A systematic review of cytoreductive prostatectomy outcomes and complications in oligometastatic disease

Objective

To analyze outcomes and complications of cytoreductive prostatectomy (CRP) for oligometastatic prostate cancer (PCa) in order to elucidate its role in this space.

Methods

We performed a systematic literature search using three databases (Medline, Scopus, and Web of Science). The primary endpoints were oncologic outcomes. The secondary endpoints were complication rates and functional results.

Results

In all studies, overall survival was better or at least comparable variable in the groups with CRP compared to no local treatment. The greatest benefit from CRP in 5-year overall survival in one study was 67.4% for CRP versus 22.5% for no local treatment. Cancer-specific survival (CSS) showed the same trend. Several authors found significant benefits from CSS in the CRP group: from 79% vs. 46% to 100% vs. 61%. CRP was a predictor of better CSS (hazard ratio 0.264, p=0.004). Positive surgical margin rates differed widely from 28.6% to 100.0%. Urinary continence in CRP versus RP for localized PCa was significantly lower (57.4% vs. 90.8%, p<0.0001). Severe incontinence occurred seldom (2.5%-18.6%). Total complication rates after CRP differed widely, from 7.0% to 43.6%. Rates of grades 1 and 2 events prevailed. Patients on ADT alone also showed a considerable number of complications varying from 5.9% to 57.7%.

Conclusion

CRP improves medium-term cancer control in patients with oligometastatic PCa. The morbidity and complication rates of this surgery are comparable with other approaches, but postoperative incontinence rate is higher compared with RP for localized disease.

Laser endoscopic procedures on the prostate: it is the small details that count

PURPOSE OF REVIEW

This review aims to highlight the pros and cons of each laser device and to consider additional possible milestones for the development of laser technologies in the surgical treatment of benign prostate hyperplasia.

RECENT FINDINGS

Over the last three decades, lasers' role in endourology has gone from strength to strength. Specifically, the primary techniques where laser surgery for BPO relief is concerned are vaporization and enucleation. The idea behind vaporization is that lasers are able to vaporize substantial amounts of tissue due to deep ablation depth and increased power. The most efficient devices for vaporization are those affecting hemoglobin as primary chromophore and/or using a continuous firing mode (KTP/LBO:YAG, diode lasers, Tm:YAG). As for enucleation, multiple devices have been suggested for the adequate anatomical enucleation of the prostate (EEP). As it is a skill-dependent technique, the EEP is effective irrespective of which device the surgeon uses. However, some devices have shown significant advances where enucleation is concerned.

SUMMARY

The choice of device should be based primarily on the technique the surgeon prefers. Although the most suitable lasers for vaporization are hemoglobin-targeting and/or continuous wave devices, the EEP may be done with any enough powered laser, yet some provides specific effects which you should be aware before the surgery.

Postoperative medical treatment of lower urinary tract symptoms after benign prostatic hyperplasia surgery. Are we underestimating the problem?

PURPOSE OF REVIEW

The aim of this study was to determine whether well timed start of medical and surgical treatment of benign prostatic obstruction (BPO) influences the treatment's effectiveness and thus the patients' overall functional outcomes and quality of life.

RECENT FINDINGS

Pharmacological therapy even in high-volume (>80 cm3) BPH typically begins with α-blockers sole and only subsequently are 5ARI added. Several studies showed that acute urinary retention (AUR) developed more frequently in men who suffered severe lower urinary tract symptoms (LUTS) and who did not start combination therapy immediately. Moreover, there are no strict criteria which determine the right time for performing surgery in patients with mild and moderate LUTS, especially when pharmacological therapy fails. However, sometimes, the surgery does not eliminate all the symptoms, as it deals effectively with BPO, but does not treat an overactive bladder. Also, data show that surgery should be performed as soon as possible and be more radical after the first episode of AUR.

SUMMARY

A combination of α-blockers and 5ARI makes for a good starting point where the treatment of high volume BPH is concerned. Ideally, surgery should be performed immediately or as soon as possible in patients with the first episode of AUR and 'anatomic' BPH tissue removal is preferable (dissection of tissue along the prostate capsule to remove its maximum volume).

