John Kourambas

DOSE A URETERAL ACCESS SHEATH FACILITATE URETEROSCOPY

PURPOSE Ureteral access sheaths were initially developed to facilitate difficult ureteroscopic access. However, to our knowledge no formal evaluations have been performed to assess the routine use of ureteral access sheaths. Therefore, we prospectively analyzed intraoperative time, symptomatic outcome, major complications, stone-free rate and overall costs related to the routine use of a new ureteral access sheath during standard ureteroscopic procedures. MATERIALS AND METHODS Patients undergoing 6.5Fr semirigid or 7.5Fr flexible ureteroscopy were prospectively randomized to unaided ureteroscopy with no access sheath or ureteroscopy via a 12-14Fr ureteral access sheath. Patients who required ureteral dilatation were randomized to the ureteral access sheath used as a dilator or a standard 18Fr ureteral balloon dilator. Patients were evaluated postoperatively on days 0, 1 and 6 with a questionnaire to assess pain, irritative symptoms and complications. The stone-free rate and long-term complications were determined by excretory urography or computerized tomography at 3 months. RESULTS Enrolled in the study were 59 consecutive patients, who underwent a total of 62 ureteroscopic procedures. Of the 47 patients (76%) who did not require ureteral dilatation 23 (49%) underwent ureteroscopy via the ureteral access sheath and 24 (51%) underwent unaided ureteroscopy. Seven of the 15 patients (28%) who required ureteral dilatation underwent access sheath dilatation, while balloon dilatation was performed in 8. There was no significant difference in postoperative symptoms, complication rate or stone-free status in the access sheath and nonaccess sheath groups in patients not requiring ureteral dilatation (p <0.05). A significant increase in postoperative symptoms was noted when the balloon was used as a dilator compared to the access sheath. Operative time and costs in all patients who underwent access sheath dilatation were less than in those in whom the access sheath was not used. In the 15 patients who required dilatation 71% of access sheath and 100% of balloon dilatations were successful. CONCLUSIONS Routine use of a ureteral access sheath appears to facilitate semirigid and flexible ureteroscopy by decreasing operative time and costs, allowing direct visualization of ureteroscope insertion with simple ureteral re-entry and assisting renal and ureteral access with minimal associated morbidity. A ureteral access sheath should be considered for routine ureteroscopic procedures.

Routine ureteral stenting is not necessary after ureteroscopy and ureteropyeloscopy: a randomized trial.

BACKGROUND AND PURPOSE Retrospective studies have suggested that routine stenting can be avoided following ureteroscopy. We prospectively analyzed the need for routine ureteral stent placement in patients undergoing ureteroscopic procedures. PATIENTS AND METHODS Fifty-five consecutive patients (60 renal units) were randomized into either a stent or a no-stent group following ureteroscopy with either a 7.5F semirigid or a 7.5F flexible ureteroscope for treatment of calculi (holmium laser or pneumatic lithotripsy) or transitional-cell carcinoma (holmium laser). Intraoperative variables assessed included total stone burden, the need for ureteral dilation, and overall operative times. All patients were evaluated by questionnaire on postoperative days 0, 1, and 6 with regard to pain, frequency, urgency, dysuria, and hematuria. RESULTS Of the 60 renal units treated, 38 received ureteral stents (mean 5.2 days), and 22 were treated without a stent. All 10 patients requiring ureteral balloon dilation had stents placed and were removed from the analysis. There was no significant difference between the groups with regard to age, sex, or stone burden. Operative time was decreased in the no-stent group (43 minutes v 55 minutes; P = 0.013). Flank discomfort was significantly less common in the no-stent group on days 0, 1, and 6 (P = 0.004, P = 0.003, P < 0.001, respectively), as was the incidence of suprapubic pain on day 6 (P = 0.002). There was no difference in urinary frequency, urgency, or dysuria between the groups on postoperative day 1, but all these symptoms were significantly reduced in the no-stent group on day 6 (P < 0.001, P < 0.001, P = 0.002, respectively). There was no significant difference in patient-reported postoperative hematuria in either group. One patient in each group developed a urinary tract infection. One patient in the no-stent group developed ureteral obstruction in the postoperative period that necessitated stenting, and one patient in the stent group experienced stent migration necessitating removal. CONCLUSIONS Routine ureteral stenting does not appear to be warranted in those patients who do not require ureteral dilation during ureteroscopic procedures. Ureteral stent placement following ureteroscopy may be avoided, thereby reducing operative time, surgical costs, and patient morbidity.

