Hyperkalemia

Background

• Defined as >6.0 mEq/L
• Consider pseudohyperkalemia (e.g. from hemolysis)
• Potassium secretion is proportional to flow rate and sodium delivery through distal nephron
  • This is how loop & thiazide diuretics cause hypokalemia

ECG

Changes NOT always predictable and sequential

• 6.5 - 7.5 mEq/L: peaked T waves, prolonged PR interval, shortened QT interval
• 7.5 - 8.0 mEq/L: widened QRS interval, flattened P waves
• 10 - 12 mEq/L: sine wave, ventricular fibrillation, heart block

Differential Diagnosis

1. Pseudohyperkalemia: hemolyzed specimen, prolonged tourniquet use prior to blood draw, thrombocytosis or leukocytosis
2. Redistribution
   1. Acidemia (see (DKA))
   2. Cellular breakdown: see Rhabdomyolysis/crush injury, hemolysis, see Tumor Lysis Syndrome
3. Increased total body potassium
   1. Inadequate excretion: Acute or chronic renal failure, hypoaldosteronemia
   2. Drug-induced: potassium-sparing diuretic (spironolactone), angiotensin converting enzyme inhibitors (ACE-I), nonsteroidal anti-inflammatory drugs (NSAIDs)
   3. Excessive intake: diet, blood transfusion
4. Other causes: succinylcholine, digitalis, beta-blockers

Treatment

Stabilize Cardiac Membranes: give if ECG changes, consider if K >7 mEq/L

1. Intravenous calcium: only if QRS interval prolonged
2. Can give as calcium gluconate or calcium chloride
   1. Calcium gluconate 2 - 3 grams IV
      1. Only 1/3 the calcium compared to calcium chloride
      2. Give over 10 minutes: can cause hypotension due to osmotic shift
   2. Calcium chloride 1 gram IV
      1. Give over 1 - 2 minutes
      2. Extravasation is bad: use a good IV
      3. Usually given in code situations
   3. Duration of action: 30 - 60 minutes
   4. Use caution if patient digitalis toxic
   5. Do serial EKGs to track progress: may need to give multiple doses

Force Intracellular Shift

1. Intravenous insulin + dextrose
   1. Give 10 units regular insulin intravenously with 25 to 50 grams (1 - 2 50 mL ampules) of 50% dextrose (D50)
      1. May withhold dextrose if blood sugar >300 mg/dl
      2. Duration of effect: 4 - 6 hours
2. Nebulized albuterol 5 - 20 mg
   1. Response is dose-dependent
   2. Peak effect: 30 minutes
   3. Duration of effect: 2 hours
3. Intravenous sodium bicarbonate 50 ml of 8.4% solution (1 ampoule) given over 5 minutes
   1. Duration of effect: 1 - 2 hours
   2. More effective if patient is acidemic

Remove from System

1. Intravenous furosemide (Lasix) 40 - 80 mg
2. Sodium polystyrene sulfonate (Kayexylate): 30 gm oral or per rectum
   1. Unreliable, slow, potential complications: falling out of favor
3. Intravenous normal saline solution for volume expansion if dehydrated, rhabdomyolysis, diabetic ketoacidosis or other acidosis
4. Definitive: hemodialysis

See Also

Acute Renal Failure

Source

Tintinalli Management Severe Hyperkalemia. Crit Care Med, 2008, 36:12 EMCrit Podcast #32