Realization of the farad from the dc quantum Hall effect with digitally-assisted impedance bridges

A new traceability chain for the derivation of the farad from dc quantum Hall effect has been implemented at INRIM. Main components of the chain are two new coaxial transformer bridges: a resistance ratio bridge, and a quadrature bridge, both operating at 1541 Hz. The bridges are energized and controlled with a polyphase direct-digital-synthesizer, which permits to achieve both main and auxiliary equilibria in an automated way; the bridges and do not include any variable inductive divider or variable impedance box. The relative uncertainty in the realization of the farad, at the level of 1000 pF, is estimated to be 64E-9. A first verification of the realization is given by a comparison with the maintained national capacitance standard, where an agreement between measurements within their relative combined uncertainty of 420E-9 is obtained.Comment: 15 pages, 11 figures, 3 table

Eine mikrorechnergesteuerte digitale Wechselstrommessbruecke mit integriertem Nulldetektor

SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Quality of life after rectal cancer surgery: differences between laparoscopic and transanal total mesorectal excision

Background: Transanal total mesorectal excision (TaTME) is a safe alternative to laparoscopic TME for mid and low rectal cancer. TaTME allows improved visualization of the surgical planes and margins, and may potentially improve oncological outcomes. However, functional results after total mesorectal excision (TME) are variable and there are currently only a few published studies that include functional data related to the outcomes of TaTME. Methods: Fifty-four consecutive patients were included in this study: one group included 27 patients who underwent laparoscopic low anterior and the other included 27 patients who underwent TaTME. All patients were asked to complete five questionnaires related to quality of life (QOL) and function [EQ-5D-3L, EORTC-QLQ C30, EORTC-QLQ C29, Low Anterior Resection Syndrome score (LARS), and International Prostate Symptom Score IPSS]. All TaTME patients were operated on at The Gelderse Vallei Hospital by a single surgeon and had a follow-up of at least 6.6 months. Results: The EORTC-QLQ C30 and EQ-5D-3L questionnaires showed comparable outcomes in terms of QOL between the two groups. Almost all items evaluated by the EORTC-QLQ C29, including sexual outcomes, were similar between the two groups. One item concerning fecal incontinence, however, was scored worse for TaTME. There were no significant differences between the groups in terms of LARS symptoms or urinary function. Conclusions: Patients undergoing laparoscopic or transanal TME showed comparable functional and QOL outcomes. Although the TaTME technique is still evolving, this study indicates that this technique is a safe alternative to laparoscopic surgery in terms of functional outcomes for mid and low rectal cancers

Residual mesorectum on postoperative magnetic resonance imaging following transanal total mesorectal excision (TaTME) and laparoscopic total mesorectal excision (LapTME) in rectal cancer

Background: The standard treatment for mid- and low-rectal cancer is total mesorectal excision. Incomplete excision is an important predictor of local recurrence after rectal cancer surgery. Transanal TME (TaTME) is a new treatment option in which the rectum is approached with both laparoscopic and transanal endoscopic techniques. The aim of the present study was to determine the prevalence and localisation of residual mesorectal tissue by postoperative magnetic resonance imaging (MRI) of the pelvis and compare this between TaTME and laparoscopic TME (LapTME) patients. In addition, we assessed correspondence with histopathological quality. Methods: Two groups of patients with cT1–T3 rectal cancer who underwent TME surgery with primary anastomosis were included, each group consisting of 32 patients. Postoperative T2-weighted MRI of the pelvis was performed at least 6 months after TME surgery and evaluated by two radiologists independently. Residual mesorectum was defined as any residual mesorectal tissue detectable after TME. Localisation of the tissue was categorised in relation to height in the pelvis and position of the level of anastomosis. Results: Residual mesorectal tissue was detected in 3.1% of TaTME patients and of 46.9% in LapTME patients (p < 0.001). Multivariate analysis identified only type of surgery as a significant risk factor for leaving residual mesorectum. Other known risk factors for incomplete TME, such as body mass index (BMI) and male gender, were not significant. No relation was seen between specimen quality and prevalence of residual mesorectum. Conclusions: The completeness of mesorectal excision was significantly better with TaTME than with standard laparoscopic technique

Clinical outcomes and case volume effect of transanal total mesorectal excision for rectal cancer: a systematic review

Transanal total mesorectal excision (TaTME) has been developed to improve quality of TME for patients with mid and low rectal cancer. However, despite enthusiastic uptake and teaching facilities, concern exists for safe introduction. TaTME is a complex procedure and potentially a learning curve will hamper clinical outcome. With this systematic review, we aim to provide data regarding morbidity and safety of TaTME. A systematic literature search was performed in MEDLINE (PubMed), EMBASE (Ovid) and Cochrane Library. Case reports, cohort series and comparative series on TaTME for rectal cancer were included. To evaluate a potential effect of case volume, low-volume centres (n ≤ 30 total volume) were compared with high-volume centres (n > 30 total volume). Thirty-three studies were identified (three case reports, 25 case series, five comparative studies), including 794 patients. Conversion was performed in 3.0% of the procedures. The complication rate was 40.3, and 11.5% were major complications. The quality of the mesorectum was "complete" in 87.6%, and the circumferential resection margin (CRM) was involved in 4.7%. In low- versus high-volume centres, the conversion rate was 4.3 versus 2.7%, and major complication rates were 12.2 versus 10.5%, respectively. TME quality was "complete" in 80.5 versus 89.7%, and CRM involvement was 4.8 and 4.5% in low- versus high-volume centres, respectively. TaTME for mid and low rectal cancer is a promising technique; however, it is associated with considerable morbidity. Safe implementation of the TaTME should include proctoring and quality assurance preferably within a trial setting