Predictive model for systemic recurrence following cisplatin-based neoadjuvant chemotherapy and radical nephroureterectomy for high risk upper tract urothelial carcinoma

INTRODUCTION

Neoadjuvant chemotherapy (NAC) is increasingly used prior to radical nephroureterectomy (RNU) for upper tract urothelial carcinoma (UTUC). Systemic recurrence (SR) carries a dismal prognosis. We sought to determine risk factors associated with SR in this setting.

METHODS

We evaluated a multi-center database of patients with UTUC who received cisplatin-based NAC before RNU. Final pathology at RNU was dichotomized into ypT<2 vs ypT≥2. Univariable and multivariable analyses were performed to identify risk factors associated with SR. Three groups were defined based on the number of significant risk factors (groups 1, 2, 3 for 0-1, 2, 3 risk factors, respectively) and evaluated for recurrence-free survival (RFS) using the Kaplan-Meier method.

RESULTS

106 patients were identified between 2004 and 2018. Median age was 67.0 years [IQR = 61-73.3]; 57 (54%) and 49 (46 %) patients received MVAC and GC, respectively. Final pathological stage was ypT<2 in 57 (54%); 23% (24/106) had SR. On univariable analysis, pathological variables on final specimen including ypT≥2, lymphovascular invasion (ypLVI), and nodal involvement were associated with SR. On multivariable analysis, ypLVI OR = 4.1 (95% CI 1.2-13.6; P = 0.024) and pathological nodal involvement OR = 4.5 (95% CI 1.3-15.7; P = 0.017) were predictive of recurrence. Stratifying by the number of risk factors, the 2-year RFS was 95%, 55%, and 18% for groups 1, 2, and 3 respectively (log-rank <0.001).

CONCLUSION

This model evaluates the risk of SR following NAC and RNU to guide counseling and decision-making after surgery. Adverse pathological variable including ypLVI and nodal involvement, in combination with ypT-stage, are strongly associated with SR.

3D modeling in adherent perinephric fat prediction in nephron-sparing surgery planning in patients with localized renal neoplasms

STUDY OBJECTIVE

To develop a 3D-image based morphometry scoring system for Adherent Perinephric Fat (APF) prediction in nephron-sparing surgery in renal neoplasm patients.

MATERIALS AND METHODS

The retrospective study involved 391 patients who underwent a laparoscopic partial nephrectomy performed by five surgeons from January 2014 till December 2018. The surgery involved the 3D virtual operation planning with «Amira» 3D modeling software. With the multivariate logistic regression models, we developed a scoring system based on 3D-models. We tested the significance and sensitivity of new scoring system in a comparative ROC analysis with Mayo Adhesive Probability Score (MAP).

RESULTS

We found APF in 111 patients (28.4%). The univariate analysis revealed that significant indicators included mean age 59.88 (55-67) (p < 0.001), male sex (p < 0.001), Body Mass Index (BMI) >30 (21.47-35.08) kg/m² (p < 0.001), arterial hypertension (p < 0.001), coronary heart disease (p = 0.019), diabetes mellitus (p = 0.005), urolithiasis (p = 0.002). The multivariate regression analysis identified three most significant indicators in 3D models evaluation: additional >5 mm shadows in perirenal space OR = 7.3 (3.6-15.3) (p < 0.001), the number of shadows >5 OR = 3.8 (2.1-6.8) (p < 0.001), the wide shadow base at the renal parenchymal level OR = 0.293 (0.146-0.588) (p = 0.001). The scoring of these indicators comprises a new prediction scale (0-5). The ROC analysis revealed AUC 0.816 (95% CI 0.772-0.861) p < 0.001 of the MAP score, and AUC = 0.803 (95% CI 0.758-0.848) p < 0.001 of the scoring system developed in the present study.

CONCLUSIONS

The statistical findings comparison of the scoring system that we developed with those of MAP scale suggests that the scoring system is efficient and applicable.

