What is the recommended initial dose of Lasix (furosemide) in acute congestive heart failure (CHF)?

Initial Furosemide Dosing in Acute Congestive Heart Failure

For acute congestive heart failure, the recommended initial dose is 20-40 mg IV furosemide, which is appropriate for diuretic-naïve patients. 1, 2, 3

Dosing Algorithm Based on Patient History

• Diuretic-naïve patients (not on oral diuretics):

  • Start with 20-40 mg IV furosemide 1, 2
  • Administer as slow IV push over 1-2 minutes 3

• Patients already on chronic oral diuretic therapy:

  • Give at least equivalent to their oral dose 2
  • The dose may need to be increased according to renal function and history of chronic diuretic use 1
  • In patients with evidence of volume overload, continuous infusion may be considered after the initial bolus 1

• For severe acute pulmonary edema:

  • Initial dose of 40 mg IV furosemide administered slowly (1-2 minutes) 3
  • If satisfactory response is not observed within 1 hour, the dose may be increased to 80 mg IV 3

Monitoring and Follow-up

• Patients should be assessed frequently in the initial phase to follow urine output 1
• Consider bladder catheterization to accurately monitor urinary output and rapidly assess treatment response 1, 2
• Regular monitoring of symptoms, renal function, and electrolytes is essential during IV diuretic therapy 2

Important Considerations and Potential Pitfalls

• Total furosemide dose should remain <100 mg in the first 6 hours and <240 mg during the first 24 hours 1
• Patients with hypotension (SBP <90 mmHg), severe hyponatremia, or acidosis are unlikely to respond well to diuretic treatment 1, 2
• High doses of diuretics may lead to:
  • Hypovolemia and dehydration 1
  • Hyponatremia and hypokalaemia 1, 4
  • Increased likelihood of hypotension when initiating ACE inhibitors or ARBs 1

Alternative and Adjunctive Treatments

• Consider high-dose nitrates with low-dose furosemide (40 mg IV) as an alternative approach, which has shown better outcomes than high-dose furosemide (80 mg IV every 15 min) with low-dose nitrates 1
• For diuretic resistance, consider combination therapy:
  • Thiazides (hydrochlorothiazide 25 mg) can be used in association with loop diuretics 1
  • Aldosterone antagonists (spironolactone, eplerenone 25–50 mg) may be added 1
  • Combinations in low doses are often more effective with fewer side effects than using higher doses of a single drug 1, 4

Special Populations

• In geriatric patients, dose selection should be cautious, usually starting at the lower end of the dosing range 3
• For patients with significantly reduced renal function, higher doses may eventually be required, but should be administered under careful monitoring 5, 6