Diagnostic Utility of Ultrasonography of Upper Airway in Screening for Obstructive Sleep Apnea

Introduction: Obstructive sleep apnea (OSA) characterized by collapse of upper airway. Diagnosis requires polysomnography and screening questionnaires help predict risk of OSA. Ultrasonographic imaging of airway has the potential to identify patients at risk of OSA by evaluating both static and dynamic anthropometric parameters of the upper airway. Methodology: This study assessed the anthropometry (static and dynamic) of upper airway in patients of suspected obstructive sleep apnea by Ultrasonography (USG) and correlation of upper airway parameters with severity of obstructive sleep apnea. All participants were ≥ 18 years and were subjected to clinical evaluation, anthropometric measurement, screening by questionnaire, complete overnight polysomnography and neck ultrasonography. Study enrolled 25 were in OSA group and 25 in control group. All patients underwent polysomnography and US measurements of tongue thickness (TT), upper airway length (UAL), lateral pharyngeal wall thickness (LPW) and oropharynx [retropalatal (RP) and retroglossal (RG) levels]. Measurements were made in tidal expiration, tidal inspiration, forced inspiration and Muller’s maneuver (MM). Dynamic shortening of RP and RG diameters at both forced inspiration and MM to tidal expiration were also calculated. Correlations of all the US parameters with PSG findings were analyzed. Results: Upper airway length, tongue thickness and lateral pharyngeal wall thickness by USG were significantly higher in OSA group compared to non-OSA group. Our study showed that Retropalatal inspiration (RP), forced inspiration, Muller’s maneuver (MM), % change in forced inspiration, and % change during MM and retroglossal diameter with % change in MM showed a statistically significant difference in OSA and non-OSA group. Retroglossal (RG) inspiration, forced inspiration, MM, and % change in MM showed a statistically significant difference in the OSA and non-OSA groups. ROC analysis of neck ultrasonography parameters showed the highest sensitivity with tongue thickness, and RP % change in forced inspiration showed the highest specificity, positive predictive value, and accuracy. Conclusion: Submental ultrasound is an objective, convenient, non-invasive and effective screening tool for OSA.