Robotic Nephroureterectomy vs Laparoscopic Nephroureterectomy: Increased Utilization, Rates of Lymphadenectomy, Decreased Morbidity Robotically

Introduction and Objective: Robotic radical nephroureterectomy (RRNU) may offer advantages over laparoscopic radical nephroureterectomy (LRNU). The purpose of this study is to evaluate the overall survival (OS) of patients with upper tract urothelial carcinoma (UTUC) who underwent RRNU vs LRNU and identify factors that account for differences. Methods: The National Cancer Database was queried from 2010 to 2016 for patients with American Joint Committee on Cancer 6th/7th edition Stage I/II/III UTUC. Kaplan-Meier analysis compared LRNU and RRNU OS. Univariate analysis detected differences between the groups. Cox regression determined factors associated with mortality rate. Logistic regression identified predictors of a lymph node dissection (LND) and 90-day mortality rate. Results: A total of 2631 patients met the criteria, 1129 of whom underwent RRNU and 1502 LRNU, with a follow-up of 33 and 35 months, respectively (p = 0.063). RRNU had a median OS of 71.1 vs 62.6 months (p = 0.033). LRNU patients were older (72.7 vs 71.4, p < 0.001) and had no differences in comorbidities, pathologic T stage, or grade. The LRNU cohort was less likely to undergo LND (19% vs 35%, p < 0.001) and had a lower median lymph node yield (3 vs 4, p < 0.001). LRNU patients more likely underwent conversion to an open procedure, had longer hospital stays, and higher 30- and 90-day mortality rates. LRNU was independently associated with mortality rate (p = 0.030). Age, grade, positive margins, pT/pN stage were associated with mortality rate. Younger age, RRNU, surgery at an academic center, and neoadjuvant chemotherapy predicted an LND. Conclusions: RRNU demonstrated increased rates of LND and may offer a short-term morbidity benefit to LRNU. Survival differences may be due to improved characterization of disease through LND.

Distal determinants of mental health conditions (MHC) for asylum-seeking children in Greece: A health system enhancement study

Mental health conditions (MHC) of asylum-seeking children in Greece are dire, but still recovering from the financial crisis, Greece cannot afford the cost of mental health treatments. We were motivated to understand the root causes of these mental health problems to explore the possibilities for prevention. We developed our inferences in four ways: (1) secondary analyses of thirty-nine semi-structured informational interviews conducted with national and international aid organizations and healthcare providers; (2) secondary analyses of nine interviews with asylum seekers; (3) direct observation during six refugee camp visits from June 1 to July 28, 2017; and (4) a literature review to develop a diagnostic tree of causal outcomes. Results revealed eight proximal causes: chronic stress, trauma, at-risk population without protection and assistance, the large number of vulnerable groups, feeling of insecurity, feeling of lacking control, a lack of autonomy, and feeling helpless and hopeless. We identified sixty-nine distal determinants of adverse MHC beneath the proximal causes. Too numerous and too diverse to treat effecvively with limited resources, these root causes of MHC were thematically grouped into: laws and regulations, capacity and resources, accountability and standards, prioritization, bias and stigma, and displacement. Using a common health systems framework, we developed strategic policy approaches to target the root causes, which could prevent ill-health while saving time and resources.

Safety and Short-Term Oncological Outcomes of Thulium Fiber Laser En Bloc Resection of Non-Muscle-Invasive Bladder Cancer: A Prospective Non-Randomized Phase II Trial

BACKGROUND: Ongoing efforts aim at overcoming the challenges of conventional transurethral resection of bladder tumor (TURBT) such as the high recurrence rate, difficulty of pathologic interpretation and complications including wall injury. OBJECTIVE: To prospectively assess the safety and efficacy of Thulium fiber en bloc resection of bladder tumor (Tm-fiber ERBT) compared to TURBT. MATERIALS AND METHODS: The prospective non-randomized study included 129 patients with non-muscle-invasive bladder cancer (NMIBC) divided into two groups: 58 patients underwent conventional TURBT and 71 –Tm-fiber ERBT with FiberLase U1 (NTO IRE-Polus, Russia). Relapse-free survival (RFS), detrusor presence and complication rates were assessed. For multivariable analysis we used the Pearson chi-squared Hosmer-Lemeshow goodness of fit test; to compare survival –Cox regression analysis; for operative data comparison –chi-square test with Fisher’s correction; for survival analysis –the Kaplan–Meier method and logrank test. RESULTS: RFS rates at 3 and 6 months were 84.5% and 67.2% for conventional TURBT versus 97.2% and 91.5% for Tm-fiber ERBT (p = 0.011 and p < 0.001, respectively). Detrusor muscle was present in 58.6% of cases treated with conventional TURBT vs 91.6% for the Tm-fiber ERBT group (p < 0.001). The obturator nerve reflex and bleeding were noted in 17.2% and 10.3% of TURBT cases, respectively; and in none of cases treated with Tm-fiber ERBT. Limitations included the non–randomized nature and the small sample size. CONCLUSIONS: Tm-fiber ERBT seems to be a safe and efficacious treatment option for NMIBC. Tm-fiber ERBT had fewer adverse events, was more likely to secure detrusor muscle in the specimen and resulted in better RFS rates than conventional TURBT. Based on these promising data, we have started a prospective randomized clinical trial comparing en bloc TURBT with conventional TURBT (ClinicalTrials.gov NCT03718754).

