Transoral flexible laser surgery of the upper aerodigestive tract with blue laser.

PURPOSE: The introduction of fiber-guided lasers was a breakthrough in laryngology practice, opening the path for treating different pathologies with minimally invasive procedures, both in the operating room and in the office. The most recent technology in the area is the blue laser, which combines photoangiolytic and cutting properties, characteristics that make this equipment suitable for its use in upper aerodigestive tract surgery. However, there is not enough experience in this area. The authors present a case series of patients with different pharyngeal, laryngeal, and tracheal pathologies who were treated by means of transoral procedures using fiber-guided blue laser. METHODS: The surgical records of patients with different upper aerodigestive tract pathologies who were treated with fiber-guided blue laser in the operating room, under general anesthesia with jet ventilation or supraglottic ventilation using suspension laryngotracheoscopy techniques between February 2018 and March 2022 were reviewed. RESULTS: A total of 80 surgical interventions in a group of 38 patients were performed. A wide variety of procedures was executed, either using the laser alone or in combination with other techniques to treat different pathologies of the aero-digestive tract safely and effectively, with adequate functional results. CONCLUSIONS: Following all necessary precautions, blue laser is a reliable tool to perform minimally invasive surgeries in the operating room using TOFLS techniques. It can be used alone or in combination with other devices to achieve the desired goals.

Automated Laser-Fiber Coupling Module for Optical-Resolution Photoacoustic Microscopy.

Photoacoustic imaging has emerged as a promising biomedical imaging technique that enables visualization of the optical absorption characteristics of biological tissues in vivo. Among the different photoacoustic imaging system configurations, optical-resolution photoacoustic microscopy stands out by providing high spatial resolution using a tightly focused laser beam, which is typically transmitted through optical fibers. Achieving high-quality images depends significantly on optical fluence, which is directly proportional to the signal-to-noise ratio. Hence, optimizing the laser-fiber coupling is critical. Conventional coupling systems require manual adjustment of the optical path to direct the laser beam into the fiber, which is a repetitive and time-consuming process. In this study, we propose an automated laser-fiber coupling module that optimizes laser delivery and minimizes the need for manual intervention. By incorporating a motor-mounted mirror holder and proportional derivative control, we successfully achieved efficient and robust laser delivery. The performance of the proposed system was evaluated using a leaf-skeleton phantom in vitro and a human finger in vivo, resulting in high-quality photoacoustic images. This innovation has the potential to significantly enhance the quality and efficiency of optical-resolution photoacoustic microscopy.

Burnback: the role of pulse duration and energy on fiber-tip degradation during high-power laser lithotripsy.

High-power holmium lasers have become popular for ureteroscopic laser lithotripsy and dusting. Our aim was to investigate the effect of pulse duration and pulse energy on fiber-tip degradation when using high-power settings for popcorn lithotripsy. BegoStones were fragmented in a glass bulb to simulate renal calyx, using a 120 W Ho:YAG laser. A 242 µm fiber was placed via the ureteroscope 2 mm distance from stones (popcorn model). To assess the effect of pulse duration on fiber-tip degradation, long pulse (LP) and short pulse (SP) settings were compared at settings of 1.0Jx20Hz (20 W), 0.5Jx70Hz (35 W), and 1.0Jx40Hz (40 W). To assess the effect of pulse energy on tip degradation, 40 W SP settings (0.5Jx80Hz, 0.8Jx50Hz, and 1.0Jx40Hz) were tested. Pulse duration was measured using a photodetector and peak power was then calculated using the pulse duration and pulse energy. Experiments were conducted for 4 min. Fiber-tip length was measured before and after using a digital caliper. Fiber-tip degradation was least when using LP for all settings tested (p < 0.01). For 40 W settings, tip degradation was significantly lower when using a pulse energy of 0.5 J compared to 0.8 J or 1.0 J (p < 0.004). LP mode results in less fiber burnback for all power settings tested. Total power is more important than frequency in the development of burnback. However, high-power 40 W settings can be utilized with less burnback if lower pulse energies are used. Understanding these parameters can improve the longevity of the laser fiber and improve procedural efficiency.

