Kari Hendlin

A pilot study on the early use of the vacuum erection device after radical retropubic prostatectomy

To evaluate the effect of the early use of the vacuum erection device (VED) on erectile dysfunction (ED) and penile shortening after radical retropubic prostatectomy (RP), as these are important concerns for men choosing among treatment alternatives for localized prostate cancer.

ALFUZOSIN STONE EXPULSION THERAPY FOR DISTAL URETERAL CALCULI: A DOUBLE-BLIND PLACEBO- CONTROLLED STUDY

PURPOSE We evaluated the efficacy of alfuzosin as medical expulsive therapy for distal ureteral stone passage. MATERIALS AND METHODS A total of 76 patients with a distal ureteral calculus provided consent for the study. Patients were randomized between placebo and study medication, and investigators and patients were blinded to the randomization scheme. Followup was done on a weekly basis and continued until the patient was rendered stone-free. The patient blood pressure, discomfort level, stone position on imaging, number of remaining pills and any adverse events were assessed. Statistical analysis was performed with the Student t test with p <0.05 considered significant. RESULTS The overall spontaneous stone passage rate was 75%, including 77.1% for placebo and 73.5% for alfuzosin (p = 0.83). Mean +/- SD time needed to pass the stone was 8.54 +/- 6.99 days for placebo vs 5.19 +/- 4.82 days for alfuzosin. (p = 0.003). There was no difference in the size or volume of stones that passed spontaneously between the placebo and alfuzosin arms, as measured on baseline computerized tomography (4.08 +/- 1.17 and 3.83 +/- 0.95 mm, p = 0.46) and by a digital caliper after stone expulsion (3.86 +/- 1.76 and 3.91 +/- 1.06 mm, respectively, p = 0.57). When comparing the improvement from the baseline pain score, the alfuzosin arm experienced a greater decrease in pain score in the days after the initial emergency department visit to the date of stone passage (p = 0.0005). CONCLUSIONS Alfuzosin improves the patient discomfort associated with stone passage and decreases the time to distal ureteral stone passage but it does not increase the rate of spontaneous stone passage.

Ureteral Obstruction: Is the Full Metallic Double-Pigtail Stent the Way to Go?

BACKGROUND The Resonance metallic ureteral stent (Cook Medical, Bloomington, Indiana, USA) has been introduced for the management of extrinsic-etiology ureteral obstruction for time periods up to 12 mo. OBJECTIVE The current study aims to determine short- and medium-term effectiveness of the Resonance stent in malignant and benign ureteral obstruction. DESIGN, SETTING, AND PARTICIPANTS In total, 50 patients with extrinsic malignant obstruction (n=25), benign ureteral obstruction (n=18), and previously obstructed mesh metal stents (n=7) were prospectively evaluated. INTERVENTION All patients were treated by Resonance stent insertion. Twenty stents were inserted in antegrade fashion, and the remaining stents were inserted in a retrograde approach. No patient dropped out of the study. The follow-up evaluation included biochemical and imaging modalities. MEASUREMENTS We evaluated the technical success rate, stricture patency rate, complications, and the presence and type of encrustation. RESULTS AND LIMITATIONS The technical success rate of transversal and stenting of the strictures was 100%. In 19 patients, balloon dilatation was performed prior to stenting. The mean follow-up period was 8.5 mo. The stricture patency rate in patients with extrinsic malignant ureteral obstruction was 100% and in patients with benign ureteral obstruction 44%. Failure of Resonance stents in all cases of obstructed metal stents was observed shortly after the procedure (2-12 d). In nine cases, stent exchange was demanding. Encrustation was present in 12 out of 54 stents. CONCLUSIONS The Resonance stent provides safe and sufficient management of malignant extrinsic ureteral obstruction. Resonance stent use in benign disease needs further evaluation, considering the untoward results of the present study.

