Insights into the Use of Point-of-Care Ultrasound for Diagnosing Obstructive Sleep Apnea

Using standardized ultrasound imaging to correlate OSA severity with tongue morphology

BACKGROUND

Ultrasound imaging has been explored as a potential diagnostic tool for obstructive sleep apnea (OSA); we reported backscatter ultrasound imaging (BUI) of the tongue correlates with OSA severity in adults. We focus on anatomical features of the tongue using standardized ultrasonography and hypothesize that differences in morphology correlate with OSA severity.

METHODS

This prospective study was IRB approved (53,172) and conducted at Stanford University Sleep Surgery Clinic. Patients ≥18 years with polysomnography (PSG) underwent a standardized submental ultrasound scan using a laser alignment tool to observe the upper airway in supine position during tidal respiration. Images acquired from this scan were divided into 4 equiangular regions (A-D).

RESULTS

A total of 144 patients (30 women) July 2020-December 2022 were included with mean age 41.6 years (±12.9 SD), BMI 27.2 kg/m2(±4.7 SD), and AHI 19.7 (±20.0 SD). Moderate-to-severe OSA patients had significantly narrower airspace at regions A, B and C with p-values ranging from <0.0001 to 0.0003. These patients had a significantly wider (p = 0.0021-0.0045 for regions A, B and C) tongue and thicker (p = 0.0403 for region B) deep tissue. The predictive model to assess the risk of moderate-to-severe OSA achieved an area under the receiver operating characteristic curve of 0.839 (95 % CI: 0.769 to 0.895).

CONCLUSIONS

With standardized, computerized ultrasound imaging of the shape and configuration of the tongue, we identified regions that correlated well with OSA severity. Further research is needed to determine the clinical implications of such pathophysiological findings.

Use of ultrasonography in the evaluation of patients with sleep apnea: a systematic review

OBJECTIVES

This study aims to review the current role of various ultrasonographic methods in the evaluation of the upper airway in patients with obstructive sleep apnea.

METHODS

A literature review was performed on the medical databases: Pubmed, Web of Science, Scopus and Embase. After analyzing the available studies, six of them were selected for data extraction.

RESULTS

All selected studies demonstrated that it is possible to use ultrasonography as a method of evaluating the upper airway. Studies with gray-scale ultrasound concluded that the lateral pharyngeal wall and tongue are thicker in patients with obstructive sleep apnea compared to non-apneic patients. Moreover, studies with tissue characterization ultrasound, nowadays called quantitative ultrasound, have identified unique features in obstructive sleep apnea patients: standardized backscatter ultrasonography demonstrated that this particular sound wave analysis is associated with the severity of obstructive sleep apnea. Ultrasonography with elastography shows that the electrical stimulus generated in the hypoglossal nerve results in greater stiffness on the side of the tongue that is stimulated; whereas studies show conflicting results regarding the evaluation of baseline tongue stiffness in obstructive sleep apnea patients compared to non-apneic subjects.

CONCLUSION

There is feasibility of different methods of ultrasonographic evaluation of the upper airway, with emphasis on ultrasonographic methods of tissue characterization, such as elastography, which proved to be a promising method of evaluating the mechanical properties of the muscles involved in the pathogenesis of obstructive sleep apnea and which require further studies for a better elucidation of its applicability.

Use of Ultrasound to Verify the Impact of Telemedicine Myofunctional Therapy on Sleep Apnea Syndrome: Study Protocol Proposal

The anatomy of the upper airways influences the risk of obstructive sleep apnea (OSA). The size of soft tissue structures, such as the tongue, soft palate, and lateral walls of the pharynx, contributes to the pathogenesis of OSA. New lines of treatment for sleep apnea, such as myofunctional therapy (MT), aim to strengthen the oropharyngeal musculature to improve the defining parameters of apnea. The present protocol uses ultrasound imaging to measure the size of the lingual musculature non-invasively and cost-effectively and evaluates the changes in its morphology. Eligible patients include those with OSA who have undergone submental cervical ultrasound and drug-induced sleep endoscopy before starting MT with the AirwayGym app. Follow-up evaluations are conducted at 3 months after beginning treatment. Patients diagnosed with OSA via questionnaires and polysomnography or respiratory polygraphy are evaluated anatomically and functionally using the Iowa Oral Performance Instrument, a tongue digital spoon, somnoscopy, and submental cervical ultrasound to assess their responses to the AirwayGym app. The lingual thickness (mm) and volume (cm3) and the distance between both lingual arteries (mm) are measured. The AirwayGym app helps users and therapists monitor the patient performance of MT. Incorporating submental ultrasound can be a useful non-invasive tool to evaluate OSA and MT.