Access Failure Research Articles

Two-year cumulative patency of endovascular arteriovenous fistula.

Background and objectives:The recent advent of a device to create a proximal radial artery arteriovenous fistula using an endovascular approach to create the anastomosis represents a significant advance in dialysis access creation. This endovascular arteriovenous fistula offers the beneficial attributes of the proximal radial artery arteriovenous fistula while adding the advantages of avoiding a surgical procedure. The endovascular arteriovenous fistula can be created safely, functions well, has excellent patency, and has a high degree of patient satisfaction. The purpose of this study is to report the 2-year cumulative patency rate for a large multicenter cohort of endovascular arteriovenous fistula cases.Design:An endovascular arteriovenous fistula was created in 105 patients using either local or regional anesthesia and conscious sedation. Patient data were obtained from each program’s electronic health record system. Data collection was truncated at 2 years postprocedure and used to calculate cumulative patency. Post-access creation patient satisfaction was assessed.Results:A physiologically mature arteriovenous fistula (blood flow ⩾500 mL/min and a target vein internal diameter ⩾4 mm) was obtained in 98%. A clinically functional arteriovenous fistula (supporting two-needle dialysis according to the patient’s dialysis prescription) was demonstrated in 95%. Access failure resulting in the loss of access occurred in eight cases during the study period. The cumulative patency rate at 6, 12, 18, and 24 months was 97.1%, 93.9%, 93.9%, and 92.7%, respectively. The post-procedure patient evaluation emphasized a high level of patient satisfaction.Conclusion:The proximal radial artery arteriovenous fistula created using an endovascular approach for the anastomosis is associated with excellent 2-year cumulative patency and is associated with a high level of patient satisfaction.

Belatacept-based immunosuppression: A calcineurin inhibitor-sparing regimen in heart transplant recipients.

Belatacept (BTC) is indicated for prophylaxis of graft rejection in adults receiving a renal transplant (Tx). This retrospective observational study (three centers) included all heart transplant recipients receiving BTC between January 2014 and October 2018. Forty EBV+ patients mean GFR 35±20mL/min/m2 were identified, among whom belatacept was initiated during the first 3months after transplantation in 12 patients, and later in 28 patients. Several patients were multiorgan transplant recipients. Study outcomes were GFR, safety, and changes in immunosuppressive therapy. The main reason for switching to BTC was to preserve renal function, resulting in discontinuation of CNI and changes in immunosuppressive therapy in 76% of cases. At study closeout, 24/40 patients were still on BTC therapy. GFR was improved (+59%, P=.0002*) within 1month, particularly in the early group. More episodes of rejection were observed among "late" patients (1 death). Sixteen treatment discontinuations were recorded: GFR recovery (n=4), DSA no longer detectable (n=1), compliance issues (n=3), poor venous access (n=2), multiple infections (n=1), 1 death (fungal lung infection), and treatment failure (n=4). Median follow-up was 24months. Four patients developed de novo DSA (MFI<1500). BTC is an effective alternative immunosuppressive for postoperative transient kidney failure, stabilizing delayed renal function, with acceptable safety profile under careful monitoring.

Evaluation of hemodynamic impact of absorbable sutures in native arteriovenous fistulas: A retrospective study.

One of the major causes of arteriovenous fistula failure is the venous stenosis due to aggressive neointimal hyperplasia. The aim of the study was to assess the arteriovenous fistula maturation comparing absorbable sutures and non-absorbable ones in native vessels. Surgeries performed during a period of 24 months by a single team of expert surgeons were evaluated. Surgeries that met the inclusion criteria, namely, age ⩾ 18 years and radio-cephalic arteriovenous fistula, were considered. According to type of suture, patients were classified as Max group (absorbable suture) and Prol group (non-absorbable). Data pertaining to 70 patients were collected; 51% were men and the mean age was 73 ± 12 years. In Max group, an increasing blood flow was observed during the first 4 weeks without post-operative complications. In Prol group, six patients had thrombosis that resulted in vascular access failure. After the first week, the duplex Doppler ultrasound of both groups showed a regular arteriovenous fistula maturation, with an increase of blood flow rate. Although pre-operative post-tourniquet mean vein diameters of Max group were not adequate, the mean vein diameter and mean blood flow rate increased after 4 weeks, respectively. On the contrary, in Prol group, mean vein diameters and blood flow rate decreased. The maturation of arteriovenous fistula and its functional performance were not altered by the type of suture (absorbable/non-absorbable). Absorbable sutures were associated with good results considering arteriovenous fistula maturation.

