In vitro comparison of two ballistic systems for endoscopic stone disintegration

Comparison of lithotripsy methods during mini-PNL: is there a role for ballistic lithotripsy in the era of high-power lasers

BACKGROUND

For renal stones > 20 mm, percutaneous nephrolithotomy (PNL) offers the best stone clearance rates with acceptable complication rates. This study aimed to compare the efficiency of high-power holmium YAG laser and ballistic lithotripsy during mini-PNL.

METHODS

Data from 880 patients who underwent mini-PNL for renal stones was investigated retrospectively. The study utilized propensity score matching to create two groups: laser lithotripsy (n = 440) and ballistic lithotripsy (n = 440). The groups were matched based on stone size, Guy's stone score, and stone density. The main objectives of the study were to assess the stone-free rate (SFR), duration of surgery, and complication rates.

RESULTS

The average age of the population was 51.4 ± 7.1 years, with a mean stone size of 28.6 ± 8.3 mm and a mean stone density of 1205 ± 159 HU. There were no significant differences between the groups. The SFRs of the laser lithotripsy and ballistic lithotripsy were 92.5% and 90.2%, respectively (p = 0.23). The laser lithotripsy group had a notably shorter surgery time (40.1 ± 6.3 min) compared to the ballistic lithotripsy group (55.6 ± 9.9 min) (p = 0.03). Complication rates were similar (p = 0.67).

CONCLUSIONS

Our study shows that a high-power holmium YAG laser provides quicker operation time compared to ballistic lithotripsy. However, ballistic lithotripsy is still an effective and safe option for stone fragmentation during mini-PNL. In places where a high-power holmium YAG laser is not available, ballistic lithotripters are still a safe, effective, and affordable option for mini-PNL.

Intracorporeal lithotripsy

Since the introduction of ESWL, PNL and URS during the early 1980s the application rate of ESWL has declined while those of PNL and URS have increased. This is mainly due to the facts that instruments and techniques for Intracorporeal Lithotripsy (IL) have made a continuous progress. This review shows that today an array of options for IL within the entire urinary tract is available to treat stones in a perfect minimal invasive way. At the same time further improvements of IL are already visible.

In vitro comparisons of retropulsion and fragmentation efficacy of 2 cordless, handheld pneumatic and electromechanical lithotripsy devices

OBJECTIVE

To compare, in vitro, probe velocity/displacement, retropulsion, and fragmentation capacity of the cordless electromechanical (LithoBreaker) (hard vs soft probe guide) and pneumatic (StoneBreaker).

MATERIALS AND METHODS

Probe velocities/displacements were measured using high-speed resolution camera (100.000 frames/s). The lithotripsy probes were projected through a 7.5F ureteroscope against a nonfrangible led ball placed in a 15F horizontally mounted silicone tube immersed in water bath as an in vitro ureter model. Retropulsion is considered as displacement distance of led ball. Fragmentation efficiency was quantified as number of shots required to break Bego-stone phantoms (hard [15:3] and soft [15:6], average size 7.5 × 5.5 mm) placed on metal mesh into <3-mm fragments. Mean and standard deviation of repetitive measurements were statistically analyzed.

RESULTS

StoneBreaker yielded higher probe velocity (22 ± 1.9 m/s) compared with LithoBreaker with hard (14.2 ± 0.5 m/s) and soft (11.5 ± 0.5 m/s) probe. Maximum probe displacement for StoneBreaker was 1.04 mm vs 0.9 mm and 1.1 mm (hard vs soft LithoBreaker-probe, respectively). Retropulsion using 1-mm probes showed no statistical differences. Using harder 2-mm probe decreased Lithobreaker retropulsion significantly compared with Stonebreaker. The amount of shots (1-mm probe) to fragment soft Bego stones was significantly higher for LithoBreaker with soft (mean 31.5 ± 11.31) and hard (mean 21.5 ± 5.29) probe guide vs StoneBreaker (mean 11.2 ± 2.65). Fragmentation efficiency for hard Bego stones showed similar statistically significant outcome. Comparison of the 2 probe guides showed higher velocity linked to harder-probe that improved LithoBreaker fragmentation performance and reduce propulsion.

CONCLUSION

Both examined lithotripters are effective in cracking stone phantoms with relatively low pulse number. They produce comparable retropulsions. Fragmentation improved substantially using LithoBreaker with hard probe guide. More tests are required to assess differences in stone clearance time.

Combining Lithoclast and ultrasound power in one device for percutaneous nephrolithotomy: in vitro results of a novel and highly effective technology

OBJECTIVES

A new device for percutaneous nephrolithotomy, combining Lithoclast (LC) and ultrasound (US) lithotripsy, was developed. Under standardized in vitro conditions, we evaluated the efficacy of the new technique using artificial stones. Combined application of pneumatic and US lithotripsy was compared with each of the two components alone.

