Hyperkalemia

Background

• High = >6.0meq/L
• Always consider pseudohyperkalemia (e.g. from hemolysis)

ECG

• Changes are not always predictable and sequential
• 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
   1. 1. Give if ECG changes or K>7
   2. Calcium
      1. Can give as calcium gluconate or calcium chloride
         1. Calcium gluconate
            1. 1/3 the calcium as compared to chloride
            2. Must give over 10min (otherwise hypotension due to osmotic shift)
            3. Requires hepatic metabolism to free Ca moiety
         2. Calcium chloride
            1. Can be given as IVP over 1-2min
            2. 3x the amount of calcium
            3. Extravasation is bad - use a good IV

1. 1. 1. Gluconate slower onset than chloride
      2. Duration of effect = 30-60min
      3. Caution in dig-toxic pts
      4. May take more than one round of calcium
      5. May require repeat dosing as effects are transient
2. Intracellular shift
   1. 10 U insulin IV w/ 1 amp D50 IV now and 1 amp in 15 min
      1. Duration of effect = 4-6h
   2. Albuterol neb 2.5mg x 3 or 20mg over 1hour
      1. Duration of effect = 2-4hr
      2. Higher doses more effective
      3. Dose 20mg over 1 hour dropped K by 0.6mEq
      4. Prior Bet-agonist use makes pts resistant to effects
   3. NaBicarb 1 amp IV (over 5 min) 
   4. Duration of effect = 1-2hr
3. Removal
   1. Dialysis
   2. Lasix 40-80mg IV
   3. Volume expansion with NS if dehydrated, TLS, rhabdomyolysis, DKA, acidosis
   4. Kayexylate 30-60gms PO - unreliable and slow to work

See Also

Acute Renal Failure

Source

Tintinalli's Emergency Medicine

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