Gastroesphageal Reflux and Asthma
There is a high prevalence of asymptomatic gastroesophageal reflux among patients with asthma. Esophageal pH-monitoring studies have shown that 32 to 84% of persons with asthma have abnormal acid reflux. About half of those patients with asthma who have reflux have no symptoms. Symptoms of asthma — cough and chest discomfort — may overlap with those of gastroesophageal reflux, making it difficult to distinguish between the two.
Pathophysiology of Reflux and Asthma
The causal relationship between asthma and gastroesophageal reflux is complex. Acid reflux causes bronchoconstriction through microaspiration into the airways, as well as through reflex-mediated effects of acid on the esophagus or upper airway. Asthma-related bronchoconstriction can induce acid reflux. Descent of the diaphragm with hyperinflation increases the pressure gradient between the abdomen and thorax and may cause the barrier function of the lower esophageal sphincter to diminish. Drugs used to control asthma, including beta-agonists and methyxanthine bronchodilators, may decrease the tone of the lower esophageal sphincter.
New England Journal of Medicine - Vol. 360, No. 15, April 9, 2009