HD & Nocturnal HD Flashcards
What is meant by flux, permeability, and efficiency of dialyzer membranes?
- Flux: rate of solute transfer across membrane.
- High-flux dialyzers have larger pores for passage of larger molecules.
- Permeability (Kuf): clearance of water and midweight molecules
- Efficiency: urea clearance (KoA) measured in mL/minute
- High efficiency dialyzers have high surface area for rapid urea
removal
What is Kt/V?
Unitless measure for the dose of dialysis treatment that is prescribed or
achieved; determined by the product of solute clearance (K) x time (t)
normalized to the individual’s body water (V)
Used to estimate how “clean” the blood is after dialysis treatment
What is the recommended target Kt/V?
KDOQI 2015 - 3.1: We recommend a target single pool Kt/V (spKt/V) of 1.4
per hemodialysis session for patients treated thrice weekly, with a
minimum delivered spKt/V of 1.2. (1B)
For patients with KrU>2 treated 2-3x/week, minimum Kt/V can be
reduced to no less than 60% of 1.2, measured at least quarterly
What is nPCR / nPNA?
nPNA = Total nitrogen appearance as protein, normalized to weight
nPCR = Amount of protein catabolized in g/day, normalized to weight
Reflects an estimate of protein intake as g/kg/day.
- Low nPCR may indicate poor nutritional intake with less urea
generation and predicts poor outcomes
- Low nPNA associated with risk for increased morbidity/mortality
What does a low nPCR / nPNA mean?
- Low nPCR may indicate poor nutritional intake with less urea generation
and predicts poor outcomes - Low nPNA of 0.7-0.9 g/kg/day indicate inadequate dietary intake,
associated with risk for increased morbidity/mortality - May require assessment for adequate dialysis dose, increased
protein/kcal intake, oral supplementation as needed - Lower nPNA may also indicate anabolism (wt gain/improved protein status)
What does a high nPCR / nPNA mean?
> 1.4 g/kg/d may indicate excessive intake, excessive LBV protein, or
catabolism
- May require reduction of protein intake if intake deemed excessive
& pt is well nourished
- Higher nPCR/nPNA than expected or than actual intake may indicate
catabolism (wt loss / decreased protein status)
What is the composition of a typical dialysate?
- Bicarbonate (35-40 mEq/L): buffer uremic metabolic acidosis, minimize
protein degradation, achieve serum bicarb >22 - Sodium (135-145 mEq/L): reduce cramps and hypotension
- Potassium (1-4 mEq/L): lower than plasma to enhance removal (70-90 mEq/L removed per HD)
- Calcium (2-3.5 mEq/L): maintain calcium balance & hemodynamic stability
- Magnesium (0.5-1 mEq/L)
- Glucose (100-200 mg/dL, optional): maintain constant serum glucose
What are the typical treatment time/parameters for
nocturnal hemodialysis (NHD)?
- In-center: 8 hours per night, 3x per week
- About 24 hours total per week, ie. twice the time of conventional dialysis
- Home: 6-10 hours per night, 5-6x per week
- Blood flow rates: 200-350 ml/h
- Dialysate flow rate: 200-300 mL/h
- Maximum ultrafiltration: 400-600 mL/h
How does the NHHD dialysate composition compare to in-center HD dialysate?
Similar except for calcium & phosphorus:
- Sodium: 137-140 mEq/L
- Potassium: 2 mEq/L
- Bicarbonate: 28-35 mEq/L
- Calcium: 3-3.5 mEq/L (higher because higher removal d/t more frequent tx)
- Phosphorus: 0-3 mg/dL
How does the NHD monitoring parameters compare to conventional in-center HD?
- Labs monitored monthly
- Weekly Kt/V and URR are 2-3x higher than the conventional HD
recommendations because longer treatment time - A single-treatment URR may be <65% of the conventional HD
recommendations d/t lower pre- and post-BUN levels - stdKt/V to account for improved efficiency of more frequent and
continuous dialysis tx
What is the HD recommendation for pregnant
women?
KDOQI 2015 - 2.5: During pregnancy, women with end-stage kidney disease
should receive long frequent hemodialysis either in-center or at home,
depending on convenience. (Not Graded)
- Observational reports → Pregnancy with conventional HD has very high
rates of neonatal complications (miscarriage, still-births, prematurity,
small-for-gestational0age births) and rate of live birth of 50-87%
- Outcomes may be improved with longer, more frequent HD
How does dialysis contribute to malnutrition?
- Nutrient losses (8-12 g amino acids per HD)
- Increased catabolism during and after HD
- Suboptimal nutrient intake d/t anorexia & increased levels of leptin
and inflammation - Metabolic acidosis, diabetes, insulin resistance
Who are at greater risk for malnutrition?
- Pts who have been undergoing HD for several years
- Pts beginning dialysis with various comorbid conditions
How much protein is lost per dialysis
treatment?
- 5-20 g of amino acids per treatment, depending on type of dialyzer
used, length of tx time, dialysate flow rate, blood flow rate - 8-12 g of amino acids per NHD tx
What is the protein recommendation for HD?
KDOQI 2020 Recommendation 3.0.3: In adults with CKD 5D on MHD (1C) or PD (OPINION) who are metabolically stable, we recommend prescribing a dietary protein intake of 1.0-1.2 g/kg body weight per day to maintain a stable nutritional status.
- KDOQI 2020 Recommendation 3.0.4: In adults with CKD 5D and who have diabetes, it is reasonable to prescribe a dietary protein intake of 1.0-1.2 g/kg body weight per day to maintain a stable nutritional status. For patients at risk of hyper- and/or hypoglycemia, higher levels of dietary protein intake may need to be considered to maintain glycemic control (OPINION).
- No recommendations on biological value (previously rec. 50% HBV protein)
