Characterisation of vent designs in flexible and navigable suction ureteric access sheaths

Commercially available FANS access sheaths are similar in most aspects but have differing vent designs. With the vents open no suction is exerted on the renal collecting system. However, because the flexible access sheath intrarenal end is within the renal pelvis, outflow resistance is low and the pelvis will deflate, giving the impression of suction. We have developed a mathematical model that predicts flow at different suction pressures and with different degrees of the pressure vents open. This allows simulations across multidimensional parameter spaces and the resulting quantitative predictions can be exploited to assess the implications of FANS access sheath and ureteroscope design.