Blood loss from the access cannulation site during hemodialysis (HD) treatment is inevitable. Nevertheless, during HD, excessive blood loss from the cannulation site is not uncommon. The clinical characteristics associated with it and whether such blood loss could impact on patient outcomes is unknown. This pilot study aims to identify the prevalence and risk factors associated with excessive bleeding (≥ 4 mL/session) from dialysis access cannulation site during regular HD treatments. Stable end-stage renal disease patients receiving maintenance HD via arteriovenous fistula (AVF) or graft (AVG) were included in this study (N = 361). They were closely monitored for one month for the occurrence of excessive access bleeding during each HD session. A total of 4152 sessions of HD were performed during the study period and 143 patients (39.6%) had at least one episode of excessive bleeding from the vascular access (≥ 4 mL/session). Individuals experiencing excessive bleeding episodes had a significantly lower hemoglobin level, higher rate of diabetes, central venous stenosis, longer dialysis vintage, lower serum albumin level, longer hemostasis time and higher AVG and anti-platelet agent use (all P < 0.05). In the multivariable logistic regression model, longer dialysis vintage, central venous stenosis, lower hemoglobin level, and AVG usage were independently associated with occurrence of excessive access bleeding. AVG users also clustered with other risk factors for excessive access bleeding. Our study identified the novel associations between excessive cannulation site bleeding with dialysis vintage, anemia and AVG usage. The significance and impact of long-term chronic, intermittent bleeding from dialysis access should be further explored.
Our group has previously reported that excessive vascular access bleeding during dialysis treatment in stable hemodialysis (HD) patients was associated with anemia and may indicate poorer health. The association between excessive blood loss from access cannulation site and clinical outcomes was unknown. We hypothesized that excessive access bleeding may have an impact on all-cause and cardiovascular (CV) mortality in this population. We prospectively conducted an observational, longitudinal study of 360 HD patients. Excessive access bleeding was defined as at least an occurrence of blood loss greater than 4 mL per HD session during a study period of one month. During a median follow-up of 83 months, all-cause mortality and CV mortality were registered. Outcomes were analyzed by Kaplan-Meier and Cox proportional hazards regression analyses. A total of 118 (32.8%) participants died and 54 of these were from CV death. Using a multivariate Cox proportional hazards regression, access bleeding was found to be an independent predictor of all-cause mortality (HR 1.67, 95% CI 0.96-2.91, P = 0.070) but not for CV death (HR 1.53, 95% CI 0.88-2.68, P = 0.135). Our study identified that excessive access cannulation site bleeding could be a novel marker for increased risk of death in HD patients.
While two-dimensional (2-D) orthogonal variable spreading factor (OVSF) codes were proposed for multicarrier direct-sequence code-division multipleaccess (MC/DS-CDMA) systems in order to eliminate multiple-access interference, the number of orthogonal sequences (or code cardinality) was restricted by the number of carrier frequencies. Non-orthogonal 2-D frequency-time-spreading (FTS) codes were then proposed to increase the code cardinality by sacrificing some code performance. To improve the code performance, we here propose a modified 2-D FTS code. We also evaluate the performance of the new code in the MC/DS-CDMA system over a non-fading additive white Gaussian noise channel and a Rayleigh fading channel, and compare with those of the 2-D OVSF, random and original FTS codes.
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