ 5. TT was greater when mask ventilation required oral airway adjunct (p = 0.044) or management by two anesthesia practitioners (p = 0.006). The DLA was higher when mask ventilation required management by two anesthesia practitioners (p < 0.001) and higher when an oral airway adjunct was required (p = 0.056). Increased TT was associated with a higher mask ventilation score (odds ratio [OR] 1.152, 95% confidence interval [95%CI] 1.011-1.314, p = 0.034). A larger DLA was associated with increased odds of difficult mask ventilation (OR 1.207, 95% CI 1.1-1.324, p < 0.001).

Submandibular POCUS could potentially be used to identify difficult mask ventilation in patients suspected of having OSA based on the STOP-BANG questionnaire.