Higher Education, Widening Access and Market Failure: Towards a Dual Pricing Mechanism in England

Over a period of around fifteen years English higher education has become characterised by an increasingly marketise and differentiated system, most recently with the encouragement of new “challenger” providers potentially creating price competition for undergraduate degrees. This paper explores shifting patterns of enrolments between different institution types (those requiring high entry grades and those requiring lower entry grades) for evidence of how these types may be responding to the new market conditions. We introduce the concept of a “dual-pricing” mechanism to model how different institution types may be reacting. Dual pricing would be exemplified as a situation where entry requirements (a “price” based on qualification tariff points required for entry) and tuition-fee are matched in a linear hierarchy of institutions: Only the most prestigious institutions offering the courses demanding the highest entry qualifications (tariff) would command the highest fee (in this case a maxima of £9250 per annum), with fees demanded by institutions requiring lower entry requirements tapering off towards £6000 per year. This dual-pricing mechanism is discussed here as a policy aim, and the intention of this paper is to locate it in relation to market failure (defined as the failing of a market intervention to meet that policy aim). This paper’s critique of the marketised direction of travel in English higher education (HE) policymaking is that a dual-price mechanism would seriously undermine efforts to widen access for underrepresented social groups, particularly those from low income households who may be more likely to access low-cost provision rather than more transformative HE opportunities (supposedly those deriving from having a degree from a more prestigious institution), even if they met the entry requirements for higher-cost provision.

Thrombophilic risk factors in hemodialysis: Association with early vascular access occlusion and patient survival in long-term follow-up.

ObjectiveThrombophilic risk factors (TRFs) occur rather frequently in hemodialysis (HD) patients. However, little is known about their significance in HD patients, besides their potential impact on arteriovenous (AV) access failure, with varying results. We examined the effects of a wide variety of TRFs on both early AV fistula occlusion and survival among HD patients in long-term follow-up.MethodsIn this single-center, observational study, 70 consecutive HD patients from our dialysis center were examined with respect to shunt occlusion within the first 2 years after fistula creation and patient survival in a long-term follow-up (at least 16 years). We examined the presence of factor V, prothrombin, and MTHFR mutations using real-time fluorescence polymerase chain reaction. Furthermore, antithrombin (AT), protein C, protein S, and antiphospholipid antibodies (APL-Abs) were assessed.ResultsAmong the 70 patients, 32 had MTHFR mutations, 10 had heterozygous factor V Leiden mutations, 4 had prothrombin mutations, 4 had protein S deficiency, 2 had protein C deficiency, 9 had AT deficiency, and 14 had APL-Abs. 40 patients had shunt occlusion. TRFs were associated with a significantly increased risk for shunt thrombosis (P<0.02). Kaplan–Meier analysis with a log-rank test revealed significantly shorter survival in HD patients with TRFs (P<0.02). Cox regression analysis showed that the presence of TRFs (P<0.05; hazard ratio, 1.94; 95% CI: 1.07–3.56), but not early shunt occlusion, was associated with short patient survival.ConclusionsTRFs in hemodialysis patients have a strong impact on patient survival and early AV fistula failure; however, patient survival is not significantly affected by early shunt occlusion.

Six-year retrospective analysis of endoscopic ultrasonography-guided pancreatic ductal interventions at a tertiary referral center.

