Underlying mechanisms of respiratory symptoms with esophageal acid when there is no evidence of airway response

Although a strong association exists between gastroesophageal reflux (GER) and asthma, results of studies designed to maximize the likelihood of identifying that GER worsens pulmonary function in patients with asthma have been negative or inconclusive. Asthma symptoms worsen during symptomatic reflux episodes, and asthma symptom severity correlates with the severity of symptomatic reflux. Various reasons have been proposed to explain these findings. Discomfort associated with GER can cause reflux-associated respiratory symptoms even when pulmonary function is normal. New findings suggest that increases in minute ventilation rather than inhibition of diaphragm activity are responsible for the changes in respiratory sensation during acid perfusion of the esophagus in nonasthmatic subjects. These results may also pertain to asthmatic patients, because increasing minute ventilation can cause dyspnea and bronchospasm in this population. Treating GER, either medically or surgically, may improve asthma symptoms by preventing GER-induced changes in minute ventilation.