How is diuresis managed in Acute Respiratory Distress Syndrome (ARDS)?

Diuresis Management in ARDS

In ARDS patients who are not in shock (off vasopressors ≥12 hours with MAP ≥60 mmHg), implement a conservative fluid strategy with active diuresis guided by the FACTT-lite protocol using CVP and urine output targets, as this increases ventilator-free days by 2.5 days without increasing mortality. 1

When to Initiate Diuresis

Begin diuretic therapy only after ensuring the patient is hemodynamically stable—specifically, off vasopressors for at least 12 hours with MAP ≥60 mmHg. 1 This critical timing prevents precipitating shock while maximizing the pulmonary benefits of fluid removal.

Absolute Contraindications to Diuresis

• Withhold diuretics in active shock or within 12 hours of last vasopressor dose 1
• Withhold in renal failure defined as: 1
  • Dialysis dependence
  • Oliguria with serum creatinine >3 mg/dL
  • Oliguria with urinary indices indicating acute renal failure
• Withhold until 12 hours after last fluid bolus 1

The FACTT-Lite Protocol Algorithm

This simplified protocol from the ARDS Network provides an algorithmic approach based on two readily available parameters: CVP and urine output. 1

High CVP (>8 mmHg) or High PAOP (>12 mmHg)

• If urine output <0.5 mL/kg/h: Give furosemide, reassess in 1 hour 1
• If urine output ≥0.5 mL/kg/h: Give furosemide, reassess in 4 hours 1

Intermediate CVP (4-8 mmHg) or PAOP (8-12 mmHg)

• If urine output <0.5 mL/kg/h: Give fluid bolus, reassess in 1 hour 1
• If urine output ≥0.5 mL/kg/h: Give furosemide, reassess in 4 hours 1

Low CVP (<4 mmHg) or PAOP (<8 mmHg)

• If urine output <0.5 mL/kg/h: Give fluid bolus, reassess in 1 hour 1
• If urine output ≥0.5 mL/kg/h: No intervention, reassess in 4 hours 1

Furosemide Dosing Strategy

Start with 20 mg IV bolus or 3 mg/h continuous infusion (or last known effective dose). 1 The FDA approves IV furosemide for acute pulmonary edema when rapid diuresis is desired. 2

Dose Escalation Protocol

• Double each subsequent dose until goal achieved (oliguria reversal or intravascular pressure target) 1
• Maximum infusion rate: 24 mg/h 1
• Maximum bolus: 160 mg 1
• Do not exceed 620 mg/day total 1

Essential Protocol Meta-Rules

Discontinue all maintenance fluids entirely—this is non-negotiable in the conservative strategy. 1, 3 Continue only medications and nutrition. 1

• Manage electrolytes and blood products per usual practice 1
• Monitor for right ventricular failure, which occurs in 20-25% of ARDS patients 1, 4
• Use norepinephrine (not additional fluids) if RV dysfunction develops, as excess fluids worsen RV function in high afterload states 1

Evidence Supporting Conservative Diuresis

The landmark FACTT trial of 1000 patients demonstrated that conservative fluid management produces 2.5 additional ventilator-free days (p<0.001) without mortality difference. 1 The FACTT-lite simplified protocol showed similar ventilator-free days with lower prevalence of new-onset shock and similar acute kidney injury rates compared to the original complex protocol. 1

Recent observational data reinforces these findings: early diuretic use (48-72 hours after ARDS onset) was independently associated with lower hospital mortality (adjusted OR 0.46,95% CI 0.22-0.96) after controlling for time-varying confounders. 5, 6 The mortality benefit was particularly pronounced in patients with worse renal function, higher CVP, sepsis-induced ARDS, PaO2/FiO2 ≤150 mmHg, and MAP ≥65 mmHg. 5

Critical Pitfalls to Avoid

Do not rely on CVP alone to guide therapy—it poorly predicts fluid responsiveness in the 8-12 mmHg range due to transmitted pleural pressure from mechanical ventilation. 1, 3 Use it as one component of the algorithm, not in isolation.

Avoid excessive diuresis in hypovolemic patients, as this can paradoxically worsen pulmonary edema through left ventricular hyperdynamic status. 7 One case report documented acute pulmonary edema from overly aggressive diuresis requiring fluid resuscitation and beta-blockade for reversal. 7

Recognize that once volume replete, further fluid administration is useless and deleterious in ARDS—particularly with RV dysfunction where fluids worsen cardiac output and blood pressure. 1 RV failure is the main factor limiting fluid efficacy in restoring perfusion. 1

Monitor for acute cor pulmonale using echocardiography, as this complication fundamentally changes management priorities toward RV support rather than aggressive diuresis. 4

Monitoring During Diuresis

• Assess fluid responsiveness using ultrasound evaluation of IVC dimension and filling dynamics, pulse pressure variation (PPV), or CVP response to intervention 1, 3
• Monitor urine output and metabolic acidosis as indices of tissue perfusion 1, 4
• Perform regular echocardiography to detect RV dysfunction 4
• Use point-of-care ultrasound to assess extravascular lung water and guide therapy 7