Nephrotube Dialysis Module Mini Exam (1)

The answer is E
A Canadian study by Lok et al. showed that all of the above variables are associated with primary failure of the
native fistula by univariate analysis (E is correct). Although diabetes was found to be associated with primary
failure of the fistula by univariate analysis, it was not significant by multivariate analysis. However, other studies
found that diabetes is a risk factor for maturation of the fistula. In the study of Lok et al., male gender and white
race were found to decrease the risk for maturation.
By using age, CAD and PVD, and other variables, Lok et al. developed a predictive risk score system to assess
the most appropriate choice of access for an individual patient. They classified the risk categories into low risk
(score 8 points).
Accordingly, low risk patients will have a failure rate of 24 %, moderate risk 34 %, high risk 50 %, and very
high risk 69 %. Therefore, patients with very high risk should have a graft rather than a native fistula because of
poor maturity. However, one study concluded that Lok model is not predictive of primary failure. It is clear from
Lok model that creation of a fistula should be based on patient preference, comorbidities, and other relevant
factors.

The answer is E
Venous catheters can be infected from several sources, including the above despite following the best practice
guidelines proposed by the Centers Disease Control and KDOQI. Also, catheters can colonize infective organisms
from recently treated bacteremia.

The answer is E
All of the above factors can affect Kt/V (E).Whenever goal Kt/V is not met, the function of A-V access should be
evaluated initially by physical examination and then by radiologic procedure. Also, recirculation can lower Kt/V. Blood and dialysate flow rates should be checked. If blood flow is 350 mL/min and dialysate flow is 500 mL/
min, increasing dialysate flow to 800 mL/min can increase Kt/V by 10–15 %. Also, blood flow to 400–450 may
increase Kt/V.
Increasing treatment time without any cutting in time can increase Kt/V. This approach has been proven to be
very effective in improving HD-associated outcomes.
KoA represents the efficiency of the dialyzer, which is the equivalent of glomerular filtration coefficient
(surface area porosity) of the native glomerular capillary. The higher the value of KoA, the more is the solute
clearance. Thus, using a filter with high KoA will occasionally improve Kt/V. However, it should be remembered
that little benefit occurs when extremely large area dialyzer is used.

The answer is A
Currently there are several options for creation of vascular accesses at different anatomical locations of the body.
In general, the preferred initial site is the wrist in a nondominant arm. Therefore, the radiocephalic access is the
preferred A-V fistula for any patient (A is correct). Once distal sites are exhausted, creation of a fistula in the
upper arm should be considered, and brachiocephalic or brachiobasilic fistulas are placed. The A-V graft has less
survival compared to the fistula, and is not the preferred access in most of the patients. The concept of FISTULA
FIRST is introduced because of superior outcomes with a fistula compared to a graft.

The answer is D
Generally 28–53%of A-V accesses never mature adequately to be usable for dialysis. When mature, the median
time for maturity is 98 days. The KDOQI guidelines defined the “rule of 6s” as the criteria for maturation of the
fistula, which include (1) vein diameter of 6 mm, (2) access flow rate of 600 mL/min, and (3) access depth of 6 mm
below the skin. According to the study of Robbin et al. the vein diameter >4 mm and access flow rate
>500 mL/min are highly predictive of fistula maturation and adequate for cannulation. Based on these criteria,
choice D is correct, suggesting that the fistula is maturing properly. Other choices are incorrect.

The answer is D
Of all of the above choices, monthly physical examination and clinical assessment are the keys to access
maintenance. Although the most common screening tests are access flow and dialysis venous pressure
measurements, a review of vascular access surveillance suggests the physical examination and clinical assessment
are the first line assessment than hemodynamic studies. Thus, D is correct. Follow-up of other measures have not
consistently shown any improvements in outcomes of graft function. Also, there is only limited evidence that
surveillance reduces thrombosis in native fistulas.

Correct answer is D: Dialysis with high molecular weight cutoff dialyzer, molecular
cutoff 45 kD
The patient has high load of free light chains and is most likely to benefit from dialysis with
high cutoff dialyzer. These dialyzers have a molecular weight cutoff of 45 kd and can
effectively remove free light chains till chemotherapy becomes effective.

The answer is E
HDF is a modality that combines both diffusion and convection. This technique requires large ultrapure volumes
of replacement fluid. This fluid can be infused pre-, post-, or mixed dilution modes. Because of convection, many
uremic toxins that have a molecular weight up to 40,000 Da can be removed. As a result, many biochemical
abnormalities associated with ESRD or uremia can be improved. Removal of middle molecules such as
β2-microglobulin is 30–40 % higher with HDF compared to high-flux dialysis. Similarly removal of phosphate
mass with HDF is 15–20 % higher than other HD modalities. It has been shown that cytokine removal is much
higher with HDF, and preservation of residual renal function is prolonged with HDF. However, most studies did
not find any significant benefit of HDF in improving nutritional, as measured by either albumin or prealbumin
concentrations. Thus, E is false.
HDF has been shown to improve β2-microglobulin-associated amyloidosis and carpal tunnel syndrome. Also,
some studies have shown reduced incidence of intradialytic hypotensive episodes. However, most studies showed
no effect of HDF on the usage of erythropoietic stimulating agents and anemia.

Answer B: Epoprostenol
Epoprostenol can effectively anticoagulate during dialysis. Enoxaparin is low molecular weight heparin
and can provoke heparin-induced thrombocytopenia. Likewise heparinization is not recommended.
Tinzaparin and clopidogrel are likely less effective than epoprostenol.

Correct answer is A: Maintenance of residual renal function
Residual renal clearance is 4 to 9 times more effective in clearing protein bound solutes
compared to peritoneal clearance. Peritoneal dialysis patients do have greater protein-bound
uremic toxin clearance compared to hemodialysis patients.