What is the comparison between continuous infusion (Furosemide (Lasix)) and intermittent bolus administration for inducing diuresis?

From the Guidelines

Furosemide should be administered as either intermittent boluses or a continuous infusion, with the dose and duration adjusted according to the patient's symptoms and clinical status. When deciding between a furosemide drip and bolus for diuresis, it is essential to consider the patient's specific clinical scenario. According to the 2016 ESC guidelines for the diagnosis and treatment of acute and chronic heart failure 1, the initial recommended dose of furosemide should be 20–40 mg i.v. (or equivalent) for patients with new-onset AHF or those with chronic, decompensated HF not receiving oral diuretics. For patients on chronic diuretic therapy, the initial i.v. dose should be at least equivalent to the oral dose.

Key Considerations

• The choice between continuous infusion and intermittent bolus dosing should be based on the patient's symptoms and clinical status, with continuous infusion potentially offering advantages in certain scenarios, such as severe heart failure or resistant edema.
• For continuous infusion, a loading dose of 20-40mg IV followed by an infusion at 5-10mg/hour, titrating up to 20mg/hour as needed, may be effective.
• For bolus dosing, administering 20-40mg IV every 6-8 hours, increasing to 80-120mg per dose if needed, can also promote diuresis.
• Regular monitoring of symptoms, urine output, renal function, and electrolytes is crucial during the use of i.v. diuretics, as recommended by the 2016 ESC guidelines 1.

Clinical Implications

• Continuous infusion may provide a more consistent diuretic effect, less ototoxicity, and potentially greater total diuresis compared to equivalent bolus doses.
• Bolus dosing is simpler to administer, requires less monitoring, and may be more practical in settings without IV pump availability.
• The patient's fluid status, electrolytes (particularly potassium), renal function, and acid-base status should be regularly monitored, and therapy adjusted based on clinical response and laboratory parameters.

From the FDA Drug Label

The onset of diuresis following intravenous administration is within 5 minutes and somewhat later after intramuscular administration. The peak effect occurs within the first half hour. The duration of diuretic effect is approximately 2 hours The intravenous administration of furosemide is indicated when a rapid onset of diuresis is desired, e.g., in acute pulmonary edema.

The FDA drug label does not directly compare furosemide drip vs bolus for diuresis, but it does indicate that intravenous administration is preferred when a rapid onset of diuresis is desired.

• The onset of diuresis is within 5 minutes after intravenous administration.
• The peak effect occurs within the first half hour.
• The duration of diuretic effect is approximately 2 hours 2. It can be inferred that intravenous bolus may be preferred for a rapid onset of diuresis, but the label does not provide direct information on the comparison between furosemide drip and bolus 2.

From the Research

Furosemide Drip vs Bolus for Diuresis

• The diuretic efficacy of furosemide administered in either conventional intravenous bolus injection or continuous infusion was studied in patients with congestive heart failure 3.
• Furosemide infusion produced a significantly greater diuresis than the bolus when compared with baseline, with a similar increase in 24-h urinary sodium, potassium, and chloride excretion 3.
• Continuous intravenous infusion of furosemide is superior to the conventional intermittent bolus injection, especially if it is administered at the very beginning of the hospital treatment, and presumably is even better with higher dosage and longer infusion time span 3.
• The use of continuous infusion of loop diuretics, such as furosemide, has a pharmacodynamic basis and has been shown to improve diuresis in critically ill patients requiring extensive diuresis 4.
• Clinical studies have demonstrated an improved diuretic response with a controlled infusion, with minimal adverse effects and reduced drug requirements compared to bolus administration 4.

Comparison of Diuretic Combinations

• The combination of metolazone and furosemide has been shown to be effective in managing refractory fluid overload in patients with congestive heart failure and end-stage renal failure 5, 6.
• The addition of metolazone to furosemide has been shown to potentiate the diuretic effects of furosemide, allowing for lower doses of furosemide to be used and reducing the risk of adverse effects 5, 6.
• The metolazone-furosemide combination has been compared to the thiazide-furosemide combination in nephrotic patients with edema, with both combinations showing an additive natriuretic and diuretic effect 7.