Geoffrey R. Wignall

Surgical Simulation: A Urological Perspective

PURPOSE Surgical education is changing rapidly as several factors including budget constraints and medicolegal concerns limit opportunities for urological trainees. New methods of skills training such as low fidelity bench trainers and virtual reality simulators offer new avenues for surgical education. In addition, surgical simulation has the potential to allow practicing surgeons to develop new skills and maintain those they already possess. We provide a review of the background, current status and future directions of surgical simulators as they pertain to urology. MATERIALS AND METHODS We performed a literature review and an overview of surgical simulation in urology. RESULTS Surgical simulators are in various stages of development and validation. Several simulators have undergone extensive validation studies and are in use in surgical curricula. While virtual reality simulators offer the potential to more closely mimic reality and present entire operations, low fidelity simulators remain useful in skills training, particularly for novices and junior trainees. Surgical simulation remains in its infancy. However, the potential to shorten learning curves for difficult techniques and practice surgery without risk to patients continues to drive the development of increasingly more advanced and realistic models. CONCLUSIONS Surgical simulation is an exciting area of surgical education. The future is bright as advancements in computing and graphical capabilities offer new innovations in simulator technology. Simulators must continue to undergo rigorous validation studies to ensure that time spent by trainees on bench trainers and virtual reality simulators will translate into improved surgical skills in the operating room.

Use of triclosan-eluting ureteral stents in patients with long-term stents.

BACKGROUND AND PURPOSE Long-term use of ureteral stents is prevented by biofilm-related infection and encrustation mandating stent changes every few months. Triclosan is a broad-spectrum antimicrobial in numerous consumer and medical products and has been incorporated into a ureteral stent. We sought to determine the clinical effects of the triclosan-eluting stent in patients who needed long-term ureteral stenting. PATIENTS AND METHODS Eight patients with long-term stents were enrolled prospectively. All received a control stent for 3 months along with preoperative and postoperative antibiotics. After 3 months, the control stent was removed, and a triclosan-eluting stent was placed for 3 months with no antibiotics administered. For both indwelling periods, urine cultures were obtained weekly and biweekly for the first and last 6 weeks, respectively, and antibiotics were prescribed when patients had both a positive urine culture and symptoms of urinary tract infection. On removal, stents were assessed for microorganisms and encrustation. RESULTS Overall, similar microorganisms were isolated during each indwell period, although Staphylococcus and Enterococcus strains were isolated more frequently during control and triclosan stenting, respectively. Significantly fewer antibiotics were used during triclosan stenting, coinciding with a slightly higher number of positive urine cultures and significantly fewer symptomatic infections. No bacterial isolates developed antibiotic resistance during triclosan stent placement. CONCLUSIONS Antibiotic use with control stents resulted in bacterial antibiotic resistance, which was not the case with the triclosan-eluting stents. Although triclosan-eluting stents did not show a clinical benefit in terms of urine and stent cultures or overall subject symptoms compared with controls, their use did result in decreased antibiotic usage and significantly fewer symptomatic infections. The triclosan-eluting stent alone is not sufficient to reduce device-associated infections in this difficult patient population.

Anti-Adhesive Coating and Clearance of Device Associated Uropathogenic Escherichia coli Cystitis