Nitinol stone retrieval-assisted ureteroscopic management of lower pole renal calculi.

OBJECTIVES Current ureteroscopic intracorporeal lithotripsy devices and stone retrieval technology allow for the treatment of calculi located throughout the intrarenal collecting system. Difficulty accessing lower pole calculi, especially when the holmium laser fiber is used, is often encountered. We retrospectively reviewed our experience with cases in which lower pole renal calculi were ureteroscopically managed by holmium laser fragmentation, either in situ or by first displacing the stone into a less dependent position with the aid of a nitinol stone retrieval device. METHODS Thirty-four patients (36 renal units) underwent ureteroscopic treatment of lower pole renal calculi between April 1998 and November 1999. Lower pole stones less than 20 mm were primarily treated by ureteroscopic means in patients who were obese, in patients who had a bleeding diathesis, in patients with stones resistant to shock wave lithotripsy, and in patients with complicated intrarenal anatomy, or as a salvage procedure after failed shock wave lithotripsy. Lower pole calculi were fragmented with a 200-micrometer holmium laser fiber by way of a 7.5F flexible ureteroscope. For those patients in whom the laser fiber reduced the ureteroscopic deflection, precluding re-entry into the lower pole calix, a 3.2F nitinol basket or a 2.6F nitinol grasper was used to displace the lower pole calculus into a more favorable position, allowing easier fragmentation. RESULTS In 26 renal units, routine in situ holmium laser fragmentation was successfully performed. In the remaining 10 renal units, a nitinol device was passed into the lower pole, through the ureteroscope, for stone displacement. Only a minimal loss of deflection was seen. Irrigation was significantly reduced by the 3.2F nitinol basket, but improved with the use of the 2.6F nitinol grasper. This factor did not impede stone retrieval in any of the patients. At 3 months, 85% of patients were stone free by intravenous urography or computed tomography. CONCLUSIONS Ureteroscopic management of lower pole calculi is a reasonable alternative to shock wave lithotripsy or percutaneous nephrolithotomy in patients with low-volume stone disease. If the stone cannot be fragmented in situ, nitinol basket or grasper retrieval, through a fully deflected ureteroscope, allows one to reposition the stone into a less dependent position, thus facilitating stone fragmentation.

Role of stone analysis in metabolic evaluation and medical treatment of nephrolithiasis.

BACKGROUND AND PURPOSE Comprehensive metabolic evaluation has become an important aspect of the management of recurrent nephrolithiasis, yet the role of stone analysis is often neglected or perhaps underestimated. The purpose of this study was to determine the role of stone analysis in medical decision making in patients with recurrent nephrolithiasis. MATERIALS AND METHODS We evaluated 100 consecutive stone-forming patients who had undergone compositional stone analysis as well as comprehensive metabolic evaluation at our institution. An analysis of stone composition in relation to metabolic disturbances was performed. Patients were stratified into two groups: calcium and non-calcium stone formers. RESULTS Patients having non-calcium stones were found to have a metabolic analysis reflecting specific metabolic disorders. Alternatively, patients with calcium stones were heterogeneous with regard to metabolic disorders, but there was a significant likelihood of renal tubular acidosis in those patients with calcium phosphate calculi. On the basis of these results, a simplified metabolic evaluation and nonselective medical therapy based on stone composition was formulated to facilitate assessment, management, and monitoring of stone disease. CONCLUSIONS Compositional stone analysis should be an integral part of the metabolic evaluation of patients with nephrolithiasis. Moreover, stone analysis alone may provide guidance for therapeutic treatment and obviate a formal metabolic evaluation.

