In vitro comparison of standard ultrasound and pneumatic lithotrites with a new combination intracorporeal lithotripsy device

Mini percutaneous nephrolithotripsy for pediatric kidney stone using 1.5mm probe size shock pulse lithotriptor: A case report

The recent development of mini-PCNL technique, allows tract formation with minimal damage to the renal parenchyma in pediatric patients. This report describes our preliminary findings with mini-PCNL using a 1.5-mm probe-size shock pulse lithotriptor. A 11-year-old child presented with multiple small inferior calyceal calculi. The patients were placed in Bartz flank-free modified supine position and underwent mini PCNL. The stone was fragmented using a 1.5-mm probe shock pulse lithotripter and fragments were suctioned out through the hollow probe. Our experience suggests that using a shock pulse lithotripter on a mini-PCNL to treat renal stones in children is both safe and effective.

Pediatric Stone Surgery: What Is Hot and What Is Not

PURPOSE OF REVIEW

We aim to highlight recent advances in technology and techniques for surgical management of urinary tract calculi in pediatric patients.

RECENT FINDINGS

Percutaneous nephrolithotomy (PCNL) is classically performed in the prone position. The supine PCNL was first attempted to overcome the shortcomings of difficult airway access, patient and surgeon discomfort. The supine PCNL, and subsequent modifications, has been successfully described in the pediatric population. Classically, PCNL has also been classically concluded with obligate placement of a nephrostomy tube and bladder catheter. Recently, tubeless and totally tubeless PCNL reduces pain and duration of hospitalization with satisfactory surgical outcomes in children. Finally, we describe the use of thulium laser technology, which offers improved efficacy in stone treatment and may supplant the current dominant technologies in coming years. Recent advances in pediatric stone surgery include supine PCNL, miniaturized PCNL instrumentation, tubeless procedures, and thulium laser technology.

New devices for kidney stone management

PURPOSE OF REVIEW

The purpose of this review is to summarize recent developments in the array of devices which are commonly used by urologists in the surgical management of kidney stones. To accomplish this goal, an extensive review of recent endourology literature, conference abstracts, and publicly available documents from manufacturers and the United States Food and Drug Administration was collected and reviewed.

RECENT FINDINGS

Recent developments in the holmium:yttrium-aluminum-garnet (Ho:YAG) laser lithotripsy include the introduction of pulse modulation. This technique delivers the laser energy in an asymmetric manner such that an initial bubble is created (the 'Moses effect') through which the remainder of the energy can then travel through without being absorbed by surrounding water. Even more novel is the thulium fiber laser, which is produced in a fundamentally different way than traditional Ho:YAG lasers and is not yet available for clinical use. Finally, novel mechanical lithotrites which effectively combine ultrasonic energy, ballistic energy, and suction capability appear to be highly effective for stone clearance in recent benchtop and clinical studies.

SUMMARY

With the introduction of both new modifications of time-tested technologies as well as completely novel modalities, the practicing urologist's armamentarium of devices for the surgical management of kidney stones continues to grow. As the popularity of 'mini' procedures continues to grow, the adaptability of these technologies to these procedures will be critical to maintain maximum relevance.

Comparison between shockpulse and pneumatic lithotripsy in percutaneous nephrolithotomy

PURPOSE

To compare the effectiveness and safety of shockpulse with pneumatic lithotripsy in percutaneous nephrolithotomy.

METHODS

A prospective randomized comparative study was performed in Department of Urology, Bir Hospital for 1-year duration with 61 patients in shockpulse (Group 1) and 58 patients in pneumatic lithoclast (Group 2) groups, respectively. Patient's demographics, stone characteristics, hemoglobin drop, hospital stay, operative duration, stone fragmentation time and postoperative complications were compared.