Endoscopic ultrasonography-guided pancreatic ductal intervention (EUS-PDI) serves as a rescue therapy in patients with failure of retrograde access to the pancreatic duct (PD) at the time of endoscopic retrograde pancreatography (ERP). We review our experience of this procedure. This is a retrospective study of patients who underwent EUS-PDI for an unsuccessful ERP and altered anatomy. A total of 44 (65.9% male) patients underwent EUS-PDI with a mean age of 43.5years, (range: 23-67). Transgastric rendezvous technique was carried out in 23/44 (52.3%), transgastric pancreaticogastrostomy in 18/44 (40.9%) and transduodenal pancreaticobulbostomy in 3/44 (6.8%). Overall technical and clinical success was seen in 88.6% (39/44) and 81.8% (36/44), respectively. Technical success of transgastric rendezvous was 95.6% and that of transgastric pancreaticogastrostomy was 77.8%. Two of seven patients with failure to access the PD had successfully undergone EUS-PD stenting at subsequent attempt. Ten immediate adverse events (AE) were noted which included abdominal pain (n=4), pancreatitis (n=2), fever (n=2), minor bleeding (n=1), and stripping of wire (n=1). Delayed AE included stent blockage in 12/39 (30.8%) and spontaneous stent migration in 5/39 (12.8%) which were managed with stent exchange at follow up. The rendezvous technique was associated with fewer AE than transgastric pancreaticogastrostomy. Endoscopic ultrasonography-PDI is an effective treatment modality and salvage therapy in patients with unsuccessful ERP. Technical and clinical success seen with this study is comparable to studies conducted across the world. EUS-PDI needs to show cost-effectiveness in future studies.

Distal Ulnar Approach in the Palmar Artery for Coronary Angiography and Intervention: Safety, Feasibility, and Reliability in 15 Patients

Highlights The distal ulnar palmar approach for both coronary angiography and intervention was safe, feasible, and reliable in our case series of 15 consecutive patients. The distal ulnar palmar approach was not a technical limitation for coronary angiography and interventional procedures in our cohort of patients. Further studies are needed to understand the potential benefits for patients and avoid medical futility. Abstract Background: Transradial and translunar approaches, associated with fewer bleeding and vascular complications than transfemoral access, have been adopted and increasingly utilized following a “radial-first strategy.” Approaches that are innovative and more distal than standard radial approaches are available, even if their clinical utility is under debate. At the price of a more difficult puncture and risk of access failure, there are possible ergonomic advantages, with lower risk of upstream artery occlusion and shorter hemostasis. Aim: The study was aimed at proving the preliminary feasibility, safety, and reliability of the right distal ulnar palmar approach in 15 consecutive patients. Results: In 15 out of the 17 patients enrolled, the distal ulnar access in the palmar artery was feasible, safe, and reliable. The diameter of the distal ulnar artery was greater than that of the distal radial in the anatomical snuff box. There were no significant complications. Conclusion: The distal ulnar palmar approach for both coronary angiography and intervention was safe, feasible, and reliable. It was not a limitation for coronary angiography and interventional procedures in our cohort of patients

Enhanced Dialysis Access Patency Using Machine Learning

Arteriovenous fistulas (AVFs) and grafts (AVGs) are associated with an overall patency of 64% to 78% at 1 year and typically require multiple primary and secondary interventions to achieve those results. Improved surveillance, routine ultrasound, medical management, and better care coordination can improve patency but require greater resources and complex process improvements. The purpose of this paper was to describe an innovative data-driven approach to significantly improve access patency through machine learning. Patients who had creation of an AVF or AVG for end-stage renal disease between May 2016 and March 2019 were monitored as part of an enhanced surveillance program intended to improve access-related patency. Patient demographics, hospital covariates, and procedural details were collected. Flow velocities were measured on a weekly basis, and ultrasound velocities were compiled on a 3-month basis during clinic visits. All data were collected within the purpose-built QuartzClinical (Chicago, Ill) data registry prospectively. A machine learning model was used to assist with clinical decision-making on access-related interventions from May 2016 through March 2018. A total of 68 AVFs and 44 AVGs were monitored by the machine learning algorithm. The algorithm recommended interventions on 29 AVFs (42.6%) and 10 AVGs (22.7%) during a 1-year period. The primary assisted patency was 77.9% for AVFs and 81.8% for AVGs. There were four secondary interventions for AVFs and three secondary interventions for AVGs. The overall patency was 83.8% for AVFs (P < .001 vs baseline) and 88.6% for AVGs (P < .01 vs baseline). The rate of interventions was significantly less after using the machine learning algorithm to guide treatment (observed-expected ratio = 0.76 [P < .00]1; observed-expected ratio = 0.72 [P < .01]). Through the decrease in number of procedures, avoidance of central venous catheters for access failure, and decreased rate of complications from secondary interventions, the total cost of care was decreased by $242,859. Machine learning offers the potential to more precisely guide clinical care in complex cases. A data-driven approach combined with sophisticated predictive analytics can reduce complications and failure rates in dialysis access while significantly decreasing the cost of care.