[Development of Gun-type Tube-Guide Device of Laser Fiber].

With the development of laryngeal microsurgery, the requirements for the flexibility and convenience of surgical instruments are increasing. The research on related instruments has important value for the clinical application of laryngeal microsurgery. We have redesigned a gun-type tube-guide device of laser fiber by comparing the shortcomings of existing laser fiber introducers. The innovation of this design lies in its rotating nut device with adjustable laser angle and pre-bent tip. The corresponding in vitro laryngeal model experiment can realize multi-angle rotation of the instrument in the laryngeal cavity, which greatly increases the scope of laser surgery. During the operation, the rotating nut can be directly adjusted to avoid repeatedly removing the instrument to adjust the angle, which greatly improves the practicability and simplicity of the operation, which is worthy of further clinical research and promotion.

Is loss of power output due to laser fiber degradation still an issue during prostate vaporization using the 180 W GreenLight XPS laser?

PURPOSE: To investigate whether heat-induced fiber degradation and loss of power output, which occurred during GreenLight laser vaporization (LV) of the prostate using the first- and second-generation 80 and 120 W laser, are still an issue during LV using the upgraded third generation 180 W GreenLight XPS™ laser. METHODS: Laser beam power output of 53 laser fibers was measured at baseline and after every 25 kJ of delivered energy during routine 180 W GreenLight XPS™ LV in 47 patients with prostatic bladder outflow obstruction. After the procedures, the fiber tips were microscopically examined. RESULTS: The median applied energy per patient was 178 kJ [interquartile range (IQR): 106-247]. Loss of power output during the procedure was detectable in all fibers. After the application of 25, 150, and 250 kJ, the median power output decreased to 77% (IQR 59-87), 57% (IQR 32-71), and 51% (IQR 37-64) of the baseline value. Nine fibers (17%) remained on a relatively high power output level (> 80% of the initial output), while 13 fibers (25%) showed an end-of-procedure power output of less than 20%. Microscopy of the fiber tip revealed mild-to-moderate overall degradation and increasing degradation with higher energy delivered. CONCLUSION: Despite changes in fiber design, heat-induced fiber damage and loss of power output remain an issue during 180 W GreenLight XPS™ LV. Whether modifications of the surgical technique can prevent impairment of fiber performance needs to be further evaluated.

Dispersion of near-infrared laser energy through radicular dentine when using plain or conical tips.

The aim of this study was to investigate the influence of tip design on patterns of laser energy dispersion through the dentine of tooth roots when using near-infrared diode lasers. Diode laser emissions of 810 or 940 nm were used in combination with optical fiber tips with either conventional plain ends or conical ends, to irradiate tooth roots of oval or round cross-sectional shapes. The lasers were operated in continuous wave mode at 0.5 W for 5 s with the distal end of the fiber tip placed in the apical or coronal third of the root canal at preset positions. Laser light exiting through the roots and apical foramen was imaged, and the extent of lateral spread calculated. There was a significant difference in infrared light exiting the root canal apex between plain and conical fiber tips for both laser wavelengths, with more forward transmission of laser energy through the apex for plain tips. For both laser wavelengths, there were no significant differences in emission patterns when the variable of canal shape was used and all other variables were kept the same (plain vs conical tip, tip position). To ensure optimal treatment effect and to prevent the risks of inadvertent laser effects on the adjacent periapical tissues, it is important to have a good understanding of laser transmission characteristics of the root canal and root dentine. Importantly, it is also essential to understand transmission characteristics of plain and conical fibers tips.

Comparison of laser fiber passage in ureteroscopic maximum deflection and their influence on deflection and irrigation: Do we really need the ball tip concept?

