???? REBEL Rundown ????️ Key Points

• ???? Peak vs. Plateau Pressures: PIP reflects total airway resistance and compliance, while Pplat isolates alveolar compliance—elevations in both suggest decreased lung compliance (e.g., ARDS, pulmonary edema, pneumothorax).
• ???? PEEP Protects Alveoli: Maintains alveolar recruitment and prevents collapse; typical range 5–8 cmH₂O, but higher levels may benefit moderate–severe ARDS.
• ️ Driving Pressure (ΔP = Pplat − PEEP): Lower ΔP reduces atelectrauma and improves outcomes; optimize by adjusting PEEP thoughtfully.
• ???? Prevent VILI: Keep Pplat < 30 cmH₂O, use low tidal volumes (6 mL/kg IBW), and monitor for barotrauma, volutrauma, atelectrauma, and biotrauma.
• ???? Evidence-Based Practice: ARDSNet and subsequent trials confirm that lung-protective ventilation—low Vt, limited pressures, and individualized PEEP—improves survival in ARDS.

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???? Introduction

This episode reviews essential ventilator pressures and how to interpret them during ICU rounds.

???? Under Pressure Peak Inspiratory Pressure (PIP)

• Definition: Total pressure required to deliver a breath.
• Reflects: Airway resistance + lung/chest wall compliance.
• Common Causes of ↑ PIP:
  • Mucus plugging
  • Biting the endotracheal tube
  • Kinked tubing or bronchospasm

Plateau Pressure (Pplat)

• Definition: Alveolar pressure measured after an inspiratory hold.
• Reflects: Lung compliance (stiffness of lung tissue).
• When Both PIP & Pplat Are Elevated:
  → Indicates poor compliance (e.g., ARDS, pulmonary edema, pneumothorax).

Positive End-Expiratory Pressure (PEEP)

• Definition: Pressure remaining in airways at end-expiration to prevent alveolar collapse.
• Typical Range: 5–8 cmH₂O but needs to titrated to meet patient requirements 
• Notes:
  • Provides physiologic “glottic” PEEP in intubated patients.
  • Using high PEEP strategy shows mortality benefit only in moderate–severe ARDS in meta-analysis.

Driving Pressure (ΔP)

• Definition: ΔP = Pplat − PEEP.
• Reflects: Pressure needed to keep alveoli open during the respiratory cycle.
• Goal: Lower ΔP → less atelectrauma & improved outcomes.
• Optimize: Increase PEEP to reduce ΔP and alveolar cycling.

???? Interpreting High PIP/High Pplat

• ↑ PIP & ↑ Pplat
  • Interpretation: ↓ Compliance
  • Common Causes: ARDS, pulmonary edema, pleural effusion, pneumothorax
• ↑ PIP & Normal/Low Pplat
  • Interpretation: ↑ Airway Resistance
  • Common Causes: Mucus plug, bronchospasm, tube obstruction or biting

???? Ventilator-Associated Lung Injury (VILI) Barotrauma:

• Mechanism: Excessive airway pressure damages alveoli.
• Prevention: Keep Pplat < 30 cmH₂O.

Volutrauma:

• Mechanism: Overdistension from excessive tidal volumes.
• Prevention: Use low tidal volume ventilation (6 mL/kg ideal body weight).
• ARDSNet trial: 6 mL/kg → lower mortality compared to 12 mL/kg.
• Ideal Body Weight: Based on height and sex, not actual weight.
• Typical patient: Tidal Volume: 6–8 mL/kg IBW
• ARDS: Tidal Volume: 4–6 mL/kg IBW

Atelectrauma:

• Mechanism: Repeated opening/collapse of unstable alveoli.
• Prevention: Optimize PEEP to keep alveoli open and reduce driving pressure.

Biotrauma:

• Mechanism: Inflammatory cascade (↑ IL-6, TNF-α) from mechanical injury.
• Effect: Can trigger systemic inflammation & multiorgan dysfunction.
• Prevention: Minimize all other forms of VILI.

Post Peer Reviewed By: Marco Propersi, DO (Twitter/X: @Marco_propersi), and Mark Ramzy, DO (X: @MRamzyDO)

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The post REBEL Core Cast 147.0–Ventilators Part 5: Key Mechanical Ventilator Pressures & Definitions Made Simple appeared first on REBEL EM - Emergency Medicine Blog.