Measurement of the anchoring force of covered self-expandable and lumen-apposing metal stents for interventional endoscopic ultrasonography.

OBJECTIVES: Interventional endoscopic ultrasonography is performed for various situations that require drainage, after which stent migration is the most severe adverse event. Several lumen-apposing metal stents (LAMS) and covered self-expandable metal stents (CSEMS) provide antimigration systems; however, their anchoring ability has not been studied well. Therefore, we measured and compared the anchoring force (ACF) of commercially available LAMS and CSEMS. METHODS: Anchoring force was measured for five types of LAMS (NAGI, SPAXUS, Plumber, and AXIOS 8 and 10 mm) and seven types of CSEMS (BCL, SHCL, BCG, BPD [four types of HANAROSTENT], HILZO, Niti-S [Spring Stopper], and Wallflex). We created a phantom model for inducing stent migration. It has a rotatable part as a curved fixture, and we measured ACF at angles between 0° and 40°. RESULTS: The mean ACF at 0° and 20° were NAGI 1.50, 1.84 N, SPAXUS 1.73, 1.72 N, Plumber 2.64, 2.03 N, and AXIOS 3.96, 3.61 N, respectively; and BCL 0.48, 0.53 N, Wallflex 0.53, 0.48 N, SHCL 0.64, 0.73 N, HILZO 1.09, 1.09 N, BCG 1.22, 1.20 N, BPD 1.78, 1.67 N, and Spring Stopper 2.29, 2.51 N. CONCLUSION: We measured ACF in LAMS and CSEMS with a new phantom model. The highest value among the LAMS was for the AXIOS and among the CSEMS was for the Spring Stopper. Some of the ACF values varied with the direction of pull. These findings may have a significant impact on stent selection for interventional endoscopic ultrasonography, and this model can be used to evaluate newly developed stents.

Effects of a Combined Geothermal and Solar Heating System as a Renewable Energy Source in a Pig House and Estimation of Energy Consumption Using Artificial Intelligence-Based Prediction Model.

This experiment evaluated the performance of a combined geothermal heat pump and solar system (GHPS). A GHPS heating system was installed at a pig house and a comparative study was carried out between the environmentally friendly renewable energy source (GHPS) and the traditional heating method using fossil fuels. The impact of both heating systems on production performance, housing environment, noxious gas emission, and energy efficiency were evaluated along with the GHPS system performance parameters such as the coefficient of performance (COP), inlet and outlet water temperature and efficiency of solar collector. The average temperature inside the pig house was significantly higher (p < 0.05) in the GHPS heating system. Similarly, the outflow temperature was increased significantly (p < 0.05) than the inflow temperature. The results of COP and efficiency of the solar system also indicated that the GHPS is an efficient heating system. The electricity consumption and carbon dioxide gas concentration were also reduced (p < 0.05) in the GHPS system. This study also predicts electricity consumption using an artificial intelligence (AI)-based model. The results showed that the proposed model justifies all the acceptance criteria in terms of the correlation coefficient, root mean square value and mean absolute error. The results of our experiment show that the GHPS system can be installed at a pig house for sustainable swine production as a renewable energy source.

Preventive effect of biodegradable stents on biliary stricture and fibrosis after biliary anastomosis in a porcine model.

