Transthoracic ultrasonography in detection of entrapped lung: a prospective study

Abstract Background Entrapped lung, a complication of pleural disease, results from visceral pleural restriction and leads to significant respiratory morbidity. Current diagnosis relies on invasive pleural manometry (PM). While thoracic ultrasound is widely used for pleural effusion assessment, its role in diagnosing entrapped lung remains undefined. This study evaluates ultrasound parameters against manometry to establish a noninvasive diagnostic approach. Objectives To evaluate the diagnostic accuracy of transthoracic ultrasonography (TUS) for entrapped lung. Patients and methods In this prospective observational study, 84 patients with pleural effusion underwent TUS to assess lung motion, diaphragmatic excursion, pleural thickness, and pleural fluid characteristics before pleurocentesis. PM was performed, and patients were stratified by pleural elastance (PEL) into two groups–Entrapped lung (PEL>14.5 cmH 2 O/L; N =39) and nonentrapped (PEL≤14.5 cmH 2 O/L; N =45) groups. Results In the entrapped lung, reduced lung motion [<9.55 mm; area under the curve (AUC) 0.77], diminished diaphragmatic excursion (<12.5 mm; AUC 0.851), and visceral pleural thickening (>1.10 mm; AUC 0.812) demonstrated moderate-to-high diagnostic accuracy (76.2, 76.2, and 75.0%, respectively). These parameters can exclude the presence of entrapped lung better than its detection, offering a valuable noninvasive tool to guide pleural intervention decisions. Conclusion TUS provides a practical, noninvasive method to exclude entrapped lung, potentially reducing reliance on PM and optimizing clinical management of pleural effusions.