title: Evaluation of a protective laser sheath for application in flexible ureteroscopy.
abstract: OBJECTIVE
  Despite the obvious utility of the holmium laser, laser fibers frequently damage flexible ureteroscope components, such as the working channel, flexible component cable system, and fiber optical systems during routine ureteroscopic procedures. As such, we investigated the effects of the use of a flexible protective sheath on ureteroscope operation and its ability to protect ureteroscopes from laser fiber damage.
  
  
  METHODS
  The effects of insertion of the FlexGuard sheath into the working channel on endoscope deflection and irrigant flow rate were documented. Additionally, the force required to advance the laser fiber through a fully deflected endoscope, as well as the amount of laser energy required to penetrate the FlexGuard sheath, were assessed using two different ureteroscopes.
  
  
  RESULTS
  The FlexGuard sheath was easily inserted through the maximally deflected ureteroscopes. The presence of the laser sheath and a laser fiber in the working channel decreased the maximum deflection angle of the ureteroscopes by a mean of 7 degrees (from 73 degrees to 66 degrees). FlexGuard sheath insertion into the working channel also significantly diminished irrigant flow rates, from 0.55 mL/sec to 0.02 mL/sec, at an irrigation pressure of 100 cm H(2)O. The FlexGuard sheath reduced the amount of maximum force required to insert the laser fiber through each ureteroscope from 0.8 N to 0.2 N. The FlexGuard sheath was unable to protect the ureteroscope from laser energy damage.
  
  
  CONCLUSIONS
  The FlexGuard laser sheath significantly reduced the amount of force required to insert the laser fiber through the working channel. This reduction in force may have be protective against mechanical damage caused by laser fiber insertion. However, deployment of the sheath significantly diminished the rate of irrigant flow and the maximal deflection of the two ureteroscopes tested. Also, the sheath does not protect the ureteroscope from damage caused by laser energy. In each case the urologist will need to determine if the mechanical protective value of the sheath outweighs the negative impact on flow and deflection.
authors.affiliation: Department of Urology, Columbia University Medical Center, 161 Fort Washington Avenue, New York, NY 10032, USA.
authors.forename: Evren
authors.initials: E
authors.lastname: Durak
authors.forename: Greg
authors.initials: G
authors.lastname: Hruby
authors.forename: Rob
authors.initials: R
authors.lastname: Mitchell
authors.forename: Franzo
authors.initials: F
authors.lastname: Marruffo
authors.forename: Jorge O
authors.initials: JO
authors.lastname: Abundez
authors.forename: Jaime
authors.initials: J
authors.lastname: Landman
mesh_terms: D006801:Humans; D017602:Lithotripsy, Laser / Q000295:instrumentation*; D020709:Ureteroscopes; D018666:Ureteroscopy