Bronchial obstruction after oesophageal acid perfusion in asthmatics

Fifteen patients with the combination of bronchial asthma and symptoms of gastro-esophageal reflux reproduced at endo-oesophageal acid perfusion (group 1) were investigated to detect bronchial obstruction, reflexly elicited from the distal oesophagus. Five patients with bronchial asthma but without symptoms of gastro-oesophageal reflux (group 2) and five patients with symptoms of gastro-oesophageal reflux but without respiratory symptoms (group 3) served as controls. The vital capacity (VC), the slope of the alveolar plateau (delta N2) and the closing volume (CV) were measured with the single breath nitrogen test before and after acid perfusion of the oesophagus, and again after antacid and glucose perfusion of the oesophagus. In group 1 a significant decrease of VC by 0.21 (P less than 0.001) and a significant increase of delta N2 by 0.9% (P less than 0.05) was seen while no change in CV was found. There was no change after acid perfusion in groups 2 or 3. After glucose and antacid the VC increased significantly in group 1 while no significant change was seen in delta N2 or CV. These findings were taken as indirect evidence of bronchial obstruction induced by the acid infusion. Since the changes were provoked in the sitting position and only in asthmatics with a positive acid perfusion test and since no patient complained of acid taste in the mouth it is unlikely that the bronchial obstruction was due to aspiration. A neural oesophago-bronchial reflex mechanism is suggested.