You sound like you agree with the author, but what conclusion would someone come to after reading this section? This supposed "voice of authority" says that in his career, he has seen only one person survive, and that person didn't actually have any cardiac problems, but his heart stopped due to an oxygen shortage.
Words have meaning. If this supposed doctor didn't mean to say CPR is worthless, what exactly do YOU think he meant to say? Substitute any other activity in there for CPR, and the meaning is evident.
You seem to be trying to extract a meaning from a part of the essay, that a complete reading of the essay does not say.
In the hospital setting I can tell you that the one's we do CPR on....very few leave the hospital. Most die. Period.
CPR has nothing to do with Dyalisis