PURPOSE A previous study showed decreased uropathogen adherence using a novel anti-fouling coating consisting of mussel adhesive protein mimics conjugated to poly(ethylene glycol). We assessed the ability of methoxy polyethylene glycol-dihydroxyphenylalanine (Nerites Corp. Ltd., Madison, Wisconsin) coated ureteral stents to resist bacterial adherence, infection development and encrustation in a rabbit model of uropathogenic Escherichia coli cystitis. MATERIALS AND METHODS Sof-Flex stent curls that were uncoated and coated with 3 coatings, including Surphys 002, 008 and 009, respectively, and uncoated Percuflex Plus stents were inserted transurethrally into the bladder of 50 male New Zealand White rabbits (Charles River Laboratories, Montreal, Quebec, Canada), followed by instillation of uropathogenic E. coli strain GR12 (10(7) cfu). Urine was examined for bacteria on days 0, 1, 3 and 7, and for cytokine levels on day 7. On day 7 the animals were sacrificed. Stent curls and bladders were harvested for analysis. In a parallel experiment stents were challenged in vitro for 7 days with GR12 in human urine. RESULTS Surphys 009 coated devices showed decreased urine and stent bacterial counts compared to those in controls. Eight of 10 rabbits in the Surphys 009 group had sterile urine by day 3 vs 1 in each control group (p = 0.013), while stent adherent organisms were decreased by more than 75%. While no statistical differences were found in encrustation and bladder inflammation across the groups, immune scoring was lowest in the uncoated Sof-Flex control and Surphys 009 groups (p = 0.030). CONCLUSIONS Surphys 009 strongly resisted bacterial attachment, resulting in improved infection clearance over that of uncoated devices. However, this did not translate to decreased encrustation, which appeared to be independent of infection in this model.

Minimally Invasive Approaches to Upper Urinary Tract Urolithiasis

The surgical management of urolithiasis is an ever-changing discipline that presents unique challenges to the urologist. This article reviews the current minimally invasive treatment options for upper urinary tract urolithiasis. First it examines several factors that influence stone-free rates, including Hounsfield units of calculi, obesity, and lower pole factors. Surgical management of ureteral calculi is reviewed along with a discussion of stone management in high-risk patients including those who are pregnant. Surgical technique of shockwave lithotripsy, ureteroscopy, percutaneous nephrolithotomy, and laparoscopy is discussed in depth, with attention paid to possible variations in technique.

Effect of Prostate Gland Size on the Learning Curve for Robot-Assisted Laparoscopic Radical Prostatectomy: Does Size Matter Initially?

BACKGROUND AND PURPOSE Widespread introduction of robot-assisted laparoscopic radical prostatectomy (RALRP) has led to multiple surgeons going through the learning curve (LC). One of the recommendations for surgeons on the LC for RALRP is to choose patients with smaller glands. We evaluated our LCs to determine whether prostate size influenced intraoperative outcomes and positive surgical margin rates. PATIENTS AND METHODS Data were obtained from a prospective database for the first 154 cases of RALRP performed by a single surgeon. Patients were divided into three groups based on prostate volume (PV): <40 cc (group 1), 40 to 60 cc (group 2), or >60 cc (group 3). PV was estimated by preoperative transrectal ultrasonography (TRUS) and correlated with pathologic weight (PW). Perioperative and immediate postoperative outcomes were evaluated. RESULTS A statistically significant difference in total operative times between the groups (206 minutes vs 201 minutes vs 233 minutes for groups 1, 2, and 3, respectively) was noted. With regard to individual intraoperative steps, the bladder neck reconstruction and anastomosis time was longer in group 3. No other statistically significant differences were noted. The Pearson correlation coefficient between PV estimation by TRUS and PW was r = 0.785, and an additional analysis based on PW supports the results of our study. CONCLUSIONS Prostate size influenced total operative times and the bladder neck reconstruction and anastomosis time. Our data support the use of preoperative TRUS to estimate PV and recommendations for surgeons starting on their LC to choose glands less than 60 cc.

The Effects of Triclosan on Uropathogen Susceptibility to Clinically Relevant Antibiotics

