Comparative Effects of Forced Expiratory Training Versus Diaphragmatic Breathing on Pulmonary Functions, Dyspnea and Sputum Diary in Chronic Bronchitis

Background: Chronic bronchitis, a common phenotype of chronic obstructive pulmonary disease, is characterized by persistent cough and sputum production, resulting in progressive airflow limitation and diminished quality of life. Airway clearance and breathing retraining are non-pharmacologic interventions frequently recommended in clinical practice, yet comparative evidence on their relative efficacy remains limited. Objective: To compare the effects of forced expiratory training versus diaphragmatic breathing on pulmonary functions, dyspnea, and sputum diary scores in patients with chronic bronchitis. Methods: In this single-center, randomized controlled trial, 30 adults with clinically diagnosed chronic bronchitis were randomized to receive either forced expiratory training or diaphragmatic breathing over six weeks. Pulmonary function was assessed by spirometry (FEV₁/FVC), gas exchange by arterial blood gases (PaO₂, PaCO₂), and symptom severity by the Breathlessness, Cough and Sputum Scale (BCSS) and Dyspnea-12 questionnaire at baseline and post-intervention. Statistical analysis included paired and independent sample t-tests with significance set at p<0.05. Results: Both interventions produced significant improvements in pulmonary function and symptom scores; however, forced expiratory training resulted in greater increases in FEV₁/FVC and PaO₂, larger reductions in PaCO₂, and more pronounced improvements in BCSS and Dyspnea-12 scores compared to diaphragmatic breathing (all p<0.05). Conclusion: Forced expiratory training is more effective than diaphragmatic breathing in enhancing pulmonary function, reducing dyspnea, and improving sputum clearance in chronic bronchitis, supporting its prioritization in respiratory rehabilitation.