What are the treatment options for acute respiratory distress syndrome (ARDS) in the absence of a high frequency oscillator?

ARDS Management Without High-Frequency Oscillatory Ventilation

Do not use high-frequency oscillatory ventilation (HFOV) for ARDS—the Surviving Sepsis Campaign explicitly recommends against it based on strong evidence showing no mortality benefit. 1

Core Lung-Protective Ventilation Strategy

Implement these fundamental ventilator settings for all ARDS patients:

• Use tidal volumes of 6 mL/kg predicted body weight (not actual body weight), which reduces mortality compared to higher volumes 1, 2, 3, 4
• Maintain plateau pressures ≤30 cm H₂O to prevent ventilator-induced lung injury 1, 2, 3, 4
• Calculate predicted body weight using height and sex, never actual weight, especially critical in obese patients 2, 3
• Apply PEEP to prevent alveolar collapse at end-expiration 1

PEEP Strategy Based on ARDS Severity

For moderate to severe ARDS (PaO₂/FiO₂ <200):

• Use higher PEEP levels (>10 cm H₂O) rather than lower PEEP 1, 2, 3
• Titrate PEEP upward to optimize oxygenation while monitoring for hemodynamic compromise 3

For mild ARDS:

• Use lower PEEP strategy (<10 cm H₂O) to minimize hemodynamic effects 3

Severe ARDS Management (PaO₂/FiO₂ <150)

When patients have severe hypoxemia, implement this algorithmic approach:

First-Line Intervention: Prone Positioning

• Position patients prone for >12 hours per day if PaO₂/FiO₂ ratio <150 mm Hg 1, 2, 3, 4
• This intervention has strong evidence for mortality reduction 1, 4
• Requires facility experience with prone positioning 1

Second-Line: Neuromuscular Blockade

• Administer cisatracurium for ≤48 hours in patients with PaO₂/FiO₂ <150 mm Hg who have persistent ventilator dyssynchrony 1, 2, 5, 3
• Dosing: 15 mg bolus followed by 37.5 mg/hour continuous infusion 5
• Ensure adequate sedation before initiating to prevent awareness 5
• Discontinue after 48 hours to avoid ICU-acquired weakness and myopathy 5

Third-Line: Recruitment Maneuvers

• Consider recruitment maneuvers in severe refractory hypoxemia 1, 2, 3
• Use judiciously as evidence is weaker (moderate quality) 1

Last Resort: ECMO

• Consider veno-venous ECMO for very severe ARDS with refractory hypoxemia despite maximal conventional therapy 4, 6
• Improves gas exchange and allows lung rest in select cases 6

Fluid Management

Use a conservative fluid strategy for established ARDS without tissue hypoperfusion 1, 2, 3, 4

• Avoid fluid overload which worsens lung edema and gas exchange 3, 6
• This has strong evidence for reducing ventilator days 1

Sedation Strategy

Minimize sedation to the lightest level possible:

• Target Richmond Agitation-Sedation Scale (RASS) of -1 to +1 5
• Use protocolized sedation with specific titration endpoints 1, 2, 5
• Prefer daily sedative interruption or intermittent bolus dosing over continuous infusions 5

Reserve deep sedation only for:

• Patients who cannot achieve lung-protective ventilation with light sedation 5
• Those requiring prone positioning 5
• Persistent ventilator dyssynchrony despite optimized settings 5

Supportive Care Measures

Implement these evidence-based interventions:

• Elevate head of bed 30-45 degrees to prevent ventilator-associated pneumonia 1, 2, 3
• Use spontaneous breathing trials regularly when patients meet weaning criteria (arousable, hemodynamically stable without vasopressors, low ventilatory requirements) 1, 2, 3
• Implement a weaning protocol for all mechanically ventilated patients 1, 2, 3

What NOT to Do

Avoid these interventions that lack benefit or cause harm:

• Do not use high-frequency oscillatory ventilation 1, 2, 3, 4
• Do not use β-2 agonists unless bronchospasm is present 1, 2, 3
• Do not routinely use pulmonary artery catheters 1
• Avoid tidal volumes >8 mL/kg predicted body weight 3, 4
• Do not use inhaled nitric oxide routinely 4

Common Pitfalls

Watch for these errors:

• Using actual body weight instead of predicted body weight for tidal volume calculation leads to excessive volumes and barotrauma 2, 3
• Delaying prone positioning in severe ARDS—implement early when PaO₂/FiO₂ <150 1, 4
• Continuing neuromuscular blockade beyond 48 hours increases weakness risk 5, 6
• Routine deep sedation for all ARDS patients increases ventilator days and mortality 5
• Ignoring plateau pressure monitoring—measure regularly to ensure <30 cm H₂O 1, 3