PURPOSE: To examine laser fiber passage capabilities through flexible ureterorenoscopes (fURSs) and to measure deflections and flow characteristics. METHODS: For this in vitro study, eight fURSs were examined (Olympus® URF-P6, URF-P6, URF-V, URF-V2; Storz® Xc and Flex-X2; Richard Wolf® Cobra Vision; and Lithovue). Four laser fibers standard 200- and 273-µm (uncleaved and cleaved), sheath-coated and ball-tip fibers were attempted to pass through each fURS while deflected at 120°, 180°, maximum deflection, and maximum deflection with reduced 9-mm radius. Measurements included maximal (up/down) deflections and irrigation flow rates achieved with each fiber. RESULTS: Wolf Cobra Vision demonstrated minimal loss of deflections with mean differences of -2°/0° (p > 0.05) when loaded with the 200-µm fiber. The 273-µm fiber provoked utmost deflections that decline when loaded in Olympus URF-P5: mean differences of -52°/-35° (p < 0.001 for upward deflection). Of overall deflections, sheath-coated fiber induced least insult (p > 0.05), while standard 273-µm fiber incited maximum degradation (p < 0.00001). With few exceptions, sheath-coated and ball-tip fibers passed through all maximally deflected scopes. Uncleaved 200- and 273-µm fibers failed to pass through most maximally deflected fURS. However, cleaving their ends allowed 200- and 273-µm fiber to pass through all angles of deflections expect in the Olympus URF-P5 and Olympus URF-P5 and URF-V, respectively. The irrigation through all fURSs was significantly impaired (p < 0.00001). CONCLUSIONS: fURS deflection was least affected by sheath-coated fibers and most affected by the 273-µm fiber. Uncleaved 200- and 273-µm fibers showed least passage capabilities; while removing the ends, the fibers greatly facilitated their passage capabilities as much as the other fibers tested.

Evaluation of a Novel Lateral Emitting Laser Fiber for Near-Infrared Photoimmunotherapy.

Near-infrared photoimmunotherapy (NIR-PIT) is a new cancer therapy that uses NIR light and conjugates of a tumor-targeting monoclonal antibody and phthalocyanine dye. In clinical practice, frontal and cylindrical diffusers are the only options for NIR illumination. However, illumination in a narrow space is technically difficult with such diffusers. Therefore, we evaluated a lateral illumination system using a lateral emitting laser (LEL) fiber. The LEL fiber illuminated a certain area in a lateral direction. NIR-PIT with an LEL fiber reduced luciferase activity in a light-dose-dependent manner in A431-GFP-luc cells in vitro and significantly suppressed tumor proliferation in a xenograft mouse model. To evaluate the usefulness of the LEL fiber in the illumination of a narrow space, a tumor was illuminated from the inside of a cylinder, mimicking a narrow space, and the fluorescence intensity in the tumor was monitored. In the frontal diffuser, NIR light was unevenly delivered and little light reached a distal tumor area from the illuminated side. By contrast, the LEL fiber allowed a uniform illumination of the entire tumor, and a loss of fluorescence was observed even in distal areas. These findings suggested that the LEL fiber can be used for NIR-PIT and is suitable for NIR light illumination in a narrow space.

Assessment of Factors Involved in Laser Fiber Degradation with Thulium Fiber Laser.