Thulium-fiber laser for lithotripsy: first clinical experience in percutaneous nephrolithotomy

PURPOSE

To evaluate the efficacy and safety of thulium-fiber laser (TFL) in laser lithotripsy during percutaneous nephrolithotomy (PCNL).

METHODS

Patients with stones < 30 mm were prospectively recruited to undergo PCNL using TFL "FiberLase" (NTO IRE-Polus, Russia). Stone size, stone density, operative time, and "laser on" time (LOT) were recorded. Study included only cases managed with fragmentation. Stone-free rate and residual fragments were determined on postoperative computer tomography. Complications were classified using the Clavien-Dindo grade. Stone retropulsion and endoscopic visibility were assessed based on surgeons' feedback using a questionnaire.

RESULTS

A total of 120 patients were included in the study with a mean age of 52 (± 1.8) years; of these 77 (56%) were males. Mean stone size was 12.5 (± 8.8) mm with a mean density of 1019 (± 375) HU. Mean operative time was 23.4 (± 17.9) min and mean LOT was 5.0 (± 5.7) min. Most used settings were of 0.8 J/25-30 W/31-38 Hz (fragmentation). The mean total energy for stone ablation was 3.6 (± 4.3) kJ. Overall stone-free rate was 85%. The overall complication rate was 17%. Surgeons reported stone retropulsion that interfered with surgery in 2 (1.7%) cases insignificant retropulsion was noted in 16 (10.8%) cases. Poor visualization was reported in three (2.5%) cases and minor difficulties with visibility in four (3.3%) cases.

CONCLUSIONS

TFL is a safe and effective modality for lithotripsy during PCNL and results in minimal retropulsion.

Extracorporeal ureter handling during laparoscopic pyeloplasty: tips and tricks for beginners

Introduction

Laparoscopic preparation of the ureter is a challenging part of upper urinary tract reconstruction, due to limited depth perception provided by the camera and lack of wristed motion of most laparoscopic instruments needed for adequate spatulation and scar tissue removal. One solution has been to perform the more difficult portions of the surgery in an extracorporeal manner. A hybrid intracorporeal-extracorporeal approach to upper tract ureteral reconstruction facilitates ureteral preparation at the stage of mastering the technique.

Material and methods

This retrospective study included 100 patients with primary ureteropelvic junction obstruction, who underwent laparoscopic pyeloplasty from 2014 to 2017. The patients were stratified into 2 groups: those who underwent conventional laparoscopic surgery and those who were managed with the hybrid approach. For the hybrid approach, externalizing the ureter to skin level required additional mobilization of the upper urinary tract.

Results

A total of 47 patients underwent conventional laparoscopic pyeloplasty and 53 - hybrid surgery. The maximum body mass index was 32. The hybrid approach was 8.5 minutes shorter compared to the conventional approach (p <0.001). No complications higher than Clavien-Dindo IIIb (n = 2) were observed (in both groups). Complete success (the resolution of pain and/or hydronephrosis) was observed in 92.5% in the hybrid group and in 95.7% in the conventional treatment group.

Conclusions

Hybrid pyeloplasty may be considered safe and effective. It has the advantage of making the surgery less challenging and time-consuming while offering improved precision. The advantages of the technique are particularly apparent during training. This technique can be recommended in the learning process of the surgeon.