PURPOSE: The current drain tubes for preventing surgically biliary anastomotic stricture are not naturally and easily removed. If a drain tube using biodegradable material is easily available and the degradation time of the tube is well controlled, surgical anastomotic stricture and fibrosis could be prevented. The aim of this animal study was to evaluate the preventive effect of novel biodegradable stents (BS) on biliary stricture and fibrosis after duct-to-duct (DD) biliary anastomosis. METHODS: Ten mini-pigs were allocated to the control group (n = 5) and or the stent group (n = 5). The common bile duct was exposed through surgical laparotomy and then resected transversely. In the stent group, a 4-mm or 6-mm polydioxanone/magnesium sheath-core BS was inserted according to the width of the bile duct, followed by DD biliary anastomosis. In the control group, DD biliary anastomosis was performed without BS insertion. RESULTS: In the stent group, stents were observed without deformity for up to 4 weeks in all animals. Eight weeks later, histopathologic examination revealed that the common bile duct of the anastomosis site was relatively narrower in circumference in the control group compared to the stent group. The degree of fibrosis in the control group was more marked than in the stent group (3.84 mm vs. 0.68 mm, respectively; P < 0.05). CONCLUSION: Our study showed that novel BS maintained their original shape and radial force for an adequate time and then disappeared without adverse events. The BS could prevent postoperative complications and strictures after DD biliary anastomosis.

Mechanical properties and degradation process of biliary self-expandable biodegradable stents.

OBJECTIVES: The clinical outcomes and prevalence of adverse events associated with biliary biodegradable stents (BS) can differ according to degradation process and time. The aim of this study was to observe the degradation process and time of different BS prototypes, and to evaluate sequential changes in their mechanical properties. METHODS: Using an in vitro bile flow phantom model, we compared degradation time, radial force changes, and morphologic changes among four different BS prototypes: polydioxanone (PDO) BS, polyglycolide (PGA) BS, polydioxanone/poly-l-lactic acid (PDO/PLLA) sheath-core BS, and polydioxaone/magnesium (PDO/Mg) sheath-core BS. Using an in vivo swine bile duct dilation model, we performed a direct peroral cholangioscopy (DPOC) examination to observe the biodegradation process and related adverse events at regular intervals. RESULTS: In the bile flow phantom model, the PGA BS and PDO/Mg BS prototypes showed rapid radial force reduction and morphological changes and complete degradation within six weeks. PDO/PLLA BS maintained high radial force and kept their original shape for longer than the PDO BS, up to 16 weeks. A total of 24 BS were inserted into the dilated bile ducts of 12 swine. In this animal model, DPOC examination revealed that PDO BS and PDO/PLLA BS maintained their original shapes for approximately 12 weeks, but PDO BS showed a greater degree of fragmentation and induced biliary stones and bile duct obstruction. CONCLUSION: Our results showed that PDO/PLLA BS maintained their original shape and radial force for a relatively long time and minimized adverse events.

Performance of disposable endoscopic forceps according to the manufacturing techniques.

BACKGROUND/AIMS: Recently, to lower the production costs and risk of infection, new disposable biopsy forceps made using simple manufacturing techniques have been introduced. However, the effects of the manufacturing techniques are unclear. The aim of this study was to evaluate which types of biopsy forceps could obtain good-quality specimens according to the manufacturing techniques. METHODS: By using an in vitro nitrile glove popping model, we compared the popping ability among eight different disposable biopsy forceps (one pair of biopsy forceps with cups made by a cutting method [cutting forceps], four pairs of biopsy forceps with cups made by a pressing method [pressing forceps], and three pairs of biopsy forceps with cups made using a injection molding method [molding forceps]). Using an in vivo swine model, we compared the penetration depth and quality of specimen among the biopsy forceps. RESULTS: In the in vitro model, the molding forceps provided a significantly higher popping rate than the other forceps (cutting forceps, 25.0%; pressing forceps, 17.5%; and molding forceps, 41.7%; p = 0.006). In the in vivo model, the cutting and pressing forceps did not provide larger specimens, deeper biopsy specimen, and higher specimen adequacy than those obtained using the molding forceps (p = 0.2631, p = 0.5875, and p = 0.2147, respectively). However, the molding forceps showed significantly more common crush artifact than the others (cutting forceps, 0%; pressing forceps, 5.0%; and molding forceps, 43.3%; p = 0.0007). CONCLUSION: The molding forceps provided lower performance than the cutting and pressing forceps in terms of crush artifact.

Evaluation of valve function in antireflux biliary metal stents.

