title: Erbium: YAG versus holmium:YAG lithotripsy.
abstract: OBJECTIVE
  We test the hypothesis that erbium:YAG (Er:YAG) lithotripsy is more efficient than holmium:YAG (Ho:YAG) lithotripsy.
  
  
  METHODS
  Human calculi composed of greater than 97% calcium oxalate monohydrate and cystine were studied. Calculi were irradiated in water using Er:YAG or Ho:YAG lasers. Er:YAG lithotripsy was done with a 425 microm sapphire optical fiber at a pulse energy of 50 mJ at 10 Hz. Ho:YAG lithotripsy was performed with a 365 microm low hydroxy optical fiber at a pulse energy of 500 mJ at 10 Hz or a 425 microm sapphire optical fiber at a pulse energy of 50 mJ at 10 Hz. Fragmentation was defined as the initial stone mass minus the final dominant fragment mass and normalized for incident laser fluence (energy per unit area of fiber tip).
  
  
  RESULTS
  Mean fragmentation plus or minus standard deviation for calcium oxalate monohydrate was 38 +/- 27 mg for Er:YAG and 22 +/- 6 for Ho:YAG (low hydroxy silica fiber) versus 5 +/- 1 for Ho:YAG (sapphire fiber, p = 0.001). When fragmentation was normalized for incident laser fluence given different optical fiber sizes, mean fragmentation efficiency was 53.6 +/- 38.7 g-microm2/J for Er:YAG lithotripsy compared with 22.6 +/- 6.4 for Ho:YAG (low hydroxy silica fiber) lithotripsy (p = 0.04). Mean cystine fragmentation was 15 +/- 3 mg for Er:YAG versus 9 +/- 1 for Ho:YAG (sapphire fiber, p = 0.0005).
  
  
  CONCLUSIONS
  Er:YAG lithotripsy is more efficient than Ho:YAG lithotripsy.
authors.affiliation: Division of Urology, Department of Ophthalmology, University of Texas Health Science Center, San Antonio, Texas, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Teichman
authors.forename: K F
authors.initials: KF
authors.lastname: Chan
authors.forename: P P
authors.initials: PP
authors.lastname: Cecconi
authors.forename: N S
authors.initials: NS
authors.lastname: Corbin
authors.forename: A D
authors.initials: AD
authors.lastname: Kamerer
authors.forename: R D
authors.initials: RD
authors.lastname: Glickman
authors.forename: A J
authors.initials: AJ
authors.lastname: Welch
mesh_terms: D006801:Humans; D017602:Lithotripsy, Laser / Q000379:methods*; D014545:Urinary Calculi / Q000628:therapy*