Percutaneous Trans-Carotid Puncture for Mechanical Thrombectomy in Acute Ischemic Stroke Patients is Safe and Effective: A Large, Single-Center Case Series

Abstract INTRODUCTION Although endovascular thrombectomy is a highly effective treatment for patients with large-vessel occlusion stroke, the procedure can be prolonged, or even impossible, due to difficult vascular access. We hypothesized that patients undergoing percutaneous transcarotid puncture (PTCP) as an alternative approach would have improved functional outcome compared to patients where a transfemoral approach was precluded. METHODS For PTCP, a 6F (5.5-cm) sheath was placed in the common carotid artery using an ultrasound-guided, micropuncture technique. Mechanical thrombectomy (MT) was performed using a stent retriever with adjunctive contact aspiration. We compared patients with unsuccessful MT due to transfemoral access failure with patients who were treated using PTCP. Functional outcome was assessed using the modified Rankin scale (mRS) at 3-mo. Associations with outcome were analyzed using ordinal logistic regression, adjusted for age and admission NIHSS. RESULTS PTCP was performed in 20 cases and carotid access was successfully obtained in 19/20 patients (1 abandoned due to inability to safely cannulate the artery). A total of 17 patients who were well matched for age, gender, and admission NIHSS served as historical controls. A total of 36 patients were included in the final analysis (82 yr [SD 11], 25 M, mean admission NIHSS 17). Successful reperfusion (TICI 2b-3) was achieved in 16/19 (84%), with 26% achieving good outcome (mRS 0-3) at 90 d compared to 6% of historical controls. In the shift analysis, PTCP was independently associated with lower (better) mRS scores at 3 mo (adjusted common OR 5.2, 95% CI 1.02-24.5, P = .048). PTCP cases also had smaller infarct volumes (median 11 vs 48 ml, P = .041) and greater reduction in NIHSS (−4 vs + 2.9, P = .034). A single patient suffered a fatal carotid blowout on post-MT day 4. CONCLUSION PTCP for emergent MT is a safe and effective strategy that yields high recanalization rates, decreased infarct volumes and improved functional outcome among patients with transfemoral access failure.

Effect of antiplatelet therapy on cardiovascular and kidney outcomes in patients with chronic kidney disease: a systematic review and meta-analysis

BackgroundThe benefits and risks of antiplatelet therapy for patients with chronic kidney disease (CKD) remain controversial. We undertook a systematic review and meta-analysis to investigate the effects of antiplatelet therapy on major clinical outcomes.MethodsWe systematically searched MEDLINE, Embase, and the Cochrane Library for trials published before April 2019 without language restriction. We included rrandomized controlled trials that involved adults with CKD and compared antiplatelet agents with controls.ResultsFifty eligible trials that included at least one event were identified, providing data for 27773patients with CKD, including 4518 major cardiovascular events and 1962 all-cause deaths. Antiplatelet therapy produced a 15% (OR, 0.85; 95% CI 0.74–0.94) reduction in the odds of major cardiovascular events (P = 0.002), a 48% reduction for access failure events (OR, 0.52; 95% CI, 0.31–0.73), but had no significantly effect on all-cause death (OR, 0.87; 95% CI, 0.71–1.01) or kidney failure events (OR, 0.87; 95% CI, 0.32–1.55). Adverse events were significantly increased by antiplatelet therapy, including major (OR, 1.33; 95% CI, 1.11–1.59) or minor bleeding (OR, 1.66; 95% CI, 1.27–2.05). Among every 1000 persons with CKD treated with antiplatelet therapy for 12 months, 23 major cardiovascular events will be prevented while nine major bleeding events will occur.ConclusionsMajor prevention with antiplatelet agents (cardiovascular events and access failure), might outweigh the risk of bleeding, and there seemed to be an overall net benefit. Individual evaluation and careful monitoring are required.