Next Generation Biodegradable Ureteral Stent in a Yucatan Pig Model

PURPOSE Ureteral stents are commonly used to facilitate kidney drainage but they may produce significant stent symptoms and morbidity, and require a secondary procedure for removal. Previous biodegradable stents showed bio-incompatibility or inconsistent degradation, requiring extra procedures to remove undegraded stent fragments. We previously reported a first generation biodegradable stent composed of suture-like material that required placement through the lumen of a sheath and degraded by 10 weeks. We now report second and third generation biodegradable stents that degrade more rapidly and can be placed directly over a polytetrafluoroethylene guidewire. MATERIALS AND METHODS Two groups of 16 Yucatan pigs each were unilaterally stented endoscopically with a control nondegradable (biostable) stent or a second generation degradable Uriprene stent. Blood studies, renal ultrasound and excretory urography were done throughout the study to determine renal function, hydronephrosis and stent degradation. Genitourinary organs were harvested at necropsy for pathological analysis. A third generation stent designed to improve degradation time was bilaterally implanted endoscopically into 4 Yorkshire Farm pigs (total of 8 stents), followed by excretory urography weekly to assess degradation and kidney function. Biomaterial parameters were tested. RESULTS Second generation stents began degrading at 2 weeks and were completely degraded by 10 weeks. All third generation stents were degraded by 4 weeks. Hydronephrosis was considerably less in the Uriprene group than in control biostable stented kidneys. Biostable stented ureters showed an average higher degree of inflammation, uropathy and nephropathy. Physical characteristics indicate that Uriprene stents are significantly more resistant to stent compression and have markedly higher tensile strength and coil strength comparable to that of other commercially available plastic stents. CONCLUSIONS Our study confirms that Uriprene stents are biocompatible and provide good renal drainage. They hold promise for decreasing the need for a secondary procedure and stent related morbidity, such as infection and irritative symptoms.

Uropathogen Interaction With the Surface of Urological Stents Using Different Surface Properties

PURPOSE Ureteral stents commonly become infected or encrusted. Various coatings have been developed to decrease bacterial adherence. To our knowledge there has been no in vitro testing of coating with heparin to date. We determined the effects of heparin coating on bacterial adherence of common uropathogens and physical stent properties. MATERIALS AND METHODS Heparin coated Radiance ureteral stents (Cook) and noncoated Endo-Sof control stents were tested against triclosan eluting Triumph(R) stents and noneluting Polaris control stents for adherence of Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, Staphylococcus aureus and Pseudomonas aeruginosa for 7 days. Adherent bacteria were determined and biofilms were visualized using fluorescent dyes. Radial, tensile and coil strength of the Radiance and Polaris stents was compared to determine the effect of heparin coating on physical stent characteristics. RESULTS Heparin coating did not decrease bacterial adhesion compared to its control. E. coli adhesion was limited by all stents tested. The Polaris stent showed significantly greater resistance to bacterial adherence for Klebsiella, Pseudomonas and Enterococcus than the Endo-Sof and Radiance stents but was more susceptible to S. aureus adherence. The Triumph stent resisted all bacteria except Pseudomonas and Enterococcus. Mature biofilms were observed on all stents with lower viability on the Triumph stent. Radiance stents showed higher tensile and lower compression strength than its control. CONCLUSIONS Heparin coating does not decrease bacterial adherence to ureteral stents. Drug eluting antimicrobials have an inhibitory effect on bacterial adherence and the Polaris stent showed the least bacterial adherence of the nondrug eluting ureteral stents tested.

