Pure Coagulation Research Articles

The Dreaded 3-Minute Wait: Does It Really Prevent Operating Room Fires? The IGNITE Trial.

Operating room fires can have devastating consequences and as such must be prevented. There exists a paucity of literature requiring further elucidation regarding manufacturer recommendations of a predefined waiting period prior to patient draping after using alcohol-based surgical antiseptics, in order to reduce the risk of operating room fires. This was further investigated by exposing two common alcohol-based surgical antiseptics to electrosurgery and open flames at various power settings and time intervals in an ex vivo porcine model. The simulated surgical site was prepped following manufacturer recommendations and exposed to monopolar electrosurgery at low and high power, using both PURE CUT and COAGULATION modes, and open flame, at 15-s increments after application. While using PURE CUT mode at both low and high power, no ignition was observed on hairless surgical sites prepped with ChloraPrep® at any time point. However, use of COAGULATION mode at both low and high powers resulted in ignition consistently out to 1-min post-application. Additionally, if the prepped area subjectively appeared wet, especially with pooling of the antiseptic, both COAGULATION mode and open flame caused ignition. Dry time was found to be about 59 s for both prep solutions. It was also observed that the amount of pressure directly correlated with the amount of prep dispersed and increased dry times. In conclusion, our data suggest an average dry time of less than 1-min, with ignition only observed when the antiseptic was visibly wet. Ignition did not occur on hairless skin with electrocautery on CUT mode using ChloraPrep at any time point. Additionally, ignition on hair-bearing skin was not observed past 3 min, with current manufacturer recommendations stating 1 h wait time for hair-bearing skin. Arbitrarily waiting a specific predetermined dry time until patient draping, as recommended by the manufacturers, may be unnecessary and lead to hours' worth of time wasted each year. Ongoing research will further investigate the utility of drying the antiseptic after application and its affect on not only preventing ignition but also antimicrobial efficacy.

Application of the finite element method to the multicomponent general dynamic equation of aerosols

This paper focuses on the numerical approximation of the multicomponent dynamic equation of aerosols (MCGDE), an integro-partial differential equation that describes the temporal evolution of the aerosol number distribution containing several compounds. More specifically, we compare the performance of the finite element method (FEM) and a commonly used sectional method. In addition to the standard Galerkin FEM, we introduce the Petrov–Galerkin Finite Element Method (PGFEM) to the MCGDE. These methods are compared to analytical solutions of the MCGDE and to accurate solutions given by the discrete multicomponent GDE which models the condensation process numerically at the monomer level. Results show that in cases where condensation is the dominating process, the accuracy of the FEM and PGFEM can be significantly better than the accuracy of the sectional method. They also generally achieve a given accuracy of the solution with a significantly lower number of discretization points than the sectional method. Moreover, the sparser the discretization is, the more beneficial is the use of the PGFEM, because it stabilizes the solution of condensation dominated MCGDEs. In the case of pure coagulation, all three numerical methods yield a similar accuracy.

Open-source modelling of aerosol dynamics and computational fluid dynamics: Nodal method for nucleation, coagulation, and surface growth

Understanding formation, growth and transport of aerosols is critical to processes ranging from cloud formation to disease transmission. In this work, a numerical algorithm of aerosol dynamics including nucleation, coagulation, and surface growth was coupled with flow and heat transfer equations enabling the solution of three-dimensional multi-physics aerosol processes in an open-source platform. The general dynamic equation was solved by a nodal method where the particle size distribution was represented by a finite number of nodes. The models were verified by comparing four test cases, (1) pure coagulation, (2) nucleation and coagulation, (3) pure surface growth, and (4) a general dynamic equation that includes the three mechanisms provided in literature. A high temperature aerosol flow in a cooled pipe is chosen as a tutorial case of coupled computational aerosol and fluid dynamics. The aerosolGDEFoam code is available at https://openaerosol.sourceforge.io and can be further modified under GNU general public licence. Programme summaryProgramme title: aerosolGDEFoamCPC Library link to programme files: https://doi.org/10.17632/3s368jpdx2.1Developer’s repository link: https://openaerosol.sourceforge.io/Licencing provisions: GNU General Public Licence 3Programming language: C++Nature of problem: aerosolGDEFoam solves the general dynamic equation coupled with flow and heat transfer equations enabling the solution of three-dimensional multi-physics aerosol processes using the open-source computational platform, OpenFOAM [1]. The general dynamic equation describes changes in aerosols due to e.g. nucleation, coagulation and evaporation/condensation, processes which depend on local conditions such as temperature and humidity. A zero-dimensional form of the general dynamic equation from Prakash et al. [2] has been implemented and verified with previously published examples.Solution method: aerosolGDEFoam employs an explicit time-stepping for the time-dependent source terms for aerosol dynamics. The solution methods and schemes provided by OpenFOAM 6 are used for spatial derivatives.