Low-Power Holmium Laser for the Management of Urinary Tract Calculi, Strictures, and Tumors

BACKGROUND AND PURPOSE Introduction of the holmium laser has provided an indispensable tool for the management of urinary tract stones, strictures, and superficial urothelial tumors. While full-power holmium lasers are required for laser resection of the prostate, lower-power devices can be utilized for all cases of stone fragmentation and stricture incision and most cases of superficial urothelial tumors. Herein, we report our initial experience in utilizing a low-power holmium laser in our endourologic practice. PATIENTS AND METHODS Over a 6-month period, we have utilized both low-power (25 W) and full-power (80 W) holmium lasers to fragment urinary tract stones, incise ureteral or urethral strictures, and ablate superficial urothelial tumors. A series of 80 consecutive patients were assessed prospectively. Laser fibers with a diameter of 200 microm and 365 microm were employed with power settings of 6.4 to 10 W. Laser fiber size and power settings were similar for the low- and full-power devices. RESULTS Overall, 95% of the stones were completely fragmented, with a stone-free rate at 3 months of 92%. All strictures were incised, with a 91% patency rate at 3 months. Complete tumor ablation was attained in 70%, with a tumor-free rate of 60% at 3 months. Results were equivalent for the low- and full-power lasers. The 200-microm laser fiber allowed adequate access throughout the upper urinary tract during flexible ureteroscopy and flexible nephroscopy. The 365-microm laser fiber was employed via rigid and semirigid endoscopes. CONCLUSIONS A low-power holmium laser supplies adequate fragmentation and incision power for virtually all endourologic cases. It also provides ablative power in most situations. The only current urologic application that cannot be performed with the low-power device is laser prostatic resection, which requires 60 to 80 W of power. The reduced-power holmium laser should be considered as a low-cost alternative for the management of urinary tract stones, strictures, and urothelial tumors, especially in centers where laser prostatic resection is not performed.

Advances in Camera, Video, and Imaging Technologies in Laparoscopy

The introduction of technological advances, such as HDTV, three-dimensional laparoscopy, and further miniaturization of high-resolution digital video cameras, will allow significantly enhanced opportunities for laparoscopic surgical proficiency and further broadening of laparoscopic applications in urology. These enhancements, coupled with the recent advances in telemedicine and surgical simulation, will improve laparoscopic training and skill acquisition, decrease operative times and costs, minimize morbidity, and improve overall patient care.

Quantification of the tip movement of lithotripsy flexible pneumatic probes.

PURPOSE We developed an optical system to quantify in vitro tip movement of the Lithoclastdouble dagger flexible probe, and correlated various physical parameters of the vibrating probe tip with resultant stone fragmentation. MATERIALS AND METHODS A noncontact optical measurement system was developed to quantify in vitro tip movement of the Lithoclast flexible probe. This system and an in vitro fragmentation model were used to determine the tip displacement, velocity, impact momentum, impact energy and stone fragmentation of the flexible probe at 5 deflection angles between 0 and 48 degrees, and the 2 pneumatic pressure levels of 2.0 and 2.5 bar. RESULTS An increase in maximum probe tip displacement, velocity, impact momentum and energy, and stone fragmentation was seen as the pneumatic pressure was increased from 2.0 to 2.5 bar. A progressive decrease in these parameters was demonstrated as the probe tip was deflected, especially at deflection angles greater than 24 degrees. Impact momentum appears to be the physical parameter most closely correlated with stone fragmentation efficiency. CONCLUSIONS The optical measurement system and in vitro fragmentation model developed allow one to quickly and reliably assess the performance of flexible pneumatic probes in vitro. This system can be used for general bench testing and basic research that can provide critical information for the design of more effective and efficient flexible pneumatic lithotripsy probes.

In vivo quantitation of regional versus systemic SWL‐induced free‐radical activity

Renal tissue injury in shock wave lithotripsy (SWL) may be attributed directly to vascular trauma and indirectly to ischemia‐reperfusion with resultant free‐radical formation. We have employed a microdialysis system to assess areas of renal injury in relation to the site of SWL treatment. Swine were assigned to a control group (N=3) and a SWL‐treated group (N=3). Microdialysis probes were inserted into the parenchyma of the lower pole, upper pole of right kidney, and the lower pole of left kidney. Seventy‐two hours following probe insertion, baseline dialysate samples were collected, after which SWL was administered exclusively to the right kidney lower pole in the treated group, using a Dornier Compact S lithotripter at its highest intensity. Dialysate samples were collected every 1000 shocks. It was found that SWL caused a significant increase in free‐radical activity, as measured by lipid peroxidation, in the right lower pole, followed by a moderate increase in the right upper pole. Yet, no free‐radica...