1,720,979 research outputs found
Pro: Vascular access surveillance in mature fistulas: is it worthwhile?
No full textGuidelines recommend regular screening of mature arteriovenous fistulas (AVFs) for preemptive repair of significant stenosis (≥50% lumen reduction) at high risk of thrombosis, identifiable from clinical signs of access dysfunction (monitoring) or by measuring access blood flow (Qa surveillance), which also enables stenosis detection in functional accesses. To compare the value of Qa surveillance versus monitoring, a meta-analysis was performed on the randomized controlled trials (RCTs) comparing the two screening strategies. It emerged that correcting stenosis identified by Qa surveillance significantly halved the risk of thrombosis [relative risk (RR) = 0.51, 95% confidence interval (CI) 0.35-0.73] and access loss (RR = 0.47, 95% CI 0.28-0.80) in comparison with intervention prompted by clinical signs of access dysfunction. One small RCT aiming to identify an optimal Qa threshold showed that stenosis repair at Qa >500 mL/min produced a significant 3-fold reduction in the risk of thrombosis (RR = 0.37, 95% CI 0.12-0.97) and access loss (RR = 0.36, 95% CI 0.09-0.99) in comparison with intervening when Qa dropped to <400 mL/min as per guidelines. To test the real-world benefits of Qa surveillance, the expected RCT-based thrombosis and access loss rates with Qa surveillance were compared with the rates with monitoring reported in observational studies: the expected thrombosis and access loss rates with surveillance were only lower than with monitoring when a Qa >500 mL/min was considered (2.4, 95% CI 1.0-4.6 and 2.2, 95% CI 0.7-5.0 versus 9.4, 95% CI 7.4-11.3 and 10.3, 95% CI 7.7-13.4 events per 100 AVFs-year, P ≤ 0.024), suggesting that in clinical practice adopting Qa surveillance may only be worthwhile at centres with high thrombosis and access loss rates associated with monitoring, and adopting Qa thresholds >500 mL/min for elective stenosis repair
Clinical access assessment
No full textBackground: Vascular access guidelines recommend routine screening for the timely detection of stenosis using noninvasive methods, including clinical assessment (monitoring) and device-based surveillance relying on access blood flow (Qa) and static intra-access pressure (sVPR, static venous pressure ratio) measurements and duplex ultrasound (DU). Methods: We reviewed the literature to see how monitoring compares with surveillance in terms of compliance with the World Health Organization's criteria for screening tests. Results: The fundamental element of monitoring, physical examination (PE), has a fair-to-good performance in detecting stenosis in both fistulas and grafts, similar to the Qa criteria recommended in the guidelines. In fistulas, the "or" combination of a positive PE with a Qa 0.5 is more sensitive in detecting stenosis (in up to 98% of cases), making it as good as DU. In grafts, PE performed significantly less well in diagnosing stenosis than sVPR or DU. In randomized controlled trials on fistulas, Qa surveillance enables a significant halving of the risk of thrombosis and access loss by comparison with monitoring alone when Qa criteria highly sensitive to stenosis are considered. In grafts, neither Qa nor DU nor sVPR is able to reduce thrombosis or access loss rates by comparison with monitoring alone. Conclusions: Our analysis indicates that regular monitoring should be the backbone of any vascular access stenosis screening program (possibly associated with Qa and sVPR surveillance for fistulas), and PE should be part of every teaching program for caregivers involved in hemodialysis
The Rise and Fall of Access Blood Flow Surveillance in Arteriovenous Fistulas
No full textVascular access blood flow (Qa) surveillance has been described as a typical false paradigm, an example of how new tests are sometimes adopted even without good-quality evidence of their benefits. This may be true for grafts, but not necessarily for arteriovenous fistulas. We reviewed the literature on Qa surveillance in fistulas to see whether it complies with the World Health Organization’s criteria for screening tests. Measuring Qa has a fairly good reproduc-ibility. Qa shows an excellent-to-good accuracy for stenosis being the only bedside screening test that achieves a very high sensitivity while retaining a fair-to-good positive pre-dictive value for Qa thresholds of 600 ml/minute or higher associated with a > 25% drop in Qa, or findings suggestingstenosis on physical examination. The