Simple Calculation Model of Combined Cycle Unit Under Off-Design Conditions

The modeling of the combined cycle unit is often limited by the lack of characteristic curve and operating data. This paper provided a simple off-design model of combined cycle unit, which was based on theoretical derivation and experimental data. The simulation results showed that the model could reflect the characteristics of gas cycle components and realize the calculation of off-design conditions. The calculation error of heat transfer of HRSG and output of steam turbine under pure coagulation the condition was less than 0.5%.

Primena radiotalasa u oralnoj hirurgiji

Appliances that use electromagnetic radiation in the form of high frequency radioablation are increasingly applied in many branches of medicine and in recent times in oral surgery. They work on the same principle as the electrocauteries, with the difference that the electrocauteries use wave frequencies from 300kHz to 500kHz and the radiolayers use the frequency of wavelengths of 4MHz. This allows them a far lower energy penetration depth, less destruction and limited lateral tissue damage, without burning effect. Wound healing is faster, scarring is less, and cosmetic effect is more pronounced. During one year at the Department of Oral Surgery, a radiotherapeutic appliance is used in many oral surgery interventions. Treatment of non-contact tissues simultaneously with a hemostatic effect or pure coagulation is performed very easily and successfully. The appliance is tested when working on soft tissue of the skin and mucous membranes. With proper and professional handling any adverse effects are avoided. Special attention should be paid to patients with cardiac pacemaker and adhere to the protocol. It patient has dental implants, touching them is contraindicated while working with active electrode. Conclusion: The radiowave surgery has advantages in relation to conventional surgery wiht respect on indication areas.

Applications of improved duality lemmas to the discrete coagulation-fragmentation equations with diffusion

In this paper, we investigate the use of so called 'duality lemmas' to study the system of discrete coagulation-fragmentation equations with diffusion. When the fragmentation is strong enough with respect to the coagulation, we show that we have creation and propagation of superlinear moments. In particular this implies that strong enough fragmentation can prevent gelation even for superlinear coagulation, a statement which was only known up to now in the homogeneous setting. We also use this control of superlinear moments to extend a recent result from [3], about the regularity of the solutions in the pure coagulation case, to strong fragmentation models.

PTU-021 Variation in diathermy use for colonic polypectomy – results from a national survey

Introduction The transition from trainee to consultant and subsequent accredited bowel cancer screening colonoscopist reveals variability in diathermy practice for colonic polypectomy. There is no standardised teaching with a paucity of guidelines. We therefore designed a survey to evaluate current practice. Method This national survey was hosted on www.surveymonkey.co.uk, it has been approved by the endoscopy committees of the BSG and Association of Coloproctology of Great Britain and Ireland (ACPGBI) and was circulated to their memberships. The questions 1. Which region do you work in? 2. Endoscopy grade and role 3. Endoscopy lists provided in a typical working month 4. What level of polypectomy do you undertake in a typical working month? 5. What diathermy modes do you use for polypectomy in the LEFT side of colon? 6. What diathermy modes do you use for polypectomy in the RIGHT side of colon? 7. Do you use lower diathermy current settings for right side polypectomy vs left side? 8. Do you feel confident in your knowledge and use of diathermy for polypectomy? Results The survey was open in 2016. Analysis shows: • 250/348 (71.8%) completed the full survey from across the United Kingdom. • 159 Gastroenterologists (63.6%), 36 Surgeons (14.4%), 34 Gastroenterology Trainees (13.6%), 21 others (8.4%). • Predominant use of coagulation current or coagulation and cutting combination for small and large pedunculated polypectomy. • Wide variance in diathermy modes for polypectomy of large sessile and very large polyps. • High use of cold snare polypectomy for small sessile polyps (right 43.2% > left 34.4%). • Low use of endocut mode irrespective of size/location of polyp (17.2%–32.0%)%). • 204/250 (81.6%) use reduced current settings for right colonic polypectomy. • 208/250 (83.2%) confident on knowledge and use of diathermy. Conclusion When designing a survey the challenge is to capture the information required and balance this with a high completion rate. We have achieved this with a large number of complete responses. The guidance for the management of large non-pedunculated colorectal polyps advises that prolonged pure coagulation current be avoided due to risks of delayed bleeding and thermal injury. 1 Many complications are as direct result of thermal injury and polypectomy is the most frequent therapeutic intervention, appropriate training and BSG formal guidance is lacking. This national survey has exposed wide variations in diathermy use for colonic polypectomy, further analysis is ongoing prior to publication of a paper and we will make representations to the BSG and ACPGBI endoscopy committees to provide a platform to develop training and guidance to improve patient safety. Reference . Rutter MD, et al. The guidance for the management of large non-pedunculated colorectal polyps. Gut2015;64:1847–1873. doi:10.1136/gutjnl-2015-30957 Disclosure of Interest None Declared