Objectives: To assess the effect of various factors on laser fiber tip degradation with the thulium fiber laser (Tm-fiber): fiber stripping, adjustable laser settings (energy, frequency, peak power), and stone density. Methods: Two hundred seventy-three micrometer fibers were used with a 50W Tm-fiber. First, we assessed the evolution of power transmission with stripped and unstripped fibers submerged in saline. The laser was continuously activated for 5 minutes. The influence of each laser parameter (energy, frequency, and peak power) on fiber degradation was assessed by loss of power transmission and reduction of tip length. Second, we assessed the evolution of power transmission after 150 seconds of lithotripsy in a quasicontact mode against soft and hard BegoStones. The influence of lithotripsy with different laser settings on fiber degradation was assessed by loss of power transmission. Results: Power transmission was close to 100% with stripped fibers, while a power gain appeared for unstripped fibers after 5 minutes of laser emission. Thus, only stripped laser fibers were used during the second series of experiments. Regardless of laser settings, there was a constant loss of measured power transmission after lithotripsy with a significant difference between soft and hard stones, p < 0.0001. Power transmission was 67% and 78% against hard and soft stones, respectively. While there was no influence of peak power on power output against hard stones, there was a significant one against soft stones. Conclusions: The main determinant of loss of power transmission during lithotripsy in contact mode with Tm-fiber is the stone density. Higher loss of power transmission occurs against hard stones than soft stones. All peak powers may be used against hard stones without a difference, while high peak power appears as an additional factor of power loss against soft stones, but this decrease will not the reach the one obtained with hard stones.

Comparison of Holmium:YAG and Thulium Fiber Lasers on the Risk of Laser Fiber Fracture.

OBJECTIVES: To compare the risk of laser fiber fracture between Ho:YAG laser and Thulium Fiber Laser (TFL) with different laser fiber diameters, laser settings, and fiber bending radii. METHODS: Lengths of 200, 272, and 365 µm single use fibers were used with a 30 W Ho:YAG laser and a 50 W Super Pulsed TFL. Laser fibers of 150 µm length were also tested with the TFL only. Five different increasingly smaller bend radii were tested: 1, 0.9, 0.75, 0.6, and 0.45 cm. A total of 13 different laser settings were tested for the Ho:YAG laser: six fragmentation settings with a short pulse duration, and seven dusting settings with a long pulse duration. A total of 33 different laser settings were tested for the TFL. Three laser settings were common two both lasers: 0.5 J × 12 Hz, 0.8 J × 8 Hz, 2 J × 3 Hz. The laser was activated for 5 min or until fiber fracture. Each measurement was performed ten times. RESULTS: While fiber failures occurred with all fiber diameters with Ho:YAG laser, none were reported with TFL. Identified risk factors of fiber fracture with the Ho:YAG laser were short pulse and high energy for the 365 µm fibers (p = 0.041), but not for the 200 and 272 µm fibers (p = 1 and p = 0.43, respectively). High frequency was not a risk factor of fiber fracture. Fiber diameter also seemed to be a risk factor of fracture. The 200 µm fibers broke more frequently than the 272 and 365 µm ones (p = 0.039). There was a trend for a higher number of fractures with the 365 µm fibers compared to the 272 µm ones, these occurring at a larger bend radius, but this difference was not significant. CONCLUSION: TFL appears to be a safer laser regarding the risk of fiber fracture than Ho:YAG when used with fibers in a deflected position.

On the Merits of Using Angled Fiber Tips in Office-based Laser Surgery of the Vocal Folds.

Office-based endoscopic laser surgery is an increasingly popular option for the treatment of many benign and pre-malignant tumors of the vocal folds. While these procedures have been shown to be generally safe and effective, recent clinical studies have revealed that there are a number of challenging locations inside the larynx where laser light cannot be easily delivered due to line-of-sight limitations. In this paper, we explore whether these challenges can be overcome through the use of side-firing laser fibers. Our study is conducted in simulation, using three-dimensional models of the human larynx generated from X-ray microtomography scans. Using computer graphics techniques (ray-casting), we simulate the application of laser pulses with different types of laser fibers and compare the total anatomical coverage attained by each fiber. We consider four fiber types: a traditional "forward-looking" fiber - not unlike the ones currently used in clinical practice - and three side-firing fibers that emit light at an angle of 45, 70, and 90 degrees, respectively. Results show that side-firing fibers enable a ~70% increase in accessible anatomy compared to forward-looking fibers.

Handheld laser-fiber vibrometry probe for assessing auditory ossicles displacement.

