How should furosemide (loop diuretic) be administered?

Furosemide Administration in Acute Heart Failure

For acute heart failure with congestion, start with an IV bolus of 20-40 mg furosemide given slowly over 1-2 minutes, but only if systolic blood pressure is ≥90 mmHg and the patient is not markedly hypovolemic. 1, 2

Initial Dosing Strategy

Dose Selection Based on Prior Diuretic Use

• Diuretic-naive patients or new-onset heart failure: Start with 20-40 mg IV bolus 1, 3
• Patients already on chronic oral diuretics: The initial IV dose must be at least equivalent to (or greater than) their home oral dose 1, 2, 4
• Severe volume overload with prior diuretic exposure: Higher initial doses may be required based on renal function and chronic diuretic history 1

Administration Technique

• Give the IV bolus slowly over 1-2 minutes to minimize ototoxicity risk 1, 3
• Place a bladder catheter immediately to monitor urinary output and rapidly assess treatment response 1, 2
• Assess patients frequently in the initial phase to follow urine output 1

Critical Pre-Administration Requirements

Absolute Contraindications - Do Not Give Furosemide If:

• Systolic blood pressure <90 mmHg without circulatory support 1, 2, 4
• Marked hypovolemia 1, 2, 4
• Severe hyponatremia 1, 2, 4
• Acidosis 1
• Anuria or dialysis-dependent renal failure 1, 2

Common Pitfall to Avoid

Never start furosemide in hypotensive patients expecting it to improve hemodynamics—it will worsen hypoperfusion and precipitate cardiogenic shock. 2, 4 If systolic blood pressure is <100 mmHg or >30 mmHg below baseline, patients require circulatory support with inotropes, vasopressors, or intra-aortic balloon counterpulsation before or concurrent with diuretic therapy. 2, 4

Dose Escalation and Continuous Infusion

When to Escalate

• If inadequate diuretic response after initial bolus, increase the dose according to renal function and chronic diuretic use history 1
• Continuous infusion may be considered after the initial starting dose in patients with evidence of volume overload 1

Continuous Infusion Protocol

• Start at 3 mg/hour, doubling the infusion rate hourly until adequate diuresis is achieved 2
• Maximum infusion rate: 24 mg/hour 2
• Alternative dosing: 5-10 mg/hour with maximum rate not exceeding 4 mg/min during administration 4, 3

Dose Limits

• Total furosemide dose should remain <100 mg in the first 6 hours 1
• Total dose should remain <240 mg during the first 24 hours 1

Evidence for Continuous vs. Intermittent Dosing

Research shows continuous infusion yields comparable urinary output with lower total doses and fewer fluctuations in urinary output compared to intermittent boluses. 5, 6 A study in congestive heart failure demonstrated that continuous infusion following a loading dose produced 12-26% greater diuresis and 11-33% greater natriuresis than intermittent administration. 6

Monitoring Requirements

Target Urine Output

• Goal: >0.5 mL/kg/hour 2, 4
• Monitor urine output continuously via bladder catheter 1, 2

Laboratory Monitoring

• Electrolytes (potassium, sodium): Check frequently, especially when doses exceed 80 mg/day 1, 4
• Renal function (creatinine, eGFR): Monitor within 6-24 hours after administration 2, 4
• Blood pressure: Monitor every 15-30 minutes in the first 2 hours after administration 2, 4

Stop Furosemide Immediately If:

• Severe hyponatremia develops 1, 4
• Progressive renal failure or acute kidney injury occurs 2, 4
• Marked hypotension develops 2, 4
• Hypovolemia and dehydration occur 1

Managing Diuretic Resistance

Combination Therapy Approach

When inadequate response occurs after reaching maximum infusion rates, add a second diuretic rather than exceeding furosemide dose limits. 1, 2

• Thiazides: Hydrochlorothiazide 25 mg PO 1, 4
• Aldosterone antagonists: Spironolactone or eplerenone 25-50 mg PO 1, 4
• Rationale: Combinations in low doses are often more effective with fewer side effects than higher doses of a single drug 1

Potential Adverse Effects

Electrolyte Disturbances

• Hypokalaemia, hyponatraemia, hyperuricaemia 1

Volume-Related Complications

• Hypovolaemia and dehydration—assess urine output frequently 1
• May increase hypotension following initiation of ACEI/ARB therapy 1

Neurohormonal Effects

• Neurohormonal activation 1

Ototoxicity

• Risk increases with rapid IV administration or very high doses 4, 3
• Administer slowly over 1-2 minutes to minimize risk 1, 3

Special Populations

Pediatric Patients

• Initial dose: 1 mg/kg IV given slowly under close medical supervision 3, 7
• May increase by 1 mg/kg not sooner than 2 hours after previous dose 3, 7
• Maximum dose: 6 mg/kg body weight 3, 7
• Premature infants: Maximum 1 mg/kg/day 3, 7

Geriatric Patients

• Start at the low end of the dosing range (20 mg) 3
• Use cautious dose selection 3

Cirrhosis with Ascites

• Prefer oral administration when possible due to better bioavailability and less acute GFR reduction 2, 4
• Start with furosemide 40 mg + spironolactone 100 mg as a single morning dose 2, 4
• Maximum dose: 160 mg/day—exceeding this indicates diuretic resistance 2, 4