What is the recommended dosing for furosemide (Lasix) in patients with cardiac failure?

Furosemide Dosing for Cardiac Failure

Oral Dosing for Chronic Heart Failure

Start with furosemide 20-40 mg once daily and titrate upward by 20-40 mg increments every 6-8 hours until achieving target weight loss of 0.5-1.0 kg daily, with maximum doses reaching 250-600 mg/day as needed. 1, 2

Initial Dosing Strategy

• Begin with 20-40 mg orally as a single dose in the morning 3, 2
• If inadequate response after 6-8 hours, either repeat the same dose or increase by 20-40 mg increments 2
• Always administer loop diuretics in combination with an ACE inhibitor—never use diuretics alone in heart failure 3, 1
• Once effective single dose is determined, administer once or twice daily (e.g., 8 AM and 2 PM) 2

Dose Escalation Protocol

• Continue increasing dose until urine output increases and weight decreases by 0.5-1.0 kg daily 1
• Maximum daily dose can reach 600 mg/day in severe edematous states, and occasionally higher 1, 2
• For persistent fluid retention despite dose escalation, switch to twice-daily administration 3
• Consider 2-4 consecutive days per week dosing for most efficient and safe fluid mobilization 2

Combination Diuretic Therapy for Refractory Cases

• If inadequate response to high-dose loop diuretics alone, combine with thiazides (but avoid thiazides if GFR <30 mL/min unless used synergistically with loop diuretics) 3
• In severe chronic heart failure, add metolazone with frequent creatinine and electrolyte monitoring 3
• Add potassium-sparing diuretics (spironolactone 25-50 mg, amiloride 2.5-5 mg, or triamterene 25-50 mg) only if hypokalaemia persists despite ACE inhibitor therapy 3

Intravenous Dosing for Acute Decompensated Heart Failure

For patients hospitalized with acute heart failure exacerbation, administer IV furosemide at a dose at least equivalent to their total daily oral dose (minimum 80 mg IV if on 40 mg PO twice daily), or 20-40 mg IV if diuretic-naïve. 1, 4

Initial IV Dosing Algorithm

• Diuretic-naïve patients: Start with 20-40 mg IV 1, 4
• Patients on chronic oral diuretics: Initial IV dose must equal or exceed total daily oral dose 1, 4
  • Example: Patient on 40 mg PO twice daily (80 mg/day total) requires at least 80 mg IV initially 1
• Administer as either intermittent boluses or continuous infusion 1, 4

IV Dose Escalation Strategy

• If inadequate diuresis, increase dose by 20 mg increments every 2 hours until desired effect achieved 1
• Maximum daily doses can reach 600 mg or occasionally higher in severe cases 1
• For continuous infusion, typical rates are 5-10 mg/hour, adjustable based on response 5

Special Consideration: Hypotension During Acute Decompensation

• If systolic blood pressure <90 mmHg with signs of hypoperfusion (cool extremities, altered mental status, oliguria, elevated lactate): Hold diuretics until perfusion restored 1
• If systolic blood pressure ≥90 mmHg: Proceed with standard IV diuretic therapy regardless of absolute blood pressure number 1
• Once perfusion restored and SBP improves, initiate diuretic therapy with careful monitoring 1

Critical Monitoring Requirements

During Active Diuresis

• Monitor urine output hourly initially, targeting 150 mL/hour or greater 5
• Check daily weights at same time each day 1
• Monitor electrolytes (especially potassium), BUN, and creatinine daily during IV therapy 1, 4
• Check blood pressure, renal function, and electrolytes 1-2 weeks after each oral dose increment, at 3 months, then every 6 months 3

Managing Complications

• Treat electrolyte imbalances aggressively while continuing diuresis 1
• If hypotension or azotemia occurs before treatment goals achieved, slow the rate of diuresis but maintain it until fluid retention eliminated 1
• If serum creatinine rises substantially, consider stopping treatment 3

Essential Concurrent Therapy

Continue ACE inhibitors/ARBs and beta-blockers during both oral and IV diuretic therapy unless patient is hemodynamically unstable (SBP <90 mmHg with end-organ dysfunction). 1

• Inappropriate diuretic dosing (too low or too high) undermines efficacy of other heart failure medications 1
• Low doses cause fluid retention that diminishes ACE inhibitor response and increases beta-blocker risk 1
• High doses cause volume contraction, increasing hypotension risk with ACE inhibitors and vasodilators 1
• Avoid NSAIDs as they antagonize diuretic effect 3

Common Pitfalls to Avoid

• Starting with doses lower than home oral dose in hospitalized patients already on chronic diuretics is inadequate 1
• Excessive concern about hypotension and azotemia leads to underutilization and refractory edema 1
• Stopping ACE inhibitors/ARBs or beta-blockers unnecessarily during exacerbation undermines synergistic effects 1
• Failing to have patients record daily weights and adjust doses based on weight changes 1

Maintenance Therapy Strategy

• Maintain diuretic treatment to prevent recurrence of volume overload, with frequent adjustments as needed 1
• Consider having patients adjust their own diuretic dose if weight increases or decreases beyond specified range (typically ±2 kg) 1
• Periodically reassess to determine minimum effective dose for maintenance 6