Safety and efficacy of a fully covered large-diameter self-expanding metal stent for the treatment of upper gastrointestinal perforations, anastomotic leaks, and fistula.

Upper gastrointestinal perforations, fistula, and anastomotic leaks are severe conditions with high mortality. Temporary endoscopic placement of fully covered self-expanding metal stent (fSEMS) has emerged as treatment option. Stent migration is a major drawback of currently used stents. Migration is often attributed to a relatively too small stent diameter as esophageal stents were initially intended for the treatment of strictures. This study aimed to investigate the safety and efficacy of a large-diameter fSEMS for treatment of these conditions. Data were retrospectively collected from patients who received this stent in the Netherlands between March 2011 and August 2013. Clinical success was defined as sufficient leak closure after stent removal as confirmed by endoscopy or X-ray with oral contrast without surgical intervention or placement of another type of stent. Adverse events were graded according a standardized grading system. Stent placement was performed in 34 patients for the following indications: perforation (n = 6), anastomotic leak (n = 26), and fistula (n = 2). Technical success rate was 97% (33/34). Clinical success rate was 44% (15/34) after one stent and 50% (17/34) after an additional stent. There were no severe adverse events and stent-related mortality. The overall adverse event rate was 50% (all graded 'moderate'). There were 14 (41%) stent migrations (complete n = 8, partial n = 6). Other adverse events were bleeding (n = 2) and aspiration pneumonia (n = 1). Reinterventions for failure of the large-diameter fSEMS were placement of another type of fSEMS (n = 4), surgical repair (n = 3), or esophagectomy (n = 1). Eleven patients (32%) died in-hospital because of persisting intrathoracic sepsis (n = 10) or preexistent bowel ischemia (n = 1). This study suggests that temporary placement of a large-diameter fSEMS for the treatment of upper gastrointestinal perforations, fistula, and anastomotic leaks is safe in terms of severe adverse events and stent-related mortality. The larger diameter does not seem to prevent stent migration.

Long-term results of palliative stent placement for acute malignant colonic obstruction.

BACKGROUND: Endoscopic placement of self-expanding-metal-stents (SEMS) is widely performed as palliative treatment for acute malignant colonic obstruction. There is ongoing debate regarding risks and benefits associated with SEMS placement. This study aimed to evaluate long-term outcomes of palliative SEMS placement in patients presenting with acute malignant colonic obstruction. METHODS: A prospectively collected patient cohort (2005-2013) from a general teaching hospital was used. In this hospital, all consecutive patients presenting with acute malignant large bowel obstruction are treated with endoscopic SEMS placement. Only colon cancer patients who underwent palliative SEMS placement were selected. RESULTS: In total, 48 patients were included. The technical and short-term clinical success rates were 91 % (44/48) and 85 % (36/48), respectively. SEMS-related mortality occurred in 6/48 patients (13 %) (early n = 4, late n = 2) and was caused by SEMS-related perforation in all cases. The SEMS-related morbidity rate was 38 % (18/48) (early n = 7, late n = 11). Endoscopic re-intervention was performed 14 times and 13 patients eventually underwent surgical treatment during follow-up. The stoma-formation rate was 15 % (7/48). Long-term clinical success was 48 % (23/48). The estimated stent patency rate (95 % confidence interval) was 69 % (52-79) at 1 month, 54 % (37-66) at 6 months and 50 % (33-62) at 12 months. CONCLUSION: Palliative SEMS placement provides rapid relief of obstruction and avoids a stoma in most patients with acute colonic obstruction caused by incurable or inoperable colon cancer. However, these benefits should be weighed against mortality and morbidity related to SEMS placement.

Oncological outcome of malignant colonic obstruction in the Dutch Stent-In 2 trial.

BACKGROUND: The Stent-In 2 trial randomized patients with malignant colonic obstruction to emergency surgery or stent placement as a bridge to elective surgery. The aim of this study was to compare the oncological outcomes. METHODS: Disease recurrence, and disease-free, disease-specific and overall survival were evaluated, including a subgroup analysis of patients with a stent- or guidewire-related perforation. RESULTS: Of 98 patients included in the original Stent-In 2 trial, patients with benign (16) or incurable (23) disease were excluded from this study, along with a patient who had withdrawn from the trial. Of the remaining 58 patients, 32 were randomized to emergency surgery (31 resection, 1 stoma only) and 26 to stenting. Unsuccessful stenting required emergency surgery in six patients owing to wire or stent perforation. Locoregional or distant disease recurrence developed in nine of 32 patients in the emergency surgery group and 13 of 26 in the stent group. Disease-free survival was worse in the subgroup with stent- or guidewire-related perforation. Five of six patients in this subgroup developed a recurrence, compared with nine of 32 in the emergency surgery group and eight of 20 who had unperforated stenting. CONCLUSION: Stent placement for malignant colonic obstruction was associated with a risk of recurrence in this trial, but the numbers are small. There is not enough evidence to refute the approach strongly. REGISTRATION NUMBER: ISRCTN46462267 ( http://www.controlled-trials.com).

