title: Pulsed holmium:yttrium-aluminum-garnet laser-induced liquid jet as a novel dissection device in neuroendoscopic surgery.
abstract: OBJECTIVE
  A pressure-driven continuous jet of water has been reported to be a feasible tool for neuroendoscopic dissection owing to its superiority at selective tissue dissection in the absence of thermal effects. With respect to a safe, accurate dissection, however, continuous water flow may not be suitable for intraventricular use. The authors performed experiments aimed at solving problems associated with continuous flow by using a pulsed holmium:yttrium-aluminum-garnet (Ho:YAG) laser-induced liquid jet (LILJ). They present this candidate neuroendoscopic LILJ dissection system, having examined its mechanical characteristics and evaluated its controllability both in a tissue phantom and in a rabbit cadaveric ventricle wall.
  
  
  METHODS
  The LILJ generator was incorporated into the tip of a No. 4 French catheter so that the LILJ could be delivered via a neuroendoscope. Briefly, the LILJ was generated by irradiating an internally supplied column of physiological saline with a pulsed Ho:YAG laser (pulse duration time 350 microsec; laser energy 250-700 mJ/pulse) within a No. 4 French catheter (internal diameter 1 mm) and ejecting it from a metal nozzle (internal diameter 100 microm). The Ho:YAG laser energy pulses were conveyed by an optical fiber (core diameter 400 microm) at 3 Hz, whereas physiological saline (4 degrees C) was supplied at a rate of 40 ml/hour. The mechanical characteristics of the pulsed LILJ were investigated using high-speed photography and pressure measurements; thermal effects and controllability were analyzed using an artificial tissue model (10% gelatin of 1 mm thickness). Finally, the ventricle wall of a rabbit cadaver was dissected using the LILJ. Jet pressure increased in accordance with laser energy from 0.1 to 2 bar; this translated into a penetration depth of 0.08 to 0.9 mm per shot in the ventricle wall of the rabbit cadaver. The gelatin phantom could be cut into the desired shape without significant thermal effects and in the intended manner, with a good surgical view.
  
  
  CONCLUSIONS
  The present results show that the pulsed LILJ has the potential to become a safe and reliable dissecting method for endoscopic procedures.
authors.affiliation: Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Japan. nakg@nsg.med.tohoku.ac.jp
authors.forename: Atsuhiro
authors.initials: A
authors.lastname: Nakagawa
authors.forename: Takayuki
authors.initials: T
authors.lastname: Hirano
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Jokura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Uenohara
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Ohki
authors.forename: Tokitada
authors.initials: T
authors.lastname: Hashimoto
authors.forename: Viren
authors.initials: V
authors.lastname: Menezes
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Sato
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Kusaka
authors.forename: Hideki
authors.initials: H
authors.lastname: Ohyama
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Saito
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Takayama
authors.forename: Reizo
authors.initials: R
authors.lastname: Shirane
authors.forename: Teiji
authors.initials: T
authors.lastname: Tominaga
mesh_terms: D000818:Animals; D002552:Cerebral Ventricles / Q000473:pathology / Q000601:surgery*; D004210:Dissection / Q000295:instrumentation*; D004867:Equipment Design; D004869:Equipment Safety; D007834:Lasers; D008297:Male; D008959:Models, Neurological; D044583:Neuroendoscopy; D011673:Pulsatile Flow; D011817:Rabbits