SIGNIFICANCE: Measurements of auditory ossicles displacement are commonly carried out by means of laser-Doppler vibrometry (LDV), which is considered to be a gold standard. The limitation of the LDV method, especially for in vivo measurements, is the necessity to expose an object in a straight line to a laser beam operating from a distance. An alternative to this approach is the use of a handheld laser-fiber vibrometry probe (HLFVP) with a curved tip. AIM: We evaluate the feasibility of an HLFVP with a curved tip for measuring sound-induced displacement of the auditory ossicles. APPROACH: A handheld vibrometer probe guiding the laser beam with a fiber-optic cable was used for displacement measurements of the incus body and the posterior crus of the stapes. Tonal stimuli at frequencies of 0.5, 1, 2, and 4 kHz were presented by means of an insert earphone positioned in the outer ear canal. The probe was fixed at the measurement site using a tripod or hand-held by one of the two surgeons. RESULTS: The measurements were carried out on six fresh temporal bones. Multivariate analysis of variance showed statistically significant differences for stimulus frequency (F3,143 = 29.37, p < 0.001, and η2 = 0.35), bone (F5,143 = 4.61, p = 0.001, and η2 = 0.01), and measurement site (F1,143 = 4.74, p = 0.03, and η2 = 0.02) in the absence of statistically significant differences for the probe fixation method (F2,143 = 0.15, p = 0.862, and η2 = 0.001). Standard deviations of the means were 6.9, 2.6, 1.9, and 0.6 nm / Pa for frequency, bone, site, and fixation, respectively. Ear transfer functions were found to be consistent with literature data. CONCLUSIONS: The feasibility of applying HLFVP to measure the displacement of auditory ossicles has been confirmed. HLFVP offers the possibility of carrying out measurements at various angles; however, this needs to be standardized taking into account anatomical limitations and surgical convenience.

Fiber optic CO2-laser induced emphysema of the supraglottis.

Subcutaneous emphysema is a rare but well-defined surgical complication. However, emphysema of the supraglottic mucosa has not been described in the literature. We present a case of a 2-year-old male who suffered supraglottic emphysema secondary to fiber optic CO2-laser use during laryngeal cleft repair. The patient required preemptive postoperative intubation; however, there were no long-lasting adverse effects at 6 and 12 weeks follow up. This report illustrates a rare CO2-laser complication and describes its sequela.

The effect of laser fiber on the damage of the working channel of a flexible ureteroscope.

INTRODUCTION: Flexible ureteroscopy involves expensive equipment that is expensive to repair. This study aimed to investigate the effects of cleavage by various tools on the laser fiber tip and to determine the extent of damage incurred to the laser passing through the working channel and firing at different degrees of deflection. MATERIALS AND METHODS: We investigated the effect of cleavage on Lumenis Slimline reusable fibers (272 and 365 µm) as performed by four cleavage tools: a scribe pen, a surgical blade, suture scissors, and ceramic scissors. Following cleavage, we recorded the pattern of light dispersion and power output. The laser fibers passed through the working channel at various. RESULTS: The ceramic scissors provided the best pattern of light dispersion and the highest power output. The suture scissors provided unacceptable levels of light dispersion. The 272 µm fiber was able to pass through the working channel at 30 and 45 degrees of deflection. The 365 µm laser fiber was only able to pass through the working channel at 30 degrees of deflection. There was no breakage of the laser fiber at any of the degrees of deflection evaluated. CONCLUSIONS: Analysis showed that the ceramic scissors were the best tool for cleaving Lumenis Slimline reusable fibers and that suture scissors were unacceptable. We also found that the deflection angle that causes damage to the working channel by laser insertion is dependent on both the size of the laser fiber and the degree of bending. Firing the laser during scope deflection could be performed safely at any degree of deflection, even with a high laser power of 40 W for a duration of 30 s.

Laser Fibers for Holmium:YAG Lithotripsy: What Is Important and What Is New.

