Hyperkalemia

Background

• High = >6.0meq/L
• Always consider pseudohyperkalemia (e.g. from hemolysis)
• K+ secretion is proportional to flow rate and Na delivery through distal nephron
  • Mechanism for loop/thiazide diuretics causing hypokalemia

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. Give if ECG changes or consider if K+ >7
   2. Calcium
      1. Can give as calcium gluconate or calcium chloride
         1. Calcium Gluconate 2-3g
            1. Only 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 (slower onset of action)
         2. Calcium Chloride 1g
            1. Can be given as slow IVP over 1-2min
            2. 3x the amount of calcium
            3. Extravasation is bad - use a good IV
      2. Duration of action = 30-60min
      3. Caution in dig-toxic pts
      4. May require multiple doses for effect (esp w/ gluconate)
2. Intracellular shift
   1. Insulin/Glucose
      1. 10 U insulin IV w/ 1-2 amp D50 IV now (unless BS already >300)
      2. Duration of effect = 4-6h
   2. Albuterol neb 5-20mg
      1. Response is dose-dependent
      2. Duration of action = 2hr
      3. Peak effect at 30min
      4. Duration of effect = 2-4hr
   3. Bicarb 1 amp IV (over 5 min)
      1. Duration of effect = 1-2hr
      2. Consider if pt is acidemic
3. Removal
   1. Lasix 40-80mg IV
   2. Volume expansion with NS if dehydrated, TLS, rhabdomyolysis, DKA, acidosis
   3. Kayexylate 30gm PO - unreliable and slow to work (2-6hr)
   4. Dialysis

See Also

Acute Renal Failure

Source

Tintinalli

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

EMCrit Podcast #32