Furosemide Continuous Infusion Protocol
Initial Bolus Dose
Start with an IV bolus of 20-40 mg administered slowly over 1-2 minutes in patients with fluid overload and adequate blood pressure (SBP ≥90-100 mmHg). 1, 2
- If the patient has been on chronic oral diuretics or has significant volume overload, consider starting at 40 mg rather than 20 mg 1
- In acute pulmonary edema specifically, the FDA-approved initial dose is 40 mg IV over 1-2 minutes 2
- Critical contraindication: Do not initiate furosemide if SBP <90 mmHg, marked hypovolemia, anuria, or severe hyponatremia is present 1, 3
Transitioning to Continuous Infusion
After the initial bolus, continuous infusion may be started if there is persistent volume overload despite bolus dosing. 1
Preparation and Administration
- Add furosemide to Normal Saline, Lactated Ringer's, or D5W only after adjusting pH to >5.5 2
- Never mix with acidic solutions (labetalol, ciprofloxacin, amrinone, milrinone) as precipitation will occur 2
- The prepared solution must maintain a weakly alkaline to neutral pH range 2
Infusion Rate
Start at 5 mg/hour (120 mg/24 hours) and titrate upward based on urine output response. 4
- Maximum infusion rate: 4 mg/min per FDA labeling 2
- Practical dosing: Start at 5-6 mg/hour, increase gradually to maximum of 6-8 mg/hour for most patients 4
- In severe refractory cases, doses up to 160 mg/hour have been used safely under close monitoring 5
Dose Escalation Algorithm
If inadequate diuresis after 2 hours, increase the infusion rate incrementally:
- Assess urine output at 1-2 hour intervals 1
- Target urine output: ≥150 mL/hour 4
- If output inadequate, increase infusion rate by 20-40 mg/24 hours (approximately 1-2 mg/hour) 5
- Do not exceed 100 mg total in first 6 hours or 240 mg in first 24 hours for acute heart failure 1
Critical Monitoring Requirements
Place a Foley catheter immediately to accurately measure hourly urine output. 1
Hourly Monitoring
- Urine output (target ≥150 mL/hour) 4
- Blood pressure (maintain SBP ≥90 mmHg) 1
- Signs of hypovolemia: decreased skin turgor, hypotension, tachycardia 1
Every 6-12 Hours
- Serum potassium and sodium 1, 3
- Serum creatinine and estimated GFR 1, 3
- Daily weights (target 0.5-1.0 kg loss per day) 1
When to Stop or Reduce Infusion
Immediately stop furosemide if any of the following develop: 1, 3
- Anuria or severe oliguria with creatinine >3 mg/dL 3
- Severe hyponatremia (sodium <125 mmol/L) 1, 3
- Marked hypotension (SBP <90 mmHg) 1
- Creatinine increase >50% from baseline 3
- Signs of severe hypovolemia 1
- Worsening hepatic encephalopathy (in cirrhotic patients) 1
Special Considerations
Diuretic Resistance
If inadequate response despite infusion rates of 5-10 mg/hour, add a thiazide (hydrochlorothiazide 25 mg) or aldosterone antagonist (spironolactone 25-50 mg). 1
Renal Impairment
Higher doses are required in renal impairment, but continuous infusion is preferred over boluses to minimize ototoxicity risk. 1, 2
- Infusions over 5-30 minutes (or continuous drip) reduce hearing loss risk compared to rapid boluses 1, 3
- In patients with rising creatinine but persistent volume overload and adequate perfusion (MAP ≥60 mmHg), continue furosemide if creatinine rise is <50% from baseline 3
Maximum Duration
High-dose furosemide (>6 mg/kg/day or >160 mg/hour) should not be continued for longer than 1 week without reassessment. 1
Pediatric Dosing
- Initial bolus: 1 mg/kg IV slowly 2, 6
- May increase by 1 mg/kg increments every 2 hours if needed 2
- Maximum 6 mg/kg/day; in premature infants, do not exceed 1 mg/kg/day 2, 6
Common Pitfalls to Avoid
- Never start furosemide expecting it to improve hypotension—it will worsen hypoperfusion and precipitate shock 1
- Never give rapid IV push faster than 1-2 minutes to avoid ototoxicity 1, 2
- Never combine with acidic IV medications in the same line 2
- Never continue if anuria develops—this indicates acute tubular necrosis, not volume overload 3
- Avoid evening doses in stable patients due to nocturia and poor adherence 1