You can sue an emergency department doctor. All licensed physicians in Pa. are subject to being held accountable for their conduct if by improper practice they harm a patient.
The limited facts you presernt suggest that your renal problem was causing you to accumutale fluid in your lungs impairing your ability to breath. You should not have been sent home. Lab tests and an assessment of your blood oxygen levels should have been carried out. The doctor was required was required to take a careful history and perform a complete physical exam. Then the doctor should have considered the possible causes for your breathing distress and developed a plan for how the cause of the problem coould be established. This process is known a differential diagnosis.
Whether you have a legitimate malpractice claim depends upon whether you sufferred harm as a consequence of any of the doctor's misconduct. You should consult a lawyer with experience in such matters. You can learn more about whther you have a potential claim at http://www.meyersmedmal.com
As I am not licensed in Pennsylvania, I can only offer you general legal advice. Luckily you went back to the emergency room and obtained an appropriate diagnosis and medical intervention. Without having major damages directly caused by the negligence of the Dr., you may have a situation where it is not economically viable to attempt to try to pursue the Dr.
I would suggest that you contact a personal injury attorney in your area who handles medical malpractice claims and see if he or she believes you have a viable claim worth pursuing.
Yes, you can sue. You will have to weigh the harm you suffered against the cost of bringing a lawsuit. It's terrible that you were in such danger from the missed diagnosis, but you can only seek damages for what actually happened (not what could have happened). If you are unsure of whether you have a case, your best bet is to consult with a medical malpractice attorney. They can give you specific advice after hearing all the facts.
Sign up to receive a 3-part series of useful information and advice about personal injury law.