Mobility of Yield Stress Fluids on Lubricant-Impregnated Surfaces

A common problem which we encounter on a daily basis is dispensing of yield stress fluids such as condiments, lotions, toothpaste, etc. from containers. Beyond consumer products, assuring the flow of yield stress fluids such as crude oil, mud, blood, paint, pharmaceutical products, and others, is essential for the respective industries. Elimination of wall-induced friction can lead to significant savings in the energy required for flow of yield stress fluids, as well as associated product loss and cleaning costs. Lubricant-impregnated surfaces (LIS) have been shown to change the dynamic behavior of yield stress fluids and enable them to flow without shearing. Despite the wide applicability of this technology and its general appeal, the fundamental physics governing the flow of yield stress fluids on LIS have not yet been fully explained. In this work, we study the mobility of yield stress fluids on LIS, and explain the relationship between their macroscale flow behavior and the microscale properties of LIS. We show that for yield stress fluids the thermodynamic state of an LIS can be the difference between mobility and immobility. We demonstrate that LIS can induce mobility in yield stress fluids even below their yield stress allowing them to move as a plug without shearing with an infinite slip length. We identify different mobility mechanisms and establish a regime map for drag reduction in terms of the shear stress to yield stress ratio and the microscopic properties of the LIS. We demonstrate these regimes in a practical application of pipe flow thereby providing key insights for the design of LIS to induce mobility of yield stress fluids in a broad range of practical applications.

Monopolar enucleation versus transurethral resection of the prostate for small- and medium-sized (< 80 cc) benign prostate hyperplasia: a prospective analysis

AIM

To assess efficacy and safety of monopolar enucleation of the prostate (MEP) and to compare it with the current treatment standard for medium-sized prostates, < 80 cc, transurethral resection of the prostate (TURP).

METHODS

A prospective analysis patients undergoing a surgical procedure for their diagnosis of BPH (benign prostatic hyperplasia) (IPSS > 20, Q_max < 10; prostate volume < 80 cc) was performed. IPSS, Q_max were assessed preoperatively, at 6 and 12 months postoperatively. The complications were classified according to the modified Clavien-Dindo grading system.

RESULTS

A total of 134 patients were included in the study: 70 underwent MEP and 64 - TURP for BPH (mean prostate volumes were comparable with p = 0.163). The mean surgery time was 44 min in the TURP group and 48.2 min in the MEP group, (p = 0.026). Catheterization time for MEP was 1.7 and 3.2 days for TURP (p < 0.001). Hospital stay for MEP was 3.2 days vs. 4.8 days for TURP (p < 0.001). Both techniques shown comparable efficiency in benign prostatic obstruction relief with IPSS drop in MEP from 23.1 to 5.9 and in TURP group from 22.8 to 7.3, whereas Q_max increased from 8.2 to 20.5 after MEP and from 8.3 and 19.9 after TURP. Urinary incontinence rate after catheter removal in TURP group was 9.0% and 7.8% in MEP group, at 1 year follow-up, it was 1.4% and 3.1% in MEP and TURP, respectively (p = 0.466).

CONCLUSIONS

Our experience demonstrated that MEP is an effective and safe BPH treatment option combining the efficacy of endoscopic enucleation techniques and accessibility of conventional TURP.

Radical prostatectomy performed via robotic, transperitoneal and extraperitoneoscopic approaches: functional and early oncological outcomes

Introduction

Oncological remission along with high postoperative functionality [continence and erectile function (EF)] are the main aspects of prostate cancer (PCa) treatment. The aim of this study was to compare functional and oncological treatment results achieved after a nerve-sparing radical prostatectomy (RP) via transperitoneal (TPRP), extraperitoneal (EPRP) and robot-assisted (RARP) approach.

Material and methods

From March 2015 to March 2016, 507 RP were performed at the Institute for Urology and Reproductive Health (Moscow, Russia). A total of 264 patients with localized (cТ1а–2с) prostate cancer [prostate-specific antigen (PSA) <20 ng/ml, Gleason score ≤7], intact prostate capsule (according to MRI), International Index of Erectile Function (IIEF-5) ≥19 and a life expectancy >10 years were included into the retrospective study. All the surgeries were performed by a single surgeon. The outcomes were evaluated after urethral catheter removal and 3–6–12 months after RP.

