Sunday, June 11, 2006

Hyperkalemia review

This review of hyperkalemia appearing in the Texas Heart Institute Journal focuses on the acute complications of hyperkalemia, the mechanisms of cardiac toxicity and emergency treatment. Modalities of treatment for hyperkalemia can be grouped in three categories in descending order of urgency and rapidity of effect, and ascending order of duration of action. These categories consist of 1) membrane stabilization to directly antagonize the cardiac effects of hyperkalemia (calcium administration), 2) measures to shift potassium into the intracellular space (insulin with or without glucose, beta agonists) and 3) measures to eliminate potassium from the body (ion exchange resins, dialysis).

The authors recommend all three categories of treatment if there are ECG abnormalities or if the serum potassium exceeds 6.5. However, the indications for calcium administration are somewhat controversial. This emedicine review of hyperkalemia recommends calcium if arrhythmia, widening of the QRS or absence of P waves is present, but not if the only electrocardiographic manifestation is peaked T waves.

Calcium is recommended only in extreme situations if the patient is taking digitalis preparations, and only as a slow infusion (over 30 minutes). If digitalis intoxication is the cause of hyperkalemia digoxin-fab fragments (digibind) are indicated.

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