Holmium:YAG laser is currently the dominant lithotripter used during retrograde intrarenal surgery. The laser energy is delivered to the target via flexible optical laser fibers. The performance characteristics of laser fibers vary. The diameter, flexibility, resistance to fracture with bending, and tip configuration are all important factors that contribute to a fiber's overall performance. Understanding these characteristics assists the end user with proper fiber selection for procedures.

Hand-Held Thulium Laser Fiber and Ultrasonic Aspirator for Opening the Internal Auditory Canal During Acoustic Neuroma Microneurosurgery: Operative Technique.

Video 1 describes the technique of microsurgery removal of acoustic neuromas (ANs) using new technologies. The Flexible 2µ-Thulium hand-held laser fiber (Revolix jr, LISA laser products, 7 OHG, Berlin, Germany) and Sonopet Ultrasound Aspirator (Stryker, Kalamazoo, Michigan, USA) can be used for a safe and facilitated opening of the internal auditory canal (IAC). We illustrate the operative technique used on a surgical series of 111 cases operated on during the past 8 years, from July 2010 to July 2018. We studied 170 consecutive patients suffering from ANs who were operated on with a microsurgical technique by the key-hole retrosigmoid approach. In 111 cases the "Sonopet" Ultrasound Aspirator was used to open the IAC and a 2µ-Thulium laser fiber was used for cutting the dura mater of the posterior aspect of petrous bone and the IAC, and it was also used to perform tumor capsule incision. From December 2017 we started to check the removal of tumor inside the IAC with a flexible endoscope 4 mm × 65 cm, (Karl Storz GmbH, Tuttlingen, Germany) in order to detect possible tumoral residue and achieve a radical tumor resection in the fundus. The use of these new technologies seems to be safe and subjectively facilitates the opening of the IAC in AN microsurgery.

Carbon debris and fiber cleaving: Effects on potassium-titanyl-phosphate laser energy and chorioallantoic membrane model vessel coagulation.

OBJECTIVES/HYPOTHESIS: Photoangiolytic precision afforded by the 532-nm potassium-titanyl-phosphate (KTP) laser relies on predictable energy delivery. Inadequate energy output can cause vessel rupture, and excessive energy can cause thermal damage. The quality of the cleaved surface and carbon deposits from ablated tissue are two factors that could negatively impact fiber performance. The effects of these on energy output and blood vessel coagulation were assessed using a chorioallantoic membrane (CAM) model. STUDY DESIGN: Comparative analysis. METHODS: Laser fibers with carbon debris, optimal fiber cleaving, and suboptimal cleaving were inspected at three times magnification, and the light dispersion pattern of each fiber was rated. The average energy output from consecutive pulses through each fiber configuration was recorded. The effect of these fiber conditions on clinical efficacy was estimated by measuring vessel coagulation versus rupture in the CAM model. Repeated measures analysis of variance compared results. RESULTS: Carbon debris and suboptimal cleaving resulted in decreased energy output in comparison to optimal cleaving ([-Δ244 mJ, d = 4.31, P < .001] and [-Δ195 mJ, d = 6.04, P < .001]). Optimal cleaving resulted in immediate coagulation of vessels. Fibers with suboptimal cleaving and carbon debris had unpredictable outcomes, requiring multiple pulses for coagulation or causing vessel rupture. CONCLUSIONS: KTP laser fiber function is significantly affected by fiber tip condition. Carbon debris and suboptimal cleaving create significant attenuation of energy, which results in an unpredictable angiolytic effect, as demonstrated by increased vessel rupture in the CAM model. Optimal recleaving of KTP laser fibers restores prior energy output and predictable coagulation. Care should be taken to avoid carbon debris on laser-fiber tips and to cleave fibers properly. LEVEL OF EVIDENCE: NA Laryngoscope, 129:2244-2248, 2019.

Suturing of the laser resection area is recommended over a depth of 2 cm in an experimental porcine lung model.