BACKGROUND: To overcome duodenobiliary reflux induced by biliary stents, antireflux valve (ARV) biliary stents have been developed and showed improvement in stent patency. However, negative study results have also been reported because stent patency may be decreased by the malfunction of ARV itself. Given such mixed results, the true efficacy of ARV remains unknown and the mechanism of its dysfunction needs to be clearly elucidated. The aim of this study was to investigate the exact mechanism of ARV dysfunction using in vitro phantom models. METHODS: Two experimental models were designed to evaluate two important environmental factors suspected to cause ARV malfunction, i.e. bile flow and pH. Three types of ARV metal stents from different companies were used for the experiments: a funnel type ARV, a windsock type ARV, and a wine glass-shaped ARV. Ten stents of each type were tested (five stents in the bile flow phantom model, and another five stents in the duodenal pH environmental model). To determine ARV malfunction, ARV-induced flow resistance was measured using a custom-made testing device. All stents from the two models were removed every 2 weeks for 12 weeks after stent insertion and were evaluated on morphological and functional changes of the ARV. RESULTS: Only ARV of wine glass-shaped ARV was morphologically changed due to silicone bond detachment in the bile flow model. All types of ARV were morphologically changed in the pH model. The morphological changes of ARV influenced the flow resistance. The antegrade pressure gradients were increased over time in the pH model (p < 0.05). CONCLUSIONS: Morphological change of the ARVs may induce dysfunction of ARV metal stents, which is mainly due to duodenal pH environment. In the future, development of new ARV that is not affected by duodenal environmental factors can be expected to improve stent patency.

Effect of preoperative administration of celecoxib on postoperative pain after laparoscopic cholecystectomy.

BACKGROUND: For laparoscopic cholecystectomy, pain is most frequent complaint and the most common cause of delayed discharge. The aim of this study was to determine the effect of preoperative administration of celecoxib on the level of postoperative pain in patient undergoing laparoscopic cholecystectomy. METHODS: We enrolled 60 patients ASA class I and II, scheduled for elective laparoscopic cholecystectomy. The patients were randomized to receive celecoxib 200 mg, celecoxib 400 mg or placebo two hour before the induction of anesthesia. The patients received the same anesthetics. The intensities of abdominal pain were assessed using VAS (visual analog scale) at 1, 2, 4, 12, 24 hours after surgery. RESULTS: In celecoxib 200 mg group, VAS score of somatic pain compared to control group decreased at 1, 2, and 4 hours after surgery. In celecoxib 400 mg group, VAS score of somatic pain compared to control group decreased at 1, 2, and 4 hours after surgery. There was no difference between celecoxib 200 mg and celecoxib 400 mg in pain scores of somatic pain. Dosage of meperidine in two celecoxib groups after surgery were each 31 mg and 26 mg and that of control group was 72 mg. There was no difference between celecoxib groups and placebo group in pain scores of visceral pain. CONCLUSIONS: The preoperative administration of celecoxib reduces the level of postoperative pain after laparoscopic cholecystectomy without adverse effects.

Very late stent thrombosis of DES implanted patient during noncardiac surgery: A case report.

Very late stent thrombosis after implantation of drug eluting stent is rare, but its consequences are potentially fatal. Stent thrombosis may be occurred in perioperative period because of interruption of anticoagulation therapy and intraoperative hypercoagulability. We report a case of very late stent thrombosis in a 49-year-old male patient during total gastrectomy. ST-segment elevation in lead II occurred during the surgery and followed by cardiac arrest. After external cardiac massage and electrocardioversion, normal sinus rhythm was restored. Postoperative 12 lead ECG showed ST-segment elevation in leads II, III, aVF and serum cardiac enzymes such as CPK, CK-MB, and Troponin T were markedly elevated. Postoperative coronary angiography showed complete occlusion of the right coronary artery stent. Emergency percutaneous transluminal coronary angioplasty was performed and the patient recovered uneventfully.