[1] Liquid-liquid equilibrium experiments indicate that there is a strong thermodynamic driving force for the reversible sequestration of cis-dichloroethene (DCE) within microbially active dense nonaqueous phase liquid (DNAPL) source zones containing chlorinated ethene solvents. Assessment of the importance of degradation product sequestration, however, requires accurate description of the mass transfer kinetics. Partitioning kinetics of cis-DCE were assessed in a series of transport experiments conducted in sandy columns containing uniformly entrapped tetrachloroethene (PCE)-nonaqueous phase liquids (NAPL). Effluent data from these experiments were simulated using an analytical solution adapted from the sorption literature. The solution permits interrogation of the relative importance of mass transfer resistance in the aqueous phase and NAPL. Column data and simulations suggest that the kinetic exchange of cis-DCE may be described with mass transfer correlations developed for the dissolution of pure component NAPLs. Diffusive transport within the entrapped ganglia was relatively fast, offering limited resistance to mass exchange. These results (1) establish the applicability of dissolution-based mass transfer correlations for modeling both absorption and dissolution of degradation products, (2) quantify the thermodynamic driving force for the partitioning of cis-DCE in PCE-NAPL by assessing the ternary phase behavior, and (3) guide incorporation and deployment of partitioning kinetics into multiphase compositional simulators when assessing or designing metabolic reductive dechlorination within DNAPL source zones. While focus is placed on examining degradation product partitioning in DNAPL source zones, results may also be useful when considering rate limitations in other liquid-liquid partitioning processes, such as partitioning tracer tests.
INTRODUCTION: Poor bowel preparation for colonoscopy is associated with reduced diagnostic yield, increased risk of perforation, and longer length of hospitalization. Prior studies have demonstrated inpatient status as a risk factor for poor bowel preparation. Research at our institution has identified risk factors that are associated with poor bowel preparation, but this study consisted primarily of an outpatient population. The aim of this study is to investigate the impact of known risk factors on bowel preparation quality in an inpatient population. METHODS: A retrospective chart review was performed for all patients undergoing inpatient colonoscopies from July 2017 - April 2019 at a single academic medical center. ICU patients were excluded. The indication for colonoscopy, amount of bowel preparation (4L vs >4L of polyethylene glycol), and documented quality of the bowel preparation (adequate vs poor) were reviewed. Previously identified risk factors for poor bowel preparation including gender, type 2 diabetes (T2DM) with end-organ damage, COPD, neurologic disease (stroke, dementia, Parkinson’s disease), TCA use, opioid use, and laxative use were recorded. Association of risk factors with poor bowel preparation was analyzed using chi-square tests. RESULTS: 306 patients underwent inpatient colonoscopy. 42 patients (13.7%) had poor bowel preparation. 31.7% (n = 13) of patients with at least 3 risk factors had poor bowel preparation while only 11.5% (n = 29) of patients with two or less risk factors had poor bowel preparation (P = 0.01). This statistically significant relationship was upheld when controlled for standard colonoscopy preparation (P = 0.03). Among the 42 patients with poor bowel preparation, 54.7% (n = 23) were male, 38% (n = 16) had active opioid use, 26% (n = 11) had T2DM with end-organ dysfunction, 26% (n = 11) had active laxative use, 14.2% (n = 6) had neurological disease, 11.9% (n = 5) had COPD, and 2.3% (n = 1) had active TCA use. CONCLUSION: To date, there is not a nationally accepted risk stratification system for identifying patients at high risk for poor bowel preparation in the inpatient setting. This study shows that patients with at least 3 risk factors were associated with a higher incidence of poor bowel preparation in hospitalized patients. Recognition of these risk factors and individualized bowel preparation could lead to a reduction in the incidence of poorly visualized colonoscopies in the inpatient setting.
INTRODUCTION: Underwater endoscopic mucosal resection (UEMR) is an alternative to conventional submucosal-lift EMR (CEMR) for removal of large non-pedunculated colorectal polyps. Retrospective studies have suggested that UEMR may be more effective at reducing lesion recurrence than CEMR, when performed by experts in this technique. The aim of this study was to compare the generalized safety and effectiveness of UEMR to CEMR for removal of large colorectal polyps when performed by expert endoscopists at a tertiary referral center. METHODS: Patients who had UEMR or CEMR performed by one of 7 experienced endoscopists (>50 large polyp resections/year) at a single university-based health system between 3/2015 and 7/2018 were included. Each of the 7 endoscopists regularly performed CEMR but adopted UEMR before or during this study. Patients were identified retrospectively using CPT codes and data was collected from our electronic medical record. RESULTS: 186 patients who underwent 142 UEMR and 98 CEMR procedures were included (Table 1). Mean size of polyps removed was 30.7 mm (range: 15-120 mm) for UEMR and 25.3 mm (range: 15- 50 mm) for CEMR (P = 0.001). There were a significantly greater number of tubulovillous adenomas in the UEMR group (22% vs. 37%, P = 0.02). For polyps ≥4 cm, the residual polyp rate on the first follow-up colonoscopy was 26% for UEMR and 60% for CEMR (OR 4.2, P = 0.05), as confirmed by biopsies. However, there was no statistically significant difference between UEMR vs. CEMR for lesion recurrence for polyps < 4 cm in size. For all polyp sizes, there was no difference in rates of complete macroscopic resection, en bloc resection, number of colonoscopies to reach clearance, and need for adjunctive resection techniques (i.e., argon plasma coagulation, hot biopsy avulsion) between the groups (Table 2). There were no instances of perforation. No significant differences in rates of intra-procedural or delayed procedural bleeding were found between groups (Table 3). CONCLUSION: When generalized across multiple endoscopists at a university-based health system, there was no observed benefit of UEMR compared to CEMR for colorectal polyps under 4 cm in size. However, for lesions 4 cm and greater, UEMR was superior in terms of reduced rates of residual lesion at the first follow-up colonoscopy. Prospective trials are required to further delineate the comparative impact of UEMR vs. CEMR with respect to rates of residual neoplasia.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.