Management of malignant bile duct obstruction

Flexible Automation System for Determination of Elemental Composition of Incrustations in Clogged Biliary Endoprostheses Using ICP-MS

Automation systems are well established in industries and life science laboratories, especially in bioscreening and high-throughput applications. An increasing demand of automation solutions can be seen in the field of analytical measurement in chemical synthesis, quality control, and medical and pharmaceutical fields, as well as research and development. In this study, an automation solution was developed and optimized for the investigation of new biliary endoprostheses (stents), which should reduce clogging after implantation in the human body. The material inside the stents (incrustations) has to be controlled regularly and under identical conditions. The elemental composition is one criterion to be monitored in stent development. The manual procedure was transferred to an automated process including sample preparation, elemental analysis using inductively coupled plasma mass spectrometry (ICP-MS), and data evaluation. Due to safety issues, microwave-assisted acid digestion was executed outside of the automation system. The performance of the automated process was determined and validated. The measurement results and the processing times were compared for both the manual and the automated procedure. Finally, real samples of stent incrustations and pig bile were analyzed using the automation system.

Application of a Dual-Arm Robot in Complex Sample Preparation and Measurement Processes

Automation systems with applied robotics have already been established in industrial applications for many years. In the field of life sciences, a comparable high level of automation can be found in the areas of bioscreening and high-throughput screening. Strong deficits still exist in the development of flexible and universal fully automated systems in the field of analytical measurement. Reasons are the heterogeneous processes with complex structures, which include sample preparation and transport, analytical measurements using complex sensor systems, and suitable data analysis and evaluation. Furthermore, the use of nonstandard sample vessels with various shapes and volumes results in an increased complexity. The direct use of existing automation solutions from bioscreening applications is not possible. A flexible automation system for sample preparation, analysis, and data evaluation is presented in this article. It is applied for the determination of cholesterol in biliary endoprosthesis using gas chromatography-mass spectrometry (GC-MS). A dual-arm robot performs both transport and active manipulation tasks to ensure human-like operation. This general robotic concept also enables the use of manual laboratory devices and equipment and is thus suitable in areas with a high standardization grade.

Fate of patients with obstructive jaundice

BACKGROUND/OBJECTIVE

Systematic data are limited on the etiology and prognosis of unselected patients with obstructive jaundice (OJ). We aimed to review the clinical features, etiology, and prognosis of patients with OJ.

METHODS

All adult patients with bilirubin >or= 5.85 mg/dL (100 micromol/L) at a university hospital in Sweden in 2003-2004 were identified. Medical records from patients with OJ were reviewed.

RESULTS

Seven hundred and forty-nine patients were identified, of whom 241 (32%) had OJ (median age 71 years, 129 women). No one was lost to follow-up. The biliary obstruction of 154 patients (64%) was a result of a malignancy: 69 patients (46%) had pancreatic cancer, 44 (29%) had cholangiocarcinoma (CC), 5 (3%) had papilla vateri cancers, and 36 patients (23%) had other malignancies. Of the 87 patients with a benign obstruction, 57 (65%) had choledocholithiasis, 7 (8%) had biliary strictures, 6% had PSC, and the obstruction of 16 patients (20.7%) had other causes. A total of 115 of the 242 patients (48%) had abdominal pain associated with jaundice, whereas 52% had painless jaundice. Thirty-four percent of patients with a malignant obstruction had abdominal pain versus 71% of patients with a benign obstruction (P < .05). At the end of follow-up, only 5% (8 patients) with a malignant obstruction were alive versus 78% with a benign obstruction.

CONCLUSIONS

Obstructive jaundice was the cause of the severe jaundice of one third of patients. Most cases of OJ were a result of a malignancy, which carried a very poor prognosis, with a 2-year mortality rate of 95%.

Radiation dose and risk from fluoroscopically guided percutaneous transhepatic biliary procedures

PURPOSE

To estimate radiation dose and associated risks after fluoroscopically guided percutaneous transhepatic biliary (PTB) drainage and stent implantation procedures.

MATERIALS AND METHODS

Organ and effective doses, normalized to dose-area product (DAP), were estimated for PTB procedures with use of a Monte Carlo transport code and an adult mathematical phantom. Exposure parameters from 51 consecutive patients were used to determine average examination parameters for biliary drainage and stent implantation procedures. Thermoluminescent dosimeters were used in an anthropomorphic phantom to verify Monte Carlo calculations. Radiation-induced cancer and genetic risks were estimated.

