Dialysis

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Types of Dialysis

1. Intermittent Hemodialysis (IHD)

  • Duration: 3-4 hours per session.
  • Frequency: Usually 3 times per week (e.g., Monday, Wednesday, Friday or Tuesday, Thursday, Saturday).
  • Mechanism: Uses diffusion to remove waste products and electrolytes. Blood flows through a dialyzer where toxins are removed by exchanging solutes with a dialysate.
  • Considerations: Associated with significant fluid shifts and potential hypotension.

2. Sustained Low Efficiency Daily Dialysis (SLEDD)

  • Duration: Approximately 12-18 hours per session.
  • Frequency: Typically daily or as needed.
  • Mechanism: Runs slower than traditional hemodialysis, providing a gentler approach and reducing fluid shifts.
  • Considerations: Useful for patients who are hemodynamically unstable but need more frequent dialysis than intermittent.

3. Continuous Renal Replacement Therapy (CRRT)

  • Duration: Continuous, 24 hours a day.
  • Mechanism: Uses convection and ultrafiltration to remove solutes and fluids continuously.
  • Considerations: Suitable for hemodynamically unstable patients. Requires a dialysis catheter rather than a fistula due to prolonged use.

4. Continuous SLED (C-SLED)

  • Duration: 12 hours at a time, often twice per day, making it effectively continuous over a 24-hour period.
  • Mechanism: Similar to SLEDD but can be tailored to adjust dialysate concentrations.
  • Considerations: Allows for more precise control of electrolyte abnormalities compared to CRRT.

5. Peritoneal Dialysis (PD)

  • Duration: Typically performed daily; can be continuous or intermittent.
  • Mechanism: Uses the peritoneal cavity as a dialyzing membrane. Dialysate is infused into the abdominal cavity where it exchanges waste and electrolytes with blood.
  • Considerations: Can be done at home. Requires patient or caregiver training.

Dialysis for Electrolyte Abnormalities

1. Potassium Management

  • Dialysate Bath Adjustment: The potassium concentration in the dialysate bath (K bath) is adjusted to manage high potassium levels. For example:
    • High Potassium: Use a lower potassium bath (e.g., K bath of 1).
    • Normal Potassium: Adjust the bath to a normal level (e.g., K bath of 5).
  • Objective: Create a gradient that facilitates the removal of excess potassium from the blood.

2. Pure Ultrafiltration (PUF)

  • Purpose: To remove excess fluid without affecting electrolytes.
  • Indication: Useful when a patient is anuric and has volume overload but normal electrolytes.

Indications for Dialysis (AEIOU Mnemonic)

  1. Acidosis: Severe metabolic acidosis, typically with a pH < 7.
  2. Electrolytes: Hyperkalemia (potassium > 6.0 mmol/L) or other severe imbalances.
  3. Intoxication: Overdoses or poisonings (e.g., lithium, methanol).
  4. Overload: Fluid overload that cannot be managed with diuretics.
  5. Uremia: Symptoms of uremia, often with BUN > 100 mg/dL, although symptoms and clinical picture are crucial.

Potential Complications

1. Dialysis Disequilibrium Syndrome

  • Description: Occurs when BUN drops too rapidly, leading to headache, nausea, and confusion.
  • Prevention: Initiate dialysis slowly and gradually.

2. Recirculation Syndrome

  • Description: Ineffective dialysis due to clotted or obstructed access causing re-entry of dialyzed blood.
  • Diagnosis: Evaluate for access issues and recirculation.

3. Calciphylaxis

  • Description: Calcification of blood vessels leading to necrotic skin lesions.
  • Management: Address calcium and phosphate imbalances, and consider specific treatments for calciphylaxis.

Management of CKD and Dialysis-Related Conditions

**1. Anemia Management

  • Iron Replacement: For ferritin < 500 ng/mL, transferrin saturation < 30%, and hemoglobin < 10 g/dL.
  • Erythropoiesis-Stimulating Agents: After adequate iron stores are replaced.

**2. CKD-Mineral Bone Disease

  • Phosphate Binders: Sevelamer, lanthanum.
  • Calcium/Vitamin D: Use calcitriol or vitamin D supplements if needed.
  • FGF23: Marker associated with phosphate metabolism and CKD severity.

**3. Consultation with Nephrology

  • Role: Management of anemia, bone disease, electrolytes, and overall renal care.