RESULTS

The two groups did not differ significantly in terms of patient's demographic and stone characteristics. The mean hemoglobin drop was 1.96 ± 1.48 g/dl in Group 1 and 2.32 ± 1.38 g/dl in Group 2 (p = 0.16) and hospital stay was 3.14 ± 1.42 days in Group 1 and 3.29 ± 1.82 days in Group 2 (p = 0.62). The number of cases that required multiple tracts were six (9.8%) in Group 1 and 12 (20.68%) in Group 2 (p = 0.12). The stone-free rates were 78.69% in Group 1 and 74.13% in Group 2 (p = 0.66). Mean total operation time was 43.23 ± 18.49 min in Group 1 as compared to 51.53 ± 19.48 min in Group 2 (p = 0.0188). Mean stone fragmentation time was 17.95 ± 15.25 min in Group 1 and 24.37 ± 11.12 min in Group 2 (p = 0.0096). Overall complications were not significant between the two Groups (p = 0.58). On sub-analysis of the patients with single tracts in both groups the results were comparable to patients with single and multiple tracts combined.

CONCLUSIONS

Despite similar stone-free rates and complications between the two Groups, shockpulse has significantly lower stone fragmentation time and total operation time as compared to pneumatic lithotripsy.

Comparison of stone elimination capacity and drilling speed of endoscopic clearance lithotripsy devices

PURPOSE

To investigate the fragmentation capacity, clearance time, and drilling speed of combined ultrasonic with impact dual-energy and single energy ultrasonic lithotripter devices.

METHODS

Stone fragmentation and clearance tests were performed under direct view in an underwater layered hemisphere by four different operators using artificial stones (n = 10/operator). Time for complete clearance was measured. Drilling tests were performed using an underwater setup, consisting of a mounting rack for fixing the lithotripter handpiece with the probe in vertical position and in contact with the stone phantom placed on one side of a balance for defined and constant contact application pressure equivalent to 450 g load. Time until complete perforation or in case of no perforation, the penetration depth after 60 s into the stone sample was recorded. Four devices, one single energy device (SED), one dual-energy dual probe (DEDP), two dual-energy single probe (DESP-1, DESP-2), with different parameters were tested.

RESULTS

Stone fragmentation and clearance speed were significantly faster for dual-energy device DESP-1 compared to all other devices (p < 0.001). Using DESP-1, the clearance time needed was 26.0 ± 5.0 s followed by DESP-2, SED and DEDP requiring 38.4 ± 5.8 s, 40.1 ± 6.3 s and 46.3 ± 11.6 s, respectively. Regarding the drilling speed, DESP-1 was faster compared to all other devices used (p < 0.05). While the drilling speed of DESP-1 was 0.69 ± 0.19 mm/s, compared to 0.49 ± 0.18 mm/s of DESP-2, 0.47 ± 0.09 mm/s of DEDP, and 0.19 ± 0.03 mm/s of SED.

CONCLUSIONS

The dual-energy/single-probe device combining ultrasonic vibrations with electromechanical impact was significantly faster in fragmentation and clearing stone phantoms as well as in drilling speed compared to all other devices.

Comparative evaluation of tissue damage induced by ultrasound and impact dual-mode endoscopic lithotripsy versus conventional single-mode ultrasound lithotripsy

OBJECTIVE

The aim of our study was to perform comparative investigation of the tissue safety of three different endoscopic lithotripter devices including a new single-probe/dual-energy lithotripter in an in vivo animal model. The Swiss LithoClast Trilogy was compared to the Storz Calcuson and the Swiss LithoClast Vario. The safety test simulated the accidental direct contact between lithotripter probes and the urothelium, which can occur when sliding off a stone or drilling through a calculus during lithotripsy. The safety test included a smallest (1.5 mm) and largest (3.3/3.4 mm) probe diameter per device.

METHODS

Testing was performed in nine pigs (three animals per device). The bladder tissue was exposed to direct lithotripter probe contact at maximum power for 10 s to produce visible tissue lesions. Acute tissue trauma was evaluated using a simplified scoring model describing the expected bladder wall injuries for histological examination. After 7 days, all animals were killed, necropsied and examined post mortem. For between-group comparisons regarding microscopic histopathologic features, a Chi-square test was used. A p value < 0.05 was considered to be statistically significant.

RESULTS

Irrespective of the lithotripter used, no systemic signs of toxicity were observed. Histologically, signs of normal ongoing healing were observed on the bladder mucosa. There were no significant differences in histological findings taking changes of the epithelium (p = 0.360), the leucocyte infiltration (p = 0.123), the vascular congestion (p = 0.929) and the edema (p = 1.0) between the groups into account.

CONCLUSIONS

The results of this study demonstrated a comparable safety between all lithotripsy devices.

