Abstract

Purpose

To evaluate the impact of direct in-scope suction (DISS) on intrarenal pressure (IRP) using two different-sized flexible ureteroscopes (7.5Fr and 9.2Fr) in combination with various sized ureteral access sheaths (UAS).

Material and methods

In this ex-vivo experimental study using a porcine kidney model, pressure measurements were conducted using two venous catheters placed in the upper and lower calyces. We tested 7.5Fr (3.6Fr working channel) and 9.2Fr (5.1Fr working channel) flexible ureteroscopes with DISS systems with 9.5/11.5Fr, 11/13Fr, and 12/14Fr UASs. Measurements were taken at irrigation pressures of 40–100 mmHg, evaluating the effects of suction modes (none vs active).

Results

The 9.2Fr scope generated higher baseline pressures (maximum 23 mmHg) compared to the 7.5Fr scope (maximum 7 mmHg) at 100 mmHg irrigation. One second of active achieved significant pressure reduction from 20–23mmHG to 3 mmHg for 9.2Fr DISS scope with 100 mmHg pressure setting and to 0 mmHg in all other settings with both scopes. The 9.2Fr scope demonstrated faster pressure recovery (8–14 s) compared to the 7.5Fr scope (10–32 s).

Conclusions

Higher intrarenal pressures can be expected with the 9.2Fr scope compared to the 7.5Fr scope, regardless of irrigation power and UAS size. Rapid and significant reduction of pressure occurs only after 1 s of suction activation. This effect is more pronounced with the 9.2Fr ureteroscope that is supplied with a wider working channel measuring 5.1Fr. The 9.2Fr scope requires shorter time to regain initial pressure compared to the 7.5Fr scope (3.6Fr working channel).