Not sure what you're talking about.
When they show up in the ED they usually either sign, or because they're so sick, have signed for them, a consent to treat form.. This encompasses most innocuous thing such as lab draws, straight catheterizations, etc. Depending on the situation, we can intrude more e.g. central line, chest tube, ventriculostomy, etc. Until family arrives and indicates wishes.
I had a whole thing written out..
In any case: No, there is not a piece somewhere. For every procedure you intend to do, you have to get informed consent. This means you have to actually talk to the patient, or call the family. Explain the risks and benefits. There is no blanket statement.