Vascular access problems in dialysis patients: pathogenesis and strategies for management

Effects of omega-3 fatty acid supplementation on vascular access thrombosis in polytetrafluorethylene grafts

OBJECTIVE

The purpose of this study was to investigate the effects of orally administered over-the-counter omega-3 (n-3) fatty acid supplements on primary patency of polytetrafluoroethylene (PTFE) grafts.

DESIGN

This study was conducted with a triple-blind, permuted-block, randomized, placebo-controlled experimental design.

SETTING

Dialysis clinics with patients who, in accordance with physician diagnosis, needed a new PTFE graft.

PATIENTS AND OTHER PARTICIPANTS

Patients on long-term hemodialysis with newly placed PTFE grafts who were unable to receive a native arteriovenous fistula.

INTERVENTION

Patients were followed prospectively for 8 months after they had been placed into an n-3 fatty acid or control group and were monitored for primary patency.

MAIN OUTCOME VARIABLE

Primary patency of the PTFE graft.

RESULTS

The n-3 fatty acid group had a mean PTFE graft primary patency rate of 254.2 days (SEM = 51.8), and the control group had a mean PTFE graft primary patency rate of 254.1 days (SEM = 34.6), revealing no significant difference in survival time between groups.

CONCLUSIONS

No significant differences in primary patency rates were noted in the experimental and control groups.

Homocysteine and vascular access thrombosis in a cohort of end-stage renal disease patients

BACKGROUND

Maintaining successful hemodialysis services is dependent upon an access to circulation that is reliable and stable. Complications of vascular access such as dysfunction, thrombosis, or infection are major causes of hospitalization with thrombosis being the most common reoccurring problem. Initial prospective evidence supports an independent association between total homocysteine (tHcy) levels and access thrombosis. The purpose of this study was to determine if significant associations exist between tHcy, age, gender, and vascular access thrombosis in patients with end-stage renal disease (ESRD).

SUBJECTS AND METHODS

One hundred eighty-five (N=185) patients undergoing dialysis were selected as subjects. The retrospective sample was divided into a one or less vascular access thrombosis (VAT) (VAT) group (n= 133) and more than one (VAT II) VAT group (n= 52). The data was collected during a 16-month period (January 2000 to April 2002). Additional subgroup analyses included gender and age.

RESULTS

The Mann-Whitney U nonparametric t-Test for variance between groups revealed no significant difference in tHcy values between VAT groups (U=1841.50, p=0.284). A two-sample t-Test for variance between tHcy and age revealed no significant differences (F-ratio = 0.832, p = 0.32). A chi-square analysis revealed no significant differences in gender and VAT groups (chi2=0.246, p=0.62). A Kolmogorov-Smirnov test for normality was calculated for tHcy with a p-value of 0.859 revealing insufficient evidence that the distribution is not normal. Spearman Rank Correlations were calculated, revealing low to moderate associations among variables.

CONCLUSIONS

While some studies have demonstrated a relationship between tHcy and VAT, this study found that chronically high homocysteine levels in patients with ESRD were not associated with incidence of VAT. There were no significant differences in the number of VATs across additional variables of age and gender.

Hydrovenous disorders in pediatric intracranial arteriovenous fistula

High-flow AVFs are a challenging problem in the pediatric age group. Venous occlusive changes develop as part of the dynamic response to these fistulas. The development of adequate venous collateral flow circumvents the destructive sequelae of longstanding venous hypertension. Without adequate collaterals, venous hypertension develops. Venous hypertension interferes with CSF resorption, resulting in increased brain water. Ventriculomegaly and tonsillar prolapse commonly develop and are reversible if therapeutic intervention is done in a timely fashion. If left untreated, chronic venous ischemic changes develop, which result in delay in important developmental milestones.