Expedited Struvite-Stone Dissolution Using a High-Flow Low-Pressure Irrigation System

Abstract

The clinical application of chemolysis for struvite stones is limited because of the need for a nephrostomy tube and the potential risk of elevated intrarenal pressures, which may be associated with sepsis and metabolic derangements. We evaluated the utility of a high-flow low-pressure irrigation system, designed to minimize the disadvantages of chemolysis, for struvite-stone dissolution. An in-vitro urinary-tract model was used to compare a novel dual-lumen ureteral catheter with a standard nephrostomy tube for struvite stone chemolysis. A laboratory-proved large human struvite stone was divided into 3.5-g fragments, which were placed in the model. In the experimental group, Renacidin (citric acid, glucono-Delta-lactone, and magnesium carbonate; Guardian Laboratories, Lake Forest, IL) irrigation was performed through the high-flow low-pressure irrigation system. In the control group, Renacidin solution was infused at 120 mL/hour through a nephrostomy tube. Three stones were tested in each group. Intrarenal pressures, irrigant-flow rates, chemolysis rates at each time interval, overall chemolysis rates, and changes in chemolysis rates over time were compared using ANOVA. The mean intrarenal pressure with the high-flow low-pressure irrigation system and the nephrostomy tube were 5.3 and 7.5 cm H(2)O, respectively (P < 0.001). The overall chemolysis rates with the high-flow low-pressure irrigation and control systems were 0.12 g/hr and 0.06 g/hr, respectively (P = 0.025). The chemolysis rates in the experimental and control groups did not differ significantly with time (P = 0.75 and 0.21, respectively). In this in-vitro model, the high-flow low-pressure irrigation system facilitated struvite-stone chemolysis by achieving significantly higher flow rates than a traditional percutaneous system. Additionally, the system yielded lower intrarenal pressures than standard nephrostomy-tube irrigation.