A nurse's scope of practice depends a lot on your geographical location and what extra training you have over and beyond your BScN. In general, nurses in Canada do quite a lot of invasive "tasks" compared to our colleagues in the US. Nurses in the UK and Australia are even more restricted in what tasks they can do (I'm not certain why).
For example, as a member of the College and Association of Registered Nurses of Alberta (CARNA, a professional body), an RN can do a variety of genertc medical/surgical procedures without a physicians order (e.g inserting a Foley catheter, nasogastric tube, etc.), and even more *with* one.
With further training in critical care and emergency, for example, I cardiovert a lethal dysrhythmias (or transcutaneously pace patients who are symptomatically bradycardic or have long sinus pauses); I perform arterial puncture, give general anesthetics, IV narcotics, keep patients chemically paralyzed (by law, a physician must give the first dose), administer inotropes (titrating to a desire BP parameter), access central IV lines, start peripheral IVs, perform complex wound dressings, help with the insertion of external ventricular drains (EVDs), and much, much more.
Each type of registered nurse has some field of specialization and usually has one or more specialized clinical competencies (SCCs) to complement the same.
I work in the largest teaching hospital in Canada in an environment where RNs, RRTs, MDs, Pharms/Pharm Ds, and PTs form a healthcare team.
Gone are the days when nurses were looked down upon and were not to question physicians' orders!
In the neurosurgical ICU, the intensivist or neurosurgeon writes general orders but the nurses carry them out. ICU nurses perform nearly all of the medical care and need to know how to troubleshoot the technical problems that arise with invasive monitoring equipment and ventilators.
RNs and RRTs (registered respiratory therapists) call and perform the codes, on many occasion before any physician has arrived on-scene. It is a physician's task to pronounce a decedent clinically dead and sign a death certificate.
Some nurses are trained at intubating (the trachea), starting arterial and central lines, giving paralytics (neuromuscular blocking drugs), changing vent parameters on intubated patients (based on arterial blood gas results, ICP, and/or patient tolerance), providing countershock and giving ACLS meds during codes, interpreting 12-lead EKGs (RNs do not diagnose), interpreting lab values, removing staples and sutures, performing a number of sterile procedures, and making specialized infusion solutions.
Nurse Aides (invaluable!) do things like restock bedsides, changing linens, give bedbaths, and other such tasks (at least where I work); LPNs are not permitted to work in ICUs at the hospital I work at.
I love my profession and enjoy helping new nurses and physicians learn how to become efficient team members in a specialized ICU setting.
I tolerate ignorance to a point, and I actually understand it ... trust me, fifteen years ago when I was finishing a science degree, working in a hospital as an orderly to support myself, I could not have imagined I would be an RN.
Fortunately, I am not so ignorant now that I am a nurse. Furthermore, Nurse Practitioners in Neurosurgery, Cardiology, and other areas are further expanding the scope of practice of nurses (in hospitals). An NP I know well works 4 days a week in the operating room, assisting pediatric neurosurgeons. It is amazing what she can do! She's been an NP in peds neurosurgery for a few years now, and the only sheets she folds are her kids' ;-)
Me -- an RN