Exploring Diaphragmatic Ultrasonography as a Diagnostic Tool for Hyperinflation in COPD Patients: A protocol study

Chronic obstructive pulmonary disease (COPD) is a widespread global health problem marked by chronic inflammation, emphysematous lung damage, and persistent airflow limitation. In COPD, hyperinflation exacerbates respiratory muscle weakness by causing diaphragmatic dysfunction. Diaphragmatic ultrasonography (US) is a non-invasive tool for evaluating diaphragmatic function, which may provide insight into the severity of hyperinflation in COPD. The purpose of this study is to evaluate the effectiveness of diaphragmatic ultrasonography in assessing lung hyperinflation in patients with COPD .

A diagnostic cross-sectional investigation will be carried out in two Tunisian pulmonology centers. COPD patients aged ≥40 years with confirmed diagnosis via spirometry and stable clinical status will be included. Exclusion criteria are other chronic respiratory diseases, neuromuscular diseases, or obesity. Diaphragmatic ultrasonography and whole-body plethysmography will be performed on the patients. During deep inspiration and forceful expiration, the diaphragmatic thickness and thickening fraction will be measured. RV > upper limit of normal (ULN) indicates lung hyperinflation. Pearson's or Spearman's correlation will be used to assess relationships between plethysmographic parameters and diaphragmatic ultrasound results. Diaphragmatic ultrasonography's diagnostic thershold for hyperinflation will be determined using ROC (receiver operating characteristic) curves.

If proven effective, diaphragmatic ultrasound could be a practical and cost-effective alternative to plethysmography for diagnosing hyperinflation in COPD.