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)
What is the energy recommendation for HD?
KDOQI 2020 Recommendation 3.1.1 In adults with CKD 1-5D (1C) or
posttransplantation (OPINION) who are metabolically stable, we
recommend prescribing an energy intake of 25-35 kcal/kg body weight
per day based on age, sex, level of physical activity, body composition,
weight status goals, CKD stage, and concurrent illness or presence of
inflammation to maintain normal nutritional status.
- Energy expenditure similar to that in healthy individuals
What are the recommendations for fat intake on HD?
Total fat: 25-35% of total kcal
- Saturated fat: <7%
- Daily cholesterol: <200 mg
- Lipid lowering meds may not show significant benefits to CV events (CV
death, non-fatal MI, stroke) in dialysis populations
What are the recommendations for omega-3 fat
intake in HD population?
KDOQI 2020 Rec 4.3.1: In adults with CKD 5D on MHD or posttransplantation, we suggest not routinely prescribing LC n-3 PUFA, including those derived from fish or flaxseed and other oils, to lower risk of mortality (2C) or cardiovascular events (2B).
- KDOQI 2020 Rec 4.3.3: In adults with CKD 5D on MHD, we suggest that 1.3-4 g/d LC n-3 PUFA may be prescribed to reduce triglycerides and LDL cholesterol (2C) and raise HDL levels (2D).
- KDOQI 2020 Rec 4.3.6: In adults with CKD 5D on MHD, we suggest not routinely prescribing fish oil to improve primary patency rates in patients with AV grafts (2B) or fistulas (2A).
What is IDWG and what is the IDWG goal?
Intradialytic weight gain (IDWG) can be used to assess adherence to
sodium and fluid restriction
- IDWG <5% of dry weight is desirable; IDWG >5.7% of dry weight
associated with 35% increase in mortality
- NKF Handbook: ID weight gain of >4.8% of body weight is associated
with higher mortality.
What is the potassium recommendation in HD?
Approximately 40-50 mg/kg ideal BW or 2-4 g/day depending on UOP
- KDOQI 2020 Rec 6.4.1: In adults with CKD 3-5D or posttransplantation, it
is reasonable to adjust dietary potassium intake to maintain serum
potassium within the normal range (OPINION).
- KDOQI 2020 Rec 6.4.2: In adults with CKD 3-5D (2D) or
posttransplantation (OPINION) with either hyperkalemia or
hypokalemia, we suggest that dietary or supplemental potassium intake
be based on a patient’s individual needs and clinician judgment.
How do you prevent hyperkalemia?
- Potassium restriction / limiting high-potassium food sources
- Correcting metabolic acidosis
- Adjusting dialysate potassium level in the bath (1-4 mEq/L)
- Lower sodium concentration in dialysate to prevent hyperkalemic
rebound after HD - Medications - oral sodium polystyrene sulfate resin
What are the calcium recommendations in HD?
KDOQI 2020 Statement 6.2.2: In adults with CKD 5D, it is reasonable to adjust
calcium intake (dietary calcium, calcium supplements, or calcium-based
binders) with consideration of concurrent use of vitamin D analogs and
calcimimetics in order to avoid hypercalcemia or calcium overload (OPINION).
- May need to limit calcium to 1000-2000 mg/d, including diet, supplements,
meds to maintain serum calcium goal (adjusted for low albumin) of 8.4-10.2
mg/dL
What is the role of calcium in the body?
- Maintenance of bone health
- Nerve impulse transmission
- Muscle contraction
- Blood coagulation
- Hormone secretion
- Intercellular adhesion
How can hypercalcemia be managed in HD?
- Limiting dietary intake of calcium
- Reduce dose of calcium-based phos binders or switch to a
non-calcium based phos binder - Reduce dose of (or discontinue) active vitamin D analogs
- KDOQI CKD-BMD 2017 Statement 4.1.4: In patients with CKD
G5D, we suggest using a dialysate calcium concentration
between 1.25 and 1.50 mmol/L (2.5 and 3.0 mEq/L) (2C)
What are the phosphorus recommendations in HD?
KDOQI 2020 Statement 6.3.1 In adults with CKD 3-5D, we recommend
adjusting dietary phosphorus intake to maintain serum phosphate
levels in the normal range (1B).
- KDOQI 2020 Statement 6.3.2 In adults with CKD 1-5D or
posttransplantation, it is reasonable when making decisions about
phosphorus restriction treatment to consider the bioavailability of
phosphorus sources (eg, animal, vegetable, additives) (OPINION).