In Vitro Comparison of a Novel Single Probe Dual-Energy Lithotripter to Current Devices

PURPOSE

The LithoClast Trilogy is a novel single probe, dual-energy lithotripter with ultrasonic (US) vibration and electromagnetic impact forces. ShockPulse and LithoClast Select are existing lithotripters that also use a combination of US and mechanical impact energies. We compared the efficacy and tip motion of these devices in an in vitro setting.

MATERIALS AND METHODS

Begostones, in the ratio 15:3, were used in all trials. Test groups were Trilogy, ShockPulse, Select ultrasound (US) only, and Select ultrasound with pneumatic (USP). For clearance testing, a single investigator facile with each lithotripter fragmented 10 stones per device. For drill testing, a hands-free apparatus with a submerged balance was used to apply 1 or 2 lbs of pressure on a stone in contact with the device tip. High-speed photography was used to assess Trilogy and ShockPulse's probe tip motion.

RESULTS

Select-USP was slowest and Trilogy fastest on clearance testing (p < 0.01). On 1 lbs drill testing, Select-US was slowest (p = 0.001). At 2 lbs, ShockPulse was faster than Select US (p = 0.027), but did not significantly outpace Trilogy nor Select-USP. At either weight, there was no significant difference between Trilogy and ShockPulse. During its US function, Trilogy's maximum downward tip displacement was 0.041 mm relative to 0.0025 mm with ShockPulse. Trilogy had 0.25 mm of maximum downward displacement during its impactor function while ShockPulse had 0.01 mm.

CONCLUSIONS

Single probe dual-energy devices, such as Trilogy and ShockPulse, represent the next generation of lithotripters. Trilogy more efficiently cleared stone than currently available devices, which could be explained by its larger probe diameter and greater downward tip displacement during both US and impactor functions.

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.

Benchtop and Initial Clinical Evaluation of the ShockPulse Stone Eliminator in Percutaneous Nephrolithotomy

PURPOSE

Standardized bench testing of the new ShockPulse™ intracorporeal lithotripter was performed against three commercially available lithotripsy systems to determine differences and nuances in performance.

MATERIALS AND METHODS

The ShockPulse intracorporeal lithotripter was tested against the LUS-2™, CyberWand,™ and EMS LithoClast™ in a standardized bench setting using hard (Ultracal-30) and soft (plaster of Paris) stone phantoms. An in vitro kidney model was used to record the time needed to fragment stone samples into retrievable-sized pieces. The time needed to fully comminute and evacuate stone samples was also recorded. The efficacy of each device at various applied pressures was determined using a hands-free apparatus, which was used to apply 1.0, 1.5, and 2.0 pounds of fixed force.

RESULTS

For hard and soft stones, the time needed to create retrievable fragments was similar among all systems (p = 0.585). The ShockPulse was significantly faster than the LUS-2 and LithoClast at fully fragmenting and evacuating stone samples (p = 0.046), while the CyberWand was significantly slower than all three systems at this task (p = 0.001). When fixed forces were applied to a large stone phantom, the ShockPulse and CyberWand were significantly faster than the LUS-2 and LithoClast (p < 0.0001). When groups of smaller stones were tested, the ShockPulse was significantly faster at 1.0 pound (p < 0.001) and 1.5 pounds (p < 0.002) of force. At 2.0 pounds, no differences were observed (p = 0.09).

CONCLUSIONS

The ShockPulse is equally as effective and, in some circumstances, more effective than the three commercially available devices against which it was tested in an in vitro setting.

Advances in percutaneous stone surgery

Treatment of large renal stones has changed considerably in recent years. The increasing prevalence of nephrolithiasis has mandated that urologists perform more surgeries for large renal calculi than before, and this has been met with improvements in percutaneous stone surgery. In this review paper, we examine recent developments in percutaneous stone surgery, including advances in diagnosis and preoperative planning, renal access, patient position, tract dilation, nephroscopes, lithotripsy, exit strategies, and post-operative antibiotic prophylaxis.

Tissue damage from ultrasonic, pneumatic, and combination lithotripsy

PURPOSE

To conduct a comparative evaluation of ultrasonic, pneumatic, and dual ultrasonic (DUS) lithotripsy to predict the safety of probes on urinary tract tissue.

