In patients with acute decompensated heart failure, should intravenous loop diuretics be administered as a bolus or as a continuous infusion?

IV Diuretics in Acute Decompensated Heart Failure: Bolus vs Continuous Infusion

Either bolus or continuous infusion of IV loop diuretics can be used as initial therapy in acute decompensated heart failure, as there is no significant difference in symptom relief, mortality, or renal function between the two strategies. 1

Initial Diuretic Strategy

Starting with Bolus Administration

Begin with intermittent IV bolus dosing of loop diuretics as the first-line approach for patients admitted with acute decompensated heart failure and significant fluid overload. 2

• Start furosemide 20-40 mg IV bolus (or bumetanide 0.5-1 mg, torasemide 10-20 mg) at admission 3, 4, 3
• If patients are already on chronic oral loop diuretics, the initial IV dose should equal or exceed their chronic oral daily dose 2
• Therapy should begin in the emergency department without delay, as early intervention is associated with better outcomes 2

Evidence Supporting Equivalence

The landmark DOSE trial (308 patients) demonstrated no significant difference between bolus and continuous infusion strategies in:

• Patient global symptom assessment (P=0.47) 1
• Change in serum creatinine (P=0.45) 1
• All-cause mortality 1

A 2024 Cochrane review (681 participants across 7 RCTs) confirmed these findings, showing insufficient evidence to support superiority of either strategy for weight loss, mortality, length of stay, readmission, or acute kidney injury. 5

When to Escalate to Continuous Infusion

Reserve continuous infusion for inadequate diuresis after initial bolus therapy. 2

Indications for Switching to Continuous Infusion

When diuresis is inadequate to relieve congestion as evidenced by clinical evaluation, intensify the diuretic regimen using one of three strategies: 2

1. Higher doses of loop diuretics (first option)
2. Addition of a second diuretic (metolazone, spironolactone, or IV chlorothiazide)
3. Continuous infusion of a loop diuretic (third-line option)

Practical Implementation of Continuous Infusion

• After initial starting bolus dose, continuous infusion may be considered in patients with evidence of volume overload 3, 4, 3
• Keep total furosemide dose <100 mg in the first 6 hours and <240 mg during the first 24 hours 3, 4, 3
• Monitor urine output frequently; bladder catheter placement is usually desirable 3, 4, 3

Important Caveats and Monitoring

Potential Concerns with Continuous Infusion

While continuous infusion may achieve greater BNP reduction, one study (82 patients) found it was associated with: 6

• Greater worsening of renal function (mean creatinine increase +0.8 mg/dL vs -0.8 mg/dL, P<0.01)
• Decreased eGFR (-9 vs +5 mL/min/1.73m², P<0.05)
• Longer hospital stays (14.3 vs 11.5 days, P<0.03)
• Higher 6-month readmission or death rates (58% vs 23%, P=0.001)

However, the 2024 Cochrane review found no significant difference in acute kidney injury between strategies (RR 1.02,95% CI 0.70-1.49). 5

Essential Monitoring Parameters

Monitor the following during IV diuretic therapy: 2

• Fluid intake and output measurement
• Daily body weight (same time each day)
• Vital signs including supine and standing blood pressure
• Daily serum electrolytes, BUN, and creatinine
• Clinical signs and symptoms of congestion and perfusion

Dosing Strategy Considerations

A high-dose strategy (2.5 times previous oral dose) showed a nonsignificant trend toward greater symptom improvement compared to low-dose strategy (equivalent to previous oral dose), with no significant difference in renal function changes. 1

• High-dose strategy was associated with greater diuresis and more favorable secondary outcomes 1
• Transient worsening of renal function may occur with higher doses but does not predict worse outcomes when patients are discharged without persistent congestion 7

Practical Algorithm

1. Start with IV bolus furosemide (dose based on prior oral use or 20-40 mg if diuretic-naive) 2, 3
2. Assess response at 48 hours by monitoring urine output, weight loss, and symptom relief 2, 1
3. If inadequate response: First increase bolus dose, then consider adding second diuretic, and only then consider switching to continuous infusion 2
4. Transition to oral diuretics once decongestion achieved, with careful attention to dosing and electrolyte monitoring 2, 7

The choice between bolus and continuous infusion should be based on institutional protocols and clinical response rather than an expectation of superior efficacy with either method, as the evidence does not support routine preference for continuous infusion over bolus dosing. 5, 1