Pilot randomised double-blind controlled trial of high-dose spironolactone in critically ill patients receiving a frusemide infusion.

BACKGROUND: Hypernatraemia may develop during intravenous infusion of frusemide. Spironolactone is an aldosterone antagonist that promotes natriuresis and may attenuate such hypernatraemia, but its effect in this setting has not been previously studied.

OBJECTIVE: To assess whether the administration of spironolactone to ventilated patients receiving a frusemide infusion attenuates the increase in serum sodium concentration.

DESIGN AND SETTING: Randomised, double-blind, placebo-controlled trial (January 2005 to December 2006).

PATIENTS: 20 patients with a serum creatinine concentration < 300 micromol/L who were undergoing mechanical ventilation in the intensive care unit and had begun a frusemide infusion as treatment for fluid overload within the previous 24 hours.

METHODS: Patients were randomly allocated to receive either spironolactone (100 mg three times daily) or placebo by nasogastric tube for the duration of the frusemide infusion. Daily serum levels of urea and creatinine, 24-hour urine sodium and potassium levels, fluid balance and 24- hour blood levels of aldosterone, human atrial natriuretic peptide and plasma renin activity were measured throughout the period of frusemide infusion.

RESULTS: Change in serum sodium concentration over 48 hours from baseline was 3.0 mmol/L for placebo versus 1.0 mmol/L for the spironolactone group (P = 0.08). Change in serum potassium concentration did not differ between the groups (0.125 mmol/L over 48 hours). There were no significant differences in total urinary sodium or potassium excretion. Serum creatinine, urea, urine volume, fluid balance, potassium requirements and hormone levels were similar in both groups.

CONCLUSIONS: In this pilot study, the administration of high-dose spironolactone to ventilated critically ill patients receiving frusemide by infusion had no significant effects on serum sodium level, natriuresis or potassium balance when compared with placebo.