INTRODUCTION Triclosan is a broad-spectrum antimicrobial agent currently used in numerous products including surgical scrubs and ureteral stents. Unfortunately, studies have shown triclosan resistance among several bacterial species. Our objective was to characterize resistance patterns of common uropathogens to triclosan and determine whether triclosan exposure would alter their susceptibility to common antibiotics. We hypothesized that triclosan exposure induces a metabolic stress rendering some bacterial strains more susceptible to other antibiotics. METHODS Using largely clinical isolates comprising seven uropathogenic species, we conducted 24 hour growth experiments to determine triclosan minimal inhibitory concentrations (MIC) for each strain. Based upon these MICs, triclosan was added to agar plates at escalating sublethal concentrations and antibiotic disk diffusion assays were conducted using a range of clinically-relevant antibiotics. RESULTS Varying susceptibility patterns were observed across all antibiotics studied. Several antibiotics demonstrated increased efficacy in conjunction with triclosan. The combined effect of triclosan with amoxicillin and gentamicin was superior when considering significant increases in susceptibility, with 6 (86%) and 5 (71%) of the 7 bacterial strains displaying enhanced sensitivity, respectively. The antimicrobial effects of nitrofurantoin and the fluoroquinolones were significantly enhanced for 4 (57%), 4 and 3 (42%) of the 7 pathogens, respectively. The two fluoroquinolones were the only antibiotics where susceptibility was negatively impacted (in one strain each) in combination with triclosan. CONCLUSIONS The synergistic effects of triclosan and several antibiotics are consistent with a triclosan-dependent metabolic strain and/or membrane disruptive effect, and offers important insight into the combined use of antimicrobial compounds in clinical practice.

Impact of body mass index on perioperative outcomes during the learning curve for robot-assisted radical prostatectomy

INTRODUCTION Previous studies of robotic-assisted radical prostatectomy (RARP) have suggested that obesity is a risk factor for worse perioperative outcomes. We evaluated whether body mass index (BMI) adversely affected perioperative outcomes. METHODS A prospective database of 153 RARP (single surgeon) was analyzed. Obesity was defined as BMI >/= 30 kg/m(2); normal BMI < 25 kg/m(2); and overweight as 25 to 30 kg/m(2). Two separate analyses were performed: the first 50 cases (the initial learning curve) and the entire cohort of 153 RARP. RESULTS In the initial cohort of 50 cases (14 obese patients), there was no statistically significant difference with regards to operative times, port-placement times and estimated blood loss (EBL). Length of stay (LOS) was longer in the obese group (4.3 vs. 2.9 days); BMI remained an independent predictor of increased LOS on multivariate linear regression analysis (p = 0.002). There was no statistically significant difference in the postoperative outcomes of leak rates, margin rates and incisional herniae. In the entire cohort, when comparing obese patients to those with a normal BMI, there was no statistically significant difference in operative times, EBL, LOS, or immediate postoperative outcomes. However, on multivariate linear regression analysis, BMI was an independent predictor of increased operative time (p = 0.007). CONCLUSION Obese patients do not have an increased risk of blood loss, positive margins or the postoperative complications of incisional hernia and leak during the learning curve. They do, however, have slightly longer operative times; we also noted an increased LOS in our first 50 cases.

Coherent scatter computed tomography for structural and compositional stone analysis: a prospective comparison with infrared spectroscopy.

INTRODUCTION Infrared spectroscopy (IRS) is a standard method of stone analysis that yields relative proportions of stone materials within a sample. IRS is destructive, as it analyzes only powdered samples, with only a fraction of the stone being analyzed. This leads to sampling bias with components over- or underestimated or even missed entirely. IRS fails to provide structural composition such as that at the stone core. Coherent scatter computed tomography (CSCT) uses diagnostic X-rays to provide detailed structural and compositional analysis of intact specimens, including detailed imaging of the stone core. METHODS Consecutive patients undergoing surgical treatment for stone disease were recruited for the study. Stones or fragments collected during surgery were subjected to both CSCT and IRS. The two methods were compared with respect to overall bulk composition of the stone and the ability to identify the material at the core. RESULTS CSCT and IRS agreed on the primary component in the majority (84.8%) of samples. CSCT detected additional components in 88.8% of stones identified as uniform by IRS. CSCT also identified a distinct stone core in 78.8% of samples, while IRS failed to detect the core component in 21.2% of these stones. In 30.3% of the stones with a core component, IRS did not identify the core mineral as the primary component. CONCLUSION CSCT provides superior quantitative stone analysis and is not prone to issues such as sampling error as the entire specimen is analyzed. CSCT offers excellent structural imaging of stone samples, including detailed analysis of core composition.

