telephone triage harkens back to the day when a physician's office rn gave advice over the phone to patients after listening to patient describe health concern/worry/problem: did they need immediate appointment, give out general info on how to treat a fever/cut finger/diarrhea etc or schedule future appointment/call in medication refill, etc.
(i fondly remember my pcp's nurse alice filling this role in 1950 and 60's)
with the advent of hmo's in the 80's and large numbers of patients in physician's practices a "gatekeeper" role was established re who /when services could be provided, "authorization" for services/er visit/ hospital admission after hours developed with nurses perfect for filling role due to listening skills and nursing education.
larger health systems got into the act in 1990's re having telephone advice lines where nurses could also schedule patients with specialists...thereby avoiding people going to "the competition". physician practices also went to nursing triage phone lines for after hours call, therefore allowing on-call doc to not be pestered with minor patient calls as hard to work 12-14 hrs then be woken up by answering service multiple times during the night.
software programs were developed that asked range of questions for common illness and depending on callers answers indicate action to be taken. specific protocols are reviewed and signed off on by hmo's or physician groups on how they want conditions treated, when to send patient to er, when to contact pcp. written documentation of call and advice given is kept, most often sent to pcp in automated report q am.
detailed info here:
telehealth: issues for nursing
ce telephone triage / nursing ceu
dialed in: nurses prepare for the future of telephone triage