Residual heat during laser ablation of metals with bursts of ultra-short pulses

Abstract The usage of pulse bursts allows increasing the throughput, which still represents a key factor for machining with ultra-short pulsed lasers. The influence of the number of pulses within a burst on the specific removal rate is investigated for copper and stainless steel. Furthermore, calorimetric measurements were performed to estimate the residual energy coefficient as well as the absorptance of machined surfaces for copper to explain the reduced specific removal rate for a 2-pulse burst and the similar or even higher rate for a 3-pulse burst compared to single pulse ablation. Based on the measurements, a description of the process using single pulses and pulse bursts with up to three pulses is presented.</jats:p

Influence of the Burst Mode onto the Specific Removal Rate for Metals and Semiconductors

For most applications, the benefit of the burst mode can easily be explained: the energy of each pulse in an n-pulse burst is n times smaller compared to single pulses with identical average power and repetition rate. Thus, the peak fluence of each pulse is nearer the optimum value and the removal rate is therefore increased. It is generally not as high as it would be if single pulses with identical peak fluence but n times higher repetition rate could be applied. However, there are situations where the burst mode can lead to higher efficiencies, i.e., specific removal rates and a real increase in the removal rate can be obtained. For copper at 1064 nm and with a 3-pulse burst, the specific removal rate amounts to about 118% of a single pulse. For silicon, a huge increase from 1.62 to 4.92 μm3/μJ was observed by applying an 8-pulse burst. Based on calorimetric measurements on copper and silicon, the increased absorptance resulting from a rougher surface is identified as an effect which could be responsible for this increase of the specific removal rate. Thus, the burst mode is expected to be able to influence surface parameters in a way that higher efficiencies of the ablation process can be realized

Extraperitoneal extravesical robot-assisted simple prostatectomy (EE-RASP) with intraprostatic urethral reconstruction

Objective: To describe a safe and effective robot-assisted surgical technique performing prostate enucleation through extraperitoneal and extravesical approach with reconstruction of the prostatic urethra. Patients: We reviewed the first 17 patients with a minimum follow up of one year who underwent extraperitoneal extravesical robot-assisted simple prostatectomy (EE-RASP) with intraprostatic urethral reconstruction between July 2019 and March 2020. Surgical procedure: : The bladder neck and proximal prostatic urethra are dissected bluntly remaining extravesical. After transection of the proximal prostatic urethra and enucleation, continuous anastomosis of the proximal with the spared distal prostatic urethra was performed thereby excluding the prostatic cavity. Our video shows all surgical key steps in a patient suffering from benign bladder outlet obstruction undergoing EE-RASP. Results: Seventeen patients who received EE-RASP were eligible for analysis. The median operative time was 173 min (interquartile range [IQR] 165–186) with blood loss of 200 ml (IQR 150–300). The transurethral catheter was removed on the first postoperative day. During 30 days follow up, one patient experienced Clavien-Dindo grade I and four patients grade II complications. The median peak urinary flow rate and post void residual volume at the 1-year follow up were 21 ml/s (IQR 16–26) and 0 ml (IQR 0–40), respectively. All patients remained continent and had significant improvement in IPSS, maximum urinary flow rate, and post void residual volume (p<0.001). Conclusions: Extraperitoneal extravesical robot-assisted simple prostatectomy with intraprostatic urethral reconstruction is a safe procedure providing improved functional outcome. The reconstruction of the prostatic urethra excludes the prostatic cavity and therefore reduces the postoperative risk of bleeding complications and early irritative symptoms

The Association of Ischemia Type and Duration with Acute Kidney Injury after Robot-Assisted Partial Nephrectomy