accuracy of Qa in predicting thrombosis is hard to establish because of the heterogeneity of published studies, though a Qa of 300 ml/minute seems the most reliable cutoff. Qa surveillanceaffords a significant 2- to 3-fold reduction in the risk of thrombosis by comparison with clinical monitoring alone when Qa criteria highly sensitive to stenosis are considered, regardless of the study design (randomized controlled trials, cohort studies with concurrent or historic controls). Usinghighly sensitive Qa screening criteria also halves the risk of access loss, although this effect is not statistically signifi-cant. Our analysis strongly suggests that Qa surveillance is an effective method for screening mature fistulas, thoughfurther, appropriately designed studies are needed to fully elucidate its benefits and cost effectiveness
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Valutazione dei risultati nel confezionamento di anastomosi per fistola artero-venosa con diversi materiali di sutura
No full textNei pazienti con insufficienza renale cronica la dialisi
extracorporea rappresenta tuttora la terapia di prima scelta
mediante l'utilizzo di una fistola artero-venosa (FAV)
ottenuta anastomizzando una vena ad una arteria al braccio. La FAV va però incontro nel 20% dei casi ad una
occlusione entro i primi 20 giorni; a tale incidenza si
aggiunge un altro 10% di occlusione ad 1 anno. Uno dei
principali meccanismi fisiopatologici chiamati in causa
per spiegare l'occlusione e la stenosi oltre alla non perfetta
tecnica chirurgica, è l'elevata presenza di turbolenza di
flusso che favorisce il danno endoteliale. A ciò si aggiunge
la reazione dell'endotelio della rima anastomotica al
corpo estraneo rappresentato dal filo di sutura. Alla contemporanea presenza di questi due fattori è dovuto il
fatto che nell' 80% dei casi la stenosi si realizza a livello
dell'anastomosi e del primo tratto di vena efferente
SURGICAL APPROACH TO RECURRENT STENOSIS IN NATIVE A-V FISTULA: NEOANASTOMOSIS OR GRAFT INTERPOSITION ?
No full textRecurrent stenosis usually located in the perianastomotlc site, is the leading cause of native arterio-venous fistula (AVF) failure. Surgery is, considered the treatment of choice: usually a more proximal, neo-anastomosis is, created, but its drawback is the loss of vessel sites available for puncture
Endovascular vs Interposition Graft Repair of Forearm Arteriovenous Fistula (AVF) Stenosis: A Prospective Study.
No full textAngioplasty (PTA) has been proposed as first-line therapy for forearm AVF stenosisbecause of no loss of the venous capital and excellent success rate and patency. Stenosisrepair by a PTFE interposition graft (IG) shares the advantages of PTA of a minor or noreduction of cannulation area and excellent success rate, but concern has been raised of a high complication rate (stenosis, thrombosis, infection) associated with this type of device. We compared prospectively the outcome of stenosis repair by PTA vs IG (by 3-12 cm dialysis PTFE grafts) in mature forearm AV
Reply to: Can blood flow surveillance and pre-emptive repair of subclinical stenosis prolong the useful life of arteriovenous fistulae? A randomized controlled study (multiple letters)
No full textIn the September 2004 issue of Nephrology DialysisTransplantaion, Tessitore et al. [1] provide further evidencethat arteriovenous (AV) access blood flow surveillanceand pre-emptive repair of subclinical stenosis reduce thethrombosis rate and prolong the life of AV fistulae. In thisreport, 12 of the 43 patients with dysfunction of AV fistulaeproposed for treatment with percutaneous transluminalangioplasty (PTA) were considered not to be amenableto PTA by radiologists, and thus were surgical candidatesfor the following reasons: stenosis segment >2.5 cm, multipleperianastomotic stenoses and critical (>90%) isolatedperianastomotic stenosis
IL DUPLEX SCANNER E L'ANGIOGRAFIA DIGITALIZZATA NELLA PATOLOGIA DEGLI ASSI CAROTIDEI
No full textThe Authors emphasize the Duplex-Scanner
validity in the diagnosis of sovraortic trunks
disease.
They compared 55 patients, examined first
with Duplex-Scanner, and after with Digita]
Su~btraction Angiography.
They found a significant agreement (max 20%
of stenosis percentage difference) in 87% of the
examined patients.
In Authors' opinion Duplex-Scanner - utilized
by ·an expert operator - is the choice
device for the screening of the sovraortic trunk
diseases, and in the follow-up of the operate patient
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