Detection of vascular access stenosis by measurement of access blood flow from ionic dialysance

BACKGROUND/AIM: The measurement of the vascular access blood flow rate (Q(a)) in chronic hemodialyzed patients was proposed to predict access thrombosis. We have recently presented a new method based on the measurements of ionic dialysance at normal and reversed positions of the blood lines. We evaluate the reliability of the measurement of Q(a) by this method in detecting significant access stenoses. METHODS: Twenty-five patients on chronic hemodialysis and having a vascular access cannulated with two needles were studied. The Q(a) was evaluated by the Diascan ionic dialysance (Q(a-id)) method and by the ultrasound dilution technique (Q(a-us); Transonic) during the same dialysis session. The measurements were available for 23 patients. In addition, the patients had ultrasonography of their fistula followed by angiography, if a stenosis was detected. RESULTS: Q(a-id) and Q(a-us) were not significantly different, showing a difference in Q(a) at 32 +/- 469 ml/min. Q(a-id) was significantly different between patients with or without stenosis (508 +/- 241 vs. 1,125 +/- 652 ml/min, p < 0.05). Among patients with a Q(a) <500 ml/min by Q(a-id), 5 had a stenosis detected by ultrasonography (sensitivity 83%), and 3 had no stenosis (false-positive rate 18%). Of these 3 patients, 2 had a thrombotic event at 1 and 3 months, suggesting that a more sensitive detection of stenosis for this range of Q(a) is needed and that a Q(a) <500 ml/min has a higher power to predict thromboses than a stenosis by ultrasonography. CONCLUSIONS: The measurement of the access flow rate by the Q(a-id) method has a clinical relevance to the detection of vascular access stenosis. An intervention program based on the Q(a-id) has to be evaluated.     

Pharmacokinetics and dosage adjustment of oseltamivir and zanamivir in patients with renal failure.

Sir, In the last few months, more and more countries in Asia, Europeand Africa have reported cases of avian influenza in migratingbirds as well as in cats and humans. The virus has expandedits geographical area, being propagated to new countries, andincreasing, as a result, the size of the population at risk.As of 21 April 2006, the World Health Organization (WHO) hasreported 204 confirmed human cases of influenza A (H5N1) acrossnine countries, with 113 deaths (a 55% mortality rate for identifiedcases) [1]. Chronic renal insufficiency is frequently encountered in thegeneral population. In the US adult population,     

Lamivudine and HBV-associated nephropathy.

Sir, Tang and colleagues [1] report that lamivudine treatment improvesrenal outcome in HBV carriers with membranous nephropathy (MN)and evidence of liver disease. In children with HBV-associatedMN, lamivudine has     

Drug-induced glomerulopathies

Normal renal function depends upon an intact glomerular apparatus. Many drugs and chemicals are capable of damaging the glomerulus, causing its increased permeability to large molecules. Glomerular lesions are usually responsible for proteinuria and the nephrotic syndrome. This also holds true for the drug-induced glomerulopathies, of which membranous glomerulo-nephritis is the most frequent type of lesion encountered. Apart from this, several cases of different glomerular changes such as focal segmental glomerulosclerosis and crescentic glomerulonephritis have also been reported. The drug-induced glomerulopathies are probably immune mediated. This is, for instance, reflected in the fact that patients with drug-induced nephritic syndrome frequently have the HLA-B8 and DR3 antigens. In depth information is provided for the previously mentioned disorders.     

Pharmacokinetic considerations in the treatment of tuberculosis in patients with renal failure

Tuberculosis is re-emerging in patients with altered immune status, such as those with chronic renal failure. Clinicians should thus be aware of the pharmacokinetics and dosage adjustment of antitubercular drugs in patients with renal insufficiency. Among patients with renal insufficiency, those who are dialysed should be treated with special care. Indeed, dosage should always be closely adjusted in these patients and potential removal by dialysis must be taken into account. However reliable the dosage adjustment recommendations are for these drugs in patients with renal failure, further pharmacokinetic investigations need to be performed, especially in dialysis patients in whom the influence of haemodialysis and continuous ambulatory peritoneal dialysis on drug pharmacokinetics needs to be detailed. In the meantime, it could be generally advised to administer all antitubercular drugs after the haemodialysis session, even though some drugs are known to be non-dialysable.