RESULTS

The results consist of doses normalized to DAP so patient dose from any technique and x-ray unit can be easily calculated for left and right biliary access and for separate or combined biliary and metallic stent implantation sessions. A good agreement was found between Monte Carlo-calculated data and data derived from thermoluminescent dosimetry. The average effective dose varied from 1.8 to 5.4 mSv depending on procedure approach (left vs right access) and procedure scheme. A maximum effective dose of 13 mSv was estimated for 30 minutes of fluoroscopy.

CONCLUSIONS

Doses delivered to patients undergoing PTB procedures are comparable to those that arise from computed tomography protocols. Radiation-induced cancer risk may be considerable for young patients undergoing PTB drainage and stent implantation procedures.

Occupational radiation exposure from fluoroscopically guided percutaneous transhepatic biliary procedures

PURPOSE

The aim of this study was to determine occupational dose levels for projections commonly used in fluoroscopically guided percutaneous transhepatic biliary (PTB) drainage and stent placement procedures.

METHODS

Exposure data from 71 consecutive PTB examinations were analyzed to determine average examination parameters for biliary drainage and stent placement procedures. An anthropomorphic phantom was exposed at three projections common in PTB interventions according to the actual geometric parameters recorded in the patient study. Scattered air-kerma dose rates were measured for neck, waist, and gonad levels at various sites in the interventional radiology laboratory. To produce technique- and instrumentation-independent data, dose rate values were converted to dose-area product (DAP)-normalized air-kerma values. In addition, sets of thermoluminescent dosimetry crystals were placed in both hands of the interventional radiologist to monitor doses during all PTB procedures.

RESULTS

Isodose maps of DAP-normalized air-kerma doses in the interventional laboratory for projections commonly used in PTB procedures are presented. To facilitate effective dose estimation, normalized dosimetric data at the interventional radiologist's position are presented for left and right access drainage procedures, metallic stent placement only, and drainage and metallic stent placement in one-session procedures with and without under-couch shielding. Doses to the hands of interventional radiologists are presented for left and right transhepatic biliary access and metallic stent placement.

CONCLUSIONS

Body level-specific normalized air-kerma distributions from commonly used projections in PTB procedures may be useful to accurately quantify dose, maximum workloads, and possible radiogenic risks delivered to medical personnel working in the interventional radiology laboratory. Normalized dose data presented will enable occupational exposure estimation from other institutions.

Biliary and gastric bypass or stenting in nonresectable periampullary cancer: analysis on the basis of controlled trials

BACKGROUND

The median survival rate of patients with nonresectable periampullary cancer is not much longer than 6-12 mo. Nevertheless, in most incurable patients palliative treatment is necessary, which has to focus on jaundice, pain, and prevention of gastric outlet obstruction. Up to now, debate remains about how to best provide palliative treatment.

METHOD

The results of controlled clinical trials and large multicenter studies comparing operative biliary bypass and biliary stent insertion in nonresectable pancreatic tumors are discussed in this review.

RESULTS

The initial success rate in palliation of jaundice is similar after endoscopic stent insertion and biliary bypass operation (range: 90-95 %). Morbidity (range: 1 1-36% vs 26-40%) and 30-d mortality (range: 8-20% vs 15-31%) is higher after bypass operation, whereas stent insertion is accompanied by a higher rate of hospital readmission and reintervention because of recurrent jaundice (range: 28-43%) and a later gastric outlet obstruction (up to 17%).

CONCLUSION

Endoscopic biliary stent insertion should be performed if there is evidence of hepatic, peritoneal, or pulmonary metastasis formation, in old patients with a high comorbidity, or if the patient has had several laparotomies. Combined biliary and gastric operative bypass procedures should be performed in nonresectable periampullary carcinomas with accompanying gastric outlet obstruction, in the absence of metastatic spread, if a locally advanced tumor is the only reason for incurability, if exploratory laparotomy demonstrates an unresectable tumor, or if endoscopic treatment fails.

Comparative costs of metal versus plastic biliary stent strategies for malignant obstructive jaundice by decision analysis

BACKGROUND

For palliation of patients with malignant obstructive jaundice, expansile metal stents provide longer patency than plastic stents but are more expensive. The optimal cost-effective strategy has not been established. Our aim was to compare the relative costs of 3 strategies: (1) plastic stent, with exchange on occlusion; (2) metal stent initially, with coaxial plastic stent insertion in the event of occlusion; or (3) plastic stent initially, with metal stent exchange in the event of occlusion.

