Here is my interpretation of standing orders vs prns.
We used to have standing orders for every physician in our hospital. If a pt was admitted to Dr. J, and at hs wanted a sleeping pill but didn't have one ordered, I could go to the standing order book, look up Dr. J, and see if he had standing orders for a sleeping pill. I could then write in the chart "Ambien, 5mg qhs prn/Per Dr J's standing orders/Bluegrass, RN".
At our facility (and I'm assuming most others), this has been discontinued. In it's place are PRN orders. The physician has to specifically order prns. If the pt is admitted, no orders for a sleeping pill have been written, and the pt wants one, I still have to call Dr J and ask for the sleeper. If a doctor writes "Dr. J's prns" then whatever is on the prn list, I can give.
There are also "protocols" which can be like standing orders, and are approved for use throughout the facility. They are developed by a committee in the facility, and are facility specific. They are NOT developed by the physicians exclusively, and they don't vary by physician. For example, we have a chest pain protocol. If one of my pts has chest pain, I can apply O2, draw an initial cardiac marker, get and EKG, and apply tele, without having a physician specifically write for that. It's in the protocol. If I do those things, then I write in the order section: "O2 at 2L, stat EKG, stat cardiac marker/per chest pain protocol/Bluegrass, RN"
Standing orders: Developed by each physician. Nurse can write for the standing orders. Apply to each pt of that physician.
PRNS: Physician must order the prns. Each practice may have it's own standard prn orders.
Procotols: Developed by the facility, and apply to practice within the facility, regardless of who the physician is.
Does that help?