How are asthma symptoms related to gastroesophageal reflux disease (GERD)?

In some cases asthma symptoms may occur when food travels in the wrong direction from the stomach backwards into the food tube or esophagus. This is gastroesophageal reflux disease (GERD). Usually evaluated by a gastroenterologist, a specialist in disorders of digestion, this condition is tested in two ways. In older children and adults the pH probe test involves measuring stomach acid in the esophagus over a 24-hour period using a device that senses changes in the acidity or pH of the esophagus. In younger children where this test may not be feasible, a test known as a milk scan may be performed. Usually performed by a radiologist in a hospital or outpatient radiology center, the test involves having the child swallow a substance such as milk with markers so it can be traced. Images of the food tube are made over time and the radiologist can determine if there is reflux of the food into the mouth or airway. These tests can aid in treatment of GERD and associated breathing problems.

In those with severe GERD, acid can reflux high enough that it can be aspirated into the lungs causing wheezing and a cough. In addition, a reflex can cause the airways to narrow and also cause breathing problems. 

Ironically, certain asthma medication can make GERD worse by relaxing the lower esophageal sphincter. This is the valve that prevents acid from backing up from the stomach into the esophagus.