Effect of gastroesophageal reflux disease on spirometry, lung diffusion, and impulse oscillometry

Abstract

Gastroesophageal reflux disease (GERD) is known to be associated with many forms of respiratory diseases, including asthma, pulmonary fibrosis, cystic fibrosis, and obstructive sleep apnea syndrome. It is frequently coexistent, and may be causative or may exacerbate pre-existing lung disease. The main purpose of this study was to assess the effects of GERD on spirometry, lung diffusion, and impulse oscillometry. This study included 48 consecutive newly endoscopically diagnosed GERD patients with no pulmonary symptoms or previous smoking history who attended the Gastrointestinal Clinic at Ain Shams Hospital and Misr University for Science and Technology with complaints of reflux symptoms. Spirometry, lung diffusion, and oscillometry were performed in all included patients. There were statistically significant differences between cases with different grades of reflux as regards age. Most of the patients were included within grade B GERD with the highest mean age being 46.33±11.51. However, there was no significant difference as regards sex. There were statistically significant differences between cases with different grades of reflux as regards forced expiratory volume at the first second/forced vital capacity, maximum expiratory flow 25–75, and diffusing capacity of the lung for carbon monoxide (DLCO), but there was a highly statistically significant difference regarding residual volume/total lung capacity and residual volume. The grade of reflux was the only independent factor affecting DLCO, and grade B patients showed lower DLCO compared with grade A patients. There was a statistically significant positive correlation between grades of reflux and forced expiratory volume at the first second/forced vital capacity, maximum expiratory flow 25–75, and maximum mid-expiratory flow/peak expiratory flow, and a statistically significant negative correlation between grades of reflux and R20. There was a negative correlation between grades of reflux and DLCO, but it was not significant. GERD severity is associated with impairment of gas exchange (DLCO) and central airway affection (R20) on impulse oscillometry. This may be due to microaspiration of gastric acid or fluid into the airways.