Bedside Diaphragm and Lung Ultrasound for Predicting Liberation from Mechanical Ventilation: A Systematic Review with Clinical Synthesis

Background: Failure of liberation from mechanical ventilation remains common despite successful spontaneous breathing trials (SBTs) and is associated with increased morbidity, prolonged ICU stay, and mortality. We aimed to evaluate the role of diaphragm and lung ultrasound for predicting composite liberation failure, including SBT failure and post-extubation failure, in adults. Methods: We conducted a systematic review with descriptive synthesis in accordance with PRISMA-DTA guidelines. The review protocol was developed a priori but was not prospectively registered. MEDLINE, EMBASE, and Cochrane CENTRAL were searched from inception to 20 January 2026. Adult studies evaluating diaphragm ultrasound (diaphragm thickening fraction [DTF], diaphragmatic excursion [DE]) and/or lung ultrasound in patients undergoing SBTs were included. Risk of bias was assessed using Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2). Results: Six studies (n = 430) were included. DTF demonstrated the most consistent association with liberation failure (AUC range 0.64–0.99; sensitivity 78–100%). DE showed a similar but less consistent association (AUC range 0.77–0.86). Elevated lung ultrasound scores—reflecting aeration loss from cardiogenic edema, acute respiratory distress syndrome (ARDS), atelectasis, or pneumonia—were associated with extubation failure. Conclusions: DTF shows potential clinical utility as an adjunct for predicting liberation outcomes. LUS offers complementary insight into aeration loss regardless of etiology. Standardization of measurement protocols and larger prospective studies are needed.