Sun21November0452PM 6

A 66-year-old man with insulin-dependent diabetes given ibuprofen for a knee injury is admitted with palpitations.

His electrocardiogram (ECG) shows a rate of 105 beats per minute, with absent P waves and tall T waves.

His urea and electrolytes show:

Sodium 132 mmol/L (137-144)

Potassium 6.4 mmol/L (3.5-4.9)

Urea 11 mmol/L (2.5-7.5)

Creatinine 180 µmol/L (60-110)

In this scenario, which of the following is the most appropriate immediate management?

(Please select 1 option)

Furosemide 1 mg/kg IV

Calcium gluconate IV Correct

Dialysis

Dextrose 50 mls 50% with 10 units insulin

Calcium resonium orally

Explanation

The ECG suggests cardiotoxicity related to hyperkalaemia and the history of palpitations is suggestive of arrhythmias.

Therefore cardio protection with calcium chloride or gluconate should be first priority and lowering potassium levels immediately thereafter.

Calcium antagonises the effects of hyperkalaemia on a cellular level by a number of mechanisms. These all return myocyte excitability to normal thereby reducing the risk of arrhythmias. Calcium gluconate is the preferred preparation, but calcium chloride can be used. Caution is needed if the patient is taking digoxin, as hypercalcaemia can potentiate its toxicity. The effects of intravenous calcium occur within one to three minutes but last for only 30-60 minutes, and therefore more definitive treatment is needed to lower potassium levels.

After calcium is given, treatment is required to shift potassium intracellularly. Insulin is most commonly used, which stimulates the Na-K ATPase pump. The effect is seen within 10-20 minutes and usually decreases potassium levels by 0.6-1mEq/L. Salbutamol can also increase the action of the Na-K ATPase pump.

Sodium bicarbonate infusion can shift potassium intracellularly by increasing blood pH, but its use is controversial. It is therefore reserved for cases of severe acidosis, or where there is another indication for its use (for example, TCA overdose).

If the above treatments fail, and the cause of hyperkalaemia cannot be treated, then potassium may need to be removed from the body. The most efficient way to do this is with haemodialysis. This is only done in resistant cases, or in patients who are already on haemodialysis. For most patients, treatment with an exchange resin such as sodium polystyrene sulphonate is more appropriate.

Reference:

Parham WA, et al. Hyperkalemia revisited. Tex Heart Inst J. 2006;33:40-7.

Answer Statistics

1

87%

2

2%

3

12%

4

1%

Times answered: 266