What diuretics are used in the diuretic phase of acute kidney injury (Impaired renal function)?

Diuretics in the Diuretic Phase of Acute Kidney Injury

Loop diuretics, particularly furosemide, are the preferred diuretics during the diuretic phase of acute kidney injury (AKI) when fluid overload is present, but they should not be used to prevent or treat AKI itself except for managing volume overload. 1

Loop Diuretics: First-Line Agents

• Loop diuretics (furosemide, bumetanide, torsemide) are the preferred agents for managing fluid overload in the diuretic phase of AKI due to their strong and brisk diuretic effect 1
• Intravenous administration is more effective than oral administration in patients with AKI 1
• Loop diuretics maintain their efficacy even with severely impaired renal function, unlike thiazide diuretics which lose effectiveness when creatinine clearance falls below 40 ml/min 1

Specific Loop Diuretic Options:

• Furosemide: Most commonly used (98.3% of cases), duration of action 6-8 hours, maximum daily dose 600 mg 1, 2
• Bumetanide: Duration of action 4-6 hours, maximum daily dose 10 mg 1
• Torsemide: Longer duration of action (12-16 hours), maximum daily dose 200 mg 1

Thiazide Diuretics and Combination Therapy

• Thiazide diuretics alone are less effective in AKI due to their reduced efficacy in impaired renal function 1
• Combination therapy may be beneficial in cases of diuretic resistance: 1
  • Furosemide + hydrochlorothiazide
  • Furosemide + spironolactone
  • Metolazone + furosemide (particularly effective even in renal failure) 1

Metolazone Considerations:

• Metolazone can produce diuresis in patients with glomerular filtration rates below 20 mL/min 3
• When administered concurrently with furosemide, metolazone has produced marked diuresis in patients with edema or ascites refractory to maximum doses of other diuretics 3
• Duration of action: 12-24 hours, maximum daily dose 20 mg 1

Monitoring and Precautions

• Monitor serum potassium, sodium, and renal function at frequent intervals (every 1-2 days) according to diuretic response 1
• Titrate diuretic therapy according to clinical response and reduce dose when fluid retention is controlled 1
• Higher cumulative diuretic doses during dialysis periods can cause hypotension and increase mortality in a dose-dependent manner 4
• Worsening renal function has been associated with higher doses of furosemide (60 mg greater total dose) compared to those who did not develop worsening renal function 1

Managing Diuretic Resistance

In cases of diuretic resistance, consider: 1

• Restricting sodium and water intake
• Increasing dose and/or frequency of diuretic administration
• Using intravenous administration instead of oral
• Combining diuretic therapy as mentioned above
• Combining diuretic therapy with dopamine or dobutamine
• Reducing ACE-inhibitor dose
• Consider ultrafiltration or dialysis if response to above strategies is ineffective

Important Caveats

• Diuretics should not be used to prevent AKI (Level 1B recommendation) 1
• Diuretics should not be used to treat AKI itself, except in the management of volume overload (Level 2C recommendation) 1
• Positive fluid balance is an independent predictor of adverse outcomes in AKI patients 4
• Maintain euvolemia when using diuretics in AKI patients to avoid further renal hypoperfusion 1, 5
• The "best dose" of diuretic is likely different for each patient given the heterogeneity of AKI presentations 1

Emerging Therapies

• New diuretic agents under investigation include vasopressin V2 receptor antagonists, brain natriuretic peptides, and adenosine receptor antagonists 1
• Spironolactone may have potential to prevent AKI progression to chronic kidney disease based on experimental data 4