Differences
RSI and DAI or MAI (medically assisted intubation) are terms that can be used semantically or prerogatively. DAI, for example can be used in conversation to describe the generic or general option of using drugs to procure intubation. That is, as an umbrella term. Thus RSI can be defined as one type of drug assisted intubation.
But in the vernacular or parlance of medicine, particularly emergency medicine and EMS, terms are contextual and specific describing separate and differing approaches to solve a clinical problem and it is best to be specific in dialogue with other care givers like ED staff. Terms also carry a certain import as well especially in the area of DAI's. The terms carry information about the patient situation at the outset in the mind of the physician if used appropriately. Using terms carefully adds to accurate information dissemination and contributes to the flow of thought and rhythm of the care provision process. Put another way, it gets everyone thinking along the same lines.
As you know, in EMS only two drug assisted intubation approaches are used - paralytics plus sedation or sedation alone.
So in conversation it is important to separate a semantic exercise from a procedural differentiation using these medical terms of reference. Thus you could correctly attend an ED and at handover tell the physician you carried out a "drug assisted intubation" using sedation or with paralytics.
Much better though to say you carried out an RSI on this head injured patient or alternately sedated and tubed this APO patient. Add the term to its clinical context. The ED doc likely knows exactly what agents you use in your procedures so he can forward plan based upon this information, what the half lives of the drugs are, side effects, how will the drugs you applied affect the patient in the short, medium and long term, did it work well or does he need to do something extra but have to wait for your drugs to wear off etc.
A couple of references.
RSI -
http://www.uptodate.com/patients/content/topic.do?topicKey=~o/U2LmwmnPvk.o
DAI -
http://www.acep.org/practres.aspx?id=29188
Cheers
MM