Vessel diameter and close surveillance helps predict early patency in native arteriovenous fistulas.

INTRODUCTION: Arteriovenous fistulas are the preferred method of vascular access for haemodialysis. Data suggests patency rates can be low and may be related to vessel diameters prior to creation. We use specific size criteria for fistula selection. We aimed to establish patency rates in relation to vessel size and whether other factors affect fistula patency. METHODS: Consecutive patients undergoing radiocephalic (RCF) or brachiocephalic (BCF) creation between 2016 and 2018 were analysed. Preoperative arterial and venous diameters were collected. Six-week and six-month primary and secondary patency rates were analysed to establish any impact of vessel size on patency and re-intervention rates between groups. A univariate analysis was performed. RESULTS: Ninety four RCFs and 101 BCFs were created. Median artery and vein size for RCF were 2.7 and 3.0 mm respectively. For BCF, they were 4.6 and 4.3 mm respectively. At 6-weeks, overall satisfactory patency for RCF and BCF combined was 91.8%. 89.7% demonstrated primary patency; 2.1% secondary patency. At 6-months, overall patency was 78.7%; 58.5% demonstrated primary patency, 20.2% secondary patency. A univariate analysis, for both groups, revealed vein size was a significant predictor of overall satisfactory patency at 6-weeks, with larger veins more likely to remain patent (p = 0.025 RCF, p = 0.007 BCF). However, artery size was not predictive (p = 0.1 RCF, p = 0.5 BCF). At 6-months, neither artery nor vein diameter were predictive in either group. When comparing size of vessel based on fistula type, vessels used to create RCFs were smaller than those for BCFs (p < 0.001). RCFs were more likely to receive endovascular intervention or occlude when compared to BCFs (p = 0.014). DISCUSSION: Excellent patency and maturation rates can be achieved using fairly strict vessel size criteria. Vein size might be the more important predictor of early success. RCFs can be challenging due to smaller vessels, but maturation rates can be optimised by close surveillance and aggressive re-intervention.

Missing expectations: Windlass tourniquet use without formal training yields poor results.

BACKGROUND: Despite significant attempts to educate civilians in hemorrhage control, the majority remain untrained. We sought to determine if laypersons can successfully apply one of three commercially available tourniquets; including those endorsed by the United States Military and the American College of Surgeons. METHODS: Preclinical graduate health science students were randomly assigned a commercially available windless tourniquet: SAM XT, Combat Application Tourniquet (CAT), or Special Operation Forces Tactical Tourniquet (SOFT-T). Each was given up to 1 minute to read package instructions and asked to apply it to the HapMed Leg Tourniquet Trainer. Estimated blood loss was measured until successful hemostatic pressure was achieved or simulated death occurred from exsanguination. Simulation survival, time to read instructions and stop bleeding, tourniquet pressure, and blood loss were analyzed. RESULTS: Of the 150 students recruited, 55, 46, and 49 were randomized to the SAM XT, CAT, SOFT-T, respectively. Mean overall simulation survival was less than 66% (65%, 72%, 61%; p = 0.55). Of survivors, all three tourniquets performed similarly in median pressure applied (319, 315, and 329 mm Hg; p = 0.54) and median time to stop bleeding (91, 70, 77 seconds; p = 0.28). There was a statistical difference in median blood loss volume favoring SOFT-T (SAM XT, 686 mL; CAT, 624 mL; SOFT-T, 433 mL; p = 0.03). All 16 participants with previous experience were able to successfully place the tourniquet compared with 81 (62%) of 131 first-time users (p = 0.008). CONCLUSION: No one should die of extremity hemorrhage, and civilians are our first line of defense. We demonstrate that when an untrained layperson is handed a commonly accepted tourniquet, failure is unacceptably high. Current devices are not intuitive and require training beyond the enclosed instructions. Plans to further evaluate this cohort after formal "Stop the Bleed" training are underway.

Global connectivity patterns of the notoriously invasive mussel, Mytilus galloprovincialis Lmk using archived CO1 sequence data.

OBJECTIVE: The invasive mussel, Mytilus galloprovincialis has established invasive populations across the globe and in some regions, have completely displaced native mussels through competitive exclusion. The objective of this study was to elucidate global connectivity patterns of M. galloprovincialis strictly using archived cytochrome c oxidase 1 sequence data obtained from public databases. Through exhaustive mining and the development of a systematic workflow, we compiled the most comprehensive global CO1 dataset for M. galloprovincialis thus far, consisting of 209 sequences representing 14 populations. Haplotype networks were constructed and genetic differentiation was assessed using pairwise analysis of molecular variance. RESULTS: There was significant genetic structuring across populations with significant geographic patterning of haplotypes. In particular, South Korea, South China, Turkey and Australasia appear to be the most genetically isolated populations. However, we were unable to recover a northern and southern hemisphere grouping for M. galloprovincialis as was found in previous studies. These results suggest a complex dispersal pattern for M. galloprovincialis driven by several contributors including both natural and anthropogenic dispersal mechanisms along with the possibility of potential hybridization and ancient vicariance events.

Membrane flux not biocompatibility determines beta-2-microglobulin levels in hemodialysis patients.

BACKGROUND: Serum beta(2)-microglobulin (beta(2)M) levels are important in dialysis-related amyloid deposition but can be influenced by dialysis technique. METHODS: We measured beta(2)M levels in 3 centres using different dialysis regimes. Centre 1 (73 patients) used high-flux biocompatible, centre 2 (72 patients) low-flux biocompatible and centre 3 (142 patients) cuprophane dialysers. RESULTS: beta(2)M levels were lower with high-flux biocompatible than with low-flux biocompatible or cuprophane dialysis (22.3 +/- 5.4 vs. 43.4 +/-13.7 and 37.6 +/-13.1 mg/l, respectively; p < 0.001). Levels were higher with low-flux biocompatible than with cuprophane dialysis (p < 0.001), but not if patients dialysed over 10 years were excluded. With low-flux biocompatible (47.4 +/- 9.8 vs. 38.7 +/- 15.2 mg/l; p < 0.01) and cuprophane dialysis (43.4 +/- 8.2 vs. 36.7 +/- 13.0 mg/l; p < 0.02), beta(2)M levels were higher in patients dialysed over 5 years than in those dialysed less. Despite beta(2)M levels increasing as residual renal function declined, there was no similar rise with high-flux biocompatible dialysis. CONCLUSIONS: Techniques allowing significant convection maintain lower beta(2)M levels over many years. Membrane flux, not biocompatibility, is the main determinant of beta(2)M levels in routine practice.