To PEEP or not to PEEP? Why This Lung Recruitment Video Changes Everything
At the top of this post is one of my favorite videos of all time.
Seriously, watch it first.
What you’re seeing is an ex vivo rat lung that starts completely de-recruited—collapsed, atelectatic, nonfunctional. Then, with the application of pressure, the lung begins to open.
Alveoli that were closed… recruit.
It’s simple. It’s visual. And it perfectly captures what we’re trying to accomplish every time we put a patient on a ventilator.
Why PEEP Matters
Positive end-expiratory pressure (PEEP) is one of the most fundamental tools we have in mechanical ventilation.
At its core, PEEP prevents alveolar collapse at end expiration. Without it, alveoli repeatedly open and close with each breath, what we call atelectotrauma, which contributes to ventilator-induced lung injury (VILI).
That’s why PEEP is considered standard of care.
In most lung protective ventilation strategies, we:
Start PEEP around 5 cmH₂O
Use low tidal volumes (6–8 mL/kg PBW)
Keep plateau pressures <30 cmH₂O
These strategies aren’t arbitrary—they’re designed to minimize lung injury while maintaining adequate gas exchange.
The Part That’s Less Clear… How Much PEEP?
Here’s where things get interesting.
Despite decades of research, we still don’t have a perfect answer for the “optimal” level of PEEP.
We know:
PEEP improves oxygenation
PEEP can recruit collapsed lung units
PEEP can reduce atelectotrauma
But…
Higher PEEP has not consistently been shown to reduce mortality
Why?
Because PEEP is not universally beneficial.
Not All Lungs Are Recruitable
One of the biggest insights from the literature is this: Not every patient has lung that can be recruited.
Some patients, especially those with severe ARDS, have very little “recruitable lung.” In these cases, increasing PEEP doesn’t open new alveoli…
It just overdistends the ones that are already open.
And that leads to a different form of injury:
Volutrauma
Barotrauma
Hemodynamic compromise
So the same intervention that helps one patient can harm another.
This Is Where Lung Protective Ventilation Comes In
Lung protective ventilation (LPV) is built around one central idea:
Minimize harm while supporting gas exchange
That means balancing competing risks:
Too little PEEP → collapse and atelectotrauma
Too much PEEP → overdistention and barotrauma
And this balance is dynamic.
Modern approaches are shifting away from “one-size-fits-all” ventilation and toward individualized strategies, including:
Assessing recruitability
Using driving pressure
Considering transpulmonary pressure
Incorporating tools like EIT or physiologic markers (PaO₂/FiO₂)
So… Why Aren’t Some People Using PEEP?
This is something I mentioned in the video—and honestly, it still surprises me.
Most providers recognize the importance of PEEP, but when it’s not used, the reasoning often falls into a few categories:
Concern for hemodynamic instability
Fear of barotrauma or high pressures
Misunderstanding of its role in preventing atelectasis
Habit or outdated practices
But completely avoiding PEEP?
That often means accepting ongoing alveolar collapse—and the cycle of injury that comes with it.
What This Video Really Teaches
That lung recruitment video is more than just cool physiology.
It’s a reminder that:
Ventilation is not just about moving air
It’s about managing alveoli
Open them.
Keep them open.
Don’t overdistend them.
That’s the art of mechanical ventilation.
Final Thought
PEEP isn’t just a number on the ventilator.
It’s a tool.
And like any tool, its effectiveness depends on how—and when—you use it.
So the next time you’re adjusting the ventilator, ask yourself:
Am I recruiting lung… or overdistending it?
References:
Slutsky, A. S., & Hudson, L. D. (2006). PEEP or no PEEP—Lung recruitment may be the solution. New England Journal of Medicine, 354(17), 1839–1841. https://doi.org/10.1056/NEJMe068045
NYSORA. (n.d.). Lung protective ventilation. Retrieved April 4, 2026, from https://www.nysora.com/anesthesia/lung-protective-ventilation
