What are the preferred ventilator (vent) settings for Acute Respiratory Distress Syndrome (ARDS)?

Preferred Ventilator Settings for ARDS

For patients with ARDS, a lung-protective ventilation strategy using low tidal volumes of 6 ml/kg predicted body weight (PBW), plateau pressures <30 cmH2O, and appropriate PEEP is strongly recommended as the preferred ventilator setting to reduce mortality. 1

Core Ventilator Settings

Tidal Volume

• Use 6 ml/kg predicted body weight (not actual body weight) for all ARDS patients 1
• Calculate PBW using height and sex, not actual weight 2
• Consider even lower tidal volumes (4-5 ml/kg PBW) in severe ARDS cases, especially when plateau pressures remain elevated 3, 4

Plateau Pressure

• Maintain plateau pressure <30 cmH2O 1
• Monitor driving pressure (plateau pressure minus PEEP) as it may be a better predictor of outcomes than tidal volume or plateau pressure alone 1

PEEP Strategy

• For mild ARDS (PaO2/FiO2 200-300 mmHg): Use lower PEEP strategy (<10 cmH2O) 1
• For moderate to severe ARDS (PaO2/FiO2 <200 mmHg): Use higher PEEP strategy (>10 cmH2O) 1
• Titrate PEEP to optimize oxygenation while monitoring for hemodynamic compromise 1

Additional Ventilator Parameters

• Respiratory rate: Set between 20-35 breaths per minute to maintain pH >7.2 and adequate ventilation 1, 5
• I:E ratio: 1:1 to 1:2 to allow adequate expiratory time and prevent air trapping 1
• FiO2: Titrate to maintain SpO2 92-97% or PaO2 70-90 mmHg 1

Adjunctive Strategies for Severe ARDS

Prone Positioning

• Strongly recommended for patients with severe ARDS (PaO2/FiO2 <150 mmHg) 1
• Implement prone positioning for >12 hours per day 1
• Ensure facility has experience with prone positioning techniques 1

Neuromuscular Blockade

• Consider neuromuscular blocking agents for ≤48 hours in severe ARDS with PaO2/FiO2 <150 mmHg 1
• Use to improve ventilator synchrony and reduce work of breathing 1

Recruitment Maneuvers

• Consider recruitment maneuvers in severe ARDS with refractory hypoxemia 1
• Monitor hemodynamic status during recruitment maneuvers 1

Fluid Management

• Implement conservative fluid strategy for established ARDS without evidence of tissue hypoperfusion 1
• Avoid fluid overload which can worsen lung edema and gas exchange 1

What to Avoid

• High tidal volumes (>8 ml/kg PBW) which increase risk of ventilator-induced lung injury 1
• High-frequency oscillatory ventilation is not recommended in ARDS 1
• Beta-2 agonists for ARDS treatment unless bronchospasm is present 1
• Routine use of pulmonary artery catheter 1

Common Pitfalls and Caveats

• Using actual body weight instead of predicted body weight leads to excessive tidal volumes, especially in obese patients 2
• Failure to recognize that PEEP requirements may differ based on ARDS severity 1
• Inadequate sedation leading to ventilator dyssynchrony and potential for self-inflicted lung injury 1
• Delaying prone positioning in severe ARDS cases 1
• Permissive hypercapnia (pH >7.2) is generally well-tolerated and preferable to increasing tidal volumes 1, 4

Special Considerations

• For obese patients: Still use PBW for tidal volume calculation, not actual weight 2
• For patients with high plateau pressures despite low tidal volumes: Consider extracorporeal CO2 removal if available 3, 4
• Elevate head of bed 30-45 degrees to reduce risk of ventilator-associated pneumonia 1
• Implement a weaning protocol when patients are ready (arousable, hemodynamically stable, low ventilatory requirements) 1