Dosing of Continuous Lasix Infusion
For continuous furosemide (Lasix) infusion, the recommended initial dose is 0.1-0.2 mg/kg/hour after a loading bolus of 20-40 mg, with adjustments based on clinical response and urine output. 1, 2
Initial Dosing Protocol
Step 1: Loading Dose
- Administer an initial IV bolus of 20-40 mg furosemide over 1-2 minutes 1
- For patients already on chronic oral diuretic therapy, the initial IV dose should be at least equivalent to their oral dose 2
Step 2: Continuous Infusion Setup
- Begin continuous infusion at 0.1-0.2 mg/kg/hour 1
- Add furosemide to either:
- Sodium Chloride Injection USP
- Lactated Ringer's Injection USP
- Dextrose (5%) Injection USP
- Ensure solution pH is above 5.5 to prevent precipitation 1
Step 3: Titration Based on Response
- Monitor urine output, renal function, and electrolytes regularly 2
- Adjust dose every 2-4 hours based on clinical response
- Maximum recommended infusion rate: 4 mg/minute 1
- For refractory cases, doses may be increased gradually, with some severe heart failure cases requiring up to 0.5-1 g/day 3
Monitoring Requirements
- Urine output (consider bladder catheterization for accurate measurement)
- Electrolytes (particularly potassium, sodium)
- Renal function (BUN, creatinine)
- Fluid status and hemodynamic parameters
- Daily weights
Special Considerations
Acid-Base Compatibility
- Furosemide is a buffered alkaline solution with pH of about 9
- Do not mix with acidic solutions (e.g., labetalol, ciprofloxacin, amrinone, milrinone) as precipitation may occur 1
- Do not add to running IV lines containing acidic products
Combination Therapy
- For diuretic resistance, consider adding thiazide diuretics (hydrochlorothiazide 25 mg) or aldosterone antagonists (spironolactone 25-50 mg) 2
- Combination therapy often allows for lower doses of each medication with fewer side effects 2
Cautions
- Avoid in patients with hypotension (SBP < 90 mmHg), severe hyponatremia, or acidosis 2
- Use cautiously in elderly patients, starting at the lower end of the dosing range 1
- Monitor for ototoxicity with high doses
- Ensure adequate potassium supplementation or spironolactone to prevent hypokalemia 3
Duration of Therapy
- Transition to oral therapy as soon as clinically appropriate 1
- Reassess diuretic requirements periodically as some patients may be maintained on lower doses than initially required 4
This evidence-based approach to continuous furosemide infusion provides a structured protocol that balances efficacy with safety while allowing for individualization based on clinical response and monitoring parameters.