Adaptive Multiservice Heterogeneous Network Selection Scheme in Mobile Edge Computing

With the coming of the fifth-generation (5G) mobile communications, in mobile edge computing (MEC), the growth of user services and the personalization of QoS requirements have posed great challenges for heterogeneous wireless networks (HWNs) access selection. Based on the multiattribute decision theory and the fuzzy logic theory, we propose a novel network selection scheme for multiservice QoS requirements in MEC. The main procedures of the scheme include dynamic adaptive process, fuzzy process, hierarchical analysis, and integrated attributes assessment. The scheme proposed contributes to efficiently reduce the ping-pong effect and effectively select accurate network in a dynamic environment. Simulation results show that our scheme can select network access according to the type of user services and whether to switch networks. In addition, compared with commonly used simple additive weighting (SAW), random access selection (RAS), and price-based and QoS-based network selection scheme, our scheme has better performance in improving average user satisfaction and reducing access failures.

Current practice in dialysis central venous catheter management: Multi-disciplinary renal team perspectives.

To explore the current practices related to the insertion, management and removal of dialysis central venous catheters (CVCs) used in patients with chronic kidney disease requiring haemodialysis. This qualitative descriptive study involved semi-structured interviews with surgeons, interventional radiologists, renal physicians, dialysis nurses, renal access nurses and renal researchers involved in the care of patients with chronic kidney disease requiring haemodialysis. Data were collected from staff at eight hospitals in six states and territories of Australia. Thirty-eight face-to-face interviews were conducted. A modified five-step qualitative content analysis approach was used to analyse the data. Improved visualization technology and its use by interventional radiologists has steered insertions to specialist teams in specialist locations. This is thought to have decreased risk and improved patient outcomes. Nurses were identified as the professional group responsible for maintaining catheter access integrity, preventing access failure and reducing access-related complications. While best practice was considered important, justifications for variations in practice related to local patient and environment challenges were identified. The interdisciplinary team is central in the insertion, maintenance, removal and education of patients regarding dialysis CVCs. Clinicians temper research-based decision-making about central dialysis access catheter management with knowledge of individual, environmental and patient factors. Strategies to ensure guidelines are appropriately translated for use in a wide variety of settings are necessary for patient safety.

Factors affecting ampullary access of ERCP after Billroth II gastrectomy

Objective To investigate factors affecting ampullary access of endoscopic retrograde cholangiopancreatography (ERCP) in patients undergoing Billroth Ⅱ gastrectomy. Methods A retrospective analysis was performed on data of 261 patients with Billroth Ⅱ gastrectomy who underwent ERCP at Changhai Hospital from January 2008 to December 2017. Multivariate logistic regression analysis was used to analyze the potential factors affecting successful ampullary access, and receiver operating characteristic (ROC) curve was used to assess the predictive ability of potential factors. Results A total of 345 ERCP sessions were collected. The successful ampullary access and cannulation rate were 82.3% (284/345) and 89.1% (253/284), respectively. The main reasons for ERCP procedural failure were unable to reach the duodenal blind end and find the papilla (66.3%, 61/92) and failure of selective cannulation (33.7%, 31/92). The ERCP-related complication rate was 14.2% (49/345), with post-ERCP pancreatitis rate was 3.2% (11/345). Multivariate logistic regression analysis indicated that the first ERCP attempt (OR=7.717, 95%CI: 2.581-23.068. P<0.001), with Braun anastomosis (OR=8.737, 95%CI: 2.479-30.797, P=0.001), and no cap-assisted forward-viewing gastroscope (OR=2.774, 95%CI: 1.283-5.997, P=0.009) were independent risk factors for failure of ampullary access. According to the B value of each risk factor in logistic regression analysis, that is, no cap-assisted as 1 point, the first ERCP attempt as 2 points, and Braun anastomosis as 2 points, the area under ROC curve was 0.773. When the cut-off point was 2.5, the sensitivity and specificity were 75.0% and 70.8%, respectively. Conclusion The first ERCP attempt, with Braun anastomosis, and no cap-assisted forward-viewing gastroscope are risk factors for failure of ampullary access of ERCP in Billroth Ⅱ gastrectomy patients. Early identification of high-risk patients may help to improve the success rate of ampullary access. Key words: Cholangiopancreatography, endoscopic retrograde; Gastrectomy, Billroth Ⅱ; Risk factors

