Emergent Treatment of Hyperkalemia

In patients with bradycardias or cardiac arrest, have a high index of suspicion for hyperkalemia, especially in patients with renal failure or hemodialysis. Death from hyperkalemia is typically secondary to diastolic arrest or fibrillation, and common symptoms include weakness, paresthesias, and nausea/vomiting. 

Causes of Hyperkalemia

• Failure to Clear: chronic renal disease or acute renal failure, missing dialysis or inappropriate dialysate. 
• Excess release: Rhabdomyolysis, tissue trauma or necrosis
• Excess intake: Oral or IV supplementation

EKG Changes

• 5.5-6.5: Tall peaked T waves assocaited with repolarization abnormalities
• 6.5-7.5: P wave widens and flattens, PR lengthens, and the P wave eventually disappears with progressive paralysis of the atria. 
• >7.5: Prolonged QRS and high-grade AV block, bradycardia, and conduction blocks (bundle branch, fascicular blocks)
• >9: asystole and ventricular fibrillation
  
• Prevalence of EKG changes is independent of severity of hyperkalemia in many patients, and cannot be used to determine the potassium level. 

Treatment

• Cardiac Stabilization: Hyperkalemia causes a shift in the membrane potential, reducing the activation of sodium channels and resulting in a slower and reduced action potential. Supplementation of calcium antagonizes the effects of potassium, raising the action potential. Calcium chloride has been stated to work faster, however there are concerns of tissue necrosis with peripheral use of calcium chloride, so calcium gluconate is typically used unless there is central access.  Typically 1-2g of calcium gluconate is given every 30 minutes. Calcium chloride has 3-times the elemental calcium when compared to calcium gluconate, which had be important treating those with volume overload. 
• Insulin/Glucose: Shifting potassium by activation of the Na-K pump in skeletal muscle. In patients without renal failure, you can dose 10u insulin for 1 amp of D50. Those with renal failure will need either more glucose or less insulin, some methods include an additional amp of glucose after 1 hour.
• Albuterol: Treatment with 4-8x the normal dose at 10-20mg over 10 minutes. Effects can last for hours, and start within 30 minutes. 
• IVF: enhance urine output in those with normal or near-normal renal function
• Furosemide: In those with normal or near-normal renal function
• Sodium polystyrene sulfonate: Initial studies (1961) on kayexalate were based on very few patients, and newer studies are now identifying kyexalate as a potential cause of harm and may not aid in hyperkalemia. 
• Hemodialysis: Indications for dialysis include arrest and severe hyperkalemia in the setting of volume overload. Can remove 1mEq/L within one the first hour, and another 1mEq/L in the next two hours. 

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