Lasix (Furosemide) Infusion Rate
For acute heart failure, start with 20-40 mg IV furosemide as a slow bolus (over 1-2 minutes), and if using continuous infusion, do not exceed 4 mg/min infusion rate. 1, 2
Initial Dosing Strategy
For Diuretic-Naive or New-Onset Acute Heart Failure
- Administer 20-40 mg IV furosemide as initial dose given slowly over 1-2 minutes 1, 2
- This represents the Class I, Level B recommendation from the European Society of Cardiology guidelines 1
For Patients Already on Chronic Diuretic Therapy
- Initial IV dose should be at least equivalent to their oral maintenance dose 1
- Patients with volume overload may require higher initial doses based on renal function and chronic diuretic history 1
Infusion Rate and Administration Methods
Continuous Infusion Protocol
- Maximum infusion rate: 4 mg/min when using high-dose parenteral therapy 2
- Furosemide must be diluted in Sodium Chloride Injection USP, Lactated Ringer's Injection USP, or Dextrose (5%) Injection USP after pH adjustment to above 5.5 2
- The prepared solution pH must remain in weakly alkaline to neutral range, as furosemide precipitates at pH values below 7 2
Bolus vs. Continuous Infusion
- Either intermittent boluses or continuous infusion are equally acceptable, with dose and duration adjusted according to symptoms and clinical status 1
- Low-dose continuous infusion (<160 mg/24 hours, approximately 5-6 mg/hour) has demonstrated efficacy with mean hourly urine output increasing from 116 mL/h to 150 mL/h 3
Dose Escalation Guidelines
Reassessment Timing
- If inadequate response occurs, increase dose by 20 mg and administer not sooner than 2 hours after previous dose 2
- For acute pulmonary edema specifically: if 40 mg IV bolus produces unsatisfactory response within 1 hour, increase to 80 mg IV slowly over 1-2 minutes 2
Maximum Dosing Considerations
- Total furosemide dose should remain <100 mg in first 6 hours and <240 mg during first 24 hours 1
- Doses greater than 6 mg/kg body weight are not recommended in pediatric patients 2
- High-dose furosemide (≥500 mg/day) has been used successfully in refractory cardiac failure, though this requires cautious administration 4
Critical Safety Monitoring
Mandatory Monitoring Parameters
- Regularly monitor symptoms, urine output, renal function, and electrolytes during IV diuretic use 1
- Place bladder catheter to monitor urinary output and rapidly assess treatment response 1
Important Hemodynamic Considerations
- Avoid use in patients with systolic blood pressure <90 mmHg, as these patients are unlikely to respond to diuretic treatment 1
- Be aware that IV furosemide can cause transient (1-2 hour) hemodynamic worsening with increased heart rate, mean arterial pressure, LV filling pressure, and decreased stroke volume 1
- This adverse hemodynamic effect can be prevented with concurrent nitroglycerin administration 1
Drug Compatibility Warning
- Never administer acidic solutions concurrently in the same infusion line, including labetalol, ciprofloxacin, amrinone, or milrinone, as they cause furosemide precipitation 2
Prognostic Considerations
Renal Function Impact
- Higher loop diuretic doses are associated with worsening renal function during hospitalization 1
- Worsening renal function (increase of 0.1-0.5 mg/dL creatinine) is associated with increased 6-month mortality and in-hospital mortality (OR 2.7,95% CI 1.6-4.6) 1
- However, low-dose continuous infusion did not significantly change mean serum creatinine or estimated glomerular filtration rate from baseline to discharge 3