When is it appropriate to put a patient on Lasix (furosemide)?

When to Use Furosemide (Lasix)

Furosemide should be administered in patients with symptoms of fluid overload and congestion, particularly those with moderate-to-severe pulmonary edema resulting from acute heart failure, and in patients with edematous states associated with cardiac, renal, or hepatic failure. 1, 2

Primary Indications for Furosemide

• Acute Heart Failure with Pulmonary Edema: Recommended in combination with nitrate therapy for moderate-to-severe pulmonary edema 1
• Chronic Heart Failure with Volume Overload: For patients with symptoms secondary to congestion 1, 2
• Hypertension: Can be used when initial therapy is insufficient or in combination with other antihypertensive agents 3
• Edematous States: Appropriate for edema associated with cardiac, renal, or hepatic failure 3, 4

Dosing Guidelines

• New-onset acute heart failure: Initial dose of 20-40 mg IV 1, 2
• Chronic heart failure patients already on oral diuretics: Initial IV dose should be at least equivalent to their oral dose 2
• Oral therapy for edema: Initial dose of 20-80 mg given as a single dose, which can be titrated up based on response 3
• Hypertension: Usually 80 mg daily, often divided into 40 mg twice daily 3
• Refractory cases: May require combination therapy with thiazide diuretics or aldosterone antagonists 1, 2

Monitoring Requirements

• Urine output: Should be assessed frequently to evaluate response 1, 2
• Electrolytes: Monitor for hypokalemia, hyponatremia, and metabolic alkalosis 1, 3
• Renal function: Diuretics should be administered judiciously given the potential association between diuretics, worsening renal function, and long-term mortality 1, 2, 5
• Blood pressure: Monitor for hypotension, especially when combining with other antihypertensive medications 3

Special Considerations and Cautions

• Hemodynamic effects: IV furosemide can cause transient worsening of hemodynamics for 1-2 hours after administration, including increased systemic vascular resistance and decreased stroke volume 1, 2, 5
• Combination therapy: In acute heart failure, combining furosemide with nitrates is more effective than aggressive diuretic monotherapy 1
• Hepatic cirrhosis: Therapy is best initiated in the hospital setting due to risk of precipitating hepatic coma 3
• Ototoxicity risk: Higher with rapid injection, severe renal impairment, higher doses, hypoproteinemia, or concomitant therapy with other ototoxic drugs 3
• Bioavailability concerns: Oral furosemide has variable absorption (12-112% bioavailability), which may affect consistent response 6, 7

Inappropriate Uses

• First-line hypertension therapy: Loop diuretics should not be used as first-line therapy for hypertension as there are no outcome data supporting this use 6
• Patients with hypotension: Those with SBP < 90 mmHg, severe hyponatremia, or acidosis are unlikely to respond to diuretic treatment 1
• Monotherapy for acute pulmonary edema: Nitrates have shown improved outcomes compared to furosemide monotherapy 1, 5

Adverse Effects to Monitor

• Electrolyte disturbances: Hypokalemia (3.6% of patients), hyponatremia, and other electrolyte abnormalities 8
• Volume depletion: Occurs in approximately 4.6% of patients and increases with higher daily doses 8
• Renal function deterioration: Higher loop diuretic doses are associated with worsening renal function 5, 9
• Metabolic effects: Can cause hyperuricemia and glucose intolerance 6

By following these guidelines, furosemide can be effectively and safely used to manage fluid overload in appropriate clinical scenarios.