Systematic evaluation of ureteral access sheaths

Objectives To compare the physical characteristics of ureteral access sheaths that affect their ability to resist buckling and kinking in the ureter. Methods Eight commercially available ureteral sheaths were tested. The buckling pressure was measured by adding sequential loads to a point 20 cm from the tip of the sheath until the mass that resulted in buckling of the catheter was determined. The kinking pressure was determined by measuring the diameter of the sheath with a digital caliper as sequential loads were applied to the surface of the sheath. The frictional properties of the sheath were measured by testing the force required to push the sheath through a mock tube. Results The Cook Flexor was more resistant to buckling, requiring 202 g of force before buckling occurred, and both the Cook Flexor and the Applied access sheaths were more lubricious. The kinking measurements demonstrated a linear loss of diameter of the sheath with added loads. The Applied Forte XE and Cook Flexor ureteral access sheaths were more resistant to kinking than were the other sheaths tested. Conclusions Understanding the physical characteristics of ureteral sheaths may help determine which sheaths will perform well with regard to buckling during insertion and kinking during use.