Enhancing interest forwarding for fast recovery from unanticipated data access failure in NDN

We show that an aggregated Interest in Named Data Networking (NDN) may fail to retrieve desired data since the Interest previously sent upstream for the same content is judged as a duplicate one and then dropped by an upstream node due to its multipath forwarding. Furthermore, we propose NDRUDAF, a NACK based mechanism that enhances the Interest forwarding and enables Detection and fast Recovery from such Unanticipated Data Access Failure. In the NDN enhanced with NDRUDAF, the router that aggregates the Interest detects such unanticipated data access failure based on a negative acknowledgement from the upstream node that judges the Interest as a duplicate one. Then the router retransmits the Interest as soon as possible on behalf of the requester whose Interest is aggregated to fast recover from the data access failure. We qualitatively and quantitatively analyze the performance of the NDN enhanced with our proposed NDRUDAF and compare it with that of the present NDN. Our experimental results validate that NDRUDAF improves the system performance in case of such unanticipated data access failure in terms of data access delay and network resource utilization efficiency at routers.

Influence of artery and vein diameters on autogenous arteriovenous access patency

ObjectivePrevious investigations have suggested that a minimum venous outflow diameter (MVOD) and perianastomotic arterial diameter are associated with successful autogenous arteriovenous maturation and patency. The goal of this study was to determine anatomic and clinical variables that may influence access patency to guide optimal autogenous access configuration selection. MethodsAccesses created from 2010 to 2016 were analyzed from data entered into a prospective database. Preprocedure duplex ultrasound mapping data of artery and tourniquet-derived vein diameters and demographic and clinical variables were collected. Survival-based cut point analysis was used to determine anatomic parameters most predictive of access failure. Kaplan-Meier and Cox proportional hazards analyses were used to assess patencies and maturation and to identify independent predictors of access failure. ResultsA total of 356 first-time autogenous accesses were created (median follow-up, 20 months; range, 0-73 months). Of these, 202 (56.7%) were radiocephalic and 154 (43.3%) were brachiocephalic. Maturation failure at end of follow-up for arteriovenous accesses was 26% ± 3% for radiocephalic accesses and 15% ± 3% for brachiocephalic accesses (P < .001). For radiocephalic accesses, MVOD <3.0 mm and radial artery diameter <2.1 mm independently predicted access maturation failure (MVOD <3.0 mm: hazard ratio [HR], 2.62 [95% confidence interval (CI), 1.27-5.39; P = .009]; radial artery diameter <2.1 mm: HR, 2.20 [95% CI, 1.20-4.05; P = .011]) and secondary patency loss (MVOD <3.0 mm: HR, 2.21 [95% CI, 1.24-3.96; P = .007]; radial artery diameter <2.1 mm: HR, 2.11 [95% CI, 1.26-3.63; P = .004]). A combination of radial artery diameter <2.1 mm and MVOD <3.0 mm most strongly predicted maturation failure (HR, 4.24; 95% CI, 1.71-10.49; P = .002) and loss of secondary patency (HR, 4.03; 95% CI, 1.88-8.64; P < .001). Only diabetes mellitus (HR, 2.24; P = .012) predicted secondary patency loss. For brachiocephalic accesses, MVOD <3.4 mm (HR, 2.12; 95% CI, 1.02-4.46; P = .043) was found to independently predict secondary patency loss in addition to previous ipsilateral (HR, 2.37; P = .038) and bilateral (HR, 4.00; P = .015) tunneled hemodialysis catheters. Brachial artery diameter was not associated with either access maturation or patency. ConclusionsArtery and tourniquet-derived vein diameters independently predict radiocephalic access patency and functional outcomes. A combination of a radial artery diameter <2.1 mm and MVOD <3.0 mm best predicts maturation failure and patency loss for radiocephalic access. MVOD <3.4 mm was associated with increased loss of brachiocephalic access secondary patency, but MVOD was not associated with maturation.