This comprehensive review covers the types of dialysis, their uses, potential complications, and management strategies for patients with chronic kidney disease (CKD)



 hemodialysis

Access to blood 

400mL/ min

Countercurrent exchange


mvmt of K+ away from the machine

for example let's say there is 5.5 mEq of K+ there is roughly 2mEq of K+ in dialysate.

mvmt of K+ away from machine rate of 350 - 450 ml/min nml 500 - 600ml/min


Indications for dialysis mnemonic (A, E, I, O, U) - acidosis, electrolyte, overload, hypervolemia, intoxication, overload, uremia)

uremic encephalopathy, uremic pericarditis, FTT malnutrition neuropathy GI sxs


increased BUN, renal failure azotemic indication to dialyze peripheral neuropathy pCKD pt Cr 10

1.5 yrs later -> 20

toxic ingestion (lithium) hospital bpd, lithium 3.5 - 4 year catheter + dialyze

big dialyzer SE: dialysis disequilibrium


dialysate variables outside 3.5 - 4.5 inside higher



Dialysate variables - K+, Na+, HCO3- , Ca2+,

K+ - 2.0mg/dl -> 4k bath

Na+ 136 - 140mEq, 138 - 140, 150

HCO3- 35 - 40

Ca2+ 2.25 mEq

potassium check 3.5 hrs


discourage checking K+ at the end of dialysis due to rebound, potassium levels tend to increase


Na+ increase ICP, don't want to decrease serum osmolarity

hypotensive increase Na+ bath

start Na+ at one end @ another

Na+ modeling

UF profiling - remove difference

150@ beginning ultrafilter fluid come out pressure down to remove

more aggressive UF less

hypercalcemic lower a bit, seizure if extreme

variables vascular access dialyzer membrane size, flux length of time / txtmt, blood flow rate, dialysate flow rate, UF (dry wt), AC, Na+ modeling


AVF decrease rate of infxn

ESA

Vit D calcimimetics

dialysis w/ fistula lower rates of dying / complication


graft takes 2 weeks lasts 2-3 years can clot

fistula > 6 weeks additional procedures ballonings to mature fistula can be forever

catheter increase rate of infection and less blood flow


dialyzer 160 surface area of dialyzer, 160 increase flux better

dialysis 2-3 hours time for dialysis important


17 gauge small dialysis 250 - 350 mL

16 gauge 350 - 400mL

15 350 - 500mL

14 enormous


dialysate flow rate 16000, 1.5x blood flow

UF amount of fluid

get weight to before 2-3 days before remove what they have, take 2-3 kg

guideliens 13cc/kg/hr

over time figure out clot w/ impairment of diffusion

transmembrane pressure 200-250 ccs blood

eqliquis, coumadin

ESA - erythrocyte stimulating count, retocrit protocols for how much to give hgb, iron studies where they are trending

5-10,000 retacrit

MRSA

Vit D analogues PTH lvls

calcimimetics


txt bone dz increase PTH in CKD, Ca2+ vitamin D


retain phosphoroushigher than should be

increase in PTH, phosphaturic on dialysis goal PTH 150 - 600 based on bone data balance w/ bones 150 - 600

increased osteitis 

blockade

decrease PTH block

Vitamin D analalogues

PTH in range Vit Ca2+


urea reduction

URR urea reduction ratio minimum

( urea beginning - end ) / Ur beginning - 65 - 70%


KT / V representation of amount of blood dialyzed / volume of distribution of urea


minimum 1.2


KT / v 1.3, 1.5 decent 3x a week

K rate of efficiency 

T time

V volume


studies three times a week is best, less than that leads to more death

home dialysis 2 years ago, minimum 4 times a week, less efficient dialysis flow lower dialysate


BUN 100 dialyze efficient BUN inside cells

dialyze blood already dialyzed 4x a week

adequate

KT/v wkly not individual txtmt 2+ for wk

roughly 3 - 3.25 minumtes if person increased fluid gains peritoneal dialysis program


monthly parameters


KT / v - URR

K+, phos, PTH, hgb, albumin, iron sat + ferritin, gluid gains

phos binders to reduce phosporous


phos can't get down

bound to proteins get pills bind to phosphorous aluminum based binders bind to brain -> dementia

Ca2+. bound calcified vessels 

sevelemar orixia, velfaro 

pltlt lvls at least quarterly

sensipar recterol

hgb monthly goal hgb btwn 9-11, 10-11 above 11 don't give ESA

study 11 good 13 better get to 13 better but EPO on 13 has higher cardiovascular events

hgb ESA to 13 stop


if natural okay transfusing low hgb < 7 transfuase 7-8 individual pt angina / gi bleed, not gi bleed, overly symptomatic might transfuase

chronically 7 leave if sickler

sicklers 5-6 as cutoffs transfuase too much iron overloaded, protocol desfuroxamine bind iron dialyzed out, every single time doesn't work well

iron saturation + ferritin clinic ferritous 15-250

CKD, CKD4 ferritin 400 iron overloaded? ferritin increased board

pt on dialysis iron sat 15%, ferritin 1500 respond to IV iron more efficient than hct


fluid gains can't drive liters / day take 3-3.5L

diuretics w/ limited success


peritoneal dialysis more common in mexico and canada 25% PD in canada

CAPD, CACD continuous ambulatory peritoneal dialysis

plastic catheter infuse fluid + drain it out

everyday 3-4 exchanges leave it to drain

9 hrs while sleeping cyclers don't want exchanges own membrane to do exchanges membranes rapid + slow transporter


slow transporter > rapid

more in body before chronic on PD -> SBP

PD -> teach teaching go thorugh training 

poor technique

peritonitis increased rates nurses less experiences once / yr peritonitis proper techniques wash hands, connectors, cloudy, 3rd gen cephalosporin gent cell count + culture stuck nurses




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