Transanal total mesorectal excision for rectal cancer: evaluation of the learning curve

BACKGROUND: Transanal total mesorectal excision (TaTME) provides an excellent view of the resection margins for rectal cancer from below, but is challenging due to few anatomical landmarks. During implementation of this technique, patient safety and optimal outcomes need to be ensured. The aim of this study was to evaluate the learning curve of TaTME in patients with rectal cancer in order to optimize future training programs. METHODS: All consecutive patients after TaTME for rectal cancer between February 2012 and January 2017 were included in a single-center database. Influence of surgical experience on major postoperative complications, leakage rate and operating time was evaluated using cumulative sum charts and the splitting model. Correction for potential case-mix differences was performed. RESULTS: Over a period of 60 months, a total of 138 patients were included in this study. Adjusted for case-mix, improvement in postoperative outcomes was clearly seen after the first 40 patients, showing a decrease in major postoperative complications from 47.5 to 17.5% and leakage rate from 27.5 to 5%. Mean operating time (42 min) and conversion rate (from 10% to zero) was lower after transition to a two-team approach, but neither endpoint decreased with experience. Readmission and reoperation rates were not influenced by surgical experience. CONCLUSIONS: The learning curve of TaTME affected major (surgical) postoperative complications for the first 40 patients. A two-team approach decreased operative time and conversion rate. When implementing this new technique, a thorough teaching and supervisory program is recommended to shorten the learning curve and improve the clinical outcomes of the first patients

Short-term outcomes of transanal completion total mesorectal excision (cTaTME) for rectal cancer: a case-matched analysis

Background: Local excision of early rectal tumors as a rectal preserving treatment is gaining popularity, especially since bowel cancer screening programs result in a shift towards the diagnosis of early stage rectal cancers. However, unfavorable histological features predicting high risk for recurrence within the “big biopsy” may mandate completion total mesorectal excision (cTME). Completion surgery is associated with higher morbidity, poorer specimen quality, and less favorable oncological outcomes compared to primary TME. Transanal approach potentially improves outcome of completion surgery for rectal cancer. The aim of this study was to compare radical completion surgery after local excision for rectal cancer by the transanal approach (cTaTME) with conventional abdominal approach (cTME). Methods: All consecutive patients who underwent cTaTME for rectal cancer between 2012 and 2017 were case-matched with cTME patients, according to gender, tumor height, preoperative radiotherapy, and tumor stage. Surgical, pathological, and short-term postoperative outcomes were evaluated. Results: In total, 25 patients underwent completion TaTME and were matched with 25 patients after cTME. Median time from local excision to completion surgery was 9 weeks in both groups. In the cTaTME and cTME groups, perforation of the rectum occurred in 4 and 28% of patients, respectively (p = 0.049), leading to poor specimen quality in these patients. Number of harvested lymph nodes was higher after cTaTME (median 15; range 7–47) than after cTME (median 10; range 0–17). No significant difference was found in end colostomy rate between the two groups. Major 30-day morbidity (Clavien–Dindo≥ III) was 20 and 32%, respectively (p = 0.321). Hospital stay was significantly longer after cTME. Conclusion: TaTME after full-thickness excision is a promising technique with a significantly lower risk of perforation of the rectum and better specimen quality compared to conventional completion TME

Structured training pathway and proctoring; multicenter results of the implementation of transanal total mesorectal excision (TaTME) in the Netherlands

Background: Transanal total mesorectal excision (TaTME) is a new complex technique with potential to improve the quality of surgical mesorectal excision for patients with mid and low rectal cancer. The procedure is technically challenging and has shown to be associated with a relative long learning curve which might hamper widespread adoption. Therefore, a national structured training pathway for TaTME has been set up in the Netherlands to allow safe implementation. The aim of this study was to monitor safety and efficacy of the training program with 12 centers. Methods: Short-term outcomes of the first ten TaTME procedures were evaluated in 12 participating centers in the Netherlands within the national structured training pathway. Consecutive patients operated during and after the proctoring program for rectal carcinoma with curative intent were included. Primary outcome was the incidence of intraoperative complications, secondary outcomes included postoperative complications and pathological outcomes. Results: In October 2018, 12 hospitals completed the training program and from each center the first 10 patients were included for evaluation. Intraoperative complications occurred in 4.9% of the cases. The clinicopathological outcome reported 100% for complete or nearly complete specimen, 100% negative distal resection margin, and the circumferential resection margin was positive in 5.0% of patients. Overall postoperative complication rate was 45.0%, with 19.2% Clavien–Dindo ≥ III and an anastomotic leak rate of 17.3%. Conclusions: This study shows that the nationwide structured training program for TaTME delivers safe implementation of TaTME in terms of intraoperative and pathology outcomes within the first ten consecutive cases in each center. However, postoperative morbidity is substantial even within a structured training pathway and surgeons should be aware of the learning curve of this new technique