The goal of this observational study is to evaluate the predictive value of diaphragmatic ultrasound compared to the Rapid Shallow Breathing Index (RSBI) in determining weaning success among mechanically ventilated patients in the ICU for more than 48 hours.

The main question it aims to answer is:

Which is more effective in predicting weaning success: diaphragmatic ultrasound (including Diaphragmatic Excursion [DE] and Diaphragm Thickening Fraction [DTF]) or RSBI, in patients ventilated >48 hours in the ICU of Dr. Sardjito General Hospital, Yogyakarta?

Participants will be adult ICU patients who are undergoing weaning from mechanical ventilation after more than 48 hours. Before extubation, each participant will undergo diaphragmatic ultrasound assessment to measure DE and DTF, along with RSBI measurement. The predictive accuracy of these parameters will be evaluated by comparing them with the actual weaning outcomes.

Secondary objectives include:

1. Assessing whether diaphragmatic ultrasound is associated with a higher weaning success rate than RSBI.
2. Evaluating the correlation between DE values and successful weaning.
3. Determining the optimal cutoff values of DE and DTF as predictors of weaning failure.
4. Analyzing the incidence of weaning failure in patients who do not meet optimal diaphragm function criteria.
5. Identifying DE and DTF thresholds that may help reduce the risk of reintubation.

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.

Inclusion Criteria:

1. Patients who have been on mechanical ventilation for more than 48 hours
2. Adult patients aged ≥18 years
3. Patients who meet the criteria for hemodynamic stability for weaning
4. Patients or their families have provided written informed consent
5. Patients with FiO₂ < 50%, PEEP level < 5 cm H₂O, respiratory rate < 30 breaths per minute, PaO₂/FiO₂ > 200, and GCS > 13
6. Patients who have successfully completed the Spontaneous Awakening Trial (SAT) and Spontaneous Breathing Trial (SBT)

Exclusion Criteria:

1. Patients with neuromuscular disorders, anatomical abnormalities of the diaphragm, or diaphragmatic palsy
2. Patients with a history of severe thoracic trauma affecting diaphragm function on one or both sides
3. Pregnancy

The study population consists of subjects who meet the predetermined criteria. The target population refers to the broader group to which the results of this study are intended to be applied. This population is general in nature but limited by clinical and demographic characteristics. The accessible population is a subset of the target population, defined by place and time, which can be reached by the researcher and will ultimately serve as the source of study participants (Sastroasmoro and Ismail, 2008).The target population in this study comprises adult male and female patients who are on mechanical ventilation in the Intensive Care Unit (ICU) at Dr. Sardjito Hospital, Yogyakarta. The accessible population includes patients with indications for weaning from mechanical ventilation in the ICU of Dr. Sardjito Hospital during the study period.