Diuretics, potassium depletion and the risk of arrhythmias.

Evidence is available which suggests that the use of thiazide diuretics in the treatment of essential hypertension causes a fall in both plasma and total body potassium. The incidence of ventricular arrhythmias is proportional to the potassium deficit and may be enhanced by concomitant magnesium deficiency. Potassium loss may be minimized by limiting the dose of diuretic and by restricting sodium intake. Potassium chloride supplements are of relatively limited value and potassium-conserving diuretics are to be preferred in aviators. To reduce the potential risk of rhythm disturbance, aircrew receiving thiazide diuretics should be managed to ensure a serum potassium level at least 3.5 mmol l-1 after stabilization on therapy.