METHODS

A decision analysis model was created using DATA 2.6 software to assess the relative costs of the three strategies. Values for variables including the probabilities of reintervention and patient survival were obtained from published data. Costs were based on Medicare reimbursements of hospital charges, and the model was evaluated from the perspective of a third-party payer. One-way and two-way sensitivity analysis of the variables was performed over a wide range.

RESULTS

The outcome is highly sensitive to the ratio of metal stent cost relative to endoscopic retrograde cholangiopancreatography cost (cost ratio M:ERCP) and to the length of survival of the patient. The most economical strategies were (2), (3) and (1) for M:ERCP cost ratios of <0.5, 0.5 to 0.7, and >0.7, respectively.

CONCLUSIONS

The choice of stent should be guided by the relative local costs of ERCP and metal stents and by the prognosis of the patient. At current metal stent costs and Medicare reimbursement rates, initial placement of a plastic stent, followed by metal stent placement at first occlusion in longer survivors, is an economical option. If metal stent cost is less than half of ERCP cost, then initial insertion of a metal stent would be most economical. Use of plastic stents is preferable for patients surviving less than 4 months, whereas metal stents are more economical for patients with longer survival.

Therapy for biliary stenoses and occlusions with use of three different metallic stents: single-center experience

PURPOSE

The authors report their experience with three different metallic stents for the treatment of biliary obstructions during a 6.5-year period (between February 1989 and June 1995).

MATERIALS AND METHODS

In an uncontrolled, nonrandomized, and prospective study, 168 patients with obstructive jaundice underwent transhepatic placement of metallic stents. Patients were excluded if they were deemed too ill for intervention or had incorrectable coagulopathy. Those patients undergoing external and/or intraluminal radiation therapy, and patients in whom an internal-external catheter was kept in place after insertion of a stent were not included. Inoperable malignant disease was diagnosed in 157 patients (93.5%). Eleven patients presented with a benign biliary stricture that could not be managed by means of angioplasty. One hundred fifty-five Wallstents were placed in 122 patients, 65 tantalum Strecker stents were placed in 30 patients, and 18 Memotherm stents were placed in 16 patients. The patients were followed until September 1996 or until death.

RESULTS

Regarding malignant obstruction, the 30-day mortality rate was 10.7% without any procedure-related death, and overall survival rates after 100 and 200 days were 63% and 22%, respectively. Regarding benign stricture, eight of 11 patients were alive after a median follow-up of 50.6 months without any 30-day mortality. Major complications occurred in 16 patients (10.2%) who had malignancy, and in two patients (18.2%) with benign biliary disease. The cumulative patency rate in malignant obstructions was significantly higher for the Wallstent than for the Memotherm stent (P < .05) and nonsignificantly higher for the Wallstent than for the tantalum Strecker stent (P > .05). Reintervention due to recurrent obstructive jaundice was necessary in 28 patients (17.8%) with malignancy, and in six patients (54.5%) with benign stricture.

CONCLUSIONS

The Wallstent is the most effective in achieving long-term palliation in patients with malignant obstructive jaundice. The treatment of benign biliary strictures with metallic stents is associated with a low long-term patency rate.

Bacterial biofilm and clogging of biliary stents

Endoscopic biliary stenting has become a standard palliative treatment for obstructive jaundice due to malignancies of the pancreas and the hepatobiliary system. Despite the high initial success rate in achieving biliary drainage, durable endoscopic stenting has been limited by the clogging of biliary stents, usually after 4-5 months, due to formation of an adherent bacterial biofilm. Various methods have been investigated for the prevention of bacterial adhesion and prolongation of stent patency. These include: 1) prophylactic use of antimicrobial agents and bile salts; 2) testing of new stent material and new designs for these biliary stents; and 3) the recent introduction of self-expandable metal stents. Each method has its own merits as well as specific problems. This article reviews the pathogenesis of biofilm formation on the biliary stents and the latest status of research in avoiding the problem of stent occlusion.

Endoscopic stenting for palliation of malignant biliary obstruction. A review of progress in the last 15 years

Since the late 1970s, endoscopic biliary stenting has become a standard palliative treatment for obstructive jaundice due to malignancies of the pancreas and the hepatobiliary system. Despite the high initial success rate in achieving biliary drainage, endoscopic stenting therapy has been limited by the clogging of biliary stents, usually after four to five months, due to formation of adherent bacterial biofilm and accumulation of biliary sludge. Various methods for the prevention of bacterial adhesion and prolongation of stent patency have been investigated, including prophylactic antimicrobial agents and bile salts, new stent materials, and new stent designs. Recently, the introduction of self-expandable metal stents has significantly improved the duration of stent patency but the cost is considerably higher. Each method has its own merits as well as specific problems. This article reviews the pathogenesis of biofilm formation on the biliary stents and the latest status of research in avoiding stent occlusion.

