"Five steps four quadrants" modularized en bloc dissection technique for accessing hepatic hilum lymph nodes in laparoscopic pancreaticoduodenectomy

BACKGROUND Although en bloc dissection of hepatic hilum lymph nodes has many advantages in radical tumor treatment,the feasibility and safety of this approach for laparo-scopic pancreaticoduodenectomy(LPD)require further clinical evaluation and investigation.AIM To explore the application value of the"five steps four quadrants"modularized en bloc dissection technique for accessing hepatic hilum lymph nodes in LPD patients.METHODS A total of 52 patients who underwent LPD via the"five steps four quadrants"modularized en bloc dissection technique for hepatic hilum lymph nodes from April 2021 to July 2023 in our department were analyzed retrospectively.The patients'body mass index(BMI),preoperative laboratory indices,intraoperative variables and postoperative complications were recorded.The relationships between preoperative data and intraoperative lymph node dissection time and blood loss were also analyzed.RESULTS Among the 52 patients,36 were males and 16 were females,and the average age was 62.2±11.0 years.There were 26 patients with pancreatic head cancer,16 patients with periampullary cancer,and 10 patients with distal bile duct cancer.The BMI was 22.3±3.3 kg/m²,and the median total bilirubin(TBIL)concentration was 57.7(16.0-155.7)µmol/L.All patients successfully underwent the"five steps four quadrants"modularized en bloc dissection technique without lymph node clearance-related complications such as postoperative bleeding or lymphatic leakage.Correlation analysis revealed significant associations between preoperative BMI(r=0.3581,P=0.0091),TBIL level(r=0.2988,P=0.0341),prothrombin time(r=0.3018,P=0.0297)and lymph node dissection time.Moreover,dissection time was significantly correlated with intraoperative blood loss(r=0.7744,P<0.0001).Further stratified analysis demonstrated that patients with a preoperative BMI≥21.9 kg/m²and a TIBL concentration≥57.7μmol/L had significantly longer lymph node dissection times(both P<0.05).CONCLUSION The"five steps four quadrants"modularized en bloc dissection technique for accessing the hepatic hilum lymph node is safe and feasible for LPD.This technique is expected to improve the efficiency of hepatic hilum lymph node dissection and shorten the learning curve;thus,it is worthy of further clinical promotion and application.

Chebyshev Fitting Way and Error Analysis for Propeller Atlas across Four Quadrants

A Chebyshev fitting way for a propeller atlas across four quadrants is discussed. As an example, Chebyshev polynomial fitting results and its error analysis are given. Because it’s difficult generally to get a propeller atlas across four quadrants, a way is used to construct an alternative with higher accuracy based on the properties. As an application example, an alternative for the propeller property of a Deep Submergence Vehicle across four quadrants is given practically and a simulation model of the four quadrants propeller for dynamic condition is set up. The model lays a foundation for DSV full operating-condition movement simulation. A lot of simulation work shows that the results are very close to the practical data and, therefore, are effective.

Experimental study of the flow field of a high head model pump turbine based on PIV technique

Pumped storage units are the main parts in China’s power construction,as a hot issue concerned by the industry.The pump turbine involves the two-way flows and a multiple condition operation,and its operation flow pattern is very complex.The particle image velocimetry(PIV)is a very effective test technique to determine the internal flow field of pump turbines.This paper discusses the key problems of the pump turbine,based on the PIV experiments under typical conditions of the pump turbine,especially for problems such as the S-shape problem,the hump problem,the pressure fluctuation problem and the cavitation problem.In the internal flow fields under typical conditions are determined.The vortices induced and their development are observed in the PTV test.The flow phenomenon is shown at each operating point.The typical problems of the pump turbine are closely related to the vortex distribution in the internal flow field.From the PIV test results under several working conditions and from the comparisons between the optimal condition and the part load condition,it is seen that the vortex distributions are very different.Vortices at the vane-less area between the guide vane and the runner are closely related to the strong pressure pulsation,the first hump and the S-shape curve.From the PIV results of the cavitation working points,it is seen that the flow angle is changed in the vane-less region and the runner leading edge because of the cavitation bubbles and that the flow angle deviates from the optimal setting angle.From the computational fluid dynamics(CFD)result of the second hump working points,it is concluded that the vortex shedding on the runner leading edge is the main cause of the second hump.