That's exactly it though. SOAP is more of an umbrella, containing specific things like SAMPLE and OPQRST (which can be used for more than just pain). For Objective, that's your general impression and vitals. Age, Sex, do they look sick? Vitals, plus skin tone/wetness. GCS. RTS. Anything "objective". A would be your differentials, given the information that you have found. P would be what are you going to do about it, your Plan. For EMS, interventions can start as soon as you arrive at the Pt's side, so the P (along with the rest of it) is constantly developing.
I don't believe SOAP should be used as a narrative/algorithm for assessment. It is meant for use of documentation. That said, I think it is just something to keep in mind while documenting, as it is simply too generic. You cannot use SOAP as a specific guide, since you still need to know the other items necessary (as specifically listed before).
I am a huge fan of a word-by-word narrative in the EMS world. Its easy, everyone can read it, and it gets the job done effectively. That said, it is meant for documentation. If that PCR is subpoenaed, the court should be able to visualize the scene without the responder's verbal guidance. That said, it is NOT meant to be used as a handoff report.
Personally (I won't speak for other folks in the ED, but it wouldn't surprise me if they agreed), I often consider a handoff report from EMS like a dispatch. Sometimes you hear everything you could ever want, and that is exactly what you get, or you get the opposite. Or, you get no information at all, and have to start from scratch. In the ED we don't base our care off of an EMS handoff. Hell, we run vitals when the Pt hits the bed, whether or not EMS did in the truck just outside. We do an EKG even when the strip we were given was timed 5 minutes ago. We treat all information provided as evidence, not fact. I think one of the big reasons for this is the big legal thing (at least here in Texas, not sure about other places) about healthcare providers doing their own assessment.
Just to provide an example, lets say the Pt had a seizure while en route. We want the time it started, time it ended, and any interventions, especially medications. The 12 lead was sinus brady? Cool, we're going to do another anyway.
It's kind of like how we as providers do not take anecdotal evidence as fact. For instance, the Pt is diaphoretic. That doesn't mean they are shocky. If you didn't feel the skin to obtain more evidence, you wouldn't have noticed it was warm to the touch with 1 second cap refill.
