Peripheral Airway Dysfunction in Symptomatic Gastroesophageal Reflux Disease: A Laboratory-Based Study Using Impulse Oscillometry

Introduction

Individuals with Gastroesophageal Reflux Disease (GERD) often experience airway inflammation and bronchoconstriction as a result of reflux aspiration and/or vagally mediated reflexes. The Impulse Oscillometry System (IOS) is a sensitive, non-invasive tool that can detect subtle changes in airway resistance. While there are few studies exploring airway resistance in GERD globally, no studies have been conducted in Sri Lanka. Therefore, we aim to compare the airway resistance using IOS in medical undergraduates with and without symptomatic GERD.

Methods

A cross-sectional study was conducted among 811 medical undergraduates (31.1% male; mean age 22.9 years) at the Faculty of Medicine, Rajarata University of Sri Lanka. Symptomatic GERD was screened using the validated GerdQ, and a cutoff of≥8 was used to diagnose those with GERD symptoms. Of the 242 (29.8%) with GERD symptoms, 188 with chronic respiratory diseases or recent respiratory symptoms were excluded, and 50 with GERD symptoms and 50 healthy, age- and sex-matched controls were recruited. Lung function was assessed using IOS and spirometry, according to American Thoracic Society (ATS) and European Respiratory Society (ERS) guidelines.

Results

Prevalence of symptomatic GERD among medical undergraduates was 29.8% (242/811). The common symptoms among GERD were heartburn (89.6%, 217/242) and regurgitation (85.5%, 207/242). Oscillometry parameters including, R5-R20 Hz (15.29% vs 9.69%, p=0.002), Fres (14.95 1/s vs 13.37 1/s, p = 0.04), and AX (0.66 vs 0.48, p = 0.02) were significantly higher in students with symptomatic GERD (mean = 15.29%) than in healthy controls (mean = 9.69%; p = 0.002). However, spirometry parameters including FEV1, FVC, and PERF did not differ between the GERD-positive and control groups.

Conclusion

Individuals with symptomatic GERD demonstrated a higher peripheral airway resistance compared to controls, whereas no significant difference was observed in upper airway resistance. This could be due to the gastric acid stimulation of vagal nerve terminations in the lower part of the esophageal wall, leading to increased resistance in the peripheral airways through vagally mediated bronchoconstriction.

What is already known on this topic

• GERD is associated with extra-esophageal conditions, including chronic cough, asthma and laryngitis.

• Pathological acid reflux can induce respiratory symptoms.

What this study adds

• Individuals with symptomatic GERD demonstrated a higher peripheral airway resistance compared to those without GERD, but no difference in upper airway resistance.

• This may be attributable to vagally mediated reflex pathways, in which esophageal stimulation triggers an esophagobronchial reflex, leading to increased parasympathetic activity and subsequent bronchoconstriction.

• The novelty of incorporating impulse oscillometry provides valuable baseline data for the Sri Lankan population and contributes to the limited global literature on small airway dysfunction in individuals with GERD.

• By combining impulse oscillometry with spirometry, this study detected changes in peripheral airway resistance that may not be identified by conventional spirometry alone.

How this study might affect research, practice or policy

• These findings highlight the potential value of impulse oscillometry for detecting subtle peripheral airway abnormalities that may not be apparent from conventional pulmonary function assessment.

• Further longitudinal and mechanistic studies are warranted to clarify the underlying pathways linking GERD with peripheral airway dysfunction

• In clinical practice, assessment of peripheral airway function may be considered in patients with symptomatic GERD who have respiratory complaints

• Future longitudinal studies should determine whether GERD treatment can modify peripheral airway resistance and whether such abnormalities have clinical or prognostic significance.