A dilation apparatus includes a shaft, a dilation balloon, and a standoff member. The shaft includes a first lumen and a second lumen. The distal end of the second lumen is proximal to the distal end of the first lumen. The dilation balloon encompasses the second distal end of the second lumen such that the dilation balloon defines an interior in fluid communication with the second lumen. A distal portion of the standoff member is positioned within the interior of the dilation balloon. The distal portion of the standoff member is distal to the second distal end of the second lumen. The standoff member provides a pathway for fluid communication between the interior of the dilation balloon and the second lumen. The standoff member may include a tube, a thread, polymeric beading, or other structures.
