You had your hands full.
Overhearing that you are getting a patient is generally NOT going to be enough to make you legally responsible.
BON's have often taken a position of shared responsibility. IF the Charge Nurse puts a CRITICAL patient in a room and you are not available or notified and this CN just leaves 'em there - I think that it will an IMPOSSIBLE situation for the the CN to be able to escape RESPONSIBILITY - now, will that mean that you are NOT responsible at all?
I think that there may be some internal guidelines (check your facility) - but, if the CN places a patient in a room and this patient is in NEED of CRITICAL INTERVENTION then expecting that this intervention will take place via MAGIC (meaning I'm tied up with another critical patient, off the unit with an ICU admit or committed to recovery of a conscious sedation AND I never actually get report AND get to the patients bedside) will not bring good things to ANYONE.
I had some issues with a CN that would document that I was given report at say 1515 - and I would NOT even be on the unit - I was away with a ICU admit. I returned at 1540 to find a CP in a room, clothed - no EKG, O2, IV, monitor - NADA. Well, my documentation reflected my arrival on unit - how I found patient and no report received from CN at the indicated time. Remainder of documentation of assessment and interventions that were done. Well, this pt had a big MI that was evolving with positive markers and in need of a cath lab. Hmmm...I will be accountable for what I am responsible for - but, I will NOT be placed in a position that can hurt me due to convenience.
Now, if this is a NORMAL patient load for you - I think you may have some serious problems. I see that you are 22 and I suspect that you may only have limited experience - the time to speak up is NOW. I know that it will be difficult. Please don't be offended - but, if this situation is NORMAL you are on a course that will eventually have consequences. BAD ONES.
When I CANNOT accept ANY patient for SAFETY reasons - I will refuse. The problem from the BON's will ONLY take place when you ACCEPT a patient. IF I have multiple other patients with life threats - I will NOT accept another patient - ANY PATIENT. I am ONE nurse (a good one most of the time - but still just ONE!) that can do ONE thing for ONE patient at ONE time. (That does not mean I have just one patient, but I know my limits!)
Now, will my "refusal" of a patient create a problem? Yep - probably. But, it will be an administration problem - not a problem where I am wanton or neglectful. It will not be a liability problem that I own. And I will not have the problem of facing a distraught family when something does not go right.
I encourage you to address this (in writing if necessary to protect you!) with ED admin and nursing admin. Wow, this is not a new issue - but, most facilities will push you as far as you let them - and if they are without staffing (as you note) on a regular basis then they are playing Russian Roulette with patients lives AND your license/livelihood. The one thing I know for certain about Russian Roulette is that there is a near CERTAIN fatal outcome if you play it long enough. For your sake - STOP now!
I think you MAY have some ammo with some internal policies regarding conscious sedation recovery (RN's have to generally be dedicated - not an additional patient load - due to risk of CS patient airway compromise) and critical patients/ICU admissions. Most facilities have written policies - and when they violate these - safety for patients IS compromised. You likely signed receipt and did competencies for these policies - so if you don't follow 'em - the facility could push it ALL back to you. Not a good situation. Think it over. Check it out. Protect yourself and your patients. Also, JCAHO can and does cite facilities that violate their own standards - anyone can report the "problems".