What is the recommended dose of furosemide (Lasix) for a 1-year-old patient with congestive cardiac failure (CCF) and an atrial septal defect (ASD)?

Furosemide Dosing for a 1-Year-Old with Congestive Heart Failure and Atrial Septal Defect

For a 1-year-old infant with congestive heart failure secondary to an atrial septal defect, start with oral furosemide at less than 2 mg/kg per day, as this dose minimizes excess potassium loss while providing adequate diuresis. 1

Initial Dosing Strategy

• Begin with furosemide 1-2 mg/kg per day orally, divided into 1-2 doses. 1, 2
• The ACC/AHA guidelines specifically state that as long as the dose remains below 2 mg/kg per day orally, excess potassium loss generally does not occur in infants with left-to-right shunts. 1
• For a typical 10 kg one-year-old, this translates to 10-20 mg per day orally, which can be given as a single morning dose or divided into twice-daily dosing. 1, 2

Dose Escalation Protocol

• If the initial dose proves inadequate (infant not gaining weight, persistent tachypnea, or ongoing signs of heart failure), increase the dose by 1 mg/kg increments every 6-8 hours until adequate diuresis is achieved. 2, 3
• At doses exceeding 2 mg/kg per day, add spironolactone to prevent potassium depletion and potentially obviate the need for potassium supplementation. 1
• The absolute maximum dose is 6 mg/kg per day (60 mg/day for a 10 kg infant), but doses exceeding 6 mg/kg per day should never be given for longer than 1 week due to significant ototoxicity risk. 2

Critical Monitoring Requirements

• Monitor weight gain as the primary indicator of treatment success - the infant should be gaining weight appropriately while on therapy. 1
• Check for resolution of tachypnea and other signs of heart failure (hepatomegaly, feeding difficulties). 1
• Monitor electrolytes (particularly potassium and sodium) within 1-2 weeks of initiation or dose changes. 4
• Assess renal function regularly, especially if doses exceed 2 mg/kg per day. 4, 2

Special Considerations for ASD with Left-to-Right Shunt

• The ACC/AHA guidelines emphasize that medical management in infants with left-to-right shunts is somewhat controversial, but furosemide is generally recommended despite limited evidence. 1
• The primary goal is to maintain the infant gaining weight and free of lower respiratory tract infections while awaiting potential spontaneous closure or surgical intervention. 1
• Most ASDs causing significant heart failure in infancy will require surgical closure, typically considered after 6 months of age if the shunt remains large and pulmonary artery pressure is significantly elevated. 1

Administration Considerations

• Oral administration is preferred for chronic management in stable infants. 4, 3
• If IV administration is required for acute decompensation, use 1 mg/kg IV as the initial dose, which can be repeated every 6-8 hours. 2
• IV infusions must be administered over 5-30 minutes to minimize ototoxicity risk. 4, 2

Combination Therapy

• Consider adding digoxin if the infant has evidence of reduced ventricular function or persistent symptoms despite adequate diuresis, though its benefit in infants with normal contractility and left-to-right shunts remains controversial. 1
• ACE inhibitors (enalapril or captopril) may be considered for refractory symptoms, though they are not beneficial in all infants with left-to-right shunts. 1

Common Pitfalls to Avoid

• Never exceed 6 mg/kg per day for more than 1 week - this is the critical threshold for permanent hearing loss. 2
• Do not initiate furosemide in a hypovolemic infant; ensure adequate intravascular volume first. 2
• Avoid excessive diuresis that prevents weight gain, as this defeats the primary therapeutic goal in this population. 1
• Do not use furosemide as monotherapy at high doses; add spironolactone when exceeding 2 mg/kg per day. 1