- May need to limit phosphorus to 800 to 1,000 mg/d (or <11 mg/kg body
weight) to maintain serum phosphorus levels between 3.5-5.5 mg/dL
How is bone mineral management different in nocturnal
HD pts compared to conventional HD pts?
Phosphorus levels mostly normal in NHD pts
- Vitamin D levels are higher and PTH lower d/t higher calcium dialysates
- Fewer NHD pts need active vitamin D therapy for PTH control, and without problems associated with hyperphosphatemia
- Hypercalcemia controlled by calcium adjustments in dialysate
- Calcium may be higher after tx/midday, no intervention needed unless symptomatic
- Cinacalcet may be used with/without active vitamin D with less risk of hypocalcemia
What is the total recommended intake of
magnesium and their food sources?
200-300 mg magnesium per day
- Sources: nuts, seeds, legumes, cereals, green leafy vegetables (cooked spinach)
What are some causes of hypomagnesemia and how
can it be managed?
Possible causes: excessive diuretics, reduced GI uptake d/t
acidosis, poor nutrition, malabsorption; low magnesium concentration in dialysate
- Associated with increased risk of vascular calcification & higher mortality
- May need IV/IM magnesium sulfate or oral magnesium salts
What are some causes and consequences of
hypermagnesemia?
Possible causes: Mg-containing antacids/laxatives, thiazide diuretics, 1-
α-hydroxyvitamin D3
- Mild hypermagnesemia (4-10 mEq/L) → drowsiness, lethargy,
hypo-/areflexia, somnolence, hypocalcemia, hypotension, bradycardia,
electrocardiographic changes
- Severe hypermagnesemia (>10 mEq/L) → muscle paralysis, quadriplegia,
apnea, heart block, cardiac arrest
What is the recommendation for zinc in HD?
DRI: 8-11 mg/day; needs in HD populations are no different than that for general population
- KDOQI 2020 Statement 5.6.1 In adults with CKD 1-5D, we suggest to not routinely supplement selenium or zinc since there is little evidence that it improves nutritional, inflammatory, or micronutrient status (2C).
What is the fiber recommendation & usual intake in
HD?
20-30 g daily to prevent constipation or diverticulosis
- Intake is usually less d/t dietary restrictions (K from fruits &
vegetables, phos from whole grains)
How does vitamin E recommendation compare w/
general population?
RDI: 15 mg/d same as healthy population
- Supplement may be beneficial to prevent muscle cramps
- Vitamin E coating to dialyzer membrane as an antioxidant shows
improved anemia management, decreased oxidative stress
- Excessive supplementation may result in deep-vein thrombosis &
vitamin K responsive hemorrhagic condition for pts on anticoagulant tx
What is the recommendation for vitamin K in HD?
KDOQI 2020 Rec 5.5.1: In adults with CKD 1-5D or posttransplantation, it
is reasonable that patients receiving anticoagulant medicines known to
inhibit vitamin K activity (eg, warfarin compounds) do not receive vitamin
K supplements (OPINION).
Supplementation may be needed for those taking antibiotics that
suppresses vitamin K production in the gut.
What are some physical signs of vitamin deficiency?
Hair → protein (pluckable), vitamin C (coiled), biotin, zinc
- Eyes → vitamin A, zinc, B6 (tearing)
- Lips → riboflavin (cheilosis),
- Tongue → riboflavin, biotin, B6, iron (glossitis), niacin (beefy-red)
- Gums → vitamin C (bleeding / ulceration)
- Skin → biotin (sensitivity), folic acid/iron (pale), zinc, vitamin A
- Nails → iron (koilonychia), protein
Which water-soluble vitamins are impacted by HD?
Folic acid need increase in HD patients, especially with EPO therapy with ESA
- 5-30% HD pts had low serum vitamin B12 if not supplemented, incidence of
deficiency increase with time spent on dialysis
- Vitamin C is removed by dialysis, increased risk of deficiency with HD
duration, smokers, and in the elderly
- Excessive vitamin C in oliguric pts may be metabolized into insoluble
oxalate crystals that precipitate in soft tissues
What is the effect of folic acid supplementation on
homocysteine in HD?
5 mg of folic acid daily reduced homocysteine levels by 25-30%,
but higher doses did not achieve normal homocysteine
What is the effect of nicotinamide supplementation
on phosphorus & lipid profile in HD?
1g/day nicotinamide or extended-release niacin (500 mg - 2g/day)
inhibit intestinal absorption of phosphorus to manage
hyperphosphatemia & increases HDL
What are some benefits of biotin supplementation
in HD patients?
Pharmacological doses of 10 mg daily → improve hair & skin, relief
from hiccups, improve restless leg syndrome
