A study of sonographic features of the diaphragm: thickness and excursion in patients with obstructive sleep apnea

Abstract

Background
Obstructive sleep apnea (OSA) is basically related to upper airway collapse. Diaphragmatic ultrasound provides a safe, easy, and available tool for the assessment of diaphragm in OSA patients.


Aim
To determine ultrasonographic features of the diaphragm, such as thickness and excursion in patients with OSA and the validity of using these features for screening of those patients.


Patients and methods
This prospective, nonrandomized, controlled study was conducted in the Chest Department, Faculty of Medicine, Tanta University Hospitals on 75 participants presenting with symptoms of OSA. The study included 15 controls with normal sleep studies and 60 patients with newly diagnosed OSA. All participants underwent overnight polysomnography and diaphragmatic ultrasound to evaluate thickness, excursion, time to peak inspiratory amplitude, and contraction speed in supine and semirecumbent positions during tidal and deep breathing.


Results

Patients with OSA had significantly greater diaphragmatic thickness (DT) than controls (
P
=0.001). In the patient group, the semirecumbent position demonstrated higher DT and mobility than supine position (
P
=0.001). Apnea–hypopnea index positively correlated with Epworth Sleepiness Scale, neck circumference, and DT in both positions during tidal and deep breathing (
P
=0.001). The Epworth Sleepiness Scale score, the DT difference during deep breathing, and the DT at end expiration in the semirecumbent position were significant predictors of OSA (
P
<0.05). DT during deep breathing in both positions provided cutoff values for OSA diagnosis with high sensitivity and specificity.



Conclusion
DT measurements were significantly higher in the OSA group than the control group and correlated with severity. DT and excursion were significantly higher in the semirecumbent than the supine position in the OSA group.