What is plateau pressure?

Plateau Pressure in Mechanical Ventilation

Plateau pressure is the pressure measured in the airway during an end-inspiratory pause when there is no airflow, representing the alveolar pressure at the end of inspiration, and should be maintained below 30 cmH2O to prevent ventilator-induced lung injury.

Definition and Measurement

Plateau pressure is a critical parameter in mechanical ventilation that:

• Represents the static pressure in the alveoli at the end of inspiration
• Is measured during an inspiratory hold maneuver (when flow is temporarily stopped)
• Reflects the distending pressure across the lung and chest wall
• Serves as an important safety parameter to prevent barotrauma

To measure plateau pressure:

• Set an inspiratory pause/hold of approximately 0.5 seconds
• Observe the pressure value displayed during this pause
• A plateau is defined when there is minimal change in the measured pressure (less than 2% change over 100 ms) 1

Clinical Significance and Target Values

The importance of plateau pressure monitoring is well-established in critical care:

• Target value: Keep plateau pressure ≤30 cmH2O in patients with ARDS 1
• This target is based on strong evidence showing decreased mortality when plateau pressures are limited 1
• The largest trial of volume and pressure-limited ventilation showed an absolute 9% decrease in mortality in ARDS patients ventilated with lower plateau pressures 1
• In pediatric patients, recommendations suggest limiting plateau pressure to ≤28 cmH2O, or ≤29-32 cmH2O in cases with increased chest wall elastance 1

Relationship to Ventilator-Induced Lung Injury

High plateau pressures are associated with:

• Barotrauma (pneumothorax, pneumomediastinum)
• Volutrauma (overdistension of alveoli)
• Biotrauma (inflammatory response)
• Right ventricular dysfunction and acute cor pulmonale 2

Research shows that mortality rates increase significantly with higher plateau pressures:

• 30% mortality when plateau pressure <27 cmH2O
• 42% mortality when plateau pressure 27-35 cmH2O
• 80% mortality when plateau pressure >35 cmH2O 2

Adjusting Ventilation to Control Plateau Pressure

When plateau pressure exceeds target values:

1. Reduce tidal volume first (can go as low as 4 mL/kg PBW if necessary) 1
2. Ensure appropriate PEEP settings based on disease severity 3
3. Consider permissive hypercapnia if not contraindicated 1
4. Monitor for right ventricular dysfunction using echocardiography 2

Special Considerations

Different patient populations may require adjustments to plateau pressure targets:

• Patients with decreased chest wall compliance (obesity, abdominal compartment syndrome, chest wall deformities) may tolerate higher plateau pressures due to less pressure transmitted to the lungs 4
• Patients with ARDS should have plateau pressures strictly controlled, with some evidence suggesting benefit even with plateau pressures <30 cmH2O 5
• Actively breathing patients may generate higher transalveolar pressures for a given plateau pressure than passively ventilated patients 1

Common Pitfalls in Plateau Pressure Monitoring

• Inadequate inspiratory pause time: Ensure a proper pause of at least 0.5 seconds to obtain accurate measurements 6
• Failing to account for patient effort: Active breathing can affect measurements
• Overlooking the relationship between plateau pressure and driving pressure: Both are important parameters 5
• Not considering chest wall compliance: The same plateau pressure may have different implications depending on chest wall mechanics 1
• Relying solely on plateau pressure: Consider it alongside other parameters like driving pressure (plateau pressure minus PEEP) 5

Plateau pressure remains one of the most important safety parameters in mechanical ventilation, with strong evidence supporting its role in preventing ventilator-induced lung injury and improving patient outcomes.