Análise radiográfica das aberturas endodônticas de dentes de pacientes referenciados a um Centro de Especialidades Odontológicas Radiographic analysis of endodontic access of patients referenced to a Center of Dental Specialities

Introduction: Coronary access is the first stage of endodontic treatment and aims at direct access to root canals. Objective: To evaluate, by radiographic analysis, endodontic access cavities through radiographic analysis of the teeth of patients coming from primary care referred to the Center of Dental Specialties (CEO) Positivo, Curitiba, PR, Brazil. Material and methods: A total of 226 periapical radiographs taken previous to attending the CDS were analyzed, from August 2015 to August 2017. Three trained and calibrated examiners verified the following criteria: oral cavity region, presence of remaining caries,removal of roof of the pulp chamber, compensatory mesiodistal wear, iatrogenic (suggestive) and temporary restoration. Data were tabulated and analyzed for distribution, followed by bivariate analysis (Fisher’s Exact Test) with significance of 5%. Results: The posterior region prevailed in 70.3% of the sample. There remaining caries were found in 14.2%, insufficient roof removal in 25.2%, iatrogenic in 35.4%, and inadequate height of the temporary restoration in 11.5% of the cases. In the posterior teeth, insufficient mesiodistal compensatory wear was identified in 35.4 of the exams. The bivariate analysis revealed no significant difference when the variable region of the oral cavity was analyzed in relation to the presence of caries (p = 0.393), remaining roof (p = 0.056) and presence of iatrogenic (p = 0.304). Conclusion: It is concluded that there are relevant failures in the endodontic access received in the CDS, which indicates the need for professional training in primary care.

The Role of MicroRNA-21 in Venous Neointimal Hyperplasia: Implications for Targeting miR-21 for VNH Treatment.

The molecular mechanism of hemodialysis access arteriovenous fistula (AVF) failure due to venous neointimal hyperplasia (VNH) is not known. The role of microRNA-21 (miR-21) in VNH associated with AVF failure was investigated by performing in vivo and in vitro experiments. In situ hybridization results revealed that miR-21 expression increased and was associated with fibroblasts in failed AVFs from patients. In a murine AVF model, qRT-PCR gene expression results showed a significant increase in miR-21 and a decrease in miR-21 target genes in graft veins (GVs) compared to contralateral veins in mouse AVF. miR-21 knockdown in GVs was performed using a lentivirus-mediated small hairpin RNA (shRNA), and this improved AVF patency with a decrease in neointima compared to control GVs. Moreover, loss of miR-21 in GVs significantly decreased the Tgfβ1, Col-Ia, and Col-Iva genes. Immunohistochemistry demonstrated a significant decrease in myofibroblasts and proliferation with an increase in terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining in miR-21-knockdown vessels, along with a decrease in hypoxia-inducible factor-1 alpha (HIF-1α) and phospho-SMAD2 (pSMAD-2) and phospho-SMAD3 (pSMAD-3) and an increase in phosphatase and tensin homolog (PTEN) staining. Hypoxic fibroblast knockdown for miR-21 showed a significant decrease in Tgfβ-1 expression and pSMAD-2 and -3 levels and a decrease in myofibroblasts. These results indicate that miR-21 upregulation causes VNH formation by fibroblast-to-myofibroblast differentiation.

