Back when I was in the US Air Force, training as a Combat Medic, we had to know Emergency Medicine to a degree, NREMT Registry, as well as Nursing. And this question, while yes: it was US as per your preference, it was also over 20 years ago. That said, when asked this question on our tests, the answer was almost word for word in similarity with an NCBI Bookshelf page I found entitled Good Samaritan Laws - StatPearls - NCBI Bookshelf that is as follows,
"In legal terms, a good Samaritan is anyone who renders aid in an emergency to an injured or ill person. Generally, if the victim is unconscious or unresponsive, a good Samaritan can help them on the grounds of implied consent [emphasis mine]. If the person is conscious and can reasonably respond, a would-be rescuer should ask permission first."
I found this here.
Written by West B, Varacallo M., it continues with explaining that:
"The premise underlying the good Samaritan law traces its origin the ancient biblical parable, ultimately yielding the definition of a good Samaritan as an individual who intervenes to assist another individual without prior notion or responsibility or promise of compensation."(Article Ref #1)
I fear of possibility of citing/quoting too much from this/any one source, but it does mention that
"All 50 states and the District of Columbia have a good Samaritan law, in addition to Federal laws for specific circumstances." "...The details of good Samaritan laws vary by jurisdiction, including who is protected(physicians, emergency medical technicians, and other first responders) from liability and under what circumstances."
As I mentioned above, my fear is directly quoting too much. I can say though that I very highly recommend checking out this page, as it lists numerous examples that are very much what I would consider what you are looking for as far as implied consent, which, for much of this topic in general, there lie intricacies that are pursuant to other countries having differing laws for such good Samaritan scenarios, most of which are under no obligation to treat
any victims of accidents, natural disasters, and the like. I was surprised to learn (from this article) that because of the Opioid Crisis, there are certain cases now whereas before was nearly carved in stone as that which you may not help and still expect to stay under the protection of the Samaritan laws. But since drug overdoses are now the leading cause of accidental death in the US, certain areas have been opened up, if you like, that were before taboo, and according to this abstract, this is the case now in 40 States and the District of Columbia. I have pushed the limit of ways to state something without quoting or outright plagiarism. All I can say is I beg anyone, especially (obviously) the original person who asked this question.
I can also say that--at least in the State in which I live--there is an outright obligation and duty to aid any person clearly in need of some assistance in the form of what would constitute a rescue of sorts. That State is Vermont. Good day, please go easy on me as I just signed up on this specific Exchange mere minutes ago. And, in case the link did not quite work, the site on which this article resides is as follows below. Thanks.
: Garneau WM, Harris DM, Viera AJ. Cross-sectional survey of Good Samaritan behaviour by physicians in North Carolina. BMJ Open. 2016 Mar 10;6(3):e010720. [PMC free article] [PubMed]