Intracorporeal laser lithotripsy

Do Stone Characteristics and Laser Fiber Size Affect Ho: YAG Laser Time and Energy During Ureteroscopy?

Objective

To assess the correlation of attenuation value measured as HU in Non-contrast computed tomography, stone size, location, fibre size and stone composition with Holmium: yttrium-aluminium garnet (Ho: YAG) laser parameters including, cumulative laser energy and final laser time.

Materials and Methods

 We prospectively analyzed 118 patients undergoing flexible/semirigid ureteroscopy and Holmium: YAG laser lithotripsy from October 2022 to October 2023 at Mogadishu Urological Centre. Our study parameters encompass preoperative stone characteristics determined in NCCT (stone size, attenuation value, and stone location), fibre size, cumulative laser energy and time, overall operative time, and postoperative stone composition analysis.

Results

There were 118 patients eligible for our prospective study. In the logistic regression model for retrograde intrarenal surgery with a fibre size of 272 μm, cumulative laser energy showed a significant difference among stone size, location, fibre size, and calcium oxalate stones (P > 0.05). However, no significant difference was noticed in the attenuation value (P = 0.078) (R2 = 0.053). Our analysis showed a positive significance among all the parameters (P < 0.05) for laser time. In logistic regression for a rigid ureteroscope with a fibre size of 365 μm, cumulative laser energy showed a significant difference between the location stone and fibre size (P < 0.05) (R2 = 0.09). However, no significant difference was seen among stone size, attenuation value, and calcium oxalate stones (P > 0.05). For laser time, our analysis showed a positive significance among all parameters except the calcium oxalate stones, which showed no significant difference (P > 0.05).

Conclusion

Our study showed that stone location, hardness, and fibre size are the most critical factors influencing the outcome of Ho: YAG laser parameters. The study revealed that CaOMH stones require more time to disintegrate into smaller ones, while PH-dependent stones such as carbonate apatite may require less time to fragment.

High-power Holmium:Yag lithotripsy in bladder urolithiasis: Is it safe and effective? A combined clinical and experimental study

Objective

To evaluate the efficacy and safety of Holmium: Yttrium-Aluminum-Garnet (Ho:YAG) laser in bladder lithotripsy using high-power settings > 100 W.

Materials and Methods

A combined experimental and clinical study was conducted. The Quanta Cyber: Ho 150 with a 550 μm Quanta optical fiber was utilized in all set-ups. Ablation rates for soft and hard artificial stones were tested in vitro using 100 W and 20 W power settings. In the experiment, a porcine bladder was used. The optical fiber was inserted through a rigid cystoscope, whilst a K-type thermocouple was inserted in the bladder dome. The tested high-power settings were 152 W, 120 W and 105 W. In every trial, the lasing time was over 60 s. In the clinical study, 35 patients underwent transurethral high-power bladder lithotripsy. Laser settings were set between 100 W and 150 W.

Results

Stone mass (stone weight) was significantly lower after stone ablation independently of the stone type or the laser settings. Significantly higher mass decrease and ablation rate were detected in high-power compared to low-power settings. In the experiment, the highest temperature recorded was 32°C at 152 W. At 120 W and 105 W, the peak temperatures didn't reach 30°C. In the clinical study, a stone-free rate of 100% and a mean operative time of 43 ± 18 min were reported. All patients stayed in the hospital for one day except for one who presented minor hematuria. Additional complications did not occur.

Conclusion

Ho:YAG laser lithotripsy > 100 W is an effective, fast and safe modality for the treatment of bladder calculi.

Assessment of stone ablation rate using the Moses technology modes with different energy and pulse settings: An experimental study

Objectives

To compare lithotripsy ablation rate with the Moses modes versus conventional pulse modes when using the Holmium:Yttrium-Aluminum-Garnet (Ho:YAG) laser.

Methods

The Lumenis® Pulse P120H Holmium Laser System and a 365 μm Moses D/F/L fiber were used to assess stone ablation rate in conventional Short and Long Pulse as well as Moses Contact and Distance at 10 W (0.5Jx20Hz and 2Jx5Hz) and 60 W (1Jx60Hz and 2Jx30Hz). Hard and soft phantom stones were formed, and all tests were conducted in a custom experimental configuration installed in a saline-filled bath. The laser was delivered up to 3 kJ of total energy. The fragmentation pattern was assessed via photographs in each cohort.