MON-132 PERCUTANEOUS TRANSHEPATIC TUNNELLED CATHETER FOR HAEMODIALYSIS: A SINGLE CENTRE EXPERIENCE

Obtaining vascular access for dialysis can be challenging in long-term haemodialysis patients who have exhausted all traditional access sites as a result of multiple catheter placements. Transhepatic dialysis catheter insertion is potentially life-saving for those with access failure. This study aims at evaluating the functionality and safety of transhepatic venous catheters in haemodialysis patients. Eight patients (3 male and 5 female, aged 59+/-17 years ) had transhepatic tunnelled dialysis catheters inserted in our haemodialysis unit in the past 3 years. The insertion method, type of catheter use, functional duration of catheters, maximum blood flow rate achieved, catheter complications and reasons for catheter removal were evaluated retrospectively. A total of eleven transhepatic catheters were placed in eight patients between January 2016 and November 2018. All the patients were on long term dialysis, with a mean dialysis vintage of 160 months. Most patients started with peritoneal dialysis, and switched to haemodialysis after peritoneal failure. The average heamodialysis duration was 85 months (range 14-144 months). Nine catheters were placed successfully (9/11, 82% technical success). Catheter insertion failed due to development of subphenic haematoma in 1 patient and the negotiation of the catheter into the proper venous position was unsuccessful in the other. One catheter was placed under general anaesthesia while the rest were done under local anaesthesia. RetrO® Long-Term Hemodialysis Catheter (BARD Access Systems) was used in 10 out of 11 of the procedures, and Permcath™ (Medtronic) was used in 1 case. Seven of the 9 functional catheters were placed in the portal vein while the remaining 2 were placed in the hepatic vein. The functional duration of transhepatic catheters ranges from 32 to 551 days, with a mean of 298 days. Of the 9 catheters, 2 were still in use at the end of the study (2/9, 22.2%). One patient died with a functional catheter. Six of the catheters were removed(6/9, 66.6%) . Arteriovenous fistular was created in 1 patient, while 3 catheters were removed due to catheter thrombosis (3/9, 33.3%). Two patients were noted to have catheter dislodgement into the pleural cavity (2/9, 22.2%), both presented with shock and haemothorax. Poor blood flow was the most common complication during the use of transhepatic catheters. Catheter revision was required in 2 cases. The maximum blood flow rate achieved for each catheter ranged from 150ml/minute to 250ml/minute, with a mean rate of 186ml/minute. The maximum blood flow rate was below 200ml/minute in 4 of the catheters (4/9,44.4%). Bleeding at the catheter site necessitating hospital admission occurred in 3 cases (3/9, 33.3%), catheter exit site infection occurred in 2 (2/9, 22.2%), but there were no catheter related sepsis. For patients who have exhausted access options for dialysis, transhepatic catheter placement is an alternative with potentially good long-term functionality. However, limitations in blood flow rate, and the high thrombosis rate with the need for high level of maintenance to preserve patency should be noted. Furthermore, physicians need to be cautious about potentially life-threatening complications such as catheter dislodgement.

Enhancing interest forwarding for fast recovery from unanticipated data access failure in NDN

Enhancing interest forwarding for fast recovery from unanticipated data access failure in NDN

Performance analysis and optimization for coverage enhancement strategy of Narrow-band Internet of Things

Narrowband Internet of Things (NB-IoT) is a clean-slate wireless protocol proposed by the 3rd Generation Partnership Project intending for massive machine type communications. The general objectives of the NB-IoT include supporting massive connections, enhanced coverage, reduced cost and complexity, ultra-low power consumption, and flexible delay characteristics. To achieve the objective of 20dB enhanced coverage of NB-IoT, the concept of narrow-band modulation, coverage classes updating and adaptive repetition were introduced. To evaluate the performance of these new techniques, a Markov chain model with coverage classes as state variables was proposed to describe the dynamics of the coverage classes updating mechanism of NB-IoT. In addition, an optimization model minimizing average probability of access failure as well as average power consumption was formulated, with which the effects of preamble repetition number, system load and global maximum transmission number on the optimal configuration of maximum transmission number of each coverage class was analyzed. To solve the aforementioned optimization model, two algorithms, namely exhaustive search method combining constraint transform and particle swarm optimization (PSO) algorithm with self-adaptive stochastic inertia weight were proposed. Numerical results show that the maximum transmission number of normal coverage and extended coverage have a great influence on the system performance and their value ranges should be set within [3,10] and [1,6] respectively; while the maximum transmission number of extreme coverage has little influence on the system performance, and its recommended value is 1 for smaller power consumption. The average power consumption of coverage classes updating mechanism with coverage classes rollback is about 61% lower than that of 3GPP proposed model. All these researches together provide good reference for scale deployment of NB-IoT.