title: Expedited struvite-stone dissolution using a high-flow low-pressure irrigation system.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Urology, Columbia University Medical Center, New York, New York 10032, USA.
authors.forename: Sean
authors.initials: S
authors.lastname: Collins
authors.forename: Jorge
authors.initials: J
authors.lastname: Ortiz
authors.forename: Franzo
authors.initials: F
authors.lastname: Maruffo
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Hruby
authors.forename: Phillip M
authors.initials: PM
authors.lastname: Pierorazio
authors.forename: Mantu
authors.initials: M
authors.lastname: Gupta
authors.forename: Manoj
authors.initials: M
authors.lastname: Monga
authors.forename: Jaime
authors.initials: J
authors.lastname: Landman
mesh_terms: D002404:Catheterization; D002951:Citrates / Q000378:metabolism*; D006801:Humans; D017616:Magnesium Compounds / Q000378:metabolism*; D008954:Models, Biological; D008961:Models, Structural; D010710:Phosphates / Q000378:metabolism*; D000069877:Struvite; D007507:Therapeutic Irrigation / Q000379:methods; D014545:Urinary Calculi / Q000737:chemistry* / Q000628:therapy*
chemical_list: D002951:Citrates; D017616:Magnesium Compounds; D010710:Phosphates; C026485:hemiacidrin; D000069877:Struvite