An advanced-practice registered nurse (APRN) is a registered nurse that has obtained education and training beyond that required for general nursing practice. There are four types of APRNs. There are specialists in nursing known as clinical nurse specialists, specialists in medical care known as nurse practitioners, specialists in obstetrics known as certified nurse midwives, and specialists in anesthesia known as certified registered-nurse anesthetists. Thus, the term APRN is really an umbrella term for any registered nurse with education and training beyond that required as a registered nurse which allows for practice at an advanced level. This advanced education and training is generally at the master’s degree level but now increasingly at a doctoral degree level. In all but a few states, APRNs must collaborate with a medical physician (MD or DO) in order to prescribe medication. In Texas, the prescription of medication by an APRN is a delegated function of a medical physician. This means that Dr. Rodriguez’s prescriptive authority is delegated and supervised by a medical physician.