MATERIALS AND METHODS

The Swiss Lithoclast Ultra (ultrasonic-only [US] and ultrasonic-pneumatic combination [US+P]) and the Gyrus ACMI Cyberwand (DUS) were evaluated. Fresh porcine ureter, bladder, and renal pelvis tissues were used with a hands-free setup to vertically apply 0, 400, or 700 g of force with each probe for a duration of 3 seconds, 5 seconds, or 3 minutes (or until perforation occurred). Data collection included whether perforation occurred and time to perforation. Histological analysis of nonperforated samples was used to compare the anatomical depth to which damage occurred.

RESULTS

The total percentage of trials resulting in perforation for all tissue types, contact durations, and forces was found to be 8.5% (10/117) for US, 13.7% (16/117) for US+P, and 26.4% (31/117) for DUS. No perforations occurred with light contact (0 g) of probe force, regardless of tissue type, lithotripsy mode, or contact duration. Overall, the renal pelvis was most resistant to perforation (p=0.0004), while no difference was found between the bladder and ureter tissue (p=0.32). Force beyond 400 g and contact greater than 5 seconds increased risk for damage.

CONCLUSIONS

Mode of lithotripsy, tissue type, probe force, and probe-tissue contact duration all significantly impacted the extent of damage and likelihood for perforation to occur. All devices and tissue types provided a reasonable margin of safety for probe-tissue contact times of 3 and 5 seconds with no more than 400 g of force.

The surgical management of kidney stone disease: a population based time series analysis

PURPOSE

We evaluate population based trends in the use of extracorporeal shock wave lithotripsy, ureteroscopy and percutaneous nephrolithotomy during the last 20 years, as well as assess the re-treatment rate and morbidity from treatment over time.

MATERIALS AND METHODS

Using administrative databases in the province of Ontario, Canada, a population based cross-sectional time series analysis was performed between July 1, 1991 and December 31, 2010. All extracorporeal shock wave lithotripsy, ureteroscopy and percutaneous nephrolithotomy procedures were identified, along with all hospital readmissions and emergency department visits within 7 days of treatment. The primary outcome was treatment use, and secondary outcomes were the need for ancillary treatment and hospital readmission or emergency department visit after treatment. Exponential smoothing and autoregressive integrated moving average (ARIMA) models were used to assess trends over time.

RESULTS

We identified 194,781 kidney stone treatments performed during the study period. Time series modeling revealed a significant increase in the use of ureteroscopy over time (25% to 59% of all procedures, p <0.0001) and a reciprocal decrease in the use of extracorporeal shock wave lithotripsy (69% to 34% of all procedures, p <0.0001). A corresponding significant decrease in the need for ancillary treatment over time (23% to 15%, p <0.0001) and increase in the need for hospital readmission (7% to 11%, p <0.0001) or emergency department visit (7% to 11%, p=0.0024) after treatment were also demonstrated.

CONCLUSIONS

Our population based study demonstrates a shift in the treatment paradigm with increased use of ureteroscopy over time and a reciprocal decrease in the use of extracorporeal shock wave lithotripsy. We also observed a corresponding decrease in ancillary treatment and increase in posttreatment morbidity over time.

Lithotrites and postoperative fever: does lithotrite type matter? Results from the Clinical Research Office of the Endourological Society Percutaneous Nephrolithotomy Global Study

OBJECTIVE

To compare the risks of fever from different lithotrites after percutaneous nephrolithotomy (PNL).

MATERIALS AND METHODS

The Clinical Research Office of the Endourological Society (CROES) PNL database is a prospective, multi-institutional, international PNL registry. Of 5,803 total patients, 4,968 received preoperative antibiotics, were supplied with complete information and included in this analysis. The lithotrites assessed included no fragmentation, ultrasonic, laser, pneumatic and combination ultrasonic/pneumatic. Risk of fever was estimated using multivariate logistic regression with adjustment for diabetes, steroid use, a history of positive urine culture, the presence of staghorn calculi or preoperative nephrostomy, stone burden and lithotrite.