Bridge-to-surgery stent placement versus emergency surgery for acute malignant colonic obstruction.

BACKGROUND: Endoscopic self-expanding metal stent (SEMS) placement as a bridge to surgery is an option for acute malignant colonic obstruction. There is ongoing debate regarding the superiority and oncological safety of SEMS placement compared with emergency surgery. This retrospective study aimed to compare outcomes of these treatment approaches. METHODS: Patients were identified from cohorts treated between 2005 and 2012 in two teaching hospitals, of which one used emergency surgery only in patients with large bowel obstruction, whereas the other attempted SEMS placement. Only patients treated with curative intent were included. RESULTS: The study included 59 patients in whom SEMS placement was attempted and 51 who underwent surgery alone. The successful primary anastomosis rate was higher in the SEMS group than in the surgery-alone group among patients with left-sided obstruction (30 of 43 versus 10 of 34 respectively; P = 0.001), whereas stoma formation was less common (11 of 43 versus 23 of 34; P < 0.001). Such differences were not apparent in patients with right-sided obstruction. Secondary stoma rates were comparable between treatment approaches (left-sided: 11 of 43 versus 13 of 34, P = 0.322; right-sided: 1 of 16 versus 1 of 17, P = 1.000). There were no significant differences in morbidity, mortality, recurrence or survival. CONCLUSION: Endoscopic SEMS placement increased the primary anastomosis rate in patients with left-sided large bowel obstruction.

First data on the Evolution duodenal stent for palliation of malignant gastric outlet obstruction (DUOLUTION study): a prospective multicenter study.

BACKGROUND AND STUDY AIMS: Enteral stent placement has emerged as a safe and effective palliative treatment option for patients with malignant gastric outlet obstruction (GOO). In an attempt to further optimize this treatment new enteral stents have been designed. This study is the first to describe the results regarding technical success, clinical success, complication rate, and stent dysfunction of the Evolution duodenal stent (Cook Medical, Limerick, Ireland). PATIENTS AND METHODS: A total of 46 patients with symptomatic malignant GOO were included in this prospective multicenter cohort study. All patients who successfully received an Evolution duodenal stent were followed until death. RESULTS: The technical and clinical success rates were 89 % (95 % confidence interval [CI] 77 % - 95 %) and 72 % (95 %CI 58 % - 83 %), respectively. The GOO Scoring System score, the Global Health Score, and the EuroQol visual analog scale improved significantly (GOOSS and Global Health Score P < 0.0001; EuroQol P = 0.005) when scores before stenting were compared with scores after stent placement. Median survival was 87 days, and stent patency was observed in 67 % for up to 395 days, accounting for death unrelated to the stent as a competing risk. Stent dysfunction occurred in 14 patients (30 %) (stent ingrowth n = 9; stent migration n = 2; extrinsic compression on the stent n = 2; food impaction n = 1). CONCLUSION: These first data on the new Evolution duodenal stent show that it is safe and effective for the palliative treatment of symptomatic malignant GOO.

Reduction of copper in porous matrixes. Stepwise and autocatalytic reduction routes.

