You make good points. But there are people who may not want that sort of thing done for a variety of reasons. In some cases religious objections exist to certain forms of medical treatment. Also in some cases there could be side effects which might prove worse than death. Its a tough call. But I think consent needs to be gotten before going into experimental methods to save someone's life. Those who are share your concerns should carry some kind of card in their wallet that says you authorize any and all measures which might prolong your life.
So, if you (or your significant other or loved one) were brought in on 9/11/01 as one of the WTC survivors, with burns so severe that your clothing was gone and you'd passed out from the pain and shock, your identity was unknown, and you were dying, you'd want the doctors to stand around and wait for you to be identified and for your next of kin or guardian to give permission before they stuffed you in a hyperbaric chamber to try to save your life. Or would you want them to stuff you in the chamber first to try to save your life and ask stupid questions later? I very much think the latter is the case here.
Hyperbaric chambers as immediate treatment for burns were an "investigative medical device" on 9/11/01. And no, it's not like an iron lung - after the treatment time was up, you are removed from the chamber.