What is the typical infusion rate for Lasix (furosemide) in ml/hour?

Furosemide Infusion Rate in ml/hr

For continuous IV furosemide infusion in acute heart failure, start at 5-10 mg/hour (5-10 ml/hr if using a standard 1 mg/ml concentration), with a maximum infusion rate not exceeding 4 mg/min during administration. 1, 2

Standard Concentration and Infusion Rates

• The typical preparation is furosemide 400 mg in 500 ml of 5% dextrose, yielding a concentration of 0.8 mg/ml 3
• Alternatively, many institutions use 1 mg/ml concentration (e.g., 100 mg in 100 ml or 200 mg in 200 ml) for easier calculation 2
• Initial infusion rate: 5-10 mg/hour (which equals 5-10 ml/hr at 1 mg/ml concentration or 6.25-12.5 ml/hr at 0.8 mg/ml concentration) 1, 2, 4
• Maximum safe infusion rate: 4 mg/min (240 mg/hour or 240 ml/hr at 1 mg/ml), though this rate is rarely used clinically 1

Dose Escalation and Limits

• Total furosemide dose should remain <100 mg in the first 6 hours and <240 mg during the first 24 hours in acute heart failure 1, 2
• If using 5 mg/hour continuously, this equals 120 mg over 24 hours (well within safe limits) 4
• Mean initial infusion rates in clinical practice are 5.1 ± 1.1 mg/hour, with maximum rates of 6.2 ± 2.2 mg/hour 4
• For patients requiring higher doses, consider combination therapy with thiazides or aldosterone antagonists rather than escalating furosemide alone 1, 2

Critical Monitoring During Infusion

• Place a bladder catheter to monitor hourly urine output and assess treatment response 1, 2
• Target urine output: >0.5 ml/kg/hour during active diuresis 2
• Monitor blood pressure every 15-30 minutes in the first 2 hours, as IV furosemide can cause transient hemodynamic worsening 1, 2
• Check electrolytes (potassium, sodium) and renal function within 6-24 hours after starting infusion 1, 2
• Mean hourly urine output increases from baseline 116 ml/hr to 150 ml/hr with low-dose continuous infusion 4

Important Safety Considerations

• Absolute contraindication: systolic blood pressure <90 mmHg without circulatory support 1, 2
• Stop infusion immediately if: severe hyponatremia develops, progressive renal failure occurs, marked hypotension develops, or anuria occurs 1, 2
• Acute renal injury develops in 19% of patients, with 70% occurring within the first 48 hours of therapy 4
• Concurrent nitroglycerin administration can prevent transient hemodynamic worsening associated with IV furosemide 1

Practical Calculation Example

For a 70 kg patient requiring 5 mg/hour infusion:

• Using 1 mg/ml concentration: Set pump at 5 ml/hr
• Using 0.8 mg/ml concentration (400 mg in 500 ml): Set pump at 6.25 ml/hr
• This delivers 120 mg over 24 hours, which is within safe limits 1, 4

Common Pitfall to Avoid

Do not start furosemide infusion in hypotensive patients expecting it to improve hemodynamics—it will worsen hypoperfusion and precipitate cardiogenic shock. These patients require circulatory support with inotropes, vasopressors, or mechanical support before or concurrent with diuretic therapy. 1, 2