In a patient with volume overload (elevated BNP) and acute kidney injury, should I continue the maintenance IV fluid at 75 mL per hour and administer 20 mg IV furosemide (Lasix)?

Should You Continue IV Fluids at 75 mL/hr and Give 20 mg IV Furosemide in Volume Overload with AKI?

No—stop the maintenance IV fluids immediately and administer IV furosemide, but 20 mg is likely insufficient; you should give at least 40 mg IV furosemide as an initial dose, with readiness to escalate based on urine output response. 1, 2

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Rationale: Volume Overload Takes Priority Over AKI Concerns

In a patient with elevated BNP indicating volume overload and concurrent acute kidney injury, the primary threat to morbidity and mortality is persistent fluid overload, not the AKI itself. 3, 4, 5, 6

• Fluid overload is independently associated with increased mortality in critically ill patients with AKI, and multiple studies demonstrate worse outcomes when positive fluid balance exceeds 10% of baseline body weight. 3, 4, 5, 6
• Continuing maintenance IV fluids at 75 mL/hr in a volume-overloaded patient directly worsens outcomes by perpetuating interstitial edema, impairing organ function (including renal recovery), delaying wound healing, and increasing infection risk. 4, 5, 6
• KDIGO guidelines explicitly recommend using diuretics to manage volume overload in AKI (Grade 2C), while simultaneously advising against using diuretics to treat or prevent AKI itself (Grade 1B). 7, 1

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Step 1: Immediately Discontinue Maintenance IV Fluids

Stop the 75 mL/hr IV fluid infusion. 4, 5

• Maintenance fluids are appropriate only in euvolemic or hypovolemic patients; in volume overload, they exacerbate congestion and worsen renal perfusion through venous congestion ("backward failure"). 7, 4, 5
• Conservative fluid management strategies—targeting neutral or negative fluid balance once hemodynamic stability is achieved—improve outcomes in critically ill patients with AKI and acute lung injury. 7, 4, 5
• The only exception would be if the patient has hypotension (SBP < 90 mmHg) with signs of hypoperfusion (cool extremities, altered mental status, oliguria, elevated lactate), in which case you would address hypoperfusion first before diuresing. 1, 2

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Step 2: Administer IV Furosemide—But 20 mg Is Too Low

Give at least 40 mg IV furosemide as an initial bolus, administered slowly over 1–2 minutes. 1, 2

Why 20 mg Is Insufficient:

• 20 mg IV furosemide is considered a low dose and is typically reserved for diuretic-naïve patients with mild volume overload. 1, 2
• In a patient with elevated BNP (indicating significant volume overload) and AKI (which reduces diuretic responsiveness due to decreased tubular secretion and fewer functional nephrons), 20 mg is unlikely to produce adequate diuresis. 1, 8
• Guideline-based dosing for volume overload in AKI recommends starting with 40–80 mg IV furosemide, with higher doses (up to 160–200 mg per bolus) reserved for severe cases or diuretic resistance. 1, 2

Dosing Algorithm:

1. Initial dose: 40 mg IV furosemide (or 80 mg if the patient has prior chronic diuretic exposure or severe volume overload). 1, 2
2. Monitor urine output hourly (place a bladder catheter for accurate measurement). 1, 2
3. If urine output remains < 0.5 mL/kg/hr after 2 hours, double the dose (e.g., 80 mg IV), but do not exceed 160–200 mg per single bolus. 1, 2
4. Target daily weight loss of 0.5–1.0 kg until euvolemia is achieved. 1, 2

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Step 3: Monitor for Diuretic Response and Complications

Critical Monitoring Parameters:

• Urine output: Target > 0.5 mL/kg/hr after furosemide administration. 1, 2
• Daily weights: Measure at the same time each morning; aim for 0.5–1.0 kg loss per day. 1, 2
• Electrolytes (especially potassium and sodium): Check within 6–24 hours after starting IV furosemide, then every 3–7 days during active diuresis. 1, 2, 9
• Renal function (BUN, creatinine): Monitor daily; a modest rise in creatinine (< 0.3 mg/dL) is acceptable if the patient remains asymptomatic and volume status improves. 1, 2
• Blood pressure: Ensure SBP remains ≥ 90–100 mmHg; hypotension without signs of hypoperfusion is not a contraindication to diuresis. 1, 2

Absolute Contraindications to Continuing Furosemide:

• Severe hyponatremia (serum sodium < 120–125 mmol/L). 1, 2, 9
• Severe hypokalemia (potassium < 3.0 mmol/L). 1, 2, 9
• Anuria (no urine output). 1, 2
• Marked hypotension (SBP < 90 mmHg) with signs of hypoperfusion (cool extremities, altered mental status, oliguria, elevated lactate). 1, 2

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Step 4: Manage Diuretic Resistance if Inadequate Response

If the patient does not achieve adequate diuresis after 24–48 hours of standard furosemide dosing (e.g., 80–160 mg/day), add a second diuretic class rather than further escalating furosemide alone. 1, 2

Sequential Nephron Blockade Options:

• Hydrochlorothiazide 25 mg PO once daily (thiazide diuretic). 1, 2
• Spironolactone 25–50 mg PO once daily (aldosterone antagonist). 1, 2
• Metolazone 2.5–5 mg PO (thiazide-like diuretic, particularly effective in refractory cases). 1, 2

Low-dose combination therapy is more effective and produces fewer adverse effects than high-dose furosemide monotherapy. 1, 2

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Step 5: Consider Renal Replacement Therapy if Refractory

If fluid overload persists despite maximal diuretic therapy (furosemide ≥ 160 mg/day plus a second diuretic), initiate continuous renal replacement therapy (CRRT) or intermittent hemodialysis with ultrafiltration. 7, 3, 4, 6

• Persistent fluid overload > 10% of baseline body weight is associated with increased mortality and should not be tolerated. 3, 4, 6
• Delaying dialysis or ultrafiltration in the setting of refractory fluid overload worsens outcomes. 3, 6

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Common Pitfalls to Avoid

1. Do not continue maintenance IV fluids in a volume-overloaded patient. This directly contradicts the goal of achieving negative fluid balance and worsens outcomes. 4, 5
2. Do not under-dose furosemide out of fear of worsening AKI. Persistent volume overload itself impairs renal perfusion and delays recovery. 1, 2, 4, 5
3. Do not withhold furosemide solely because of elevated creatinine. A modest rise in creatinine (< 0.3 mg/dL) during diuresis is acceptable if the patient remains asymptomatic and volume status improves. 1, 2
4. Do not persist with furosemide monotherapy beyond 160 mg/day without adding a second diuretic. This represents the ceiling effect for loop diuretics and further escalation is ineffective. 1, 2
5. Do not delay renal replacement therapy if the patient remains fluid-overloaded despite maximal medical therapy. Early initiation of CRRT improves outcomes. 7, 3, 6

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Summary Algorithm

Step	Action	Key Details
1	Stop IV fluids	Discontinue 75 mL/hr maintenance fluids immediately. [4,5]
2	Give IV furosemide	Start with 40 mg IV (or 80 mg if severe overload/prior diuretic use). [1,2]
3	Monitor response	Target urine output > 0.5 mL/kg/hr; daily weight loss 0.5–1.0 kg. [1,2]
4	Escalate if needed	Double dose every 2 hours if inadequate response (max 160–200 mg/bolus). [1,2]
5	Add second diuretic	If no response after 24–48 hours, add thiazide or aldosterone antagonist. [1,2]
6	Consider CRRT	If refractory fluid overload despite maximal diuretics. [7,3,6]