In a patient with eGFR <30 mL/min and high risk of volume overload, should torsemide be administered as a continuous infusion rather than intermittent IV bolus doses?

Torsemide Administration: Infusion vs Bolus in Severe Renal Impairment

In patients with eGFR <30 mL/min and high risk of volume overload, either continuous infusion or intermittent bolus dosing of torsemide can be used, as there is no proven superiority of one method over the other for clinical outcomes, mortality, or renal function. 1

Evidence-Based Recommendation

The 2013 ACC/AHA Heart Failure Guidelines explicitly address this question: the DOSE trial found no significant difference between continuous infusion versus intermittent bolus strategies for symptoms, diuresis, or outcomes. 1 This landmark finding applies to loop diuretics in general, including torsemide, and is particularly relevant for patients with renal dysfunction who require aggressive diuresis.

Key Guideline Principles

Theoretical advantages of continuous infusion exist but have not translated to clinical benefit:

• Continuous diuretic delivery theoretically avoids rebound sodium and fluid reabsorption that occurs when tubular drug concentrations decline between bolus doses 1
• Loop diuretics have a relatively short half-life, and sodium reabsorption resumes once tubular concentrations drop 1
• Despite this pharmacologic rationale, the DOSE trial definitively showed no advantage in patient-centered outcomes 1

When to consider switching strategies:

• It is reasonable to try an alternate approach (switching from bolus to continuous infusion or vice versa) among patients who are resistant to diuresis with the initial strategy 1
• This represents a Class IIa recommendation when standard dosing fails to achieve adequate decongestion 1

Practical Dosing Considerations for Severe Renal Impairment

Higher initial doses are required in patients with eGFR <30 mL/min:

• Moderate to severe renal dysfunction blunts the diuretic response, necessitating higher initial doses 1
• The dose should be sufficient to achieve optimal volume status and relieve congestion without causing excessively rapid intravascular volume reduction 1

For torsemide specifically in this population:

• Initial IV doses of 10-20 mg are recommended, with maximum single doses up to 100-200 mg 1
• Torsemide has advantages in renal failure: longer duration of action and no accumulation in renal dysfunction 2, 3
• Studies show torsemide may demonstrate better dose-dependent diuretic effects in acute renal failure patients compared to furosemide 3

If using continuous infusion:

• A loading bolus of 20 mg followed by 5-20 mg/hour infusion is appropriate 1
• Continuous infusion of torsemide results in greater efficiency (more diuresis per mg of drug) but not necessarily greater total diuresis 4
• The 24-hour diuresis and natriuresis are numerically but not statistically greater with continuous infusion versus bolus 4

Monitoring Requirements in Severe Renal Impairment

Daily assessment is mandatory:

• Serum electrolytes, urea nitrogen, and creatinine should be measured daily during active diuretic titration 5, 6
• Volume status assessment including weight, peripheral edema, and pulmonary congestion 5, 6
• Urine output tracking to confirm adequate diuresis (target >100 mL/hour in first 2 hours) 5
• Blood pressure monitoring for both supine and upright hypotension, particularly critical in patients with renal dysfunction 5, 6

Strategies for Diuretic Resistance

If initial torsemide therapy (bolus or infusion) fails:

1. Increase the loop diuretic dose to ensure adequate drug levels reach the kidney, which is particularly important in severe renal dysfunction 1

2. Add a second diuretic (thiazide or metolazone) for sequential nephron blockade, which can improve diuretic responsiveness 1, 5, 6

3. Switch administration method from bolus to continuous infusion or vice versa as a reasonable alternative strategy 1

4. Consider ultrafiltration for refractory congestion not responding to aggressive medical therapy 1, 6

Common Pitfalls to Avoid

Premature dose escalation without adequate trial:

• Allow sufficient time (at least 1-4 hours) to assess response before increasing doses 1
• Confirm that congestion persists and that another hemodynamic profile is not present before intensifying therapy 1

Inadequate dosing in severe renal impairment:

• Reduced GFR decreases drug delivery to the site of action in the renal tubule, requiring higher doses 1, 6
• The initial dose should equal or exceed previous effective doses 5, 6

Excessive volume depletion:

• Avoid excessively rapid reduction in intravascular volume, which can result in hypotension, worsening renal dysfunction, or both 1
• This is particularly problematic in patients with baseline eGFR <30 mL/min 1

Clinical Decision Algorithm

Choose your initial approach based on practical considerations rather than efficacy:

• Bolus dosing is simpler, requires less nursing time, and allows for dose titration every 6-12 hours
• Continuous infusion may be preferred if you want more stable drug levels and are concerned about hemodynamic fluctuations from high peak concentrations

If inadequate response after 24-48 hours:

1. Verify persistent congestion with physical exam and consider right heart catheterization if uncertain 1
2. Double the torsemide dose (up to maximum 200 mg bolus or 24 mg/hour infusion) 1
3. Add sequential nephron blockade with thiazide or metolazone 1, 5
4. Switch from bolus to infusion or vice versa 1
5. Consider ultrafiltration for truly refractory cases 1