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Hemodialysis

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Hemodialysis, Dialysis, Dialyzable Drug

  1. End Stage Renal Disease
  2. Acute Renal Failure with uremic complications
    1. Encephalopathy
    2. Pericarditis
    3. Uncontrolled bleeding
    4. BUN >100-150
    5. Persistent Nausea and Vomiting
  • Indications
  • Toxins and Overdose substances cleared by Hemodialysis
  1. General
    1. Low protein binding (<80%)
    2. Small volumes of distribution (<1 L/kg)
    3. High water solubility
    4. Low Molecular weight (<100 daltons)
    5. Non-ionized
    6. Unstable Overdose patient of Unknown Ingestion
  2. Specific (Mnemonic: "I STUMBLED")
    1. Isopropanol
    2. Salicylates
    3. Theophylline, Tenormin (Atenolol)
    4. Uremia
    5. Methanol
    6. Barbiturates (e.g. Phenobarbital)
    7. Lithium
    8. Ethylene Glycol
    9. Depakote (esp. if level >500)
  • Indications
  • Fluid and Electrolyte Abnormalities
  1. Serum Potassium >6 mEq/L (or Hyperkalemia Related EKG Changes)
  2. Serum Uric Acid >10 mg/dl
  3. Serum Creatinine >10 mg/dl
  4. Serum Phosphate >10 mg/dl
  5. Symptomatic Hypocalcemia
  6. Significant Fluid Overload
  • Background
  • Dialysis
  1. Duration of Hemodialysis: 3.5 hour (average)
  2. Frequency of Hemodialysis: 3 times weekly
  3. Total hours of Dialysis per week: 9 to 12 hours (depending on calculation below)
  4. Dialysis adequacy estimation
    1. Where
      1. Dialyzer clearance = K
      2. Dialysis duration = t
      3. Urea volume of distribution = V
    2. Calculation
      1. Kt/V >1.2 per session suggests adequate Dialysis
  • Preparations
  • Shunt types
  1. Fistulas (autogenous subcutaneous shunts)
    1. Most common Dialysis permanent shunts in United States
    2. Preferred long-term Dialysis shunt
      1. Lower risk of infection (no artificial material as contrasted with grafts)
      2. Lower risk of thrombosis than with other shunts
      3. Higher blood flow rates than with other shunts
    3. Internal Radiocephalic AV fistula (wrist)
      1. Radial artery to cephalic vein anastomosis at the wrist (1966, Brescia and Cimino)
    4. Internal Brachiobasilic fistula (proximal to elbow)
      1. Brachial artery to cephalic vein anastomosis proximal to the elbow
  2. Grafts (Internal subcutaneous shunts
    1. Indicated when a patient in need of longterm Dialysis does not have native vessels amenable to fistula placement
    2. Intermediate life span (2 years)
    3. Typically made of Dacron and polytetrafluoroethylene (Gortex)
    4. Synthetic shunts require 3-6 weeks to mature
      1. Fastest with polytetrafluoroethylene
      2. Contrast with fistulas (autogenous shunts) which require at least 3-6 months to mature
  3. Percutaneous catheters
    1. Highest rate of complications including infection
    2. Non-tunneled-Lines
      1. Very short-term access of <10 days and typically only one Dialysis run
      2. Indicated for emergent Dialysis in Toxin Ingestion or for Acute Renal Failure until surgical tunneled-line placement
    3. Tunneled-Lines (e.g. Hickman Catheters)
      1. Temporary lines for Acute Renal Failure, or while awaiting fistula maturity
      2. Tunnel-cuffed catheters in the internal Jugular Vein or the subclavian vein
  4. External Arteriovenous Shunt (historical)
    1. First Dialysis shunt developed (1960, Quinton and Scribner)
    2. Highest shunt survival rate (75% at 2 years)
  • Precautions
  1. Venipuncture
    1. Avoid drawing blood from nondominant arm
    2. Avoid drawing blood from dominant upper arm
    3. Avoid draw blood from Central DIalysis line or fistula (unless emergency without other access)
      1. High risk of complication (shunt injury, infection, bleeding)
      2. Immature shunts risk pseudoaneurysm development with venipuncture
  2. Blood Pressure readings
    1. Avoid obtaining Blood Pressure on the shunt arm
  • Technique
  • Emergency access of the shunt for venipuncture (avoid if at all possible, especially in immature shunts)
  1. Carefully cleanse access site with topical disinfectant before venipuncture
  2. Apply firm, non-occlusive pressure to site for 10 minutes or more
  3. Document palpable thrill over shunt before and after access
  • Complications
  • Acute
  1. Hypotension (very common)
    1. See Hypotension in the Dialysis Patient
    2. Most commonly related to excessive ultrafiltration volume or rate
    3. Critical to exclude other serious causes (e.g. bleeding, electrolyte disturbance, infection)
  2. Hypersensitivity Reaction
    1. Reactions include Anaphylaxis
    2. Reactions to Dialysis membrane
    3. Phthalate (in PVC tubing)
    4. Ethylene oxide (sterilizing solution)
    5. Polyacrylonitrile (in membrane)
  3. Hemolysis (associated with dialysate components or overheated)
  4. Air embolism (rare now in U.S. with current technology)
  5. Electrolyte abnormalities (Sodium, Potassium, calcium, Magnesium, osmolality)
  6. Dialysis Disequilibrium Syndrome (rare, but potentially lethal)
  7. Bloodstream Infections in Hemodialysis
  • Complications
  • Chronic
  1. See Dialysis Emergencies
  2. Graft Occlusion (common)
    1. Flow may be assessed via Ultrasound
    2. Access salvage techniques
      1. Embolectomy balloon
      2. Mechanical Thrombolysis
      3. Pulsed urokinase
  3. Calciphylaxis
    1. Vascular calcification secondary to abnormal metabolism of calcium and phosphorus
    2. Exclusive to Dialysis patients (may require cessation of Dialysis)
    3. Severe generalized pain
    4. Skin ischemia may progress to skin necrosis
  • References
  1. Glauser (2013) Crit Dec Emerg Med 27(10): 2-12
  2. Mallemat, Swaminathan and Egan in Herbert (2014) EM:Rap 14(10): 5