Prescription Quiz

What is flow fraction?
It is dialysis flow rate divided by the blood flow rate, assuming ultrafiltration rate is negligible.

How is flow fraction related to dialysate saturation?
They are inversely related. The lower is the flow fraction (DFR/BFR), the higher will be the dialysate urea saturation (D/P urea). The slower the dialysate flow allows more time for urea to cross over into the dialysate.

How do you assess dialysis adequacy for home hemodialysis patient?
Weekly std Kt/V and overall clinical picture including uremic symptoms, volume management, electrolyte balance.

What is the relationship between standard Kt/V and single pool Kt/V.

The relationship between the standard Kt/V and single pool Kt/V is not linear, i.e. sum of the clearance of each dialysis session does not equal weekly clearance. As the sessions per week increases, spKt/V decreases.Graph showing relationship between std weekly Kt/V and per session sp Kt/V (With permission from copyright holder.)

What is the target weekly standard Kt/V for home hemodialysis?
Greater than 2 to 2.2

What is the single pool Kt/V for a person doing 5 times a week home hemodialysis?

0.6

 

What factors affect the duration of each home hemodialysis session?
It depends on frequency of session, flow fraction, blood flow rate, dialysate volume, total fluid removal required.

What is the low dialysate volume approach?
By decreasing the dialysate volume, we are achieving the same clearance by making dialysate fluid nearly fully saturated with urea. This requires dialysate flow rate (DFR) to be sufficiently slow relative to the blood flow rate (BFR) to allow for complete diffusive equilibration of urea across the membrane.

How are the HHD parameters different in low flow dialysate, short daily HHD and low flow dialysate nocturnal HHD ?
Low flow dialysate, short daily HHD low flow dialysate nocturnal HHD
Frequency5-63.5-6
Time each session2-3 hr6-8 hr
Flow fraction (FF)30-4020-30
Blood flow rate (BFR)300-400200-350
Dialysate flow rate (ml/min)90-30060-130

Ibrahim et al. CJASN 2019;14(8):1268-73

What is the recommended UFR for the home hemodialysis patient?

Less than 8 ml/kg/hr.

Weinhandl, Collins, Kraus. Ultrafiltration Rates with More Frequent Home Hemodialysis. Oral Presentation. 2017 ADC.
Assimon, M.M. et al. Ultrafiltration Rate and Mortality in Maintenance Hemodialysis Patients. Am J Kidney Dis. 2016;68(6):911-922.

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