Think of it as the same as a regular ER, except it's psych. You will triage, assess, stabilize, administer medications, and either admit them to your inpatient/medical facility, or send them on their happy way. Depending on what facility you're at and/or where it's located, you may also be a receiving unit for those under involuntary holds, so you may also get a chance to meet a wide variety of local law enforcement.
Like regular ERs, the acuity can vary: you have those who walk in because they to have their meds adjusted and want a new script....and then you have those who are having the psych equivalent of a MI. And then there's a whole range in-between.
The nice thing about working in the psych ER is that patients usually stay for 24 hours or less before they're either admitted, transferred or discharged. Occasionally you get a few patients who stay longer for whatever reason, but even those usually don't say more than a few days. Downside? Since the patients turn over so frequently you don't have days to try to build a therapeutic relationship with them: you need to be good at starting the groundwork for it ASAP. You also have to get used to dealing with a whole new set of faces--and lots of them--every day.
Personally, I love it. Some days are mellow, and some days it's like they opened the gates of Hell. Most days are in the middle...the pace is definitely faster than on most psych units, even ICUs.
You will triage & assess, do many more restraints than on an inpatient unit (think of how some of the patient's you receive on the inpatient you must be BEFORE they get to you and are stabilized - very aggressive, hostile, detoxing, etc. - obviously not all pt's, but it can be more chaotic for sure), medicate and admit/transfer/discharge. You will have tons of repeat patients, just like at any emergency department and any psychiatric unit. You will get homeless people who will say they are suicidal or homicidal just to be able to get into a secure location and get food and water. That's what I see a lot of in my ED.
It is exciting and rewarding, but at the same time it's very different than a regular ED. You won't be doing the IV lines, the trauma workups, the EKGs, etc. On occasion, perhaps. But all the skills you use on the regular psychiatric unit incorporated into a fast-pace, triage & assess mode is pretty much what a Psych ED will offer you.
It's a very fast-paced environment. Patients come and go (often time within 3-4 hours). It's admission and discharge all day long. Things can and do get crazy really quickly. For instance, you may start your shift with 3 patients, then while you are in the middle of assessing your second patient, you have an admission to go do. Often time, patients are very psychotic and out-of-control, so you would most likely have to restraint them and give a cocktail. While you're doing all of these, 2 of your assigned patients have orders for transfer or admit to the floor (transfer is the worst because you gotta do it quick before the ambulance arrives to pick up patients). So, there could be many things going on all at once.
If you are the triage nurse, then you control the flow of the whole unit. Many times, I have 2-3 police cases trying to come in one door and 2 or more ambulance cases waiting to come in another. Plus, the regular ED units keep calling trying to transfer their psych patients to my unit. I think the most I have done (as a triage nurse) was 17 admissions in a 12-hour shift. I was dead tired by the end of that.