This prospective observational cohort study will be conducted in Lady Hardinge Medical College, New Delhi. Adult patients (more than equal to 18 years) on invasive mechanical ventilation for more than 48 hours who meet standard criteria for a spontaneous breathing trial (SBT) will be enrolled after informed consent. Each participant will undergo comprehensive cardiorespiratory ultrasound assessment—including echocardiographic, lung, and diaphragmatic evaluation—at three stages: during pressure-support ventilation, during SBT on a T-piece, and after SBT completion. Conventional weaning parameters such as the rapid-shallow-breathing index and airway occlusion pressure (P0.1) will also be recorded. Patients will be followed for 48 hours post-extubation to determine weaning success or failure. The diagnostic performance of ultrasound parameters will be analyzed using sensitivity, specificity, predictive values, and area under the ROC curve, with statistical significance set at p < 0.05.

Importance of the Research

Weaning failure remains a major determinant of prolonged ventilation, ICU stay, and mortality in critically ill patients. Conventional indices like the RSBI often fail to identify patients at risk because they assess only ventilatory mechanics and ignore cardiac or diaphragmatic contributions. This study addresses an important gap by evaluating an integrated ultrasound approach that simultaneously examines the heart, lungs, and diaphragm to predict weaning outcomes. If validated, this bedside, non-invasive method could enhance clinical decision-making, reduce extubation-related complications, and improve resource utilization in critical care settings.