Results

Nerve preservation (NP) was performed for 153 patients without significant distinctions in time (р = 0.064) and blood loss (р = 0.073). The International Consultation on Incontinence Questionnaire-Urinary Incontinence Short Form (ICIQ-SF) score was lower for NP: 9.23 ±6.59 and 3.86 ±5.38 after 3 and 12 months respectively compared with continence after RP without nerve preservation (NP): 14.27 ±5.1 vs. 6.15 ±4.76 (р <0.001). Continent was 52.2% vs. 83.3% vs. 81.8% in TPRP, RARP and EPRP groups; р <0.001. IIEF-5 scores were 14.67 ±9.4, 4.2 ±4.26 and 4.0 ±2.07 after RARP, TPRP and EPRP respectively (р = 0.002). After 12 months the PSA: TPRP = 0.11 ±0.19, RARP = 0.03 ±0.05 and EPRP = 0.53 ±1.87 ng/ml (р <0.001). Outcomes depend on surgical approach and was better in the RARP-group (AUC = 0.768 ±0.034 (CI 95% 0,701–0.834; р <0.001).

Conclusions

We suggest RARP with NP as a method of choice for treatment of prostate cancer in patients interested in preservation of EF and quality of life in general.

Impact of endoscopic enucleation of the prostate with thulium fiber laser on the erectile function

Background

The impact of number of endoscopic enucleation of the prostate techniques (holmium laser enucleation - HoLEP for example) on erectile function have already been investigated. However, the thulium-fiber laser, in this setting remains unstudied. In this study, we compared sexual function outcomes in patients with benign prostatic hyperplasia (BPH) treated with transurethral resection of the prostate (TURP) or thulium-fiber laser enucleation (ThuFLEP).

Methods

We performed a retrospective analysis of patients who underwent transurethral resection and endoscopic enucleation of the prostate for BPH; inclusion criteria was the presence of infravesical obstruction (IPSS > 20, Qmax < 10 mL/s). Erectile function (EF) was assessed using the International Index of Erectile Function (IIEF-5) both prior to endoscopic examination, and six months after.

Results

A total of 469 patients with BPH were included in the study; of these, 211 underwent to ThuFLEP, and 258 TURP. Preoperative IIEF-5 in TURP and ThuFLEP groups were 11.7 (±4.5) and 11.1 (±5.0), respectively (p = 0.17). At six month the IIEF-5 score was unchanged (p = 0.26 and p = 0.08) and comparable in both groups (p = 0.49). However, mean IIEF-5 score shown significant increase of 0.72 in ThuFLEP group, comparing to decrease of 0.24 in TURP patients (p < 0.001).

Conclusions

Both TURP and ThuFLEP are effective modalities in the management of infravesical obstruction due to BPH. At six months follow-up after surgery, both techniques lead to comparable IIEF-5 score. However, our results demonstrated that the ThuFLEP is more likely to preserve the erectile function leading to increase of IIEF-5 at six months in contrast to TURP which lead to slight drop in IIEF-5 score.

A Randomized Trial Comparing The Learning Curve of 3 Endoscopic Enucleation Techniques (HoLEP, ThuFLEP, and MEP) for BPH Using Mentoring Approach-Initial Results

OBJECTIVE

To assess the differences in the learning curve associated with different techniques of endoscopic enucleation of the prostate.

MATERIALS AND METHODS

Ninety patients were randomly assigned into 3 groups (30 patients in each): HoLEP, ThuFLEP or MEP. Inclusion criteria for the study included prostate volume <80 cc, IPSS > 20, or Qmax < 10. The EEPs were performed by 3 surgeons experienced in transurethral resection of the prostate. Assignment of surgeons to surgical technique was also randomized. None of the surgeons had prior experience in EEP.

RESULTS

ThuFLEP was slightly superior (with no significant difference [P > .05]) to HoLEP and MEP in terms of overall enucleation rate-1.0 g/min vs 0.8 g/min and 0.7 g/min, respectively. We observed similar enucleation rates at the initial stages of training (first 20 surgeries) with insignificant increase in ThuFLEP efficiency. At next 10 surgeries ThuFLEP and HoLEP efficiency were higher than of MEP (P < .001) without significant difference between techniques of laser EEP (P = .07).

CONCLUSION

Endoscopic enucleation of the prostate can be adopted safely and effectively within 30 surgeries if the technique is learned with a mentoring approach. EEP is shown to be safe and effective even in the initial stages of learning. Laser EEP (HoLEP, ThuFLEP) appears to lend itself to quicker adaptation compared MEP.

Risk factors for urethral stricture and/or bladder neck contracture after monopolar transurethral resection of the prostate for benign prostatic hyperplasia

Objective:

To identify risk factors for urethral stricture and/or bladder neck contracture after transurethral resection of benign prostatic hyperplasia.

