Validation and Clinical Utility of the Lung Sliding Index (LSI) for Differentiating Pulmonary Diseases

• The study will enroll adults with various pulmonary pathologies and healthy controls. Lung ultrasound will be performed on all subjects using a standardized 12-zone protocol; each zone will be scored for pleural sliding using the LSI (0-3 per zone; total 0-36). Operator training and calibration will precede enrollment to ensure scoring consistency.
• A subset of patients will undergo repeat assessments to evaluate intra- and interobserver reliability, using independent, blinded raters.
• For correlation with LSI, we will collect clinical data, including spirometry, blood gases, symptom scores, and 6-minute walk tests. Diagnostic utility will be evaluated using ROC curves. Satisfaction and feasibility will be assessed via Likert questionnaires, with validation analyses (internal consistency, test-retest reliability).
• All data will be de-identified and securely stored. Written informed consent will be obtained from all participants.
• The study groups will include:

1- Pneumothorax 2. Interstitial lung disease (ILD/IPF) 3. COPD/emphysema 4. Bronchiectasis 5. Community-acquired pneumonia 6. Pulmonary edema 7- Pleural effusion 8. Healthy controls

• Data Collection Methods:
• Standardized data entry forms for clinical, imaging, and outcome data.
• Centralized digital storage with access limited to study personnel.

Statistical Methods:

• Descriptive statistics for baseline data ANOVA or Kruskal-Wallis for group comparisons; post hoc testing as appropriate ROC analysis for diagnostic cut-offs Pearson/Spearman correlation for clinical associations Intraclass correlation coefficients (ICC) for reliability Cronbach's alpha for Likert scale validation Multivariable regression for confounder adjustment

Inclusion criteria

• Age 18 years and older.
• Diagnosed with one of the specified pulmonary diseases, or a healthy control
• Able to provide written informed consent

Exclusion criteria

• Inability to tolerate or undergo a lung ultrasound
• Extensive chest wall pathology precluding assessment
• Unscorable >2 zones per protocol
• Withdrawal of consent
• Mechanically-ventilated patients