METHODS

Five different artificial stones of defined hardness were used. Disintegration was performed under defined pressure in a water bath. The time until the first fragmentation and until complete disintegration to fragments of 2 mm or smaller was measured for LC and US alone and for combined lithotripsy. Furthermore, the disintegrated partition after 1 minute and time until 50% disintegration of each stone was determined.

RESULTS

With regard to first fragmentation and complete disintegration, LC and US combination showed superior efficacy. First fragmentation was achieved 25 to 200 times faster and complete disintegration in a range of 11 to 15 minutes. No complete disintegration was possible by LC and US alone within a time limit of 20 minutes. The disintegrated stone mass after 1 minute was 1.5 to 4 times larger in combined lithotripsy and the 50% disintegration time was 30% to 50% compared with LC or US alone. No technical defects occurred.

CONCLUSIONS

Combining LC and US in one device for percutaneous nephrolithotomy shows promising in vitro results in an artificial stone model. It seems to provide superior efficacy in the disintegration parameters important for clinical practice.

Experimental studies and first clinical experience with a new Lithoclast and ultrasound combination for lithotripsy

OBJECTIVES

A new lithotriptor for intracorporeal lithotripsy was developed combining the two most effective lithotriptors. A combination of the mechanically driven Lithoclast Master and a new ultrasonic device was constructed. Efficacy was tested in standardized model stones and in patient treatment.

MATERIAL

The new lithotriptor is composed of a Lithoclast Master and an ultrasonic device (EMS, Nyon, Switzerland). The 1.0 mm Lithoclast probe is advanced off-center through the hollow 3.3 mm ultrasonic probe and protrudes about 1 mm. Five different artificial stones of defined hardness and density were used as model stones for disintegration. Time until first fragmentation and complete fragmentation (particles smaller than 2.2 mm to fit through the ultrasonic probe), percent disintegration after 1 min and time until 50% disintegration were determined for the new device as well as lithoclast and ultrasound alone. A total of 68 patients were treated by percutaneous nephrolitholapaxy (PNL) with the new device from February 1999 to August 2001. Lithotripsy was performed after fluoroscopically guided puncture of the lower calix and dilatation of the nephrostomy tract with coaxial bougies. Thirty-five patients had complete and 33 patients partial staghorn calculi.

RESULTS

First fragmentation was reached 25-200 times faster with the combination as with either mode alone. Disintegrated stone mass after 1 min was 1.5-4 times larger in combined lithotripsy and 50% disintegration time 30-50% shorter. Clinically, complete stone free rate (KUB and ultrasound) was 66% after the first PNL. Sixteen out of 68 patients had a second look PNL with an overall stone free rate of 89.7% by dismission. Stone composition was calcium-oxalate-monohydrate in 13%, Ca-ox-monohydrate/uric acid in 35%, apatite in 20% and cystine in 11%.

CONCLUSION

In in vitro experiments and clinically the new lithotriptor provides easy handling and high effectivity in fragmentation of all stones regardless of their composition.

A randomized trial comparing lithoclast with an electrokinetic lithotripter in the management of ureteric stones

OBJECTIVE

To compare two in situ ballistic lithotripters, the lithoclast and the electrokinetic lithotripter (EKL), both of which can be used through the newer small-bore ureteroscopes, for their ease of use, robustness, fragmentation time, adequacy of fragmentation and stone-free rate.

PATIENTS AND METHODS

Forty-six consecutive patients with ureteric stones refractory to treatment by extracorporeal shock wave lithotripsy were randomized to undergo fragmentation using the lithoclast (23 patients) or the EKL (23 patients). One patient was excluded from analysis in the EKL group. The adequacy of fragmentation was recorded, with the degree and significance of proximal migration for each device. After treatment patients were assessed by plain X-ray and the stone-free rate was determined.

RESULTS

The mean (median) initial stone burdens in the lithoclast and EKL groups were 69 (50) mm2 and 72 (52) mm2, respectively. The respective mean (median) procedure duration and fragmentation time were 54 (50) min and 90 (49) s in the lithoclast group, and 50 (42.5) min and 87 (52.5) s in the EKL group; the differences were not statistically significant. In four (14%) patients of each group there was significant proximal migration of the stones. The stones were completely fragmented in 17 of 23 (74%) patients in the lithoclast group and 19 of 22 (86%) in the EKL group. There was no fragmentation in one patient in each group. In the lithoclast and EKL groups, 20 of 23 (87%) and 17 of 22 (77%) were rendered stone-free, respectively (P > 0.5). The equipment failed on two occasions in each group.

CONCLUSION

In this randomized trial there was no significant difference in the stone-free rate, procedure duration, fragmentation time, proximal stone migration rate and equipment failure between these in situ ballistic lithotripters.