Results

The time to reach the target energy was 5 min and 50 s in all 10 W and 60 W trials, respectively. In both stone types, ablation was more effective when high-power, high-energy and Moses Distance was utilized. In soft stones, the lowest ablation rate was detected in the Long Pulse modality in all power, energy and frequency settings. Overall, when dusting settings (high-frequency, low-energy) were used, a deeper single cavitation was observed rather than small cavitations.

Conclusions

The most effective pulse modality as evaluated via stone ablation rate depends on the stone hardness as well as energy and frequency settings. In both hard and soft stones, ablation is more effective when 60 W (2Jx30Hz) power settings and Moses Distance are used. Tailored laser settings in terms of energy and frequency could be set for each case scenario.

Peri-Ureteral Abscess Formation Following Ureteroscopic Laser Lithotripsy: A Case Report

We report the case of a patient with a previous history of obstructive renal calculus disease who initially presented with a symptomatic calculus in her right mid-ureter, requiring ureteroscopy with laser lithotripsy and ureteral stent placement. Shortly after the removal of the stent, the patient was found to have a peri-ureteral abscess, necessitating percutaneous drainage by interventional radiology, and placement of an additional ureteral stent. Adverse reactions to these procedures are rare and, to our knowledge, this is the only documented case of peri-ureteral abscess as a complication of ureteroscopic laser lithotripsy or of ureteral stenting. In addition to developing a peri-ureteral abscess, this patient also experienced deep vein thrombosis (DVT) and subsegmental pulmonary embolism (PE), which also have not been found to be a common complication of laser lithotripsy or ureteral stent placement in any of the studies that we reviewed for this article. The complications that were previously rare are unfortunately on the rise, possibly in the setting of both increased access to invasive therapies as well as the increased rates of diabetes and obesity. Survivability hinges on prompt recognition and treatment of these complications. In the event that a peri-ureteral abscess is discovered, prompt treatment with broad-spectrum antibiotics is recommended in addition to interventional radiology and urology consultation. Antibiotics should cover conventional intra-abdominal and urologic abscess regimens.

New Lasers for Stone Treatment

Laser technology has been a breakthrough in urology. The new era in endocorporeal laser lithotripsy has recently begun in mid-2020, where promising technologies tested in vitro have reached their approval for clinical use and, in that way, have made it possible to confirm their safety and advantages in the real world, for the patient and for the urologist.

In vitro investigations of propulsion during laser lithotripsy using video tracking

OBJECTIVES

Ureteroscopic laser lithotripsy is an important and widely used method for destroying ureter stones. It represents an alternative to ultrasonic and pneumatic lithotripsy techniques. Although these techniques have been thoroughly investigated, the influence of some physical parameters that may be relevant to further improve the treatment results is not fully understood. One crucial topic is the propulsive stone movement induced by the applied laser pulses. To simplify and speed up the optimization of laser parameters in this regard, a video tracking method was developed in connection with a vertical column setup that allows recording and subsequently analyzing the propulsive stone movement in dependence of different laser parameters in a particularly convenient and fast manner.

MATERIALS AND METHODS

Pulsed laser light was applied from below to a cubic BegoStone phantom loosely guided within a vertical column setup. The video tracking method uses an algorithm to determine the vertical stone position in each frame of the recorded scene. The time-dependence of the vertical stone position is characterized by an irregular series of peaks. By analyzing the slopes of the peaks in this signal it was possible to determine the mean upward stone velocity for a whole pulse train and to compare it for different laser settings. For a proof of principle of the video tracking method, a specific pulse energy setting (1 J/pulse) was used in combination with three different pulse durations: short pulse (0.3 ms), medium pulse (0.6 ms), and long pulse (1.0 ms). The three pulse durations were compared in terms of their influence on the propulsive stone movement in terms of upward velocity. Furthermore, the propulsions induced by two different pulse energy settings (0.8 J/pulse and 1.2 J/pulse) for a fixed pulse duration (0.3 ms) were compared. A pulse repetition rate of 10 Hz was chosen for all experiments, and for each laser setting, the experiment was repeated on 15 different freshly prepared stones. The latter set of experiments was compared with the results of previous propulsion measurements performed with a pendulum setup.