RESULTS

The overall fever rate was 10%. Pneumatic lithotrites were used in 43% of the cohort, followed by ultrasonic (24%), combination ultrasonic/pneumatic (17.3%), no fragmentation (8.4%) and laser (7.3%). Fever rates were no different between patients who underwent no or any fragmentation (p = 0.117), nor among patients when stratified by lithotrite (p = 0.429). On multivariate analysis, fragmentation was not significantly associated with fever [Odds Ratio (OR) 1.17, p = 0.413], while diabetes (OR 1.32, p = 0.048), positive urine culture (OR 2.08, p < 0.001), staghorn calculi (OR 1.80, p < 0.001) and nephrostomy (OR 1.65, p < 0.001) increased fever risk. Fever risk among lithotrites did not differ (p ≥ 0.128).

CONCLUSIONS

Risk of post-PNL fever was not significantly different among the various lithotrites used in the CROES PNL study.

Histologic impact of dual-modality intracorporeal lithotripters to the renal pelvis

OBJECTIVE

To test the hypothesis that dual-modality intracorporeal lithotripters used during percutaneous nephrolithotomy create a degree of tissue trauma in the dual-modality mode (ballistic and ultrasonic) similar to that in the single-modality mode (ultrasonic).

MATERIALS AND METHODS

The lithotripter devices tested were the Cyberwand and Swiss LithoClast Select. The activated probes, in both single- and dual-modality modes, were applied directly to the renal pelvis of 11 fresh nephrectomy specimens. The treated tissue sites were then processed for light microscopy and reviewed by a single genitourinary pathologist.

RESULTS

Microscopic examination of the renal pelvis after 2 seconds of direct contact showed minimal denudation of the urothelium, with no changes noted in the subepithelial or muscle layers for the 2 devices evaluated. Direct contact for 4 seconds showed urothelial denudation and subepithelial changes (n = 13 of 23). Muscle injury was observed in some dual-modality specimens (n = 6 of 12). Increasing the contact time to 8 seconds resulted in fragmentation of the muscle layers more frequently with both settings (n = 15 of 22), except for when the Cyberwand was used at the small stone setting (n = 0 of 7).

CONCLUSION

In the ex vivo setting, minimal differences were noted in the degree of histologic trauma between the Cyberwand and Swiss LithoClast Select at 2 seconds. However, both dual-modality devices resulted in muscle damage at 4 and 8 seconds of contact time. Care should be taken during clinical procedures to avoid prolonged contact with the renal pelvis to minimize the potential for tissue trauma.

Comparison of percutaneous nephrolithotomy using pneumatic lithotripsy (lithoclast®) alone or in combination with ultrasonic lithotripsy

PURPOSE

Percutaneous nephrolithotomy (PCNL) is the procedure of choice for treating large renal stones. Pneumatic lithotripsy (Lithoclast®) is effective regardless of the stones' composition, and ultrasonic lithotripsy allows the aspiration of small debris during lithotripsy. We investigated the efficacy and safety of PCNL via Lithoclast® alone or combined with ultrasonic lithotripsy.

MATERIALS AND METHODS

Thirty-five (group A) and 39 (group B) patients underwent Lithoclast® PCNL and combination therapy, respectively, from May 2001 to March 2010, and the two groups were compared in terms of stone size, location, and composition; operative time; average number of treatments; hospital days; hemoglobin loss; ancillary procedures; rate of device failure; and initial and total stone-free rates.

RESULTS

The two groups did not differ significantly in preoperative stone size, location, or composition; the average number of treatments; or the initial and overall stone-free rates. However, combination therapy was associated with a significantly lower operative time (181±50 vs. 221±65 min, respectively, p=0.004), number of hospital days (11.6±3.8 vs. 14.2±4.4 days, respectively, p=0.009), and average hemoglobin loss (1.12±0.61 vs. 1.39±1.02 g/dl, respectively, p=0.013). Transfusions were required in 6 patients (4 and 2 in each group, respectively), but there were no significant complications related to percutaneous access. There were 2 (5.7%) mechanical failures (Lithoclast® probe fracture) in the group A and 5 (12.8%) in the group B (2 cases of suction tube obstruction, 3 cases of overheating).

CONCLUSIONS

The combination of ultrasonic lithotripter and Lithoclast® is more effective than Lithoclast® alone because it significantly decreases operative time, hemoglobin loss, and the hospital stay. This may reflect the superior power of Lithoclast® and the ability to aspirate the debris during ultrasonic lithotripsy.