Background: Acute kidney injury (AKI) after robot-assisted partial nephrectomy (RAPN) is a robust surrogate for chronic kidney disease. The objective of this study was to evaluate the association of ischemia type and duration during RAPN with postoperative AKI. Materials and methods: We reviewed all patients who underwent RAPN at our institution since 2011. The ischemia types were warm ischemia (WI), selective artery clamping (SAC), and zero ischemia (ZI). AKI was defined according to the Risk Injury Failure Loss End-Stage (RIFLE) criteria. We calculated ischemia time thresholds for WI and SAC using the Youden and Liu indices. Logistic regression and decision curve analyses were assessed to examine the association with AKI. Results: Overall, 154 patients met the inclusion criteria. Among all RAPNs, 90 (58.4%), 43 (28.0%), and 21 (13.6%) were performed with WI, SAC, and ZI, respectively. Thirty-three (21.4%) patients experienced postoperative AKI. We extrapolated ischemia time thresholds of 17 min for WI and 29 min for SAC associated with the occurrence of postoperative AKI. Multivariable logistic regression analyses revealed that WIT ≤ 17 min (odds ratio [OR] 0.1, p p = 0.002), and ZI (OR 0.1, p = 0.035) significantly reduced the risk of postoperative AKI. Conclusions: Our results confirm the commonly accepted 20 min threshold for WI time, suggest less than 30 min ischemia time when using SAC, and support a ZI approach if safely performable to reduce the risk of postoperative AKI. Selecting an appropriate ischemia type for patients undergoing RAPN can improve short- and long-term functional kidney outcomes

A systematic review and meta-analysis of the impact of lymphovascular invasion in bladder cancer transurethral resection specimens

International audienceThe aim of the present review was to assess the prognostic impact of lymphovascular invasion (LVI) in transurethral resection (TUR) of bladder cancer (BCa) specimens on clinical outcomes. A systematic review and meta-analysis of the available literature from the past 10 years was performed using MEDLINE, EMBASE and Cochrane library in August 2017. The protocol for this systematic review was registered on PROSPERO (Central Registration Depository: CRD42018084876) and is available in full on the University of York website. Overall, 33 studies (including 6194 patients) evaluating the presence of LVI at TUR were retrieved. LVI was detected in 17.3% of TUR specimens. In 19 studies, including 2941 patients with ≤cT1 stage only, LVI was detected in 15% of specimens. In patients with ≤cT1 stage, LVI at TUR of the bladder tumour (TURBT) was a significant prognostic factor for disease recurrence (pooled hazard ratio [HR] 1.97, 95% CI: 1.47-2.62) and progression (pooled HR 2.95, 95% CI: 2.11-4.13), without heterogeneity (I2 = 0.0%, P = 0.84 and I2 = 0.0%, P = 0.93, respectively). For patients with cT1-2 disease, LVI was significantly associated with upstaging at time of radical cystectomy (pooled odds ratio 2.39, 95% CI: 1.45-3.96), with heterogeneity among studies (I2 = 53.6%, P = 0.044). LVI at TURBT is a robust prognostic factor of disease recurrence and progression in non-muscle invasive BCa. Furthermore, LVI has a strong impact on upstaging in patients with organ-confined disease. The assessment of LVI should be standardized, reported, and considered for inclusion in the TNM classification system, helping clinicians in decision-making and patient counselling

The impact of moderate wine consumption on the risk of developing prostate cancer

Objective: To investigate the impact of moderate wine consumption on the risk of prostate cancer (PCa). We focused on the differential effect of moderate consumption of red versus white wine. Design: This study was a meta-analysis that includes data from casecontrol and cohort studies. Materials and methods: A systematic search of Web of Science, Medline/PubMed, and Cochrane library was performed on December 1, 2017. Studies were deemed eligible if they assessed the risk of PCa due to red, white, or any wine using multivariable logistic regression analysis. We performed a formal meta-analysis for the risk of PCa according to moderate wine and wine type consumption (white or red). Heterogeneity between studies was assessed using Cochranes Q test and I2 statistics. Publication bias was assessed using Eggers regression test. Results: A total of 930 abstracts and titles were initially identified. After removal of duplicates, reviews, and conference abstracts, 83 full-text original articles were screened. Seventeen studies (611,169 subjects) were included for final evaluation and fulfilled the inclusion criteria. In the case of moderate wine consumption: the pooled risk ratio (RR) for the risk of PCa was 0.98 (95% CI 0.921.05, p=0.57) in the multivariable analysis. Moderate white wine consumption increased the risk of PCa with a pooled RR of 1.26 (95% CI 1.101.43, p=0.001) in the multivariable analysis. Meanwhile, moderate red wine consumption had a protective role reducing the risk by 12% (RR 0.88, 95% CI 0.780.999, p=0.047) in the multivariable analysis that comprised 222,447 subjects. Conclusions: In this meta-analysis, moderate wine consumption did not impact the risk of PCa. Interestingly, regarding the type of wine, moderate consumption of white wine increased the risk of PCa, whereas moderate consumption of red wine had a protective effect. Further analyses are needed to assess the differential molecular effect of white and red wine conferring their impact on PCa risk.(VLID)468868