RESULTS

For a fixed pulse energy (1 J/pulse), the mean upward propulsion velocity increased (from 120.0 to 154.9 mm · s^-1 ) with decreasing pulse duration. For fixed pulse duration (0.3 ms), the mean upward propulsion velocity increased (from 91.9 to 123.3 mm · s^-1 ) with increasing pulse energy (0.8 J/pulse and 1.2 J/pulse). The latter result corresponds roughly to the one obtained with the pendulum setup (increase from 61 to 105 mm · s^-1 ). While the mean propulsion velocities for the two different pulse energies were found to differ significantly (P < 0.001) for the two experimental and analysis methods, the standard deviations of the measured mean propulsion velocities were considerably smaller in case of the vertical column method with video tracking (12% and 15% for n = 15 freshly prepared stones) than in case of the pendulum method (26% and 41% for n = 50 freshly prepared stones), in spite of the considerably smaller number of experiment repetitions ("sample size") in the first case.

CONCLUSION

The proposed vertical column method with video tracking appears advantageous compared to the pendulum method in terms of the statistical significance of the obtained results. This may partly be understood by the fact that the entire motion of the stones contributes to the data analysis, rather than just their maximum distance from the initial position. The key difference is, however, that the pendulum method involves only one single laser pulse in each experiment run, which renders this method rather tedious to perform. Furthermore, the video tracking method appears much better suited to model a clinical lithotripsy intervention that utilizes longer series of laser pulses at higher repetition rates. The proposed video tracking method can conveniently and quickly deliver results for a large number of laser pulses that can easily be averaged. An optimization of laser settings to achieve minimal propulsive stone movement should thus be more easily feasible with the video tracking method in connection with the vertical column setup. Lasers Surg. Med. 50:333-339, 2018. © 2017 Wiley Periodicals, Inc.

Combined usage of Ho:YAG laser with monopolar resectoscope in the treatment of bladder stone and bladder outlet obstruction

OBJECTIVE

Bladder stones in elderly men are commonly associated with bladder outlet obstruction, and many different treatment modalities have been presented for both these conditions. To evaluate the effectiveness and safety of a novel method concerning spontaneous usage of both monopoplar transurethral resection of the prostate and Holmium Laser cystolithotripsy, we compared the transurethral use of resectoscope and cystoscope lithotripsy approaches retrospectively.

METHODS

Patients data of one hundred and nine male patients with benign prostatic hyperplasia (BPH) and bladder stone(s) were analyzed retrospectively. Two groups of patients were compared: Group I was treated with combination of transurethral holmium laser cystolithotripsy (HLC) and transurethral resection of the prostate (TURP) using the 24F resectoscope, and group II used 22F cystoscope and 24F resectoscope for treating both these conditions.

RESULT

We reviewed the records of 109 patients undergoing transurethral cystolithotripsy with holmium laser and simultaneous TURP. The mean bladder stone size were 3.6±1.5 cm in Group-I and 3.7±1.1 cm (mean 3.8) in Group-II (p>0.05). The mean operation time of Group-I and Group-II was 49.0±22.5 minutes and 79.0±28.5 minutes, respectively (p<0.05). Stone fragments were removed completely and TURP procedures were done successfully in all of the patients. Mild hematuria was found more frequently in Group-II (22.2%), and four (7.4%) patients had urethral stricture in the same group during the late follow-up.

CONCLUSION

Combination of transurethral laser cystolithotripsy and TURP using the same 24F resectooscope is an effective, safe and economical treatment for bladder stones in BPH patients. It is minimally invasive and involves and has lower complication rates and shorter hospital stay. However, this combined approach should be taken in the treatment of calculus within 4 or 5 centimeters.

Positions for percutaneous nephrolithotomy: Thirty-five years of evolution

Objectives

To present the chronological development of the different positions described for percutaneous nephrolithotomy (PCNL), in an attempt to identify the reasons for their development and to highlight their specific advantages and disadvantages.

Methods

Previous reports were identified by a non-systematic search of Medline and Scopus.

Results

The classic prone position for PCNL was first described in 1976. The technique was gradually standardised and PCNL with the patient prone became the generally accepted standard approach. In the next 35 years many other positions were described, with the patient placed prone, lateral or supine in various modifications. Modifications of the classic prone position in the early 1990s aimed to provide the option of a simultaneous retrograde approach during the procedure. As PCNL became more popular the lateral position was first described in 1994, to allow the application of PCNL to patients who were unable to tolerate being prone because of their body habitus. The supine position for percutaneous access was originally described even before 1990, but become more popular after 2007 when the Galdakao modification was reported. Several other modifications of the supine position have been described, with the latest being the flank-free modified supine position, which allows the best exposure of the flank among the supine positions. Each position has its specific advantages and disadvantages.

Conclusion

Urologists who perform PCNL should be familiar with the differences in the positions and be able to use the method appropriate to each case.