CPR was invented in Viet Nam, and spread stateside as military docs returned to the world. The American Heart Association began promoting CPR as a public service, and it rapidly turned into a major revenue source for them in providing the trainer certification, workbooks, and all the rest of the stuff that goes along with it. I learned CPR before AHA started the program, and have been duly recertified every couple of years for 3 decades, and the AHA guidelines have changed each time, as they should . AHA guidelines always lag a bit behind the research in CPR, cuz AHA guidelines are approved by a committee, and approval becomes political.
Latest example: 'The "new CPR" — developed at the University of Arizona — has tripled survival rates for cardiac-arrest patients rescued by Phoenix paramedics, a preliminary study shows.
This is the latest in a mounting body of evidence suggesting that the "new CPR" — doing chest compressions only — can save more lives than the old CPR, which includes mouth-to-mouth breathing.
However, the evidence has not persuaded the American Heart Association — the group that issues national guidelines for cardiopulmonary resuscitation — to fully adopt chest-compression-only CPR for victims of sudden cardiac arrest.'
http://www.azstarnet.com/allheadlines/156249.php

The other complicating factor is that is that the research suggests that less than 4% of the patients resuscitated in the field leave the hospital alive. Of those that survive, more tha 14% have moderate to severe brain damage. http://www.ispub.com/ostia/index.php?xmlFilePath=journals/ijrdm/vol4n1/survival.xml

Like most things in life, CPR is complicated. We try to do the right thing. We try to use our skills. We try not to disappoint the family. We try not to be criticized, or sued, by folks who feel that we could have done more. But it is also true that there is a reason that the patient arrested. That reason may (96% of the time) be something that cannot be fixed by medical science. Doing CPR may give them some time to spend with their loved ones, or it may give them a loneger life with permanent brain damage.
We always err on the side of life-honor the do not resuscitate request if your state permits us to do so, but proceed with resuscitation if in doubt. I have participated in resuscitating 95 year old folks with brain cancer-no DNR, no choice. Gotta do it. But also, gotta recognize that, sometimes, resuscitation prolongs death, rather than prolonging life.