Transient detailed balance and product form for reaction networks

ABSTRACTThis paper explores the boundary of the set of reaction networks that have an exact transient (truncated) multidimensional Poisson or product-form distribution for the number of particles of different types. Motivated by the birth–death process, we introduce the notions of transient detailed balance and delay functions, and use these notions to obtain the novel transient product-form distribution in a coagulation-fragmentation process for polymers with a tree-like structure from that of the pure coagulation process.

Numerical simulations of particle size distributions: Comparison with analytical solutions and kaolinite flocculation experiments

The population balance equation has been used to describe the evolution of particle populations caused by aggregation and breakup processes for several decades. Only recently has it been used to efficiently and directly predict the temporal variation of particle size distribution (PSD) for cohesive sediments by using the quadrature method of moments (QMOM). In this study, an extension of that effort carries out additional validations that compare with analytical solutions for pure coagulation systems, pure breakup systems, and combined coagulation and breakup systems. Besides, a laboratory experiment is conducted in a five liter mixing chamber to provide steady state PSD of suspended kaolinite with a chamber-averaged kaolinite concentration 0.52g/L and shear rate 45s−1. The model results match reasonably well with both of those from analytical solutions and kaolinite flocculation experiment results. Sensitivities regarding the selecting of different model input parameters (such as fractal dimensions, primary particle sizes, aggregation and breakage fitting parameters, and fragmentation distribution functions) are also checked. The results further confirm the capability of QMOM to predict PSD using its quadrature nodes and the corresponding weights.

Electrosurgical generators

Electrosurgical generators

A Novel Submucosal Gel Permits Simple and Efficient Gastric Endoscopic Submucosal Dissection

A Novel Submucosal Gel Permits Simple and Efficient Gastric Endoscopic Submucosal Dissection

Coagulation Processes with Gibbsian Time Evolution

We prove that a stochastic process of pure coagulation has at any time t ≥ 0 a time-dependent Gibbs distribution if and only if the rates ψ(i, j) of single coagulations are of the form ψ(i; j) = if(j) + jf(i), where f is an arbitrary nonnegative function on the set of positive integers. We also obtain a recurrence relation for weights of these Gibbs distributions that allow us to derive the general form of the solution and the explicit solutions in three particular cases of the function f. For the three corresponding models, we study the probability of coagulation into one giant cluster by time t > 0.

Coagulation Processes with Gibbsian Time Evolution

We prove that a stochastic process of pure coagulation has at any timet≥ 0 a time-dependent Gibbs distribution if and only if the rates ψ(i,j) of single coagulations are of the form ψ(i;j) =if(j) +jf(i), wherefis an arbitrary nonnegative function on the set of positive integers. We also obtain a recurrence relation for weights of these Gibbs distributions that allow us to derive the general form of the solution and the explicit solutions in three particular cases of the functionf. For the three corresponding models, we study the probability of coagulation into one giant cluster by timet> 0.

