Israel Medical Association Journal

Background: Hemodialysis requires reliable, recurrent access to the circulatory system. Central venous tunneled dialysis catheters (TDC) are frequently used for patients receiving hemodialysis as a bridge to permanent vascular access or as a final option. TDC are prone to complications such as infection and dysfunction.

Objective: To assess the prevalence and predictors of TDC dysfunction in a cohort of chronic hemodialysis patients.

Methods: This single-center, retrospective study was based on data from an electronic database of chronic hemodialysis patients during 5 years of follow-up.

Results: A total of 625 TDC were inserted in 361 patients, of which 234 (37.4%) were replaced due to dysfunction. The main insertion site was the right internal jugular vein. Diabetes mellitus was an important predictor of TDC dysfunction and was significantly correlated with TDC extraction. Chronic anticoagulation and antiplatelet treatment did not affect the rate of TDC dysfunction or replacement.

Conclusions: TDC use for chronic dialysis patients is increasing and dysfunction is a major problem. In our study, we highlighted the high prevalence of TDC dysfunction and the need for further research to improve hemodialysis access as well as TDC patency and function.

Background: Freeze dried plasma (FDP) is a commonly used replacement fluid in the prehospital setting when blood products are unavailable. It is normally administered via a peripheral intravenous (PIV) line. However, in severe casualties, when establishing a PIV is difficult, administration via intraosseous vascular access is a practical alternative, particularly under field conditions.

Objectives: To evaluate the indications and success rate of intraosseous administration of FDP in casualties treated by the Israel Defense Forces (IDF).

Methods: A retrospective analysis of data from the IDF-Trauma Registry was conducted. It included all casualties treated with FDP via intraosseous from 2013 to 2019 with additional data on the technical aspects of deployment collected from the caregivers of each case.

Results: Of 7223 casualties treated during the study period, intravascular access was attempted in 1744; intraosseous in 87 of those. FDP via intraosseous was attempted in 15 (0.86% of all casualties requiring intravascular access). The complication rate was 73% (11/15 of casualties). Complications were more frequent when the event included multiple casualties or when the injury included multiple organs. Of the 11 failed attempts, 5 were reported as due to slow flow of the FDP through the intraosseous apparatus. Complications in the remaining six were associated with deployment of the intraosseous device.

Conclusions: Administration of FDP via intraosseous access in the field requires a high skill level.

Background: Reliable vascular access is a fundamental tool for providing effective hemodialysis. Vascular access dysfunction is associated with increased morbidity and mortality among hemodialysis patients. Current vascular access guidelines strongly recommend creating an arteriovenous fistula (AVF) as the first option; however, a substantial proportion of new AVFs may not be usable.

Objectives: To assess possible predictors of primary and secondary failure of vascular access.

Methods: This retrospective cohort study included all vascular access sites created at Meir Medical Center from 2006 through 2012. Vascular access site, primary and secondary failure rates, and relevant demographic and clinical data were recorded during 60 months of follow-up.

Results: A total of 612 vascular accesses were created and followed for a median of 32 ± 29.4 months. Of these, 490 (80%) were suitable for initiating hemodialysis. Vascular access site was the most important predictor of primary failure but did not predict secondary failure. Co-morbidities such as diabetes mellitus and congestive heart failure, as well as the use of antiplatelet agents did not predict primary or secondary failure. Preoperative vascular mapping using Doppler ultrasonography was performed in 36.4% of cases and was not associated with lower rates of primary or secondary failure.

Conclusions: Vascular access site is an important predictor of primary failure. We did not find a benefit of pre-operative vessel mapping or chronic antiplatelet therapy in terms of decreasing primary and secondary failure rates. Physicians should carefully consider the characteristics of the patient and blood vessels before creating vascular access in patients requiring chronic hemodialysis.

Background: Hyperhomocysteinemia is a well-recognized risk factor for accelerated atherosclerosis in hemodialysis patients.

Objectives: To examine the effects of two doses of vitamins B6 and B12 and folic acid on homocysteine levels in hemodialysis patients and assess the functional impact of the methylenetetrahydrofolate reductase genotype on the response to treatment.

Methods: In a randomized prospective study, we assessed the effects of folic acid and two doses of B-vitamins in 50 hemodialysis patients with hyperhomocysteinemia. Patients were divided into two groups: 26 patients (group A) who received 25 mg of vitamin B₆ daily and one monthly injection of 200 µg vitamin B12, and 24 patients (group B) who received 100 mg of vitamin B6 daily and one monthly injection of 1,000 µg vitamin B12. In addition, both groups received 15 mg folic acid daily. Patients were evaluated for homocysteine levels as well as for coagulation and a thorough lipid profile. Baseline Hcy[1] levels were determined after at least 4 weeks washout from all folic acid and B-vitamins that were given. MFTHR[2] alleles were analyzed, as were activated protein C resistance, von Willebrand factor and lupus anticoagulant.

Results: Basal plasma Hcy levels were significantly elevated in hemodialysis patients compared with normal subjects (33.8 ± 4.3 vs. 4.5 to 14.0 mmol/L). Following treatment, Hcy levels were significantly reduced to 21.2 ± 1.6 in group A and 18.6 ± 1.4 mmol/L in group B (P < 0.01). There was no difference in Hcy reduction following the administration of either high or low dosage of vitamins B6 and B12 utilized in the present study. There was no correlation between Hcy levels or thrombophilia and high incidence of thrombotic episodes in hemodialysis patients. Genotypic evaluation of MTHFR revealed that the presence of homozygous thermolabile MTHFR (n = 5) was associated with higher Hcy levels and better response to treatment (Hcy levels decreased by 58%, from 46.2 ± 14.6 to 19.48 ± 4.1 mmol/L following treatment). In patients with heterozygous thermolabile MTHFR (n = 25), Hcy levels decreased by 34%, from 31.2 ± 3.7 to 18.1 ± 1.1 mmol/L following treatment. The efficacy of high and low doses of B-vitamins on the reduction of homocysteine levels was comparable.

Conclusions: Treatment with B-vitamins in combination with folic acid significantly decreased homocysteine levels in hemodialysis patients, independently of the tested doses. In addition, mutations in MTHFR were associated with elevated plasma levels of Hcy. Neither vascular access nor.