To paraphrase myself, since we have been perfecting CPR for about fifty years now, why isn't it perfect?
1. As Z said, sort of, these are dead people we are doing it to. I do not hear the old distinction about clinical versus biological death spoken of anymore. As Magic Max said, there's dead and there's almost dead
2. Personal hypotheses:
a. Many or most so-called successful codes away from a hospital (and some there) didn't need CPR, or only needed it long enough for their homeostatic mechanisims to survive anoxia and kick in again (e.g., electrocution, blunt chest concussion with subsequent arrythmia, asphyxia by exclusion of air, and a few others). I've seen this.
b. As long as there is so much money and clout to be made from CPR, constant but irrelevant-to-clinical outcome revisions will continue, justifying updates and pormpting frequent refreshers and purchase of new training materials. (If CPR is such a universal lifesaver, how come we can't just have the updates, but have to pay significantly for them?).
c. As long as people do not recover from whatever led someone to perform CPR on them, whomever is teaching it is obligated to continue to "improve" it as a matter of due dilgence or be "guilty" of teaching a "faulty" procedure, whether it is or not.
I think I might have some insight on the question.
The first part of the problem is we don't actually know what perfect CPR is. This can be evidenced by the outcome of compression only cpr.
AHA then delved into the resuscitative medicine concept in both ACLS and PALS. Only the American academy of Pediatrics in their NRP course took issue with the AHA and have so far held their ground.
As we learned more about medicine AHA did start research as to how well our intervention of CPR worked. It would seem from the research, (available in a nice book from the AHA for about $80 because book sales is how research is funded) The problem wasn't CPR the problem was the "advanced stuff." Most of it doesn't work and people were neglecting CPR to do it. In response to this an an increase of 20% mortality in cardiac arrest between 2000 and 2005, an effort was made to refocus on CPR and less on the "advanced" stuff. But the world is not filled with people like you and I. It requires breaking the habits of tens of thousands of providers.
CPR throughout history has gone through numerous changes in the effort to make it better. compression ratios, ventilation ratios, the importance of ventilation, compression depth, etc. The AHA has the largest body of compiled research and on going study anywhere. But as with all research some of it is inconclusive, some is poorly reported, and some is set up with bias.
Believe it or not, we know what perfect cpr is, there are some problems. 250 compressions a minute is impossible to maintain any quality not to mention without a professional compressor, most people don't have the physical ability to perform that without going into arrest themselves.
In the short term the body has an oxygen reserve, but what about 6+ minutes later? How do we maintain perfusion pressures and ventilate? What is the perfect medium? Add in the compressions and perfusion pressure, when and how is the most beneficial ratio?
Then the AHA has to get a large body (hundreds) of "experts" to come to a consensus. In the EU they don't like the AHA consensus and use the same body of research to create their own guidlines which look quite different from the AHA.
Look at what the AHA really "credentials" you in. It simply means you have attended the course and demonstrated competency in their procedures. That's what CPR, ACLS, and PALS is. A procedure. No different from starting an IV, intubating, changing dressings, or whatever.
It is the basic guidlines of "resuscitation" that epidemiologically make sense until "reversible causes" can be found. It is not a class designed to make people experts in the subject. After all of my education I would feel like a retard if I could have learned how to bring people back to life following a procedure that can be taught in 16 hours and I can sum all of it up in 342 words. (I know because I made a bet I could summarize ACLS to get people to pass in less than 500 words)
The guidlines are simply what the non expert does, until the expert can be brought to bear. If that were not so, "reversible causes" would be the number one thing on the algorythm, not an afterthought at the bottom of the page. People survive because the cause of the arrest is dealt with, not because anyone flawlessly followed an algorythm. It would be like saying a septic patient should be cured because you flawlessly started an IV and started antibiotics without regard to what antibiotics you were using.
Change must also come slowly. Not because I said so, but because it seems most people don't like radical change. So I expect to see a series of changes over time instead of radical shifts. Look at other medical breakthroughs. We know high concentration O2 is harmful in most cases, we know backboards don't really help, we know capnography is a better indicatior than Spo2, we know about hypothermia therapy, but we still keep doing some and are not so fast to adopt others. Hell we can't even get paramedics in the US to universally interpret a 12 lead EKG, how else do we go about changes the ingrained experiences and habits of the entire US healthcare population?
. I have witnessed the micturation contests between ARC (who has not been in the conversations here) and AHA for decades.