REBEL Core Cast 141.0–Ventilators Part 1: Simplifying Mechanical Ventilation — Types of Breathes
Sep 15, 2025
Dive into the fundamentals of mechanical ventilation with an engaging breakdown of the three types of breaths: Control, Assist, and Spontaneous. Discover how each breath type influences patient involvement and care. The discussion also highlights breath delivery methods—Volume vs. Pressure—unpacking their implications for lung compliance. Use fun sports analogies to make these concepts more relatable and easier to grasp, ensuring that even the most complex ventilator modes become manageable!
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question_answer ANECDOTE
Learning Vents By Repeating Numbers
Frank recounts learning ventilator numbers by rote as a resident without understanding their meaning.
That experience motivated him to teach ventilators from first principles to avoid the same confusion.
insights INSIGHT
Three Functional Breath Types
Mechanical ventilation breaths fall into three functional types: control, assist, and spontaneous (supported).
Understanding who starts and finishes each breath clarifies all ventilator modes.
question_answer ANECDOTE
Pull-Up Analogy For Breaths
Frank uses a pull-up trainer analogy to illustrate control, assist, and supported breaths with a relatable gym example.
The trainer fully does the pull-up (control), the trainer finishes after a triggered effort (assist), and bands support the user's effort (supported).
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For many medical residents, the ICU can feel like stepping into a pressure cooker. At the heart of that stress often lies one intimidating machine: the ventilator. Rather than diving headfirst into complex ventilator modes, this episode lays a critical foundation by breaking down the basic building blocks of mechanical ventilation, something every clinician should master before moving on to more advanced concepts. Once you know the 3 types of breaths and how those breaths are delivered, you can more easily understand most of the mechanical ventilator modes.
🧮 The 3 Types of Breaths
To simplify things, we use a pull-up analogy to explain the types of ventilator breaths:
🫁 The 3 Types of Breaths…It's Like
😮💨 Breath Delivery: Volume vs. Pressure
Once you know the type of breath, the next key concept is how it’s delivered:
1. Volume-Targeted Delivery
The ventilator delivers a fixed tidal volume (e.g., 400 mL) with each control or assist breath.
What to monitor:Pressure. As lung compliance worsens, pressure increases.
Risk: Barotrauma if the pressure becomes too high.
2. Pressure-Targeted Delivery
The ventilator delivers air to a preset pressure (e.g., 15 cm H₂O).
What to monitor:Tidal volume. As compliance drops, so does delivered volume.
Adjustment: Modify pressure to maintain appropriate ventilation.
🧱 Putting It All Together: Lung Compliance
The relationship between pressure and volume is described by compliance:
📐 Compliance = Δ Volume / Δ Pressure
In volume mode:
Rising pressure to achieve the same volume = decreased compliance (stiff)
Decreasing pressure to achieve the same volume = increased compliance (loose)
In pressure mode:
Dropping tidal volume at a constant pressure = decreased compliance (stiff)
Rising tidal volume at a constant pressure = increased compliance (loose)
🚨 Clinical Bottom Line
Before tackling advanced ventilator modes, master these foundational concepts:
The three breath types
The two delivery methods
The role of lung compliance
Once you’ve got these down, the rest of mechanical ventilation becomes far easier to understand.
Stay tuned for Part 2, where we’ll build on this foundation and unpack the most commonly used ventilator modes.
Post Peer Reviewed By: Marco Propersi, DO (Twitter/X: @Marco_propersi), and Mark Ramzy, DO (X: @MRamzyDO)