During CPR, Every Breath Matters
When we ventilate a patient during CPR, we tend to think about oxygenation and CO₂ clearance.
But every breath also affects circulation.
A recent editorial by Lurie explores the physiology behind ventilation during CPR and provides a potential explanation for why continuous oxygen insufflation, such as with the Boussignac device, may actually worsen outcomes.
Think About the Agonal Gasp
The agonal gasp generates negative intrathoracic pressure.
This can increase venous return, improve right-heart filling, reduce intracranial pressure and potentially improve cerebral perfusion.
Effective chest recoil during CPR produces a similar negative intrathoracic pressure.
But what happens when we increase pressure inside the chest?
Excessive ventilation, large tidal volumes, incomplete chest recoil and sustained positive airway pressure can all increase intrathoracic pressure.
The result may be:
↓ Venous return → ↓ cardiac preload → ↑ cerebral venous pressure → ↑ ICP → ↓ coronary and cerebral perfusion
This may help explain why continuous oxygen insufflation devices haven’t produced the outcomes we might expect.
What Does This Mean for Our CPR?
Ventilation during CPR isn’t just about oxygenation.
It’s also about circulation.
Avoid hyperventilation. Avoid excessive tidal volumes. Allow complete chest recoil. And be cautious about interventions that produce sustained positive intrathoracic pressure.
Want the Deep Dive?
How does airway pressure affect venous return, intracranial pressure and cerebral perfusion during CPR—and could the way we ventilate actually influence survival?
