Presented by: Akin S. Amasyali MD
Loma Linda University Health

Introduction

Mini-PCNL is gaining popularity among endourologists as it is associated with less bleeding and shorter hospital stays. One of the few drawbacks of mini-PCNL has been increased renal pelvic pressure (RPP) and subsequent increased risk for infection/sepsis. The purpose of this study was to compare the RPP between two commercially available mini-PCNL scopes and a standard 30 Fr PCNL.

Materials

A previously created prone PCNL model constructed from an actual patient was utilized to compare RPPs in a benchtop experiment. Two mini-PCNLs (Storz and Olympus) and a standard PCNL (Storz) were compared (Table 1). RPPs were measured by connecting an a-line monitor to a flexible ureteroscope retrogradely positioned in the renal pelvis. In all trials, inflow irrigation was set at 60 cmH₂O. Five trials were performed in each of the following scenarios for each scope: outflow open, outflow closed (not available in the Storz mini-PCNL), 272 µm laser fiber, 3-prong grasper, and ultrasonic lithotripter with and without suction. If RPP exceeded 65 cmH₂O, the trial was terminated. RPP was compared between scopes and conditions using a Kruskal-Wallis test with post-hoc analysis, or Mann-Whitney U test. A p-value <0.05 was considered significant.

Results

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There was no significant difference between the two mini-PCNL nephroscopes used in any scenario (Table 1). With the outflow open, both mini-PCNLs resulted in significantly higher RPP compared to the standard PCNL (Table 1). Closure of the outflow with the Olympus mini-PCNL resulted in pressures >65 cmH₂O. When working with both mini-PCNL scopes, addition of the 3-prong grasper and the ultrasonic lithotripter significantly reduced RPP. Adding suction to the lithotripter further reduced pressure. During mini-PCNL with both nephroscopes, pressures exceeded 30 cmH₂O during irrigation and when using the laser. In contrast, using the standard PCNL, RPP never exceeded 30 cmH₂O.

Conclusion

There was no difference in the RPPs between the Storz and the Olympus mini-PCNL scopes, except that closure of the outflow with the Olympus resulted in very high RPPs. Addition of the 3-prong grasper and lithotripter significantly reduced the pressure. The standard PCNL had significantly lower pressures while irrigating and when using the laser.

Funding

None

Lead Authors

Ala'a Farkouh, MD
Loma Linda University Health

Co-Authors

Matthew Wilson,
Loma Linda University Health

Kanha Shete, DO
Loma Linda University Health

Matthew Buell, MD
Loma Linda University Health

Akin S. Amasyali, MD
Loma Linda University Health

Rose Leu, MD
Loma Linda University Health

Sikai Song, MD
Loma Linda University Health

Zhamshid Okhunov, MD
Loma Linda University Health

D. Duane Baldwin, MD
Loma Linda University Health