BACKGROUND: Lung metastases can be removed by an Nd:YAG laser to save lung parenchyma. At these sites, a coagulated lung surface remains. Airtightness was investigated in relation to the depth of resection on an ex vivo porcine lung model. METHODS: Freshly slaughtered porcine double lung preparations were connected to a ventilator via a tube. Non-anatomical laser resections were performed with an 800 µm laser fiber and the Nd:YAG laser LIMAX® 120 (power: 40 and 60 watts). The following resection depths (each n=12) from the lung surface were examined: 0.5, 1, 1.5 and 2.0 cm. After resection the lungs were submerged under water and ventilated (frequency 10/min, Pinsp =25 mbar, PEEP =5 mbar). Airtightness of resection surfaces was determined by a leakage score, as well as the measurement of the leakage volume (in mL) per respiration (Group 1). Afterwards, the resection areas were coagulated for 5 seconds with a laser power of 60 watts at a distance of approximately 1 cm from the surface. This was followed by a re-evaluation for airtightness (Group 2). Finally, the resection surface was closed by a suture (PDS USP 4-0) and re-tested for airtightness (Group 3). The individual groups were compared for their significance (P<0.05) using a nonparametric test. RESULTS: Up to a resection depth of 1.5 cm, the ventilated resection surfaces were completely airtight regardless of the laser power. From a depth of resection of 1.5 cm, a mean air volume loss of 28.9±5.3 mL/respiratory cycle at 40 watts and of 26.4±5.8 mL at 60 watts was found. Additional surface coagulation did not significantly reduce the leakage rate. In contrast, suturing significantly reduced (P<0.0001) to 7.2±3.7 mL/ventilation (40 watts) and 6.0±3.4 mL/ventilation. At a resection depth of 2 cm, the leakage volume was 42.9±3.3 mL/respiratory cycle (40 watt) and 46.3±6.4 mL/respiratory cycle (60 watt). Additional surface coagulation failed to significantly reduce leakage volume, but suture closure provided airtightness. CONCLUSIONS: In non-ventilated porcine lungs, Nd:YAG laser resection surfaces up to a resection depth of 1.5 cm are airtight after ventilation onset. From a depth of 1.5 cm, closure of resection surfaces by an additional suture is needed. Airtightness of resection surfaces was not increased by additional coagulation.

Laser Fiber and Flexible Ureterorenoscopy: The Safety Distance Concept.

INTRODUCTION: The costs of flexible ureterorenoscopes (fURSs) and their repair oblige the surgeon to know the proper handling of instruments. There is a lack of evidence in the literature about the safety distance that the laser fiber should have once out from the ureterorenoscope to avoid instrumental damages. MATERIALS AND METHODS: We performed an in vitro observational study. Seven fURSs were tested. The distance from the laser fiber tip and the fURS camera was measured at the first appearance on the endoscopic screen and when the fiber was reaching one-fourth of the screen. Second, to evaluate the impact of the holmium laser bubble according to different fiber distances, an assessment of the size and shape of the bubble created at the tip of the fiber with the laser activated was done, recording the images with a high-speed camera. RESULTS: The first appearance on the screen of the laser tip is different in different ureterorenoscopes. In all the ureterorenoscopes, we observed that when the laser fiber was at » of the screen, the bubble was never touching the fURS tip. CONCLUSION: Even if there is a big limitation of this study due to the impossibility to measure and to evaluate the damage of the fURS tip surface, we observed that when the laser fiber tip reaches » of the screen, the bubble generated by laser activation is never rebounding on the camera of the ureterorenoscope, preserving it from laser damages. We can define this position as the safety distance.

Development of Gun-type Tube-Guide Device of Laser Fiber / 中国医疗器械杂志

With the development of laryngeal microsurgery, the requirements for the flexibility and convenience of surgical instruments are increasing. The research on related instruments has important value for the clinical application of laryngeal microsurgery. We have redesigned a gun-type tube-guide device of laser fiber by comparing the shortcomings of existing laser fiber introducers. The innovation of this design lies in its rotating nut device with adjustable laser angle and pre-bent tip. The corresponding