Randomized controlled, multicentre clinical trial comparing a dual-probe ultrasonic lithotrite with a single-probe lithotrite for percutaneous nephrolithotomy

OBJECTIVES

• To compare the Cyberwand (Gyrus/ACMI, Southborough, MA, USA), a dual-probe ultrasonic lithotrite, with a single-probe ultrasonic lithotrite. • The Cyberwand incorporates coaxial high- and low-frequency ultrasonic probes that work synergistically.

PATIENTS AND METHODS

• An institutional review board-approved, multicentre, randomized controlled trial to compare the Cyberwand to the Olympus LUS-II (Olympus America, Inc., Melville, NY, USA) single-probe lithotrite was performed. • Patients undergoing a percutaneous nephrolithotomy (PCNL) with a target stone > 2 cm in diameter were eligible for the study. • The primary outcome was the time to removal of the targeted stone.

RESULTS

• A total of 57 PCNLs were performed after randomization: 25 Cyberwand and 32 LUS-II. • There was no difference (P > 0.05) observed between the two devices for target stone surface area (Cyberwand 526.6 cm³ vs LUS-II 540.1 cm³), time to clearance of target stone (Cyberwand 15.8 min vs LUS-II 14.2 min) and target stone clearance rate (Cyberwand 61.9 mm²/min vs LUS-II 75.8 mm²/min). • Of the patients with stone analysis, hard stones (calcium oxalate monohydrate, brushite and cystine) were noted in 14 (56.0%) of the 25 Cyberwand and 18 (62.1%) of the 29 LUS-II patients. • Fifteen of the 25 (60.0%) Cyberwand and 20 of the 32 (62.5%) LUS-II patients were stone-free after the initial PCNL. • Those patients not rendered stone-free went on to receive a secondary PCNL. • Device malfunction occurred in eight of 25(32.0%) Cyberwand and five of 32 (15.6%) LUS II patients. • Complications were similar in both treatment groups.

CONCLUSION

• No appreciable difference between the dual-probe Cyberwand and the standard ultrasonic Olympus LUS-II lithotrites can be identified.

Prospective randomized comparison of a combined ultrasonic and pneumatic lithotrite with a standard ultrasonic lithotrite for percutaneous nephrolithotomy

PURPOSE

To compare the efficiency and cost effectiveness of a combined pneumatic and ultrasonic lithotrite (Lithoclast Ultra) and a standard ultrasonic lithotrite, (LUS-1) during percutaneous nephrolithotomy.

MATERIALS AND METHODS

In a prospective randomized trial, 30 patients undergoing percutaneous nephrolithotomy (PCNL) were randomized to PCNL with either the combined pneumatic and ultrasonic lithotrite (PUL) or a standard ultrasonic lithotrite (SUL). Patient demographics, stone composition, location, pre- and post-operative stone burden, fragmentation rates, and device failures were compared.

RESULTS

There were 13 patients in the PUL group and 17 patients in the SUL group. Stone burden and location were equal. Overall, 64% of the PUL group had hard stones (defined as stones that were either pure or a mixture of cystine [3], calcium oxalate monohydrate [CaOxMono; 2], and calcium phosphate [CaPO4; 2]), and four had soft stones (3 struvite and 1 uric acid [UA]). In the SUL group, there were eight hard stones (5 CaOxMono and 3 CaPO4), and six soft stones (4 calcium oxalate dihydrate [CaOxDi] and 2 UA) (P = 0.51). Stone composition data were unavailable for five patients. Fragmentation time for the PAL was 37 minutes versus 31.5 minutes for the SUL (P = 0.22). Stone retrieval and mean operative times were similar for both groups. There were a total of three (23.1%) device-related problems in the PUL group, and eight (47%) in the SUL group. There was one (7.7%) device malfunction in the PUL group due to probe fracture. There were two (11.7%) device failures in the SUL group; one failure required the device to be reset every 30 minutes, and the second was an electrical failure. Suction tubing obstruction occurred twice (15.3%) in the PUL group and 35.3% in the SU group (P = 0.35). The stone-free rates for the PUL and SUL were 46% and 66.7%, respectively (P = 0.26).

