Key Takeaway:
Adding PEEP to your preoxygenation strategy can improve oxygenation and ventilation—especially in kids and adults with obesity. If you’re still using a nonrebreather mask, it may be time to level up.
Introduction
Preoxygenating a critically ill patient is rarely straightforward. You’re balancing time pressure, limited resources, other resuscitation tasks, and the experience level in the room. But one thing is clear: the better your preoxygenation, the more safe apnea time you gain—and the more protection your patient has from the dangers of hypoxia.
This study builds on that essential truth. Like the recent PREOXI trial, it reinforces a powerful message: PEEP works.When it comes to optimizing patients before intubation, adding PEEP isn’t just a minor adjustment—it may be a game-changing standard of care for your sickest patients who need effective preoxygenation.
What This Study Asked
This crossover randomized trial from Roveri et al. (JAMA Network Open, May 2025) asked a straightforward but high-stakes question: how do different preoxygenation methods compare in their ability to prepare patients for intubation? Specifically, the researchers looked at nonrebreather masks (NRM), bag-valve masks (BVM), and BVM with positive end-expiratory pressure (BVM + PEEP)
How It Was Done
The study was done across three different populations:
- Adults with normal weight
- Adults with overweight or obesity (OW-OB)
- Children aged 6–12
All participants were lung-healthy volunteers.
In a tightly controlled setting, each participant underwent three preoxygenation trials—one with each device—in randomized order. Every session lasted three minutes, used 15 L/min of oxygen, and involved spontaneous breathing without assisted ventilation.
The investigators measured several key outcomes:
- Primary: Expired oxygen concentration (FeO₂)
- Secondary: Ventilation distribution (via EIT), Oxygen Reserve Index (ORI), and time for ORI to return to baseline
They also monitored ventilation in dependent lung regions and changes in oxygenation during and after preoxygenation.
What They Found
1. BVM + PEEP wins on FeO₂:
BVM and BVM + PEEP were significantly more effective than NRMs in raising FeO₂ across all groups. In adults with normal weight, BVM + PEEP even outperformed BVM alone (75.6% vs 72.1%, P = .03).
2. Ventilation improved in dependent lung regions:
Using EIT, the researchers showed that PEEP improved dependent lung ventilation in adults with normal weight and children—likely preventing atelectasis and improving functional residual capacity (FRC).
3. ORI adds another dimension:
Although differences in ORI were less dramatic in healthy adults and kids, BVM + PEEP extended the time before ORI returned to baseline in children and adults with obesity—suggesting a longer safe apnea window.
Why It Matters
This study reinforces what many in emergency medicine already suspect: PEEP improves preoxygenation. While NRMs are still commonly used, especially in prehospital settings, they offer inferior oxygenation and no alveolar recruitment. BVM + PEEP improves both.
That matters most in high-risk patients—like children or those with obesity—where FRC is lower and the risk of desaturation is higher. The fact that PEEP improved both FeO₂ and EIT-measured dependent ventilation shows its potential to reduce hypoxemia and extend safe apnea time.
Study Strengths
- Crossover design with the same participants across all three interventions
- Inclusion of high-risk groups (children, obesity) often excluded from similar trials
- Use of EIT and ORI for deeper physiological insight
Study Weaknesses
- Conducted only in lung-healthy volunteers—not critically ill patients
- Didn’t directly measure safe apnea time
- Results from controlled settings may not translate perfectly to real-world chaos
Practice-Changing Insight?
Yes, for prehospital and ED clinicians still relying on NRMs, this study offers a compelling reason to make BVM + PEEP the default—especially when NIV is not an option. Even modest PEEP (5–8 cm H₂O) makes a measurable difference.
That said, these were healthy volunteers in a controlled setting. We still need real-world studies in critically ill patients. And the big missing piece? Safe apnea time wasn’t directly measured—arguably the most clinically relevant metric.
My Thoughts
If you want to optimize preoxygenation, nonrebreather masks (NRMs) are simple—but not optimal. This study reinforces what many clinicians already suspect: adding PEEP makes a meaningful difference. Compared to NRMs, preoxygenation with BVM plus PEEP improved expired oxygen concentration (FeO₂), enhanced ventilation in dependent lung regions, and extended the time before desaturation, especially in children and adults with obesity.
These physiologic advantages echo the findings from the PREOXI trial (2023), which showed that noninvasive ventilation (NIV) reduced peri-intubation hypoxemia more effectively than facemasks alone in critically ill adults. But in many settings—especially prehospital or resource-limited environments—NIV isn’t always an option.
That’s where BVM + PEEP comes in.
It’s a practical, scalable alternative when NIV isn’t available, and this study gives us the physiologic data to back that up. For patients at high risk of desaturation, especially those with reduced FRC like pediatric and obese populations, it’s likely time to move beyond NRMs as the default.
Bottom Line
When time is tight and oxygen is dropping, the right preoxygenation method could buy you critical seconds.
“This crossover randomized clinical trial underscores the inferiority of NRM for preoxygenation and demonstrates significantly lower FeO₂ levels compared with both BVM and BVM plus PEEP.”
— Roveri et al., JAMA Network Open, 2025