Introduction to biofilms in urology

Abstract Despite significant resources and several decades of research aimed at their prevention and treatment, biofilm-associated infections continue to be the major cause of urological device failure. Numerous strategies have been targeted towards improving device design, biomaterial composition, surface characteristics and drug elution, but have been largely thwarted by microorganisms and their arsenal of attachment, host evasion, antimicrobial resistance and dissemination strategies. This is not entirely surprising considering that natural biofilm formation has been occurring for billions of years and remains a significant element of microbe survival and evolution. Thus, the fact that biofilms develop on and in the biomaterials and tissues of humans is largely an extension of this natural tendency and underscores why they are so difficult to combat. Biofilm structure and composition intrinsically offer a protective environment for microorganisms, shielding them from the shear stress of urine flow, attack by the host immune system and antimicrobials. Furthermore, many biofilm organisms go into a metabolically quiescent state that renders them more tolerant to antibiotics and host immune factors able to penetrate the biofilm matrix. Finally, most organisms causing biofilm-associated urinary tract infections originate from the hosts own oral cavity, skin, gastrointestinal and urogenital tracts and therefore have already adapted to many host defense mechanisms. Ultimately, while biofilms continue to hold the upper hand with respect to recurrent infections and urinary tract biomaterial use, significant progress has been made in understanding these dynamic microbial communities and novel approaches offer promise for biofilm prevention and removal. These include novel device designs, antimicrobials, anti-adhesive coatings, biodegradable polymers and biofilm-disrupting compounds and therapies.

Implications of Biofilm Formation on Urological Devices

Despite millions of dollars and several decades of research targeted at their prevention and eradication, biofilm‐associated infections remain the major cause of urological device failure. Numerous strategies have been aimed at improving device design, biomaterial composition, surface properties and drug delivery, but have been largely circumvented by microbes and their plethora of attachment, host evasion, antimicrobial resistance, and dissemination strategies. This is not entirely surprising since natural biofilm formation has been going on for millions of years and remains a major part of microorganism survival and evolution. Thus, the fact that biofilms develop on and in the biomaterials and tissues of humans is really an extension of this natural tendency and greatly explains why they are so difficult for us to combat. Firstly, biofilm structure and composition inherently provide a protective environment for microorganisms, shielding them from the shear stress of urine flow, immune cell attack and some antimicrobials. Secondly, many biofilm organisms enter a metabolically dormant state that renders them tolerant to those antibiotics and host factors able to penetrate the biofilm matrix. Lastly, the majority of organisms that cause biofilm‐associated urinary tract infections originate from our own oral cavity, skin, gastrointestinal and urogenital tracts and therefore have already adapted to many of our host defenses. Ultimately, while biofilms continue to hold an advantage with respect to recurrent infections and biomaterial usage within the urinary tract, significant progress has been made in understanding these dynamic microbial communities and novel approaches offer promise for their prevention and eradication. These include novel device designs, antimicrobials, anti‐adhesive coatings, biodegradable polymers and biofilm‐disrupting compounds and therapies.Despite millions of dollars and several decades of research targeted at their prevention and eradication, biofilm‐associated infections remain the major cause of urological device failure. Numerous strategies have been aimed at improving device design, biomaterial composition, surface properties and drug delivery, but have been largely circumvented by microbes and their plethora of attachment, host evasion, antimicrobial resistance, and dissemination strategies. This is not entirely surprising since natural biofilm formation has been going on for millions of years and remains a major part of microorganism survival and evolution. Thus, the fact that biofilms develop on and in the biomaterials and tissues of humans is really an extension of this natural tendency and greatly explains why they are so difficult for us to combat. Firstly, biofilm structure and composition inherently provide a protective environment for microorganisms, shielding them from the shear stress of urine flow, immune cell attack and so...