CONCLUSION

Although the PUL was more costly, stone ablation and clearance rates were similar for both the combined pneumatic and ultrasonic device and the standard ultrasonic device. When stratified with respect to stone composition, the PUL was more efficient for harder stones, and the SUL was more efficient for softer stones.

Advances in Percutaneous Nephrostolithotomy

Percutaneous nephrolithotomy was first performed in 1976. In the past 30 years, many refinements to the procedure have been made and it has become the gold standard for the management of large and complex renal calculi. This article reviews advances made in the field and highlights the nuances of the technique. The large published series are reviewed and their results discussed.

In vitro assessment of a novel dual probe ultrasonic intracorporeal lithotriptor

PURPOSE

The Cyberwand (Cybersonics, Erie, Pennsylvania) is a novel intracorporeal lithotrite that uses coaxial ultrasonic elements operating at 2 frequencies. We compared this device to the LithoClast(R) Ultra, which we previously noted is the most efficient commercially available intracorporeal lithotripsy device.

MATERIALS AND METHODS

An in vitro test system was used to assess the efficiency of stone penetration for the Cyberwand and the LithoClast Ultra. The devices were mounted upright with the probe tip up in a modified irrigation sheath. A gypsum artificial stone was centered on the probe tip and a mass was placed atop the stone to provide a constant force. The manufacturer recommended setting was selected for the Cyberwand, while for the LithoClast Ultra a pneumatic frequency of 12 Hz with an ultrasonic power setting of 100% was selected, representing optimal settings in previous in vitro tests. The time required for complete stone penetration was measured. Differences in mean stone penetration times were compared using ANOVA.

RESULTS

Mean +/- SD penetration time for the Cyberwand was significantly shorter than for the LithoClast Ultra (4.8 +/- 0.6 vs 8.1 +/- 0.6 seconds, p <0.0001). Neither device showed any difficulties with overheating, occlusion or another malfunction.

CONCLUSIONS

Initial assessment using our hands-free in vitro test system, in which stone penetration time is not affected by operator bias, suggests that the Cyberwand is an efficient lithotrite. These promising results justify in vivo testing.

Use of Amplatz sheath in male urethra during cystolitholapaxy of large bladder calculi

Large-burden bladder stones often require percutaneous cystolithotomy or an open procedure. These approaches may not be feasible in certain patients who are at increased risk of operative complications. We present a novel technique for transurethral cystolitholapaxy using Amplatz sheath in the male urethra.

In Vitro Assessment of Lithoclast Ultra Intracorporeal Lithotripter

PURPOSE

The Lithoclast Ultra (Boston Scientific Corporation, Natick, MA) enables the simultaneous application of ultrasonic and pneumatic modalities for the fragmentation and removal of stones during percutaneous nephrolithotomy (PCNL). We evaluated the effectiveness of this unit using a hands-free in vitro testing system.

MATERIALS AND METHODS

An in vitro test system was used to assess the efficiency of stone penetration when the Lithoclast Ultra was operated at different settings of ultrasonic power and pneumatic frequency. The pneumatic and ultrasonic handpieces were assembled, the probes were inserted into an irrigation sheath (Cook Urological, Spencer, IN), and the complete unit was mounted upright (probe tip up). A gypsum artificial stone (mean length 12.8 +/- 0.6 mm; mean diameter 7.6 +/- 0.1 mm) was centered on the probe tip. A weight (63.4 g) was placed atop the stone to provide a constant force. Pneumatic frequency settings of 12, 8, 4, and 1 Hz were tested in conjunction with ultrasonic power settings of 100%, 70%, and 40%. The times required for complete stone penetration were assessed for each combination of settings. Differences in mean stone penetration times were compared using ANOVA.

RESULTS

The combination of 12 Hz and 100% produced the fastest mean stone penetration time (8.9 +/- 1.1 seconds). Stone penetration times decreased significantly with increases in pneumatic frequency (P< 0.001) as well as with increases in ultrasonic power (P= 0.001). When analyzing the effect of each modality on the total improvement in penetration time, increasing the pneumatic frequency accounted for approximately 80% of the performance improvement. The stone penetration times were better than those of the most efficient ultrasonic device previously evaluated using this test system.