Solitary Necrotic Nodules of the Liver: Histology and Diagnosis With CT and MRI

BackgroundA solitary necrotic nodule (SNN) of the liver is an uncommon lesion, which is different from primary and metastatic liver cancers.ObjectivesTo analyze the classification, CT and MR manifestation, and the pathological basis of solitary necrotic nodule of the liver (SNN) in order to evaluate CT and MRI as a diagnosing tool.Patients and MethodsThis study included 29 patients with liver SNNs, out of which 14 had no clinical symptoms and were discovered by routine ultrasound examinations, six were found by computed tomography (CT) due to abdominal illness, four had ovarian tumors, and five had gastrointestinal cancer surgeries, previously. Histologically, these SNNs can be divided into three subtypes, i.e., type I, pure coagulation necrosis (14 cases); type II, coagulation necrosis mixed with liquefaction necrosis (five cases); and type III, multi-nodular fusion (10 cases). CT and magnetic resonance imaging (MRI) patterns were shown to be associated with SNN histology. All patients were treated surgically with good prognosis.ResultsCT and MRI appearance and correlation with pathology types: three subtypes of lesions were hypo-density on both pre contrast and post contrast CT, 12 lesions were found the enhanced capsule and 1 lesion of multi- nodular fusion type showed septa enhancement. The lesions were hypo-intensity on T2WI and the lesions of type II showed as mixed hyperintensity on T2WI. The capsule showed delayed enhancement in all cases, and all lesions of multi- nodular fusion type showed delayed septa enhancement on MR images. 15 cases on CT were misdiagnosed and Four cases on MRI were misdiagnosed and the accuracy of CT and MRI were 48.3% and 86.2% respectively.ConclusionsIn conclusion, CT and MRI are useful tools for SNN diagnosis.

Solitary Necrotic Nodules of the Liver: Histology and Diagnosis With CT and MRI

Background: : A solitary necrotic nodule (SNN) of the liver is an uncommon lesion, which is different from primary and metastatic liver cancers. Objectives:: To analyze the classification, CT and MR manifestation, and the pathological basis of solitary necrotic nodule of the liver (SNN) in order to evaluate CT and MRI as a diagnosing tool. Patients and Methods:: This study included 29 patients with liver SNNs, out of which 14 had no clinical symptoms and were discovered by routine ultrasound examinations, six were found by computed tomography (CT) due to abdominal illness, four had ovarian tumors, and five had gastrointestinal cancer surgeries, previously. Histologically, these SNNs can be divided into three subtypes, i.e., type I, pure coagulation necrosis (14 cases); type II, coagulation necrosis mixed with liquefaction necrosis (five cases); and type III, multi-nodular fusion (10 cases). CT and magnetic resonance imaging (MRI) patterns were shown to be associated with SNN histology. All patients were treated surgically with good prognosis. Results:: CT and MRI appearance and correlation with pathology types: three subtypes of lesions were hypo-density on both pre contrast and post contrast CT, 12 lesions were found the enhanced capsule and 1 lesion of multi- nodular fusion type showed septa enhancement. The lesions were hypo-intensity on T2WI and the lesions of type II showed as mixed hyperintensity on T2WI. The capsule showed delayed enhancement in all cases, and all lesions of multi- nodular fusion type showed delayed septa enhancement on MR images. 15 cases on CT were misdiagnosed and Four cases on MRI were misdiagnosed and the accuracy of CT and MRI were 48.3% and 86.2% respectively. Conclusions:: In conclusion, CT and MRI are useful tools for SNN diagnosis.

Outcomes of EMR of defiant colorectal lesions directed to an endoscopy referral center

Flat and sessile lesions are being identified more frequently because of increased awareness, improved endoscopic skills, and enhanced imaging. The defiant polyp (DP) is a lesion identified at colonoscopy that defies resection by the standard snare polypectomy technique. Increasingly, the DP undergoes photodocumentation and tissue sampling, and the patient is referred for an attempt at curative colonoscopic resection. To evaluate the current nature of the DPs and outcomes of their endoscopic resection. Retrospective study. Tertiary referral center. Patients with colorectal polyps not amenable to standard snare polypectomy were referred to a single endoscopist at a tertiary center for an attempt at curative endoscopic resection. The indication DP was applied prospectively, as defined previously, beginning in June 2007. An electronic endoscopy report database was searched for this indication from June 2007 to October 2009 for a single endoscopist at an endoscopy referral center. Data pertaining to patient age and sex, polyp site and histopathology, resection technique, use of adjunctive ablation, adverse events, and residual/recurrent neoplasia at follow-up were culled. Submucosal injection of varying quantities of normal saline solution tinted with methylene blue dye was used for endoscopic resection. Standard and mini-snares were used with pure coagulation current. Complete resection, complications, recurrence. This study included 274 patients (50.4% women, age 65 [standard deviation 12] years) with a total of 315 DPs who were referred for attempted endoscopic resection. The majority of DPs were located in the right side of the colon (226; 72%). The mean size was estimated at 23 mm (range 8-100 mm; standard deviation 13). In 29 DPs (10%), surgery was required because endoscopic resection was deemed unsuitable because of the unfavorable appearance (n = 3), the location (n = 9), or the inability to lift (n = 10) or because of submucosal invasion on post-EMR histopathology (n = 7). Complete endoscopic eradication (R0) was achieved in a single session in 286 DPs (91%). En bloc resection was performed in 153 polyps (53.5%) and piecemeal resection in 132 (46%). Histopathology revealed 178 tubular adenomas (56.5%), 62 serrated adenomas (20%), 27 tubulovillous adenomas (9%), 10 hyperplastic polyps (3%), and 14 adenocarcinomas (4.5%). Adjunctive ablation of focal residual neoplastic tissue was applied in 69 DPs (24%) to achieve R0. Procedure-related adverse events were recorded in 29 of 249 patients (11.6%). Acute bleeding occurred in 9 patients (1 required hospitalization and repeat endoscopy). There was 1 microperforation managed with clip closure and antibiotics. Delayed bleeding (1-6 days post-procedure) was observed in 18 patients (7.2%), of whom 8 required hospitalization and 4 colonoscopy for hemostasis. Among the patients who underwent follow-up surveillance colonoscopy (135 of 258 patients), residual/recurrent neoplastic tissue at the site of the previous EMR was identified in 36 (27%). Residual/recurrent neoplasia was successfully eradicated with further endoscopic resection or ablation. A retrospective design. DPs consist predominantly of sessile and flat adenomas including serrated adenomas. Most DPs can be successfully eradicated at dedicated therapeutic colonoscopy by using adjunctive resection and ablation techniques. The R0 rate is high and the adverse event rate is low. A relatively high rate of local residual/recurrent neoplasia at the resection site underscores the importance of follow-up colonoscopy.