Quality of Life in palliative management of malignant obstructive jaundice

Studies comparing different methods of palliating patients with malignant obstructive jaundice have mainly concentrated on short-term success and complication rates. Seen from the patients perspective, Quality of Life issues may be of equal importance. Instruments are being developed and modified to permit sequential assessment of Quality of Life as an essential part of any studies attempting to evaluate the contribution of different palliative procedures.

Decreased bacterial adherence to silver-coated stent material: an in vitro study

Bacteria are important in causing biliary stent blockage through adherence and subsequent biofilm formation. In our in vitro system, surface modification using test polyurethane discs with silver coating led to a reduction in the number of adherent bacteria compared with untreated controls by 10- to 100-fold in an apparently dose-related manner. The effect was more marked in the presence of bile. These results suggest that silver coating may have a potential benefit in preventing stent blockage.

Peroral radiographic placement of biliary stents

The authors describe a modification of peroral-transhepatic placement of biliary stents for patients with malignant biliary obstruction. A stent is "pulled" into place perorally. The procedure can be performed with simple, readily available commercial materials. An endoscopist is not required. This method is cost-effective, less cumbersome, and easier to perform than the standard methods. In the authors' four cases, this modified approach appears equally effective.

Self-expanding mesh stent for endoscopic palliation of rectal obstructing tumors: a preliminary report

The endoscopic insertion of self-expanding mesh stents in four patients affected by obstructing rectal malignant tumors is reported. The preliminary experience shows that, in the short term, normal defecation was achieved, with no complications. Longer follow-up is necessary to evaluate the duration and the quality of the palliative effect.

Experimental clogging of biliary endoprostheses. Role of bacteria, endoprosthesis material, and design

The major problem facing patients treated with biliary endoprostheses is their frequent clogging, necessitating their exchange. Clogged endoprostheses contain mainly bacteria embedded in an amorphous proteinaceous material with the occasional presence of food fibres. We studied this problem in an in vitro model, evaluating the role of bacteria, endoprosthesis design, and material in sludge formation. We found endoprostheses perfused with artificially contaminated bile to contain significantly more sludge than those perfused with sterile bile (p less than 0.05). The amount of sludge varied with the bacterial species used. Endoprostheses perfused with bacteria producing beta-glucuronidase were not associated with a particularly large amount of sludge. Endoprostheses with side holes contained significantly more sludge than those without (p less than 0.05). Furthermore, endoprostheses made of material with a low friction coefficient, such as Teflon, contained significantly less sludge than endoprostheses made of materials with a higher friction coefficient, such as polyethylene and polyurethane (p less than 0.05). These results emphasize the role of bacteria in endoprostheses clogging and clearly demonstrate the harmful effect that side holes have on endoprosthesis function.

Clogging of biliary endoprostheses. A morphologic and bacteriologic study

The main problem encountered with the use of biliary endoprostheses is their tendency to clog, which necessitates their exchange. We studied this problem by performing light and electron microscopy and bacterial cultures on both unused and clinically used endoprostheses. These examinations showed several basic defects in their manufacture, such as irregular inner surfaces and badly constructed side holes. The deposit that ultimately led to their occlusion was found mainly to be concentrated around the side holes. Minimizing the amount of material, bacteria, and plant fibres adhering to the endoprosthesis is the desired goal and may be achieved by improving their manufacture and design.

Clogging and other complications of endoscopic biliary endoprostheses

This study included 236 patients treated with endoscopic biliary endoprostheses. Malignant strictures were responsible for the obstruction in 87% of the patients. The 1-week and 1-month mortality for patients with malignant strictures was 10% and 22%, respectively, whereas that of patients with benign conditions was 3% and 10%, respectively. The major complication encountered was the frequent hospital readmissions of patients owing to clogging of their endoprostheses. Late clogging had an overall occurrence of 33% and presented with recurrence of jaundice with or without fever or pain. Late signs of cholangitis occurred in 15% of the patients, whereas other late complications were rather infrequent. Although 10-french endoprostheses had a significantly longer patency period than 7-french--that is, 6 months versus 2 months (p = 0.01)--the proportion of patients in whom clogging occurred was nearly the same, 30% for 10-french and 32% for 7-french endoprostheses.