Cannulas ranging from 2 to 6 mm can be used to dilate vessels, locate blocks, flush out clots, and determine the size of a lumen. They function as a catheter and dilator in one instrument. A locking fitting facilitates irrigation and a small diameter 25.4-cm stem makes it possible to work within the artery while the cannula is in place.
Robb HJ. A Dilating Cannula for Arterial Surgery. Arch Surg. 1974;109(4):584. doi:10.1001/archsurg.1974.01360040094026