I must respectfully disagree with your comment regarding only certified nurses in the ICU. I worked ICU for a long time as a Med/Surg Nurse but was ACLS certified. Many hospitals across the country have Med/Surg RNs working ICU. Some of these patients require them.
You may have an ICU nurse who is accustomed to handling cardiac issues and neurological, vent, etc. but if it's an ortho/surgical patient, there are certain things the ICU nurse may not be use to doing and really may not have time to do, hence the Med/Surg nurse.
I must also disagree with making a scene in an ICU regarding reassessment. You can do that quietly and professionally, without alarming patients and visitors, as you certainly would do otherwise had she done what you suggest.
And it's a nice way to get fired.
I would suggest documenting the facts, leaving out the emotion. Then present it to the Director of Nursing first. If that doesn't resolve it, the Patient Rep. They have a lot of power so don't over-look them.
There are ways to deal with that without catering to drama and unsettling everyone.