Early ultrasound surveillance of newly-created haemodialysis arteriovenous fistula

IntroductionWe assess if ultrasound surveillance of newly-created arteriovenous fistulas (AVFs) can predict nonmaturation sufficiently reliably to justify randomized controlled trial (RCT) evaluation of ultrasound-directed salvage intervention.MethodsConsenting adults underwent blinded fortnightly ultrasound scanning of their AVF after creation, with scan characteristics that predicted AVF nonmaturation identified by logistic regression modeling.ResultsOf 333 AVFs created, 65.8% matured by 10 weeks. Serial scanning revealed that maturation occurred rapidly, whereas consistently lower fistula flow rates and venous diameters were observed in those that did not mature. Wrist and elbow AVF nonmaturation could be optimally modeled from week 4 ultrasound parameters alone, but with only moderate positive predictive values (PPVs) (wrist, 60.6% [95% confidence interval, CI: 43.9–77.3]; elbow, 66.7% [48.9–84.4]). Moreover, 40 (70.2%) of the 57 AVFs that thrombosed by week 10 had already failed by the week 4 scan, thus limiting the potential of salvage procedures initiated by that scan’s findings to alter overall maturation rates. Modeling of the early ultrasound characteristics could also predict primary patency failure at 6 months; however, that model performed poorly at predicting assisted primary failure (those AVFs that failed despite a salvage attempt), partly because patency of at-risk AVFs was maintained by successful salvage performed without recourse to the early scan data.ConclusionEarly ultrasound surveillance may predict fistula maturation, but is likely, at best, to result in only very modest improvements in fistula patency. Power calculations suggest that an impractically large number of participants (>1700) would be required for formal RCT evaluation

Early Ultrasound Surveillance of Newly-Created Hemodialysis Arteriovenous Fistula

Introduction: We assess if ultrasound surveillance of newly-created arteriovenous fistulas (AVFs) can predict nonmaturation sufficiently reliably to justify randomised controlled trial (RCT) evaluation of ultrasounddirected salvage intervention. Methods: Consenting adults underwent blinded fortnightly ultrasound scanning of their AVF after creation, with scan characteristics that predicted AVF non-maturation identified by logistic regression modelling. Results: Of 333 AVFs created, 65.8% matured by 10 weeks. Serial scanning revealed that maturation occurred rapidly, whereas consistently lower fistula flow rates and venous diameters were observed in those that did not mature. Wrist and elbow AVF non-maturation could be optimally modelled from the week four ultrasound parameters alone, but with only moderate positive predictive values (wrist, 60.6% (95% CI 43.9 – 77.3); elbow, 66.7% (48.9 - 84.4)). Moreover, 40 (70.2%) of the 57 AVFs that thrombosed by week 10 had already failed by the week 4 scan, thus limiting the potential of salvage procedures initiated by that scan’s findings to alter overall maturation rates. Modelling of the early ultrasound characteristics could also predict primary patency failure at 6 months, but that model performed poorly at predicting assisted primary failure (those AVFs that failed despite a salvage attempt), partly because patency of at-risk AVFs was maintained by successful salvage performed without recourse to the early scan data. Conclusions: Early ultrasound surveillance may predict fistula maturation, but is likely, at best, to result in only very modest improvements in fistula patency. Power calculations suggest that an impractically large number of participants (>1700) would be required for formal RCT evaluation

A comparison of New Zealand and overseas white clover cultivars under grazing in New Zealand

A large number of white clover cultivars bred both in New Zealand and overseas are available for use by New Zealand pastoral farmers. Unfortunately, there is little published data on the merits of these cultivars under New Zealand conditions. Data from a series of trials established in the Manawatu between 1996 and 2005, containing a range of cultivars from Europe, the Mediterranean, North and South America and New Zealand were used in a meta-analysis to assess the general adaptive yield and persistence potential of these contrasting cultivar types. All trials were maintained over two to four years, and revealed significant cultivar effects. Overall, New Zealand bred cultivars showed better adaptation than overseas cultivars in these New Zealand-based trials. However, overseas cultivars containing Mediterranean germplasm, particularly from southern France, Italy and Syria exhibited beneficial features in the trials, and many recently bred New Zealand cultivars contain germplasm from these origins. In addition to using the appropriate parent germplasm when developing cultivars, it is equally important to evaluate and select under local conditions in competition with grass under grazing over multiple years. New Zealand farmers may benefit from an industry-wide benchmarking system for white clover cultivars, possibly by incorporation into the Forage Value Index

Integrated circuits for channel coding in 3G cellular mobile wireless systems

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