Twenty-three consecutive patients who had persistent respiratory symptoms of unexplained etiology were evaluated to determine the presence of gastroesophageal reflux (GER) and its relationship to their respiratory complaints. Lower esophageal sphincter (LES) and upper esophageal sphincter (UES) pressures and the characteristics of the peristaltic waves in the proximal and distal esophagus were determined. Esophageal acid exposure 5 cm and 20 cm above the LES was measured using a pH probe with two antimony sensors. Aspiration was diagnosed when respiratory symptoms occurred during or within 3 minutes after a reflux episode, recorded at both levels of the esophagus. Based on these criteria, 12 patients were considered nonaspirators (group A), and 11 were categorized as aspirators (group B). Aspirators had: (1) lower LES pressure (6.1 +/- 3.1 versus 12 +/- 4.8 mm Hg, p less than 0.01); (2) decreased amplitude of peristalsis in the proximal esophagus (34 +/- 16 versus 59 +/- 21 mm Hg, p less than 0.01) and distal esophagus (46 +/- 25 versus 91 +/- 28 mm Hg, p less than 0.01), and higher incidence of simultaneous, nonperistaltic waves (30% versus 4%); and (3) lower UES pressure (44 +/- 23 versus 74 +/- 38 mm Hg). Impaired peristalsis in aspirators caused a higher acid exposure (11.4% +/- 8.0% versus 1.0% +/- 0.7% of time pH less than 4, p less than 0.01) and delayed clearance (5.5 +/- 6.5 versus 0.7 +/- 0.4 min) in the proximal esophagus. Our study shows that, in patients with respiratory symptoms of unexplained etiology, esophageal manometry and 24-hour pH monitoring will identify a subgroup of true aspirators. These patients suffer from a panesophageal motor dysfunction that affects all three barriers to aspiration: the LES, the esophageal "pump mechanism," and the UES.