REBEL Core Cast 143.0–Ventilators Part 3: Oxygenation & Ventilation — Mastering the Balance on the Ventilator

Oct 2, 2025

Explore the art of mechanical ventilation with insights on balancing oxygenation and ventilation. Discover why aiming for adequacy over perfection can prevent harm. Learn how Mean Airway Pressure (MAP) truly drives oxygenation, and understand the importance of PEEP in keeping alveoli open. The hosts discuss optimizing tidal volume and respiratory rate while managing patients with obstructive diseases, emphasizing the need for time to exhale. Tune in for practical strategies that transform chaos into calm control at the bedside!

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ADVICE

Aim For Adequate, Not Perfect Support

Provide adequate oxygenation and ventilation rather than chasing perfection that harms the lungs.
Use permissive hypercapnia when appropriate to avoid ventilator-induced injury while treating the underlying cause.

INSIGHT

PEEP Preserves Surface Area For Diffusion

Oxygenation works by diffusion from alveoli into blood down a concentration gradient.
PEEP preserves alveolar surface area so FiO2 actually translates into arterial oxygenation.

INSIGHT

Mean Airway Pressure Drives Oxygenation

Mean airway pressure (MAP) is the true driver of oxygenation beyond FiO2 and PEEP.
Increasing inspiratory time or using modes like APRV raises MAP and improves oxygenation but risks barotrauma.

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🗝️ Key Points

- ❌ Don’t chase perfect numbers: Adequate and safe is often better than “perfect but harmful.”
- 💨 Oxygenation levers: Start with FiO₂ and PEEP, but remember MAP is the true driver.
- 🫁 Ventilation levers: Adjust RR and TV, tailored to underlying physiology.
- 🚫 Watch your obstructive patients: Sometimes less RR is more.

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📝 Introduction

When you take the airway, you take the wheel and you now control the patient’s oxygenation and ventilation. In this REBEL Crit episode, Dr. Lodeserto and Dr. Acker walk through the physiology, ventilator strategies, and clinical curveballs that separate calm control from chaos at the bedside.

️ The Two Pillars of Vent Management

1. Oxygenation — Getting O₂ In

Primary levers: FiO₂ (fraction of inspired oxygen) and PEEP (positive end-expiratory pressure).
Real driver: Mean Airway Pressure (MAP) : the average pressure applied to the lungs across the entire respiratory cycle.
Key physiology:
- Oxygen enters blood by diffusion down a concentration gradient.
- Adequate alveolar surface area is critical → PEEP keeps alveoli open, prevents collapse/reopen injury, and ensures FiO₂ delivery actually translates into effective oxygenation.
MAP analogy: Just as mean arterial pressure drives perfusion, mean airway pressure drives oxygenation. Prolonged inspiratory time or sustained pressure (e.g., APRV, inverse I:E) can raise MAP.
Risks: Excessive pressure/volume can cause barotrauma or volutrauma.

2. Ventilation — Getting CO₂ Out

Primary levers: Tidal Volume (TV) and Respiratory Rate (RR).
Minute Ventilation = RR × TV.
Mechanism: Ventilation removes CO₂ through bulk convection (movement of air in and out).

Disease-specific strategies:

Obstructive Disease (COPD / Asthma)
- RR ↓ to allow more time for exhalation.
- Ensure expiratory flow = inspiratory flow → prevents air trapping.
- If not equal → auto-PEEP → increased intrathoracic pressure → ↓ preload, risk of hypotension, cardiac arrest, or pneumothorax.
Metabolic Acidosis
- RR ↑ to blow off CO₂ and buffer acidosis.
ARDS
- Tidal volume limited to 4–6 mL/kg IBW to minimize ventilator-induced lung injury.
- RR becomes the main adjustment knob.
- Exception: in obstructive lung disease, patients need extra time to exhale (I:E may be 1:4–1:6).

💡 Why This Matters

Ventilator management is part science, part art. Understanding the physiology and knowing when to bend or break the rules helps protect patients from ventilator-induced injury and improves outcomes.

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

Show Notes By: Rubén Tapia-Bucheli, M.D.

👤 Guest Contributors

Rubén Tapia-Bucheli, M.D.

3rd Year Internal Medicine Resident

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

🔎 Your Deep-Dive Starts Here

The post REBEL Core Cast 143.0–Ventilators Part 3: Oxygenation & Ventilation — Mastering the Balance on the Ventilator appeared first on REBEL EM - Emergency Medicine Blog.

REBEL Core Cast 143.0–Ventilators Part 3: Oxygenation & Ventilation — Mastering the Balance on the Ventilator

Aim For Adequate, Not Perfect Support

PEEP Preserves Surface Area For Diffusion

Mean Airway Pressure Drives Oxygenation

🧭 REBEL Rundown

🗝️ Key Points

📝 Introduction

️ The Two Pillars of Vent Management

💡 Why This Matters

👤 Guest Contributors

Rubén Tapia-Bucheli, M.D.

🔎 Your Deep-Dive Starts Here

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