Electrokinetic lithotripsy: safety, efficacy and limitations of a new form of ballistic lithotripsy

OBJECTIVE

To investigate the safety and efficacy of electrokinetic lithotripsy (EKL), a ballistic lithotripter which uses high-energy magnetic fields to propel an impactor to fragment calculi.

PATIENTS AND METHODS

The records and radiographs of 121 patients who underwent ureteroscopy using the EKL for stones in the upper (26), mid (28) or lower (67) ureter were reviewed retrospectively. Ureteroscopy was performed with an 8.5 F semi-rigid ureteroscope, through which a 3 F EKL probe was passed.

RESULTS

A total of 148 stones (mean stone size 11.5 mm, range 6-40) in 121 patients were treated using the EKL. One patient was lost to follow-up. Of 148 stones, 147 (99.3%) were fragmented, including five that had resisted fragmentation with either pulsed-dye laser or electrohydraulic lithotripsy. Despite this, only 45 of 56 patients (80%) with a single stone in the lower ureter were rendered stone-free after a single ureteroscopic procedure. Seven patients in this group (12%) required shock-wave lithotripsy for fragments that had been propelled into the kidney, while four patients (7%) required repeat ureteroscopy for retained ureteric fragments. Complications were limited to minor ureteric perforations in two patients, both of which were treated with a stent.

CONCLUSION

EKL is an inexpensive and reliable endoscopic method which fragments nearly all urinary calculi. Its limitations include the propulsion of fragments and the need to use an offset, semi-rigid ureteroscope. We recommend the use of a basket or graspers to remove fragments of >/=4 mm after EKL.

Laboratory and clinical assessment of pneumatically driven intracorporeal lithotripsy

A pneumatically driven intracorporeal lithotripter (the Swiss Lithoclast) has recently been approved for use in the United States. We compared its performance in vitro with ultrasonic, electrohydraulic and laser lithotripsy devices using a standard plaster-of-Paris stone phantom. The probe sizes and output settings were identical to those used during clinical treatment. The fragmentation efficiency index (measured as the lithotripsy time needed to reduce the stone phantom to particles <2 mm divided by the initial stone weight) ranged from 5.0 to 8.5 min/g of stone mass, with this value increasing from pneumatic to electrohydraulic to laser and to ultrasonic lithotripsy. We also performed an objective study in a swine model, which showed no adverse consequence of pneumatic lithotripsy. Finally, we evaluated our initial 41 patients who had undergone pneumatic stone fragmentation. We treated 8 patients having 11 renal calculi, 30 patients having 37 ureteral calculi, and 3 patients having 6 bladder calculi employing pneumatic probes ranging in size from 0.8 to 2.0 mm. Stone fragmentation was successful in a single session in 95% of the ureteral calculi and 100% of both renal and bladder calculi. Stone analysis in 23 patients revealed 17 (74%) calcium oxalate monohydrate and 1 (4%) cystine calculi. Our clinical and laboratory assessment of this newly developed pneumatic lithotripsy device further validates its efficacy in fragmenting stone of all compositions and its overall safety associated with clinical application.

Holmium:YAG lithotripsy yields smaller fragments than lithoclast, pulsed dye laser or electrohydraulic lithotripsy

PURPOSE

The mechanism of lithotripsy differs among electrohydraulic lithotripsy, mechanical lithotripsy, pulsed dye lasers and holmium:YAG lithotripsy. It is postulated that fragment size from each of these lithotrites might also differ. This study tests the hypothesis that holmium:YAG lithotripsy yields the smallest fragments among these lithotrites.

MATERIALS AND METHODS

We tested 3F electrohydraulic lithotripsy, 2 mm. mechanical lithotripsy, 320 microns pulsed dye lasers and 365 microns. holmium:YAG fiber on stones composed of calcium hydrogen phosphate dihydrate, calcium oxalate monohydrate, cystine, magnesium ammonium phosphate and uric acid. Fragments were dessicated and sorted by size. Fragment size distribution was compared among lithotrites for each composition.

RESULTS

Holmium:YAG fragments were significantly smaller on average than fragments from the other lithotrites for all compositions. There were no holmium:YAG fragments greater than 4 mm., whereas there were for the other lithotrites. Holmium:YAG had significantly greater weight of fragments less than 1 mm. compared to the other lithotrites.

CONCLUSIONS

Holmium:YAG yields smaller fragments compared to electrohydraulic lithotripsy, mechanical lithotripsy or pulsed dye lasers. These findings imply that fragments from holmium:YAG lithotripsy are more likely to pass without problem compared to the other lithotrites. Furthermore, the significant difference in fragment size adds evidence that holmium:YAG lithotripsy involves vaporization.