Comparison of Diaphragm Ultrasound and RSBI for Predicting Weaning Success in Mechanically Ventilated ICU Patients

This observational cohort study aims to investigate the diagnostic utility of diaphragm ultrasound (specifically diaphragmatic excursion (DE) and diaphragm thickening fraction (DTF)) as alternative weaning predictors in adult ICU patients undergoing mechanical ventilation for more than 48 hours. Given the limitations of the Rapid Shallow Breathing Index (RSBI) in predicting weaning outcomes, ultrasound-based parameters offer a promising physiological assessment tool by directly evaluating diaphragmatic function. Diaphragm ultrasound will be performed within a defined period prior to planned weaning, following standardized imaging protocols to obtain DE and DTF measurements. All ultrasound assessments will be conducted by trained clinicians using point-of-care ultrasound devices available in the ICU. These values will be compared with the corresponding RSBI obtained as part of routine care, without interfering with the clinical decision-making process. The study will analyze predictive accuracy metrics (such as sensitivity, specificity, and area under the receiver operating characteristic curve) to compare RSBI with diaphragm ultrasound indices. Subgroup analyses will assess the relationship between suboptimal diaphragm function and weaning failure, as well as evaluate threshold values of DE and DTF that may serve as reliable predictors for extubation outcomes. The study will also explore how these indices correlate with rates of reintubation and prolonged weaning.