Hemoclip Assisted Polypectomy Following Epinephrine Volume Reduction of a Massive Bleeding Brunnerʼs Gland Hamartoma

Purpose: Brunner's gland hamartomas (BGH) are rare tumors of the duodenum caused by hyperplasia of exocrine glands within the duodenal mucosa. They are usually asymptomatic, but may cause occult or massive gastrointestinal bleeding or intestinal obstruction. We present a case of BGH in a high-risk patient where polyp volume reduction techniques facilitated polypectomy. A 60-year-old man with a history of schizophrenia and coronary artery disease was admitted with 4-days of melena. He denied abdominal pain, nausea, or vomiting. He had no prior history of GI bleeding or endoscopy. He had a bare metal coronary stent placed 3 months prior to presentation and was being treated with aspirin and clopidogrel by his cardiologist, who recommended against discontinuing the clopidogrel. On admission, his vitals were stable, and rectal exam was positive for occult blood. His hemoglobin was 8.7 gm/dL, which later decreased to 6.6 gm/dL, and was transfused. The EGD revealed a 6 cm pedunculated polyp with a thick stalk in the duodenal bulb. The head of the polyp was bleeding. The polyp was injected with epinephrine, but could not initially be resected with the snare due to its size. Biopsies revealed hyperplastic mucosa. Two days later, the patient continued to bleed and underwent repeat EGD in attempt to avoid surgery. The EGD revealed a large, lobulated, polyp with a thick stalk in the duodenal bulb with the polyp head invaginating into the second portion of the duodenum. A total of 13 cc of epinephrine was injected into the polyp head, decreasing its size, and 3 hemoclips were placed on the stalk, which reduced the polyp volume. A standard snare was now able to be placed around the head immediately above the hemoclips. Using pure coagulation current, the polyp was resected. On histology, the polyp was composed of lobules of benign tubuloalveolar glands separated by fibromuscular connective tissue consistent with a BGH. Following the procedure the patient had no further bleeding. BGHs account for 5-11% of duodenal tumors. They are an extremely rare cause of gastrointestinal bleeding. They are generally benign, but malignant transformation has been described. Intervention is required in cases of bleeding or obstruction. Endoscopic biopsies are rarely sufficient for diagnosis since these lesions often have normal superficial mucosa. Surgical or endoscopic resection is often required to obtain a diagnosis. There are limited data on endoscopic resection of BGHs. Epinephrine volume reduction has been described for removal of giant colon polyps. To our knowledge, this is the only case in which epinephrine injection for volume reduction of a polyp was used to allow successful snare polypectomy of a BGH.