Celecoxib in the Management of Acute Renal Colic: A Randomized Controlled Clinical Trial

OBJECTIVES To evaluate the efficacy of celecoxib as an analgesic and medical expulsive agent in acute renal colic. METHODS A prospective randomized double-blind study was conducted on patients presenting with an obstructing ureteral calculus < 10 mm in largest diameter. Patients were randomized to 400 mg of celecoxib, followed by 200 mg every 12 hours for 10 days, or to placebo. Patients with a solitary kidney, renal insufficiency (CR > 1.8), urinary tract infection, or significant cardiovascular disease were excluded. RESULTS A total of 57 patients provided consent of which 53 completed the study. Four patients were excluded from the analysis because of stone passage or withdrawal of consent before the first dose of study medication. No significant difference was noted in the spontaneous stone passage rate (celecoxib 55.2%, placebo 54.2%) and between celecoxib and placebo with regard to days to stone passage (7.0 vs 9.0, P = .6) or size of stone passed (3.9 vs 4.6 mm, P = .18). No significant difference was noted in pain analog scores (2.6 vs 3.5, P = .71) or narcotic doses (13.2 vs 13.6, P = .74). Furthermore, a 25% decrease in narcotic use (or 19 mg based on placebo mean) was outside the 80% one-sided confidence interval for the change in mean narcotic use between the 2 groups. Thus, it is unlikely (< 20%) that we missed a clinically significant beneficial effect of celecoxib on narcotic consumption because of sample size. CONCLUSIONS Celecoxib does not facilitate stone passage or decrease narcotic requirements in patients with acute renal colic.

Impact of Irrigation Systems on Stone Migration

PURPOSE To evaluate forces exerted on a stone with different ureteroscopic irrigation systems that could impact stone migration during ureteroscopy. MATERIALS AND METHODS A 3-mm steel simulated stone was welded to a 3F stone basket. The basket wire was then backloaded into the working channel of a 4.5F Wolf semirigid ureteroscope. The basket shaft was attached to a 50 g load cell. The ureteroscope was placed in a ureteral model (14F silicon tubing). Simulated blood was dripped adjacent to the stone at 12 drops/min. Endo-irrigation devices were attached to the ureteroscope, and irrigation was applied at a rate sufficient to maintain visualization of the stone. Force on the stone was measured with the following endo-irrigation systems: Gravity (183 cm H2O); pressurized irrigation (150 mm Hg, 300 mm Hg); Kosin Technology Universal Piggyback Irrigation System (UPIS) at gravity (183 cm H2O), 150 mm Hg and 300 mm Hg; EMS Medical Peditrol Foot Pump; Cook Ureteroscopy Irrigation System; ACMI Irri-Flo Irrigation Delivery System; and Boston Scientific Single-Action-Pump System (SAPS). RESULTS SAP required the least number of pumps (0.35/sec) to maintain a clear endoscopic field while the Peditrol device required the most (1.88/sec). Pulse duration was longest for the ACMI (1.6 sec) and shortest for pressurized gravity and UPIS (<0.3 sec). The average total maximum impulse during a pump was significantly greater with the Cook (0.017 Ns) and ACMI (0.027 Ns) systems. On average, gravity-based systems applied the least amount of force, < or =0.0006 Ns, maximum impulse at any given time. CONCLUSIONS Gravity-based systems exert less force than hand-held and foot-pump devices. Of the hand-held devices, the SAP exerted the least average maximum impulse on the stone.

New Metallic Ureteral Stents: Improved Tensile Strength and Resistance to Extrinsic Compression

BACKGROUND AND PURPOSE Extrinsic ureteral compression challenges a ureteral stents ability to facilitate urinary drainage and to protect the kidney. Our purpose was to evaluate the performance of new metallic coil-based ureteral stents in terms of tensile strength and radial compression force. MATERIALS AND METHODS Three stent designs tested from Prosurg Inc included Passage 7.0F, Snake 6.0F, and Snake 7.0F with the straight section covered with a biocompatible polymer tubing. A MTS Microbionix Testing System using Testworks II software, vibration isolation table, and a 5-N load cell were used to measure tensile and compressive strength. Stents were placed in hydraulic grips and stretched at a rate of 5 mm/s for 1 second under uniaxial tension. Extrinsic compression was exerted in 0.1-mm increments to maximum compression. The Young Modulus, E, was calculated from each trial using engineering stress. Data were analyzed using Mann-Whitney and t tests. RESULTS The Passage, Snake 6F, and Snake 7F stents had tensile strengths of 27±3, 5±0.1, and 73±26 kPa, respectively. Mann-Whitney tests show statistically significant difference between stents (P<0.05). Elastic modulus needed to cause extrinsic compression was highest for Snake 6F (145,842±14332 Pa) compared with that of Passage (124,999±3182 Pa) and Snake 7F (126,132±19316 Pa), (P<0.05). CONCLUSION The Snake 6F stent had the lowest tensile strength and was least resistant to extrinsic compression. The Snake 7F had the highest tensile strength and was most resistant to extrinsic compression. All three stents are more resistant to extrinsic compression than the Applied Silhouette or Cook Resonance, yet have lower tensile strengths.

