Hyperkalemia

Background

High = >5.5meq/L

High! = >6.5meq/L

Diagnosis

• Always consider pseudohyperkalemia (e.g. from hemolysis)

ECG

6.5-7.5 - peaked Ts, inc PR, dec QT

7.5-8.0 - QRS widening, P flattening

10-12 - sine wave, v-fib, heart block

Differential Diagnosis

1. Pseudohyperkalemia
   1. Hemolysis of specimen
   2. Pronged tourniquet use prior to blood draw
   3. Thrombocytosis/leukocytosis
2. Redistribution
   1. Acidemia (DKA)
   2. Cellular breakdown
      1. Rhabdomyolysis/crush injury
      2. Hemolysis
      3. Tumor lysis syndrome
3. Increased total body potassium
   1. Inadequate excretion
      1. Renal caused (acute or chronic renal failure-must have GFR<10)
      2. Hypoaldo
      3. Drug-induced
         1. K sparing diuretics (spironolactone), ACEI, NSAIDs
   2. Excessive intake
      1. Diet
      2. Blood transfusion
4. Misc
   1. Sux, Dig, B-blockers

Treatment

• 1. Membrane Stabilization
  • Calcium gluconate 1-3 amp IV or chloride 1amp IV
    • Give if ECG changes/hypotension or >7
    • Gluconate requires hepatic metabolism to free Ca moiety
    • Gluconate slower onset than Ca-chloride
    • Chloride extravasation is very bad - use a good IV
    • Duration of effect = 30-50min
    • Caution in dig-toxic pts
    • May take more than one round of calcium
    • May require repeat dosing as effects are transient

             

• 2. Intracellular shift
  • 10 U insulin IV w/ 1 amp D50 IV now and 1 amp in 15 min
    • Duration of effect = 4-6h
  • Albuterol neb 2.5mg x 3 or 20mg over 1hour
    • Duration of effect = 2-4hr
    • Higher doses more effective
    • Dose 20mg over 1 hour dropped K by 0.6mEq
    • Prior Bet-agonist use makes pts resistant to effects
  • NaBicarb 1 amp IV (over 5 min) 
  • Duration of effect = 1-2hr

3. Removal

• Dialysis
• Lasix 40-80mg IV
• Volume expansion with NS if dehydrated, TLS, rhabdomyolysis, DKA, acidosis
• Kayexylate 30-60gms PO - unreliable and slow to work

Source

Tintinalli

Management Severe Hyperkalemia. Crit Care Med, 2008, 36:12