ASSOCIATIONS BETWEEN ESOPHAGEAL MOTILITY, REFLUX, AND LUNG MECHANICS AND FUNCTION ARE DISEASE SPECIFIC, BOTH BETWEEN AND WITHIN RESTRICTIVE AND OBSTRUCTIVE LUNG DISEASE.

Introduction: Gastroesophageal reflux is common in respiratory disease, but the inter-play between gastrointestinal mechanisms that expose individuals to reflux and potentially aspiration, and lung mechanics and function remain incompletely understood. Our aim was to investigate this in patients with chronic obstructive pulmonary disease (COPD) and non-IPF interstitial lung disease (non-IPF ILD), and compare with our published findings in idiopathic pulmonary fibrosis (IPF).

Methods: 57 patients with COPD (aged: 34-75yrs) and 64 with non-IPF ILD (22-75yrs) who underwent high-resolution impedance manometry and 24-hour pH-impedance, together with pulmonary function assessment were compared with 35 IPF patients (51-84yrs).

Results: COPD patients were less likely to exhibit ineffective esophageal motility (IEM) and/or absent contractility (p=0.009; p=0.028), and tended to exhibit esophagogastric junction outflow obstruction (EGJOO) and/or hyper-contractility (p=0.09, p=0.14) than IPF and non-IPF ILD patients. Notably, integrated relaxation pressure correlated with esophageal length index (ELI) (p=0.048) and inspiratory LESP (p=0.003), with latter two correlating with each other (p<0.001). EGJOO patients tended to have fewer proximal reflux events and reduced pulmonary function; the latter inversely correlating with ELI (p<0.05).Non-IPF ILD patients were less likely to exhibit EGJOO than COPD patients (p=0.27), and less likely to exhibit IEM (p=0.07) than IPF patients. However, those with IEM or EGJOO, exhibited greater proportions of reflux events reaching the proximal esophagus than those with normal motility (p<0.03), which in contrast to IPF, appeared not to associate with worse pulmonary function.

Conclusions: Associations between esophageal motility, and lung mechanics and function, and consequently reflux, are very disease specific.