Ultrasonographic Assessment of Diaphragmatic Function in Obstructive Sleep Apnea Patients

Background Obstructive sleep apnea (OSA) is associated with altered respiratory mechanics, including diaphragmatic function. Ultrasonography provides a non-invasive tool to assess diaphragmatic structure and performance, which may correlate with OSA severity. Objectives To evaluate diaphragmatic function in OSA patients using ultrasonography and to investigate its relationship with OSA severity and other sleep-related parameters. Methods This case-control study was conducted at the Chest Medicine Department, Mansoura University Hospitals, Egypt, from July 2023 to July 2024. After ethical approval (MS.23.03.2352) and informed consent, 30 newly diagnosed OSA patients (AHI ≥ 5) and 30 non-OSA controls (AHI < 5) were included. Exclusion criteria included systemic organ failure, uncontrolled diabetes, chronic respiratory diseases, neuromuscular disorders, prior OSA treatment, and steroid use. Overnight, attended polysomnography (PSG) was performed following AASM guidelines. Diaphragm ultrasonography measured excursion, thickness at end-expiration and thickness at inspiration, and diaphragm thickening fraction (DTF). Results OSA patients had significantly higher BMI, comorbidities, and sleepiness scores compared to controls (p < 0.05). PSG confirmed mild (10%), moderate (33.3%), and severe (56.7%) OSA among patients. Diaphragmatic excursion was significantly lower in OSA patients, while diaphragm thickness and DTF were higher (p < 0.05). Diaphragm ultrasound parameters were independently associated with OSA presence. ROC analysis demonstrated excellent predictive performance for diaphragmatic excursion (AUC = 0.841) and inspiratory thickness (AUC = 0.874). AHI correlated inversely with excursion (r=-0.39) and positively with inspiratory (r = 0.47) and expiratory thickness (r = 0.28) as well as DTF (r = 0.26). Conclusion Diaphragmatic ultrasonography reveals significant structural and functional alterations in OSA patients and may used be as a reliable, non-invasive tool for predicting OSA presence and its severity.