Stray Electrical Currents in Laparoscopic Instruments Used in da Vinci® Robot-Assisted Surgery: An In Vitro Study

The da Vinci(®) surgical system requires the use of electrosurgical instruments. The re-use of such instruments creates the potential for stray electrical currents from capacitive coupling and/or insulation failure. We used objective measures to report the prevalence and magnitude of such stray currents. Thirty-seven robotic instruments were tested using an electrosurgical unit (ESU) at pure coagulation and cut waveforms at four different settings. Conductive gel-coated instruments were tested at 40W, 80W, and maximum ESU output (coagulation 120W, cut 300W). The magnitude of stray currents was measured by an electrosurgical analyzer. At coagulation waveform in open air, 86% of instruments leaked a mean of 0.4W. In the presence of gel-coated instruments, stray currents were detected in all instruments with means (and standard deviation) of 3.4W (± 2), 4.1W (± 2.3), and 4.1W (± 2.3) at 40W, 80W, and 120W, respectively. At cut waveform in open air, none of the instruments leaked current, while gel-coated instruments leaked a mean of 2.2W (± 1.3), 2.2W (± 1.9) and 3.2W (± 1.9) at 40W, 80W, and 300W, respectively. All tested instruments in our study demonstrated energy leakage. Stray currents were higher during coagulation (high voltage) waveforms, and the magnitude was not always proportionate to the ESU settings. Stray currents have the potential to cause electrical burns. We support the programmed end of life of da Vinci instruments on the basis of safety. Consideration should be given to alternate energy sources or the adoption of active electrode monitoring technology to all monopolar instruments.

Outcomes Following Referral for Colonoscopic Resection of the “Defiant Polyps”: A Single Center Experience

Purpose: Flat and sessile lesions are being identified with increasing frequency owing to increased awareness and enhanced imaging. The “defiant polyp” [DP] is a lesion identified at colonoscopy that defies resection by standard snare polypectomy technique. Increasingly, the DP undergoes photodocumentation, tissue sampling and is referred for subsequent curative colonoscopic resection. The aim of this study was to detail the current nature of the DPs and outcomes with referral for curative colonoscopic resection. Methods: The indication term “defiant polyp” was ascribed prospectively as defined above beginning June ‘07. An electronic endoscopy report data set was searched for this indication from June’07 to Sept'09 for a single endoscopist at a tertiary center. Data pertaining to patient age and gender, polyp site and histopathology, resection technique, use of adjunctive ablation, adverse events, and residual/recurrent neoplasia at follow up were culled. Patients underwent resection following submucosal injection of varying quantities of normal saline solution tinted with Methylene blue dye. Standard and min-snares were used with pure coagulation current. Results: Two hundred seventy six patients (50.4% Female, age 65; SD12) with a total of 302 DP were identified for resection. The morphology of DPs according to Paris classification was Ip 22, Is 196, IIa 82, IIb 2. The majority of DPs were located in the right colon (218; 72%). The mean size was estimated as 23 mm (8-100 mm, SD12). In 29 (9.6%), endoscopic resection was deemed unsuitable due to unfavorable appearance (7), access (12), or non-lifting (10). Endoscopic complete eradication (R0) was achieved in a single session in 268 of DPs (98.2%). Five polyps required up to 3 additional sessions for R0. En bloc resection was done in 146 polyps (53.5%)and piecemeal in 126 (46.2%). Histopathology revealed 173 tubular adenomas (61.1%), 57 serrated adenomas (20.1%), 26 tubulo-villous adenomas (9.2%), 17 hyperplastic polyps (6%) and 10 adenocarcinomas (3.5%). Adjunctive ablation of focal residual neoplastic tissue was applied in 66 cases (24.2%) to achieve R0. Procedure related adverse events were recorded in 22 (9.5%) of 231 patients. Acute bleeding occurred in 7 patients (one required hospitalization and repeat endoscopy). There was one microperforation managed with clip closure and antibiotics. Delayed bleeding (1 to 6 days post procedure) was observed in 14 patients (6.1%) of whom 8 patients required hospitalization and 4 patients colonoscopy for haemostasis. Conclusion: DPs consist predominantly of sessile and flat adenomas including serrated adenomas. Most DPs can be successfully eradicated at dedicated therapeutic colonoscopy using adjunctive resection and ablation techniques. The R0 rate is high and adverse events are low.

Gelation time in the discrete coagulation–fragmentation equations with a bilinear coagulation kernel

The discrete coagulation–fragmentation equations with a bilinear coagulation kernel, describing the evolution of clusters of particles undergoing binary reactions, are studied. We compute the gelation time and post-gelation mass for the pure coagulation equation. A method of characteristics is developed to solve numerically the partial differential equation satisfied by a moment generating function for a product coagulation kernel and a constant fragmentation rate. The accuracy of the numerical method is verified by comparison of the numerical results with an exact solution for the number density of monomers. For a given coagulation rate, a critical value of the fragmentation rate, values greater than which lead to mass conservation, is identified.