The reduction of Cu(II) oxide species in siliceous matrixes of different porosity (MFI, FAU, MCM-48) and in alumosilicate MFI was studied by temperature-programmed reduction in hydrogen (TPR), by X-ray absorption fine structure (after stationary hydrogen treatments), and by transmission electron microscopy. It was found that the reduction may proceed in one or in two reduction steps. The two-step scheme known for zeolites was observed also for Cu(II) in siliceous microporous matrixes, with similar temperature of Cu(II) reduction onset as for the alumosilicate MFI. Therefore, the two-step scheme cannot be explained by the stabilization of Cu ions by intra-zeolite electrical fields. CuOx clusters in MCM-48 were reduced in a one-step scheme (similar to bulk CuO) at high Cu content (6 wt %) but in a two-step scheme at low Cu content (1 wt %). The two reduction steps observed with most samples cannot be identified with the transitions of all Cu(II) to Cu(I) and of Cu(I) to Cu(0). Instead, Cu(0) nuclei were observed already at low reduction temperatures and were found to coexist with Cu ions over temperature ranges of different extension. This coexistence range was narrow in materials that favor aggregation of the Cu nuclei into particles: Cu-MCM-48 of low Cu content and Cu-ZSM-5. In the latter, metal segregation from the pore system was found to be accompanied by an autocatalytic initiation of the second reduction step. In the siliceous microporous matrixes, the Cu(0) nuclei were observed to coexist with Cu ions over wide temperature ranges (100 K for MFI) at temperatures far above that of Cu reduction in the bulk oxide. These observations suggest that oligomeric Cu metal nuclei which may have been formed, e.g., at the intersections of the MFI channel system, may be unable to activate hydrogen, which would be required for rapid reduction of the coexisting Cu ions.

Nucleation and growth of ZnO in organic solvents--an in situ study.

ZnO is a metal oxide material which possesses versatile properties and applications. Therefore, the target-oriented preparation of ZnO has become a major issue. Many preparation techniques involve bottom-up methods from precursor solutions. In the current contribution, a special precursor system is described that enables a fine-control of kinetic parameters for the nucleation and growth of ZnO in various organic solvents. A large variety of analytical techniques could be applied in an in situ fashion to probe for the ZnO formation at all times and all length scales. Among the analytical techniques are UV/vis, Raman, Fluorescence, X-ray absorption, 1H NMR-spectroscopy, dynamic light-scattering, and TEM. Three different regimes for nucleation and growth with different characteristics could be identified. Furthermore, the effect of different parameters on the resulting ZnO particle size was investigated.

The reduction of copper in porous matrices--the role of electrostatic stabilisation.

The redox properties of Cu(II) species in FAU matrices have been studied by temperature programmed reduction (TPR) in hydrogen and by XAFS analysis of the products obtained after (stationary) reduction treatments at various temperatures. The influence of the matrix polarity was investigated by comparing aluminosilicate FAU (Y zeolite) with siliceous FAU. In addition, the influence of Zn ions on the reduction process was studied. It was found that both the matrix composition and the presence of zinc ions exert a significant influence on the course of the reduction. In Y zeolite, heat treatment which is known to transfer Cu(II) ions to remote sites (SI, SI', SII') affects the reduction process dramatically. Cu(II) is most easily reduced in siliceous FAU, but the reduction proceeds in two clearly separated steps. Between these steps, small Cu(0) nuclei coexist with Cu(I) species, apparently unable to activate hydrogen for the autocatalytic reduction of the remaining Cu ions. The polarity of the matrix causes an upshift of the Cu(II) reduction temperature (in TPR by ca. 80 K for sites in the large cavity, by ca. 105 K for the remote sites), but the reduction of Cu(I) depends strongly on the simultaneous presence of Cu(0) and on its ability to activate hydrogen and induce an autocatalytic reduction mechanism. While Cu(I) species in the large cavities are easily reduced to the metal, tending to segregate from the zeolite lattice, Cu(I) ions in remote sites are strongly stabilized towards further reduction and even traces of Cu metal form only at very high temperatures. In the presence of zinc ions, the Cu metal particles formed were found to be smaller than in zinc-free samples.

Mesosynthesis of ZnO-silica composites for methanol nanocatalysis.

Methanol catalysis meets chemistry under confined conditions. Methanol is regarded as one of the most important future energy sources. ZnO/Cu composite materials are very effective in heterogeneous catalysis for methanol production due to the so-called strong metal-support interaction effect (SMSI). Therefore, materials of superior structural design potentially representing model systems for heterogeneous catalysis are highly desired. Ultimately, such materials could help to understand the interaction between copper and zinc oxide in more detail than currently possible. We report the preparation of nanocrystalline, size-selected ZnO inside the pore system of ordered mesoporous silica materials. A new, liquid precursor for ZnO is introduced. It is seen that the spatial confinement significantly influences the chemical properties of the precursor as well as determines a hierarchical architecture of the final ZnO/SiO(2) nanocomposites. Finally, the ability of the materials to act as model systems in methanol preparation is investigated. The materials are characterized by a variety of techniques including electron microscopy, X-ray scattering, solid-state NMR, EPR, EXAFS, and Raman spectroscopy, and physisorption analysis.