The relevance of reducing Veress needle overshooting.

Safe insertion of the Veress needle during laparoscopy relies on the surgeons' technical skills in order to stop needle insertion just in time to prevent overshooting in the underlying organs. To reduce this risk, a wide variety of Veress needle systems were developed with safety mechanisms that limit the insertion speed, insertion depth or decouple the driving force generated by the surgeon's hand on the needle. The aim of this study is to evaluate current surgeons' perceptions related to the use of Veress needles and to investigate the relevance of preventing overshooting of Veress needles among members of the European Association of Endoscopic Surgery (EAES). An online survey was distributed by the EAES Executive Office to all active members. The survey consisted of demographic data and 14 questions regarding the use of the Veress needle, the training conducted prior to usage, and the need for any improvement. A total of 365 members residing in 58 different countries responded the survey. Of the responding surgeons, 36% prefer the open method for patients with normal body mass index (BMI), and 22% for patients with high BMI. Of the surgeons using Veress needle, 68% indicated that the reduction of overshoot is beneficial in normal BMI patients, whereas 78% indicated that this is beneficial in high BMI patients. On average, the members using the Veress needle had used it for 1448 (SD 3031) times and felt comfortable on using it after 22,9 (SD 78,9) times. The average years of experience was 17,6 (SD 11,1) and the surgeons think that a maximum overshoot of 9.4 (SD 5.5) mm is acceptable before they can safely use the Veress needle. This survey indicates that despite the risks, Veress needles are still being used by the majority of the laparoscopic surgeons who responded. In addition, the surgeons responded that they were interested in using a Veress needle with an extra safety mechanism if it limits the risk of overshooting into the underlying structures.

The changing face of reoperative parathyroidectomy: a single-centre comparison of 147 parathyroid reoperations.

INTRODUCTION: Reoperative parathyroidectomy for persistent and recurrent primary hyperparathyroidism is dependent on radiology. This study aimed to compare outcomes in reoperative parathyroidectomy at a single centre using a combination of traditional and newer imaging studies. MATERIALS AND METHODS: Retrospective case note review of all reoperative parathyroidectomies for persistent and recurrent primary hyperparathyroidism over five years (June 2014 to June 2019; group A). Imaging modalities used and their positive predictive value, complications and cure rates were compared with a published dataset spanning the preceding nine years (group B). RESULTS: From over 2000 parathyroidectomies, 147 were reoperations (101 in group A and 46 in group B). Age and sex ratios were similar (56 vs 62 years; 77% vs 72% female). Ultrasound use remains high and shows better positive predictive value (76% vs 57 %). 99mTc-sestamibi use has declined (79% vs 91%) but the positive predictive value has improved (74% vs 53%). 4DCT use has almost doubled (61% vs 37%) with better positive predictive value (88% vs 75%). 18F-fluorocholine positron emission tomography-computed tomography and ultrasound-guided fine-needle aspiration for parathyroid hormone are novel modalities only available for group A. Both carried a positive predictive value of 100%. Venous sampling with or without angiography use has decreased (35% vs 39%) but maintains a high positive predictive value (86% vs 91%). Cure rates were similar (96% vs 100%). Group A had 5% permanent hypoparathyroidism, 1% permanent vocal cord palsy and 1% haematoma requiring reoperation. No complications for group B. CONCLUSION: Optimal imaging is key to good cure rates in reoperative parathyroidectomy. High-quality, non-interventional imaging techniques have produced a shift in the preoperative algorithm without compromising outcomes.

Magnetic assessment and modelling of the Aramis undulator beamline.

Within the SwissFEL project at the Paul Scherrer Institute (PSI), the hard X-ray line (Aramis) has been equipped with short-period in-vacuum undulators, known as the U15 series. The undulator design has been developed within the institute itself, while the prototyping and the series production have been implemented through a close collaboration with a Swiss industrial partner, Max Daetwyler AG, and several subcontractors. The magnetic measurement system has been built at PSI, together with all the data analysis tools. The Hall probe has been designed for PSI by the Swiss company SENIS. In this paper the general concepts of both the mechanical and the magnetic properties of the U15 series of undulators are presented. A description of the magnetic measurement equipment is given and the results of the magnetic measurement campaign are reported. Lastly, the data reduction methods and the associated models are presented and their actual implementation in the control system is detailed.

Transverse gradient in Apple-type undulators.

Apple-type undulators are globally recognized as the most flexible devices for the production of variable polarized light in the soft X-ray regime, both at synchrotron and free-electron laser facilities. Recently, the implementation of transverse gradient undulators has been proposed to enhance the performance of new generation light sources. In this paper it is demonstrated that Apple undulators do not only generate linear and elliptical polarized light but also variable transverse gradient under certain conditions. A general theoretical framework is introduced to evaluate the K-value and its transverse gradient for an Apple undulator, and formulas for all regular operational modes and different Apple types (including the most recent Delta type and Apple X) are calculated and critically discussed.

The distribution of fixation durations in infants and naive adults.

The distributions of durations of fixations from infants and free-viewing adults are shown to be basically exponential for different stimulus conditions. It is found that fixation duration can be divided into two periods. One, the alpha-period, is a refractory period during which a saccade does not occur and fluctuates across fixations. The other, the beta-period, is a random variable intrinsic to each fixation and constitutes a waiting-time for a saccade that occurs with constant probability per unit time. It is shown that mean duration decreases when stimulus size increases. These results suggest that fixations are terminated by saccades triggered by non-foveal stimulation.