What are the etiologies of high peak and plateau airway pressures and what are the best ventilator (vent) management strategies?

Etiologies and Management of High Peak and Plateau Airway Pressures

The most effective approach to managing high airway pressures is to identify the specific cause and implement targeted interventions, with the primary goal of reducing plateau pressures below 30 cmH2O to minimize ventilator-induced lung injury and improve mortality outcomes. 1

Understanding Airway Pressures

Peak vs. Plateau Pressure

• Peak pressure: Reflects resistance to airflow in the airways
• Plateau pressure: Reflects lung and chest wall compliance (elasticity)

Etiologies of High Airway Pressures

High Peak and Normal Plateau Pressure (Increased Airway Resistance)

• Bronchospasm/asthma/COPD: Airway narrowing due to smooth muscle contraction
• Secretions/mucus plugging: Physical obstruction of airways
• Endotracheal tube issues:
  • Kinking or compression
  • Small diameter tube
  • Tube obstruction by secretions or patient biting
  • Tube malposition (endobronchial intubation)
• Circuit problems:
  • Kinked tubing
  • Water in the circuit
  • Obstructed expiratory filter

High Peak and High Plateau Pressure (Decreased Compliance)

• Pulmonary causes (decreased lung compliance):
  • ARDS
  • Pulmonary edema
  • Pneumonia
  • Atelectasis
  • Pulmonary fibrosis
  • Pneumothorax
  • Auto-PEEP/dynamic hyperinflation
• Extrapulmonary causes (decreased chest wall compliance):
  • Obesity
  • Abdominal distension/ascites
  • Chest wall deformity
  • Pleural effusion
  • Circumferential chest burns
  • Patient-ventilator dyssynchrony 2

Management Strategies

General Approach

1. Identify the cause: Differentiate between high resistance (high peak, normal plateau) vs. low compliance (high peak, high plateau)
2. Target plateau pressure: Maintain plateau pressure <30 cmH2O to reduce mortality 1

For High Resistance Problems (High Peak, Normal Plateau)

1. Inspect the circuit and ET tube:

   • Check for kinks, water, or obstructions
   • Suction the ET tube if secretions are suspected

2. Treat bronchospasm:

   • Administer bronchodilators
   • Consider inhaled anesthetics in life-threatening asthma 1

3. Adjust ventilator settings:

   • Decrease inspiratory flow rate
   • Increase inspiratory time
   • Consider changing to pressure-controlled ventilation

For Low Compliance Problems (High Peak, High Plateau)

1. Reduce tidal volume:

   • Use low tidal volume strategy (4-8 mL/kg predicted body weight) 1
   • Consider further reduction to as low as 4 mL/kg if plateau pressure remains >30 cmH2O 1

2. Optimize PEEP:

   • Use higher PEEP strategy (>10 cmH2O) for moderate-severe ARDS 1
   • For obstructive diseases, set PEEP to counterbalance intrinsic PEEP but not exceed it 1
   • For restrictive diseases, higher PEEP may improve recruitment and compliance 1

3. Adjust respiratory rate and I:E ratio:

   • For obstructive diseases: Lower respiratory rate (10-15 breaths/min) and longer expiratory time (I:E ratio 1:2-1:4) 1
   • For restrictive diseases: Higher respiratory rate (15-25 breaths/min) with I:E ratio 1:1-1:2 1

4. Consider permissive hypercapnia:

   • Accept pH >7.2 to avoid barotrauma 1
   • Monitor for cerebral vasodilation and myocardial depression

5. Advanced strategies for refractory cases:

   • Neuromuscular blockade for 48 hours in moderate-severe ARDS 1
   • Prone positioning for 12-16 hours in moderate-severe ARDS 1
   • Recruitment maneuvers for refractory hypoxemia 1
   • Consider ECMO in severe cases with refractory hypoxemia 1, 3

For Auto-PEEP/Dynamic Hyperinflation

1. Ventilator adjustments:

   • Decrease respiratory rate
   • Increase expiratory time
   • Reduce tidal volume
   • Consider external PEEP (set at 80-90% of intrinsic PEEP) 1

2. Disconnect from ventilator briefly if severe cardiovascular compromise occurs 1

Special Considerations

Asthma/COPD

• Prioritize longer expiratory times to prevent air trapping 4
• Consider permissive hypercapnia to avoid barotrauma
• Monitor for pneumothorax, which is more common in these patients 5

Neuromuscular Disease/Chest Wall Deformity

• Lower inflation pressures (10-15 cmH2O) often sufficient for adequate tidal volumes 1
• Higher PEEP may be needed for chest wall deformity due to reduced chest wall compliance 1

COVID-19

• Follow ARDS protocols with low tidal volumes and plateau pressure <30 cmH2O 1
• Higher PEEP strategy for moderate-severe ARDS 1
• Consider prone positioning and neuromuscular blockade for refractory cases 1

Monitoring and Troubleshooting

• Regularly check plateau pressure (end-inspiratory hold)
• Assess for auto-PEEP (end-expiratory hold)
• Monitor patient-ventilator synchrony
• Use the "DOPE" mnemonic for acute deterioration: Displacement of tube, Obstruction, Pneumothorax, Equipment failure 1

By systematically identifying the cause of high airway pressures and implementing targeted interventions, clinicians can optimize ventilator management, reduce the risk of ventilator-induced lung injury, and improve patient outcomes.