Materials and methods:

We performed a retrospective analysis of 402 patients, which underwent a monopolar transurethral resection of the prostate in the urology clinic of Sechenov First Moscow State Medical University for prostatic hyperplasia during the period 2011–2014. Urethral stricture and (or) bladder neck contracture in the postoperative period were diagnosed in 61 (15.27%) patients; 34 patients (8.6%) had urethral stricture, 20 (4.97%) bladder neck contracture, and 7 (1.7%) had a combination of urethral stricture and bladder neck contracture. In 341 of cases (84.73%), no late postoperative complications were observed. A total of 106 of the 341 patients met the inclusion criteria, hence, containing all the information necessary for analysis such as the volume of the prostate, the duration of the surgery, the size of the endoscope, data on concomitant diseases, analysis prostatic secretion, and so on. Thus, two groups were formed. Group 1 (106 patients) is the control group in which urethral strictures and/or bladder neck contractures did not occur in the long-term postoperative period and group 2 (61 patients), in which was observed the formation of these complications. To calculate the statistical significance of the differences for categorical data, Fisher criterion was used. For quantitative variables, in the case of normal data distribution, an unpaired t-test or one-way analysis of variance was used; for data having a distribution different from normal, a Mann–Whitney rank test was used.

Results:

Regression analysis established the significance of the influence of four factors on the development of scar-sclerotic changes of urethra and bladder neck: the tool diameter 27 Fr ( p < 0.0001), presence of prostatitis in past medical history ( p < 0.0001), prostate volume ( p = 0.003), and redraining of the bladder ( p = 0.0162).

Conclusion:

The relationship between the diameter of the instrument, presence of chronic prostatitis in anamnesis, increased volume of the prostate, and repeated drainage of the bladder using the urethral catheter with the risk of developing scar-sclerotic changes in the urethra and/or bladder neck are statistically reliable and confirmed as a result of regression analysis.

Crystallization-Induced Fouling during Boiling: Formation Mechanisms to Mitigation Approaches

Boiling is significantly altered by the presence of dissolved salts. In particular, salts whose solubility decreases with temperature have the tendency to crystallize and adhere to the heat transfer surface and adversely affect the thermal performance. Scaling due to the precipitation of such salts poses serious operational and safety challenges in several practical applications, including heat exchangers, pipelines, and desalination. Here, we study the effect of dissolved salts on the dynamics of pool boiling and its impact on the heat transfer coefficient and critical heat flux (CHF). We find that even undersaturated conditions can lead to crystallization and scale buildup on the boiling surface and dramatically lower heat transfer performance. For example, the CHF for a salt solution that is 75% of the saturation concentration is found to be at least 2 times lower than that for deionized water. Using simultaneous high-speed optical and infrared imaging, we determine the interdependence between crystallization-induced scale formation and bubble evolution dynamics, including bubble nucleation, growth, and departure. We find that salt crystallizes in a "coffee-ring" pattern due to evaporation at the contact line of the bubble. On the basis of the role of the microlayer and triple contact line on scale formation, we propose manipulating surface wettability as a means to avoid scale formation and the associated decrease in the heat transfer coefficient. Surfaces with hybrid wettability are demonstrated as a means to mitigate the reduction in the heat transfer coefficient and CHF in the presence of dissolved salts.

Radially Ejected Bubbles Driven by Thermocapillarity in Equilibrated Vapor-Liquid Mixtures

We report a novel nucleation method that exploits thermocapillary forces in binary fluids to generate a cloud of bubbles ejected radially from a thermally pulsed wire. The bubbles are nucleated within milliseconds of the extinction of the microsecond pulse and are ejected outward from the wire surface due to the thermocapillary force created by the radial temperature gradient. At low temperatures the surface tension of the vapor-liquid mixture, consisting of ethane-n-octane, increases with increasing temperature, ejecting the bubbles away from the heated wire. By proper choice of fluid composition, temperature, or pressure, the sign of the surface tension gradient can be inverted such that nucleated bubbles are attracted to the wire. As opposed to water-alcohol mixtures that have a surface tension minimum, we show that this mixture-which we refer to as an equilibrated vapor-liquid mixture-exhibits a surface tension maximum, creating a unique set of behaviors which have not yet been fully examined in the literature.