A Certified Registered Nurse Anesthetist (CRNA) is a type of advanced practice nurse who administers anesthesia in the United States. CRNAs account for approximately half of the anesthesia providers in the United States and are the main providers (80%) of anesthesia in rural America. Historically, nurse anesthetists have been providing anesthesia care to patients since the American Civil War and the CRNA credential came into existence in 1956. CRNA schools issue a doctorate degree to nurses who have completed a program in anesthesia, which is roughly 3 years in length. Scope of practice and practitioner oversight requirements vary between healthcare facility and state, with 22 states and Guam granting complete autonomy as of 2021. In states that have opted out of supervision, the Joint Commission and CMS recognize CRNAs as licensed independent practitioners. In states requiring supervision, CRNAs have liability separate from supervising practitioners and are able to administer anesthesia independently of physicians, such as anesthesiologists. History American Civil War and the 19th Century Among the first American nurses to provide anesthetics was Catherine S. Lawrence during the American Civil War. It was during the Second Battle of Bull Run in 1863 that she administered chloroform to wounded soldiers who needed emergency operations in the battlefield. Nevertheless, it still took several years for nurses to step forward and formally answer the call to provide anesthesia. Reasons for this delay included lack of training, the non-emergency nature of civilian surgical practice after the war was over, and the paucity of role models and sponsors. However, the wartime concept of nurses providing anesthesia care gradually took root as surgeons trained and encouraged nurses to take on this important role. Catholic nuns played an important role in the training of nurses and also in anesthesia. The earliest recorded nurse to specialize in anesthesia was Sister Mary Bernard Sheridan, a Catholic nun who practiced in 1877 at St. Vincent's Hospital in Erie, Pennsylvania. Her influence spread throughout the Midwest, and many other Catholic nuns who were also nurses began training to administer anesthesia. Nuns of the Third Order of the Hospital Sisters of St Francis from Münster established a community in Springfield, Illinois, and on June 22, 1879, they founded St John's Hospital. At St John's, the administration of chloroform and ether was taught to the nurses by surgeons, and many of the Franciscan Sisters were assigned as anesthetists throughout the Midwest. Nurse anesthesia