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The following is a summary of “Effect of nephrostomy sheath size on renal pelvic pressure during endoscopic combined intrarenal surgery: artificial kidney model study,” published in the April 2024 issue of Urology by Iguchi et al.

This study sought to assess intrarenal pelvic pressure dynamics during endoscopic combined intrarenal surgery, utilizing an artificial kidney model as a surrogate for real-world scenarios. Through the implementation of the Urovac evacuator™, an artificial kidney model was meticulously constructed. This model incorporated four distinct sizes of nephrostomy sheaths (MIP-L: 25/26 Fr, MIP-M: 16.5/17.5 Fr, MIP-S: 11/12 Fr, MIP-XS: 8.5/9.5 Fr) alongside two variants of ureteral access sheaths (12/14 Fr and 10/12 Fr). Intrarenal pelvic pressure measurements were meticulously recorded under varying configurations of nephrostomy and ureteral access sheath combinations, both with and without retrograde flexible ureteroscope insertion. 

Adjustments in irrigation pressure, ranging from 40–160 mmHg, were applied using an automatic irrigation device, while ureteroscope irrigation relied on spontaneous dripping at 80 cmH2O. Each condition was meticulously replicated six times to ensure the robustness of the findings. Subsequent analysis revealed that renal pelvic pressure consistently remained below 30 mmHg without the ureteroscope insertion. However, with the introduction of the ureteroscope, renal pelvic pressure exhibited a discernible increase, particularly in configurations featuring narrower nephrostomy and ureteral access sheaths, alongside escalated irrigation pressures. Intrarenal pelvic pressure surpassed the 30 mmHg threshold under specific conditions, notably with thinner nephrostomy and ureteral access sheaths. 

In conclusion, the utilization of slender nephrostomy sheaths in endoscopic combined intrarenal surgery may precipitate heightened intrarenal pelvic pressure. While these findings emanate from an artificial kidney model, they underscore the imperative for careful consideration when concurrently employing a retrograde flexible ureteroscope in clinical practice, warranting heightened vigilance to mitigate potential complications.

Source: bmcurol.biomedcentral.com/articles/10.1186/s12894-024-01458-z