This test is used to measure how well the esophagus is functioning. It evaluates the strength and coordination of the contractions of the muscles of the esophagus. Patients with heartburn, chest pain, and swallowing issues may undergo this test. A very thin tube is placed through the nose into the esophagus and takes measurements as the patient swallows. At the end of the test, the tube is removed and the data is analyzed by a physician.