Acetazolamide in the treatment of metabolic alkalosis in critically ill patients

Metabolic alkalosis is a common acid-base disturbance in critically ill patients. In many patients correction of fluid and electrolyte status does not fully correct the metabolic derangement. In this study we examined the effect of 500 mg of intravenous acetazolamide, after correcting for fluid and electrolyte abnormalities, on the acid-base status of 30 ventilated patients. In all patients studied there was a fall of total serum bicarbonate; the mean reduction at 24 hours was 6.4 mmol/L, with a normalization of the base excess and pH. The onset of action was rapid (within 2 hours), and the maximal effect occurred at a mean of 15.5 hours, although there was wide variation. The effect of acetazolamide was still apparent at 48 hours. No adverse effects were noted. We conclude that in patients with metabolic alkalosis, once fluid and electrolyte abnormalities have been corrected, acetazolamide is an effective and safe form of therapy with a quick onset and long duration of action.