Subject(s)
Laparoscopy , Leiomyosarcoma , Stomach Neoplasms , Humans , Leiomyosarcoma/surgery , Gastrectomy , Stomach , Stomach Neoplasms/surgerySubject(s)
Leiomyoma , Rectal Neoplasms , Robotic Surgical Procedures , Robotics , Humans , Leiomyoma/surgery , Rectal Neoplasms/surgeryABSTRACT
PURPOSE: Robotics has shown encouraging results for a number of technically demanding abdominal surgeries including pancreaticoduodenectomy, which has originally represented a relative contraindication to the application of the minimally-invasive technique. We aimed to investigate the perioperative, clinicopathologic, and oncological outcomes of robot-assisted pancreaticoduodenectomy by assessing a consecutive series of totally robotic procedures. METHODS: All consecutive patients who underwent robotic pancreaticoduodenectomy were included in the present analysis. Perioperative, clinicopathologic and oncological outcomes were examined. In order to investigate the role of the learning curve, surgical outcomes were also used to compare the early and the late phase of our experience. RESULTS: A total of 59 patients underwent surgery. Median hospital stay was 9 days (5 - 110), with an overall morbidity and mortality of 37% and 3%, respectively. Of note, the rate of clinically relevant pancreatic fistula was 11.8%. R0 resections were achieved in 96% of patients and the 3-year disease-free and overall survivals were 37.2 and 61.9%, respectively. Overall, surgical outcomes did not vary significantly between the first and the late phase of the series. CONCLUSIONS: Robotic pancreaticoduodenectomy can be performed competently. It satisfies all features of oncological adequacy and may offer a number of advantages over standard procedures in terms of surgical results.
Subject(s)
Neoplasm Staging/methods , Pancreatic Neoplasms/surgery , Pancreaticoduodenectomy/methods , Robotic Surgical Procedures/methods , Adult , Aged , Aged, 80 and over , Biopsy, Fine-Needle , Endoscopy, Digestive System , Endosonography , Female , Follow-Up Studies , Humans , Laparoscopy/methods , Learning Curve , Length of Stay/trends , Male , Middle Aged , Pancreatic Neoplasms/diagnosis , Prospective Studies , Tomography, X-Ray Computed , Treatment Outcome , Young AdultABSTRACT
The tunneling region below cutoff frequency of the different modes in an elliptical step-index fiber is examined. The whispering modes can undergo either a pure tunneling or a tunneling-radiating effect, whereas the bouncing modes show only the tunneling-radiating effect.
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Modal dispersion is explained through the frequency dependence of modal caustics in the ray optics treatment of propagation in multimode optical fibers. Examples are shown for different index profiles that give rise to dispersion equalization or deterioration.
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A theoretical investigation is presented on modes and losses of an open resonator terminated by plane mirrors with rims along the edges. Three different shapes are examined: namely, step, sloped, and curved rims. The appropriate integral equation has been solved with the iterative procedure by computer for some low order modes. The losses exhibit an oscillating trend when the rim height varies. For some values of the Fresnel number and of the ratio between the rim width and the mirror semi-aperture, some mode crossings and/or mode inversions have been observed. When suitable rim dimensions are chosen, the losses are noticeably reduced with negligible variations of the field inside the resonator and hence of the mode volume.
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The integral Squation of a "flat-roof resonator" is solved by the Fox and Li method of iteration in a number of particular cases. Mode patterns, phase shifts, and power losses are derived. A good overall agreement is found with the approximate theory previously developed by Toraldo di Francia. Some experimental tests carried out on a microwave model give a further confirmation of the theoretical predictions.
