REBEL Core Cast 147.0–Ventilators Part 5: Key Mechanical Ventilator Pressures & Definitions Made Simple

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Dec 22, 2025

Delve into the dynamics of mechanical ventilation with a focus on vital pressures. Discover the distinctions between Peak Inspiratory Pressure and Plateau Pressure, and what they reveal about lung compliance. Learn how PEEP is crucial in preventing alveolar collapse, especially in severe ARDS cases. Explore the significance of driving pressure in minimizing lung injury. The experts also uncover how to safeguard against barotrauma and the benefits of low tidal volumes in ventilation strategies. It's a must-listen for anyone in critical care!

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INSIGHT

PIP Versus Plateau Pressure

Peak inspiratory pressure (PIP) equals the total pressure needed to deliver a breath, reflecting airway resistance plus compliance.
Plateau pressure (Pplat) estimates alveolar pressure and is more directly linked to alveolar injury risk.

ADVICE

Use Both Pressures To Localize Problems

If both PIP and Pplat are high, suspect reduced lung compliance (eg, ARDS, pulmonary edema, pneumothorax) and investigate accordingly.
If PIP is high but Pplat is low, look for airway resistance causes like mucus plug, bronchospasm, or tube issues.

INSIGHT

Driving Pressure Links PEEP And Injury

Driving pressure (ΔP = Pplat − PEEP) reflects the pressure needed to distend aerated lung and correlates with outcomes.
Optimizing PEEP can lower ΔP and reduce repetitive alveolar opening and closing.

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🗝️ 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)

👤 Show Notes

Joel Rios Rodriguez, MD

PGY 3 Internal Medicine Resident

Cape Fear Valley Internal Medicine Residency Program Fayetteville NC Aspiring Pulmonary Critical Care Fellow

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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.