I have heard on several occasions anecdotally (e.g. [1]) that hands-only CPR can replace the air in the lungs with new air (with more oxygen) due to the mechanical compression of the rib cage. This makes sense to me, but I have been unable to find any mentions of studies, which somewhat surprises me, as I would expect it to be relatively easy to at least some basic level of tests, for example by filling a CPR doll's "lungs" with a different gas and something to measure oxygen. Is anyone aware of studies?

[1] https://www.quora.com/How-can-hands-only-CPR-work-if-you-arent-introducing-new-oxygen-into-the-system

  • Usually, they measure effectivity by survival rate and not by amount of oxygen replaced. As CPR with and without airway and breathing management for untrained first aiders proves to be st least as efficient, the „why“ isn’t as important. I couldn’t find any studies discussing oxygen renewal, but I have found multiple discussing effectivity of CPR with and without rescue breaths. It is also worth pointing out that (at least I was taught) a circulation without oxygen renewal can still provide some residue oxygen to the cells and is always better than no circulation. – Narusan May 9 '18 at 11:28
  • But, as rescue breaths are not recommended for untrained first responders anymore, I strongly suspect that the circulation is strong enough to ensure survival of the patient until paramedics arrive // Paramedics work with larynxtubes or masks, they can administer oxygen directly and endotracheal intubation is the optimum airway support. Because professionals have much better options than rescue breaths, the studies are skewed in that regard, as it only shows the level of survivability at the current skill level of first responders. – Narusan May 9 '18 at 11:31
  • From what I had heard/read it was based on survival rates as above, and measurements of O2 saturation stayed higher than expected with hands-only CPR. – DoctorWhom May 10 '18 at 1:31
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    @DoctorWhom - That is what I recall as well. Circulation trumped saturation, so getting that going as quickly as possible had a better outcome than rescue breathing for untrained responders. – JohnP May 10 '18 at 16:28
  • Yes, when I think about it I was interested in the reasons as to why it is more effective in order to better understand how it might change with circumstances (e.g. would a trained responder without a larynx tube handy still be more effective with rescue breaths or not? Is hands-only still more effective if CPR has to continue for long periods of time?) So I would be better served with a more general question, such as "Are there studies of how effective CPR is with and without rescue breaths in different situations?", which I should probably be asking a search engine in the first place. – michaeljt May 10 '18 at 19:14

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