Subjects will undergo the manometry procedure. After finishing the procedure, when the catheter would normally be withdrawn after the procedure, it will remain in place for the study. A CPAP mask will be placed over the subject's nose. CPAP blows air in the nose with a mild pressure. The air pressure will be slowly increased while pressure in the esophagus is being recorded. As done with the regular manometry, the subject will be asked to swallow small amounts of water during the test. The test will be completed in 10 minutes. The CPAP and the tube will be removed.