The Influence of Minimally Invasive Percutaneous Nephrolithotomy on Renal Pelvic Pressure In Vivo

To inspect the renal pelvic pressure during minimally invasive percutaneous nephrolithotomy (MPCNL) and to investigate whether the use of the 14 to 18-Fr percutaneous tract, 8/9.8-Fr rigid ureteroscope, and a perfusion with high pressure furnished for MPCNL results in high renal pelvic pressure.Between July 2005 and February 2006, 76 patients were selected for renal pelvic pressure measurement during MPCNL. The renal pelvic pressure was measured by a baroceptor of the invasive blood pressure channel in a MAIDRAY PM9000 monitor, which was connected to the open-ended ureteric catheter indwelled in the renal pelvis retrogradely. The computer collected the renal pelvic pressure data each second and all the data were evaluated statistically with SPSS 12.0 software.During MPCNL within the 14, 16, 18, and double-16-Fr percutaneous tracts, the average renal pelvic pressures were 24.85, 16.23, 11.68, and 5.8 mm Hg, respectively. The average lasting times of renal pelvic pressure >/=30 mm Hg were 283, 96, 44, and 10 seconds, respectively. A postoperative fever >/=38 degrees C was recorded in 2 (2/12), 3 (3/30), 2 (2/21), and 1 case (1/13), respectively.Renal pelvic pressure generally remains lower than the level required for a backflow (30 mm Hg), during MPCNL via 14 to 18-Fr percutaneous tract. Any factor, which causes bad drainage, will result in a temporarily elevated renal pelvic pressure greater than 30 mm Hg; and multiple temporary high-pressure episodes can have a cumulative effect, which means that there will be enough backflow to cause a bacteremia.