Here's one of my posts from.....somewhere else..... answering a question about the role of PAs in the surgical theatre. Hope this helps:
Your question, although seemingly simple can actually be quite complex to answer given the variable roles and situations encompassing SPA practice. For the most part PAs perform assistant surgeon duties in the OR under the supervision of a surgeon. This can mean either direct or indirect supervision. For example PAs may provide the initial exposure for an operative procedure provided their supervising physician is immediately available and in the OR unit. Also and quite frequently, PAs close the patient without direct supervision, but with the surgeon nearby (ie. PACU, ICU, etc..). Also PAs frequently primarily perform parts of the operation under indirect supervision, meaning that the PA does a part of an operation him/herself without the surgeon, or more frequently while the surgeon is performing other parts of the operation. Examples include when the PA harvests the saphenous vein independently while the thoracic surgeon opens the chest and dissects the internal thoracic artery, or when a PA in orthopedic surgery prepares the tendon graft during an ACL reconstruction independent of the surgeon, or when a PA performs their side of the dissection and ligation of the uterine arteries and ligaments in an abdominal hysterectomy......and on and on. Surgery, perhaps more than any other area of medicine requires a team effort and in particular requires two practioners who are very familiar with the procedure and techniques to efficiently and competently perform an operative procedure. At times the logistics of any operation requires that one person who has the best vantage point or exposure perform the necessary task and many time this is simply a function of which side any one person might be standing on the OR table. So if it is easier for the guy on the left side of the table to get to that bleeder and tie it off, or to dissect the tissue or place the screw or what have you, that person on the left side of the table should be as competent at that task as the other person....this is sort of the crux of having a good "assistant".....really the best assistant is someone the surgeon can trust to do the job he does given that many times the "assistant" is called upon to perform any and all tasks the surgeon does.
The procedures that PA's perform, without direct supervision usually occur outside of the OR and usually in the pre or post-operative phase. These would include insertion/removal of chest tubes, Swan-Ganz catheters, central venous lines, and Intra-aortic Balloon pump. Also many procedures performed by PAs encompass care in an acute care settings such as application of traction devices, closure of lacerations and wounds, reduction of nondisplaced or non-operative fractures and placement of casts/splints etc.. Also many procedures are performed by PAs in a non-acute care setting, like clinics and offices such a removal of skin and subcutaneous lesions, laceration/wound closures, joint injections and aspirations and the list goes on and on........I hope this was helpful and that you get a feel for what PA's do. I feel I must add that although PAs can and do perform many complex and invasive procedures, it should be noted that ultimately they must have some degree of physician supervision, whether indirect or direct, whether actual or implied......by definition PAs are not independent practioners, but that does not mean they don't perform tasks/procedures independently.
Below are links to scope of practice descriptions for PAs in various surgical specialties from the American Association of Surgical Physician Assistants:
http://www.aaspa.com/cts.htm
http://www.aaspa.com/ns.htm
http://www.aaspa.com/os.htm