ARTICLE | doi:10.20944/preprints202001.0076.v2
Subject: Medicine & Pharmacology, Gastroenterology Keywords: endoscopic retrograde cholangiopancreatography; periampullary diverticulum; difficult cannulation; biliary cannulation; cannulation techniques; adverse events
Online: 17 January 2020 (04:12:23 CET)
Aim: This study aimed to investigate the association between periampullary diverticulum (PAD) and difficult biliary cannulation, as well as to evaluate the impact of different types of PAD on the cannulation success rate and adverse events. Methods: A total of 636 patients who underwent endoscopic retrograde cholangiopancreatography (ERCP) during the study period were prospectively studied and divided into two groups based on the presence or absence of PAD. In group A, 126 patients had PAD compared with 510 patients in group B without PAD. The primary outcome measurements were ERCP procedures time, selective cannulation techniques, and cannulation difficulty in addition to cannulation success rate and ERCP-related adverse events. The difficult cannulation was analyzed using logistic regression considering age, co-morbidities, the presence of PAD types, and indications as independent factors. Results: The average cohort age was 65.30±16.67 years, and 52.7% were male. Significant higher rates of choledocholithiasis, cholangitis, and biliary pancreatitis were reported in the group of PAD (p<0.05). Successful selective cannulation was achieved in 97.6% in group A and 95.3% in group B (p>0.05). The cannulation time was significantly longer in the presence of PAD (5.1 min, vs. 4.09 min, p<0.05). There was no significant difference in the rate of overall adverse events and post ERCP pancreatic PEP. Conclusion: The presence of PAD did not affect the duration or success of the ERCP procedure. Furthermore, it was associated with longer cannulation time and increase in the cannulation difficulty, especially with PAD type 1.
ARTICLE | doi:10.20944/preprints201909.0214.v1
Subject: Medicine & Pharmacology, Gastroenterology Keywords: endoscopic retrograde cholangiopancreatography; elderly; adverse event; difficult cannulation
Online: 18 September 2019 (17:54:04 CEST)
Endoscopic retrograde cholangiopancreatography (ERCP) is a routinely used therapeutic procedure for the biliary and pancreatic diseases. Population aging may increase the typical indications of ERCP and come with more complexity and difficulties, especially in cannulation. This study aimed to evaluate the incidence, causes, and management of difficult biliary cannulation during ERCP in super-aged patients and the role of difficult cannulation as a risk factor for adverse events. A total of 614 patients, underwent ERCP, were prospectively studied as a cohort and divided into two groups based on their age. There were 146 patients aged 80 years or older in group A and 468 patients aged less than 80 years in group B. The primary outcome measures were the difficulty grade of papilla cannulation, clinical outcomes, and ERCP-related complications in the two groups. The adverse events were analyzed using logistic regression for patient age, co-morbidities, indications, and cannulation difficulty grade variables. There was no difference in the incidence of difficult cannulation between the two groups (32.9% vs. 34.4%, p=0.765) though, as expected, super-aged Group A had a higher prevalence of periampullary diverticulum (29.5% vs. 16.7%, p=0.001). The technical cannulation success rate was (96.6% vs. 96.8%, p= 0.54). All used cannulation techniques in the elderly group were efficient and safe. Logistic regression showed that age ≥80 was not associated with increased adverse events; however, difficult cannulation (adjusted odds ratio [AOR]=3.478; 95% confidence interval [CI]=1.877, 6.442; p<0.001) and CCI ≥2 (AOR=1.824; 95% CI=0.993, 3.349; p=0.045) were more likely to have adverse events. Age ≤65 (AOR=3.460; 95% CI=1.511, 7.922; p=0.003), female gender (AOR=2.362; 95% CI=1.089, 5.124; p=0.030), difficult cannulation (AOR=4.527; 95% CI=2.078, 9.860; p<0.001), and patients with cholangitis (AOR=3.261; 95% CI=1.204, 8.832; p=0.020) were strongly associated with increasing Post-ERCP Pancreatitis (PEP). Advanced age has not proved to be a risk factor of difficult cannulation, and secondary cannulation techniques can be safely and efficaciously utilized for this group. CCI ≥2 and difficult cannulation are associated with increased overall adverse events rate while age ≥80 factor is not.
ARTICLE | doi:10.20944/preprints201810.0685.v1
Subject: Engineering, Mechanical Engineering Keywords: Laser-assisted milling; Curved workpiece; Difficult-to-cut material; Milling tool path; Nickel alloy
Online: 29 October 2018 (13:19:51 CET)
Difficult-to-cut materials are being increasingly used in many industries because of their superior properties, including high corrosion resistance, heat resistance and specific strength. However, these same properties make the materials difficult to machine using conventional machining techniques. Laser-assisted milling (LAM) is one of the effective methods for machining difficult-to-cut materials. In laser-assisted milling machining occur after the workpiece is locally preheated using a laser heat source. Laser assisted machining has been studied by many researchers on flat workpiece or micro end-milling. However, there is no research on the curved shape using laser assisted milling. This study investigated the use of laser assisted milling to machine a three-dimensional curved shape workpiece based on NURBS. A machining experiment was performed on Inconel 718 using different tool paths (ramping, contouring) under various machining conditions. Finite elements analysis was conducted to determine the depth of cut. Cutting force, specific cutting energy and surface roughness characteristics were measured, analyzed and compared for conventional and LAM machining. LAM significantly improved these machining characteristics, compared to conventional machining. There results can be applied to the laser-assisted machining of various three-dimensional shapes.