It seems that his heart was beating, although irregularly to a degree that they couldn't detect a pulse. Is the article saying that estimating the CO2 output via this new method is a more modern / sensitive way of detecting a pulse?
> Is the article saying that estimating the CO2 output via this new method is a more modern / sensitive way of detecting a pulse?
No, it has nothing at all to do with a pulse. It has to do with a much better indicator: blood flow through organs.
The goal of compressions in CPR is to keep blood flowing so organs (especially the brain) can get "fresh" (oxygen-rich) blood and get rid of their CO2 buildup. Because blood "naturally" goes through the gas exchange of the lungs during its travels, CO2 output is a very good indicator of blood circulating correctly, and therefore internal organs having a chance.
As long as the CO2 output is good, the brain (and other organs, but mainly the brain) can be considered protected (alive) and the patient can be saved if whatever went wrong is fixed (generally the heart restarted or arrhythmia managed)
The problem of checking the pulse is that it's a very bad indicator of whether your compressions are working: it does not indicate anything about them, it just tells you if the heart is beating strong enough to generate a pulse. Even though CPR might be keeping the patient alive with a stopped heart.
No, it detects the release of CO_2 from the blood to the pulmonary alveoli.
Presence of CO_2 in the alveoli signs the presence of a blood flow, regardless of the nature of the pump (heart vs CPR).
If the blood flows, the organs (including the brain, which is the most sensitive to oxygen deprivation) are properly fed and viable (assuming CPR started soon enough).
Indeed, the valves must be in working order, and there must be enough blood in the vessels to close the circuit and prime the pump. I don't know if it was confirmed, but while I was a student, there were strong suspicions that blood in the whole thorax (pulmonary circulation), not only in the heart, contributed to the assisted flow.
Another fun fact: CPR is more efficient if you use a plunger to perform the chest compressions, because you can push and pull it, thus not only pumping blood out of the heart (through the arteries), but also actively sucking it back in (from the veins).
As a consequence, at the end of a cycle, there is more blood in the chest to be pumped out on the next one.
the most common phenomena that leads to that kind of heart activity without any actual pumping result is a ventricular fibrillation, which looks like this: http://www.ecglibrary.com/ecgs/VFNORWCH.gif, compared to a regular rhythm looking like http://www.grundkurs-ekg.de/definition/ekg1_neu.jpg. This is ( likely ) the underlying problem. What's described here is the fact that the medical personel was able to determine whether their actions ( CPR ) where effective enough to maintain blood circulation. there are, of course other metrics, like o2-saturation levels etc, but this one seems to be especially suitable.
One note aside, it's not uncommon for a resuscitation to go on for 1 or even 2 hours, it depends on the circumstances, the patient, the medical situation and most importantly, the timespan that elapsed before cpr was first administered, which was obviously quite fast in this example.
