What is the recommended management for a patient with acute respiratory distress syndrome?

Management of Acute Respiratory Distress Syndrome

Immediately initiate lung-protective mechanical ventilation with tidal volumes of 4–8 mL/kg predicted body weight and plateau pressure ≤30 cmH₂O in all intubated ARDS patients, as this is the only intervention proven to reduce mortality and represents the single most critical intervention across all ARDS severities. 1, 2

Mechanical Ventilation Strategy

Core Ventilator Settings

• Set tidal volume at 4–8 mL/kg predicted body weight (not actual body weight), calculating predicted body weight as: male = 50 + 2.3 × [height (inches) − 60]; female = 45.5 + 2.3 × [height (inches) − 60]. 1, 2

• Maintain plateau pressure ≤30 cmH₂O (ideally <28 cmH₂O) by performing serial end-inspiratory pauses of 0.3–0.5 seconds to confirm lung-protective ventilation and minimize ventilator-induced lung injury. 1, 2

• Monitor and minimize driving pressure (plateau pressure minus PEEP), as values >15 cmH₂O correlate directly with increased mortality. 2

• Target PaO₂ of 70–90 mmHg or SpO₂ of 92–97% to avoid oxygen toxicity while ensuring adequate tissue oxygenation; do not pursue normal-range oxygen levels. 1, 2

PEEP Strategy

• Use higher PEEP without prolonged lung recruitment maneuvers in patients with moderate to severe ARDS, adjusting according to oxygenation response, maximal respiratory system compliance, or highest safe plateau pressure. 1, 2

• Strongly avoid prolonged lung recruitment maneuvers (such as 40 cmH₂O for 40 seconds) in moderate to severe ARDS, as randomized trials demonstrate no mortality benefit and potential hemodynamic harm. 1, 3

• Promptly reassess and reduce PEEP if higher levels worsen oxygenation, dead-space ventilation, compliance, or hemodynamics. 2

Severity-Based Adjunctive Therapies

Severe ARDS (PaO₂/FiO₂ <150 mmHg)

• Implement prone positioning for ≥12 hours daily (ideally 16–20 hours) as soon as PaO₂/FiO₂ falls below 150 mmHg, as this reduces 28-day mortality from approximately 32% to 16% in severe ARDS. 1, 2, 3

• Administer cisatracurium continuous infusion for 48 hours in early severe ARDS to eliminate patient-ventilator dyssynchrony, limit excessive transpulmonary pressures, and potentially reduce mortality compared with deep sedation alone. 1, 2, 3

• Discontinue neuromuscular blockade after 48 hours (or sooner if rapid improvement occurs) to limit ICU-acquired weakness and myopathy, especially when systemic corticosteroids are also used. 2

• Use corticosteroids when initiated early in the disease course for moderate-to-severe ARDS, as this may reduce mortality; however, avoid high-dose or pulse-dose steroids, which do not improve survival and are associated with significant long-term muscle weakness. 1, 2

Mild-to-Moderate ARDS

• Do not routinely apply prone positioning or neuromuscular blockade in mild-to-moderate ARDS, as these interventions are reserved for severe disease (PaO₂/FiO₂ <150 mmHg). 2

• Consider high-flow nasal cannula (HFNC) at 30–40 L/min with FiO₂ 50–60% only in mild ARDS with close ICU monitoring, but proceed to early intubation in a controlled setting if deterioration occurs within 1 hour, as failure rates are high in moderate-to-severe cases. 3

Fluid and Hemodynamic Management

• Implement conservative fluid management strategy after hemodynamic stabilization, aiming for negative fluid balance to lessen pulmonary edema, improve lung mechanics, and reduce mortality. 2, 3

• Monitor right ventricular function with echocardiography to detect acute cor pulmonale, which occurs in 20–25% of ARDS patients and can be exacerbated by high PEEP or excessive fluid administration. 2

Rescue Therapy for Refractory Severe ARDS

• Consider venovenous ECMO (VV-ECMO) in selected patients with severe ARDS after optimizing lung-protective ventilation, prone positioning, and neuromuscular blockade if PaO₂/FiO₂ remains <70 mmHg for ≥3 hours or <100 mmHg for ≥6 hours. 1, 2, 3

• Transfer patients meeting ECMO criteria to centers with ECMO expertise, as such transfer is associated with reduced mortality in carefully selected severe ARDS cases; VV-ECMO probably decreases mortality and increases ventilator-free days in severe ARDS. 2

• Do not use high-frequency oscillatory ventilation (HFOV) routinely, as randomized trials demonstrate no mortality benefit and a trend toward harm when applied early; HFOV may be considered only as a last-resort rescue option in the most severe cases (PaO₂/FiO₂ <70 mmHg). 2

• Consider a trial of inhaled pulmonary vasodilators (such as inhaled nitric oxide) as rescue therapy for severe hypoxemia, but discontinue if no rapid improvement in oxygenation occurs; these agents confer short-term oxygenation improvement without proven survival benefit. 2, 4

Sedation and Ventilator Synchrony

• Titrate sedation according to protocols with regular drug interruption to minimize sedative exposure and improve outcomes. 2

• Ensure patient-ventilator synchrony, as even assisted ventilation can induce ventilator-induced lung injury through high tidal volumes and transpulmonary pressures; assess for dyssynchrony continuously. 2

Weaning and Liberation from Mechanical Ventilation

• Perform daily spontaneous breathing trials (SBT) using T-piece, CPAP, or low levels of pressure support ventilation once the patient's condition improves, as this consistently reduces duration of mechanical ventilation. 2, 3

• Use noninvasive ventilation after extubation for patients at high risk for extubation failure to reduce ICU length of stay and mortality. 3

Supportive Care

• Provide stress ulcer prophylaxis and venous thromboembolism prophylaxis in all ARDS patients. 2

• Elevate head of bed ≥30 degrees to reduce aspiration risk. 2

• Initiate early enteral nutrition with formulations containing antioxidants and anti-inflammatory amino acids, which may improve gas exchange. 2

Critical Pitfalls to Avoid

• Never allow tidal volumes to exceed 8 mL/kg predicted body weight when oxygenation is difficult, as this leads to ventilator-induced lung injury and increased mortality. 2

• Do not delay prone positioning in severe ARDS while attempting less effective measures, as this is a critical error that worsens outcomes. 2

• Avoid applying high PEEP indiscriminately without monitoring for adverse hemodynamic effects, reduced compliance, or worsening oxygenation. 2

• Do not use noninvasive ventilation in severe ARDS, as it can delay definitive intubation, increase nosocomial transmission risk, and worsen outcomes. 2