Evaluation of Optical Feedback for Preventing Tissue Damage in Dye Laser Lithotripsy

Thomas, S.; Engelhardt, Ralf; Meyer, Wilhelm; Pensel, J.

doi:10.1007/978-3-642-74438-9_43

Cited by 11 publications

(8 citation statements)

References 2 publications

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“…Nevertheless the use of transpapillary cholangioscopy is troublesome and need two e�perienced biliary endoscopists. In addition, when high power setting laser impulses, steered by the endoscopist, fail to reach the stone, they can produce duct injuries such as perforation and bleeding (15,21,22) . These same complications can be provo�ed by EHL.…”

Section: Discussionmentioning

confidence: 99%

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Endoscopic laser lithotripsy for complicated bile duct stones: is cholangioscopic guidance necessary?

Jakobs

Pereira-Lima²,

Schuch³

et al. 2007

Arq. Gastroenterol.

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-Background -Endoscopic papillotomy is successful in more than 95% of the cases of choledocholithiasis. For patients with difficult bile duct stones not responding to mechanical lithotripsy, different methods for stone fragmentation have been developed. Aims -To compare the results of laser lithotripsy with a stone-tissue recognizing system, when guided by fluoroscopy only or by cholangioscopy. Methods -Between 1992 and 2002 we have treated 89 patients with difficult bile duct stones by endoscopic retrograde cholangiopancreatography endoscopic retrograde cholangiopancreatography and laser lithotripsy. Unsuccessful e�tracorporeal shoc�-wave lithotripsy and electrohydraulic were also performed before laser in �5% e�tracorporeal shoc�-wave lithotripsy and electrohydraulic were also performed before laser in �5% and electrohydraulic were also performed before laser in �5% electrohydraulic were also performed before laser in �5% were also performed before laser in �5% and 26% of the cases, respectively. Results -Laser was effective in 79.2% of 72 patients guided by cholangioscopy and in 82.4% of 17 cases steered by fluoroscopy. The median number of impulses in the latter was 4,��5 and 1,800 with the former technique. Two parameters influenced the manner of laser guidance. In cases of stones situated above a stricture, cholangioscopic control was more effective (64.7% vs. �1.9%). When the stones were in the distal bile duct, fluoroscopic control was more successful. Conclusion -In cases of difficult stones in the distal bile duct, laser lithotripsy under fluoroscopic control is very effective and easily performed. Cholangioscopic guidance should be recommended just in cases of intrahepatic stones or in patients with stones situated pro�imal to a bile duct stenosis. In these cases, cholangioscopy should be performed either endoscopically or percutaneously.

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Section: Discussionmentioning

confidence: 99%

“…These same complications can be provo�ed by EHL. The development of STDS was a great step for LISL safety (6,14,22) . This system is based from an optical analysis of the irradiated object by the glass fibers that recognize if the targeted object is tissue or stone (1�) .…”

Section: Discussionmentioning

confidence: 99%

Endoscopic laser lithotripsy for complicated bile duct stones: is cholangioscopic guidance necessary?

Jakobs

Pereira-Lima²,

Schuch³

et al. 2007

Arq. Gastroenterol.

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“…For dye lasers used in the 1980s and 1990s (typical wavelength 595 nm, microsecond pulse durations), light emission at the beginning of the laser pulse was measured. If the signal was below a certain threshold, the pulse was interrupted before laser‐plasma and shockwave could form . This automatic feedback prevented the laser being triggered when the fiber was incorrectly positioned on tissue.…”

Section: Introductionmentioning

confidence: 99%

Exploiting the aiming beam to increase the safety of laser lithotripsy: Experimental evaluation of light reflection and fluorescence

2019

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Background and Objectives In Holmium laser lithotripsy, usually, the surgeon is guided by a visible beam superimposing the infrared (IR) treatment radiation. It has been shown that a green aiming beam excites stone autofluorescence. This fluorescence signal can be used for calculi detection to check the correct fiber position before triggering the IR laser, thus preventing damage to soft tissue and application devices. However, also the directly reflected green light from the fiber tip gives valuable information on fiber position and its surface condition. Materials and Methods An external fiber‐fiber‐coupling‐box (fiber core diameter 365 µm) for pulsed holmium laser radiation (2.1 µm) was set up containing a green diode laser module (520 nm, average power on the sample <0.5 mW) and optics and detectors for measuring the reflected light of this aiming beam as well as the fluorescence excited with it. Measurements were done via a lock‐in technique with more than 20 human calculi samples and porcine calix in vitro. After the implementation of automatic data storage signals during ongoing in vitro lithotripsy procedures were recorded with the fiber positioned on tissue, stone, or in/on medical equipment (working channel of an endoscope, stone retrieval basket). Results Stone fluorescence signals measured were a factor of 7 to >100 higher than those of tissue. Stone fluorescence was detectable in “non‐contact mode” with a linear signal decrease over a distance up to ~1 mm in front of the fiber tip (core diameter 365 µm) and with severely damaged fibers (max. decrease: 75% with pinched off fiber). Reflection signals of the fiber tip surface in air and water surrounding decreased significantly when the fiber was damaged; measured ratios of intact to damaged fiber found in the air were (5–17):1 and in water (1.6–3.7):1. Surfaces in front of the fiber aggravated the evaluation of fiber condition due to reflections but enabled to detect, for example, the working channel of a flexible endoscope in combination with the (missing) fluorescence signal. Conclusions Autofluorescence induced by a green aiming beam can be exploited for stone detection in laser lithotripsy. A reflection measurement can give further information on fiber condition and position. Implementing this kind of safety features for an automatic block of IR laser emission in case of weak or missing fluorescence and un‐normal reflections can assist the surgeon by avoiding tissue perforation, and damage to medical devices such as endoscopes. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

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“…With pulsed dye lasers (wavelength λ = 590 nm, pulse duration τ ∼ 2 µs) used for lithotripsy in the 1980s and 90s, an optical feedback system had been implemented which interrupted the laser pulse by an optical switch after t = 300 ns if a certain threshold of a luminescence signal was not reached . Using a dye laser, short pulse durations (few microsecond) and high pulse energies lead to plasma formation (energy density >100 J/cm 2 ) and shockwave generation which fragment the stones.…”

Section: Introductionmentioning

confidence: 99%

Stone/tissue differentiation during intracorporeal lithotripsy using diffuse white light reflectance spectroscopy: In vitro and clinical measurements

et al. 2014

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Evaluation of Optical Feedback for Preventing Tissue Damage in Dye Laser Lithotripsy

Cited by 11 publications

References 2 publications

Endoscopic laser lithotripsy for complicated bile duct stones: is cholangioscopic guidance necessary?

Endoscopic laser lithotripsy for complicated bile duct stones: is cholangioscopic guidance necessary?

Exploiting the aiming beam to increase the safety of laser lithotripsy: Experimental evaluation of light reflection and fluorescence

Stone/tissue differentiation during intracorporeal lithotripsy using diffuse white light reflectance spectroscopy: In vitro and clinical measurements

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