[Pressure study of two miniaturised amplatz sheaths of 9.5 F and 12 F outer diameter for minimal invasive percutaneous nephrolithotomy (MIP): An ex vivo organ model measurement].

Unlabelled: Over the last decade, several devices for percutaneous nephrolithotomy with smaller diameters have been introduced in order to reduce renal trauma. Recent studies have found comparable stone free rates but also exhibit the same rate of postoperative fever and septicaemia. One possible cause is the influence of irrigation fluid during stone treatment procedures. The purpose of this ex vivo study was to compare two new miniaturised PNL nephroscopy sheaths with an outer sheath diameter of 9.5 F and 12 F to the well-established MIP M Set (17.5 F) by Karl Storz.

Material And Methods: The new devices were tested in a perfused organ model of fresh porcine kidneys with different irrigation pressures, applied either by gravitation or the use of a pressure pump (Uromat E.A.S.I. Pump, Karl Storz, Tuttlingen, Germany).In addition, the 9.5 F sheath was examined for active irrigation evacuation, i. e. suction of irrigation fluid through a mono-J-catheter. An urodynamic pressure probe measured intrapelvic pressure levels throughout the procedures.

Results: Regardless of the sheath diameters used, the intrapelvic pressure did not exceed 40 cmHO (30 mmHg) when applying moderate irrigation pressure levels, either by pump or gravitation. The active suction of irrigation fluid from the kidney basin via the mono-J-catheter had no measurable impact on the detected intrarenal pressures. A crucial increase in the intrapelvic pressure was detected only when using the 9.5 F sheath in combination with applying high irrigation pressures.

Conclusion:  The newly designed miniaturised MIP sets maintain the favourable pressure features of the earlier 17.5 MIP sheath. Although the diameter has been reduced to 12F or 9.5 F, the intrapelvic pressures remained below 40 cmHO when regular irrigation settings by gravitation or pump irrigation were used.