CONCLUSIONS

The Lithoclast Ultra exhibited excellent stone penetration efficiency when evaluated with a hands-free in vitro test system. Increases in either pneumatic frequency or ultrasonic power significantly improve penetration times, with the pneumatic modality contributing the majority of the effect.

Intracorporeal lithotripsy: which modality is best?

PURPOSE OF REVIEW

A large number of related articles published within the last year were reviewed. Different types of intracorporeal lithotripter devices were compared according to their advantages, disadvantages, efficacy, safety and clinical applications. General directions of future developments are discussed.

RECENT FINDINGS

Ultrasound lithotripters employed through rigid endoscopes provide high fragmentation rates (97-100%) and stone free rate (94%). Clinical evaluation of a new combination ultrasound and pneumatic lithotripter reported an overall stone free rate of 80-89.7%. No major complications were observed. The holmium:YAG (Yttrium-Aluminum-Garnet) laser lithotripter is able to destroy all compositions of stone. The stone free rate for ureteral stones is close to 100%. Complications are rare and minimal. Newer wavelengths such as erbium:YAG are currently impractical. There are limited clinical data regarding frequency-doubled double-pulse neodymium:YAG laser lithotripsy.

SUMMARY

Ultrasound lithotripsy is still the preferable modality applied through rigid endoscopes. A new combination of ultrasound and pneumatic impactor includes the advantages of each mode. The holmium:YAG laser lithotripter is the method of choice for flexible endoscopic procedures. Further development of new lithotripters with different energy sources and their combination is necessary.

Percutaneous nephrolithotomy: an update

PURPOSE OF REVIEW

Percutaneous nephrolithotomy has undergone an evolution in technique and in equipment since its introduction in the late 1970s. This evolution continues today and is evidenced by the numerous publications about the technique. This review summarizes some of the important articles over the past year.

RECENT FINDINGS

Although ureteroscopy and shock wave lithotripsy predominate in the treatment of urolithiasis, percutaneous nephrolithotomy continues to play an important role. Percutaneous nephrolithotomy is advantageous as it causes minimal renal injury and maximizes stone clearance, especially in patients with complex stone disease. Although nephrostomy drainage tubes have always been placed after percutaneous nephrolithotomy, there may be specific indications for tubeless percutaneous nephrolithotomy.

SUMMARY

Percutaneous nephrolithotomy continues to be an important part of the urologist's armamentarium. Recent studies have redefined the role of percutaneous nephrolithotomy and future studies will further delineate the importance of this procedure in the treatment of urolithiasis.

Clinical efficacy of a combination pneumatic and ultrasonic lithotrite

PURPOSE

A new combination pneumatic/ultrasonic intracorporeal lithotriptor has been developed for percutaneous applications. It combines the stone clearing efficiency of an ultrasonic device with the fragmentation strength of a pneumatic probe into a single handpiece. We present our early clinical experience with this device in a prospective, randomized comparison a combination pneumatic/ultrasound lithotrite and standard ultrasonic lithotripsy.

MATERIALS AND METHODS

A total of 20 consecutive patients undergoing percutaneous nephrolithotomy for symptomatic calculi were randomized to receive stone fragmentation and removal using a standard ultrasonic device or a new combination pneumatic/ultrasonic unit. Stone location and burden were assessed before the operative procedure. The stone clearance rate in mm.2 per minute was calculated for the 2 devices. Complications and stone-free rates were compared in the 2 groups.

RESULTS

There were no significant differences in stone location and composition in the 2 groups of patients. Average time required for complete stone clearance was considerably less for the combination device (21.1 versus 43.7 minutes, p = 0.036). The opposite was true for the average rate of stone clearance in mm.2 per minute, in that the standard ultrasonic device could clear 16.8 versus 39.5 mm.2 per minute for the combination unit (p = 0.028). Stone-free and complications rates were slightly superior for the combination device but it was likely attributable to patient factors.

CONCLUSIONS

The combination pneumatic/ultrasonic lithotrite is capable of disintegrating and extracting stone material at a more rapid rate than standard ultrasonic devices. Moreover, stone-free and complication rates appear to be slightly superior with the combination unit. This new combination pneumatic/ultrasonic device appears to be efficacious and safe for removing large renal calculi.