Intrarenal Pressures Generated During Flexible Deflectable Ureterorenoscopy

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Abstract
Refinements in ureteroscopic instrumentation have provided flexible ureterorenoscopes of small external diameter with the capacity for active tip deflection. Despite the many advantages offered by these instruments, the concomitant decrease in the caliber of the working channels to 3.6F to 4.0 F has necessitated significantly higher irrigant pressures. Renal pelvic pressures were measured via a percutaneous nephrostomy tube in six patients undergoing procedures with both rigid and flexible ureterorenoscopes. Gravity, manual (60-ml syringe), and roller-pump forms of irrigation were evaluated at various levels in the ureter and renal pelvis. Gravity irrigation at 1 m height resulted in uniformly low (<55 mm Hg) intrapelvic pressures but was inadequate for vision during flexible ureterorenoscopic procedures. Forceful manual irrigation was highly variable and resulted in peak intrapelvic pressures as high as 440 mm Hg. The roller-pump device at maximum pressure settings provided continuous flow with a pop-off mechanism that prevented intrapelvic pressures from exceeding 110 mm Hg during flexible ureterorenoscopy. The high intrapelvic pressures that can be reached with forceful manual irrigation during ureterorenoscopic procedures may be damaging to the kidney. Routine monitoring of applied irrigant pressures and decompression of the renal pelvis during long procedures is recommended.