The present disclosure relates generally to the field of medical devices and procedures for isolating a treatment region in the body from other regions, such as a treatment region in the digestive tract from other regions of the digestive tract. In particular, the present disclosure relates to devices and methods for performing a treatment within the upper gastrointestinal tract, esophagus, gastroesophageal junction, and/or stomach that utilizes a barrier member to isolate a proximal region of the digestive tract from a distal region of the digestive tract such that fluids introduced during the treatment do not substantially communicate between the regions.