Dilation catheters including a mechanism used in, for example, removing gas or air from the catheters are disclosed. A dilation catheter may include an elongated tubular member having a distal end and a proximal end, a proximal handle proximate the proximal end of the tubular member, and an inflatable balloon proximate the distal end of the tubular member with inflatable balloon being in fluid communication with a fluid port to supply inflation liquid to the inflatable balloon. The inflatable balloon may include an opening for permitting gas to exit the inflatable balloon. In the proximate location of the opening, an expandable material or a barrier material that permits gas to exit through the opening, while retaining inflation liquid in the inflatable balloon.