Small-diameter nitinol stone baskets: radial dilation force and dynamics of opening.

PURPOSE To evaluate the radial dilation force and basket opening dynamics of three small (<1.5F) stone baskets. MATERIALS AND METHODS Boston Scientific OptiFlex (1.3F), Cook N-Circle Nitinol Tipless Stone Extractor (1.5F), and Sacred Heart Medical Halo (1.5F) baskets were tested for radial dilation force in 10 repetitions using a floating block atop a stationary block secured to a digital scale. The floating block, attached to a plastic frame and base, pressed down on the scale to measure the radial dilation of the open basket while being passed through the cylindrical opening between the blocks. These same baskets were tested in triplicate for basket width in 0.5- to 2-mm length increments using a mechanical caliper under optical light microscope visualization to evaluate the linearity of basket opening and length at which target basket width (5 mm) was reached. RESULTS The Sacred Heart Medical Halo had the best radial dilation (2.97 ± 0.22 g), followed by the Cook N-Circle (1.29 ± 0.04 g), and finally Boston Scientific OptiFlex (1.19 ± 0.12 g). The N-Circle was the only basket to exhibit linear opening, while the Halo exhibited an exponential curve. The OptiFlex exhibited a polynomial curve, with linear opening across the midrange of the basket length. From these curve equations, the target basket width (5 mm) was calculated. The N-Circle and the OptiFlex reached the target basket width at a basket length of 9.4 mm and 9.6 mm, respectively. The Halo reached the target basket width at a basket length of 11.5 mm. CONCLUSIONS The radial dilation force differs significantly among commercial baskets and may affect ureteral stone extraction. Linear basket opening may provide the physician more control in stone retrieval.

Radial dilation of nephrostomy balloons: a comparative analysis

PURPOSE The dynamics of percutaneous balloon expansion may differ with increasing extrinsic compressive forces and increasing inflation pressures. This study compares the ability of percutaneous balloons to expand under different radial constrictive forces. MATERIALS AND METHODS Three 30F nephrostomy balloons were tested: Bard X-Force, Boston Scientific Microvasive Amplatz Tractmaster, and Cook Ultraxx. With a super stiff guidewire in place, the balloon tip was secured by elevated vice grips on either side of the balloon. A string was wrapped around the balloon center once, and incremental increases in load were added (2g, 42g, 82g, and 122g) to represent increasing extrinsic compression. The balloon was inflated with a contrast agent and circumference changes were measured at increments of 4 ATM, 10 ATM, and burst pressure. Balloons were tested in triplicate for each load. RESULTS All balloons were unable to reach 90% of their expected diameter with larger constrictive loads (122g) at low (4 ATM) and nominal (10 ATM) inflation pressures. Only the Bard and Cook balloons reached at least 90% of the expected diameter with a coefficient of variance (CV) less than 10% at burst pressure under the larger constrictive load (122g), 94.3% +/- 6.7%, CV 7.1% and 96.3% +/- 2.9%, CV 3.0% respectively. All balloons performed well under low constriction forces and reached at least 80% of the expected diameter by 10 ATM under all constrictive loads. CONCLUSIONS The Bard X-Force and Cook Ultraxx percutaneous nephrostomy balloons achieved the most reliable radial dilation against large constrictive forces simulating fascial or retroperitoneal scar tissue.