Functional heartburn (FH) and reflux hypersensitivity (RH) are disorders of gut-brain interaction characterized by persistent reflux-related symptoms despite the absence of significant esophageal acid exposure or structural abnormalities. Although proton pump inhibitors are widely used for reflux-related disorders, many patients with FH and RH continue to experience persistent symptoms, resulting in reduced health-related quality of life. Current evidence suggests that altered esophageal sensory processing, autonomic nervous system dysfunction, and impaired gut-brain axis regulation contribute to symptom generation in these disorders.
Diaphragmatic breathing exercise has emerged as a promising non-pharmacological intervention that may improve diaphragmatic function, enhance vagal activity, and reduce reflux-related symptoms. Volume-oriented incentive spirometry (VIS) provides visual feedback during breathing training and may improve the consistency and effectiveness of diaphragmatic breathing. However, evidence regarding the therapeutic effects of VIS-assisted diaphragmatic breathing exercise in patients with FH or RH remains limited.
This prospective, parallel-group, pilot randomized controlled trial is designed to evaluate the clinical effectiveness of VIS-assisted diaphragmatic breathing exercise in adults with FH or RH. Participants will be randomly assigned to receive either VIS-assisted diaphragmatic breathing exercise in addition to usual care or usual care alone. The study will assess whether the intervention improves reflux-related symptoms and health-related quality of life compared with usual care.
The findings of this study are expected to provide preliminary evidence regarding the feasibility and potential clinical benefits of VIS-assisted diaphragmatic breathing exercise as an adjunctive non-pharmacological treatment for functional heartburn and reflux hypersensitivity, and to support the design of future larger randomized controlled trials.