The Difference Between CRNAs and AAs

For those who are considering a career in the field of anesthesia, or for patients who are interested in learning more about their anesthesia care providers, a common question that often arises is, what is the difference between a CRNA and an AA?


A Certified Registered Nurse Anesthetist (CRNA) is an Advanced Practice Registered Nurse (APRN), who has acquired a graduate-level education and board certification in anesthesia. CRNAs have the ability to practice independently, or under the medical direction of an anesthesiologist or other physicians. CRNAs are the sole anesthesia providers in most rural hospitals in the United States, and they are the main provider of anesthesia to those serving in the U.S. Armed Forces.

An Anesthesiologist Assistant (AA) is non-physician anesthesia provider, who must acquire a graduate-level education and clinical training that qualifies them to work in co-operation with an anesthesiologist. An Anesthesiologist Assistant is required by law to work only under the medical direction and supervision of an anesthesiologist. A majority of states in America do not allow Anesthesiologist Assistants to practice, however, for the states that do, Anesthesiologist Assistants can work in hospitals and clinics, helping to provide anesthesia care under the supervision of an anesthesiologist.


Nurse Anesthetists are the oldest nurse specialty group in the United States, and Nurse Anesthetists have been providing anesthesia care in the United States for 150 years. Historical records show American nurses were administering anesthesia during the American Civil War in 1861 to 1865.

Prior to 1976, CRNAs in the United States received bachelor’s degrees in Nurse Anesthesia, a diploma, or a certificate. In 1976, the Council on Accreditation began developing requirements for CRNA degree programs. In 1982, the American Association of Nurse Anesthetists took the official position that all registered nurses will be baccalaureate prepared and then attend a master’s level anesthesia program.

Currently, the American Association of Colleges of Nursing has endorsed a position to move the current entry level of training for Nurse Anesthetists in the United States to the Doctor of Nursing Practice (DNP) or Doctor of Nurse Anesthesia Practice (DNAP). This will affect all advance practice nurses, with a mandatory implementation by the year 2015. In 2007, The American Association of Nurse Anesthetists announced its support of this advanced clinical degree as an entry level for all Nurse Anesthetists. Several Nurse Anesthesia programs in the United States are currently offering the (soon to be) required Doctorate level education format (DNP or DNAP programs) for students.

The Anesthesiologist Assistant position was created in the mid-1960s, when a group of physicians designed a new educational program to train non-physician anesthesia providers, who would be called Anesthesiologist Assistants. The two stated goals of their new educational program were:

1. Train a non-physician anesthesia provider with a premedical background, so that the individual may be better eligible for a transition into medical school later in their career.

2. Ensure that the new anesthesia professional would always remain under the supervision of an anesthesiologist.

The first AA training programs formed at Emory University in 1969, and today the two original goals of the program are still upheld.


The educational, training, and medical experience requirements needed to become an AA or a CRNA are very different.

To become a Nurse Anesthetists:

1. The individual must first complete a Bachelor of Science in Nursing (most common), or another qualifying bachelor degree.

2. The individual must become a licensed registered nurse in the United States.

3. The individual is required to have a minimum of 1 to 2 years of full-time nursing experience in an a medical intensive care unit or surgical intensive care unit, working with critically ill patents.

4. The individual must complete a Master’s degree from an accredited program. (Currently, the American Association of Colleges of Nursing has endorsed a position to move the current entry level of training for Nurse Anesthetists in the United States to the Doctor of Nursing Practice (DNP) or Doctor of Nurse Anesthesia Practice (DNAP). This will affect all advance practice nurses, with a mandatory implementation by the year 2015.)

Program length is typically 28-36 months in duration. The didactic curricula of Nurse Anesthesia programs are governed by the Council on Accreditation (COA) standards and provide students with the scientific, clinical, and professional foundation upon which to build a safe clinical practice. Many programs will additionally require study in methods of scientific inquiry and statistics, and an active participation in student-generated and faculty-sponsored research. The clinical portion of Nurse Anesthesia programs provide supervised experiences for students during which time they are able to learn anesthesia techniques, test theory, and apply knowledge to clinical problems. During the clinical portion of the program, students gain experience with patients of all ages who require medical, surgical, obstetrical, dental, and pediatric interventions.

To become a Anesthesiologist Assistant:

1. Individuals must complete a bachelor’s degree, which includes the standard required premedical coursework.

2. Individuals are required to obtain eight hours of documented anesthesia exposure by observation in the operating room.

3. Individual’s must obtain a Masters degree from one of ten available Anesthesiologist Assistant programs in the United States.

AA program lengths will range from 24 to 28 months, and will involve a didactic and clinical instruction. The didactic training includes courses such as physiology, pharmacology, airway management, simulation laboratory, Basic Life Support (BLS) certification, Pediatric Advanced Life Support (PALS) certification, Advanced Cardiac Life Support (ACLS) certification, anatomy, monitoring, and applied principles and practices. In addition to the didactic portion, programs will include 2000 to 2700 clinical hours per student.


Before becoming a practicing CRNA, all graduates of a Nurse Anesthesia Master’s or Doctoral program will be required to take and pass, The National Certification Exam (NCE), administered by the National Board of Certification & Recertification for Nurse Anesthetists (NBCRNA).

In 2012, the National Board of Certification and Recertification for Nurse Anesthetists adopted a new standard for the recertification of Certified Registered Nurse Anesthetists, known as The Continued Professional Certification Program. This will take effect as of January 1, 2016.

– Nurse Anesthetists are required to rectify every 4 years, with a progress audit for each individual completed every 2 years.

– Nurse Anesthetists must complete 15 assessed Continuing Education units per year, and 10 non-assessed units per year.

– In every 4-year certification cycle, Nurse Anesthetists must complete 4 core competency modules, one in each of the following categories: Airway Management Techniques, Applied Clinical Pharmacology, Human Physiology and Pathophysiology, and Anesthesia Technology.

– Nurse Anesthetists are required to take a recertification examination every 8 years (starting in 2016). Any Nurse Anesthetists who does not meet the passing standard in any major content area of the diagnostic exam is required to complete additional Continuing Education credits in those content areas.

The certifying examination for Anesthesiologist Assistants is administered by the National Board of Medical Examiners (NBME), which is contracted by the National Commission for Certification of Anesthesiologist Assistants (NCCAA). The NCCAA will award certification to each candidate who successfully completes the exam.

To maintain certification, Anesthesiologist Assistants need to complete 40 hours of Continuing Medical Education every 2 years, and complete a Continued Demonstration of Qualifications examination every 6 years.

Scope of Practice

Nurse Anesthetists are allowed to practice in all 50 United States. The scope of practice for CRNAs varies from state to state, and is dependent on the institution in which the CRNA practices. Due to their extensive nursing and critical care background, CRNAs are allowed to practice independently, or together with other CRNAs and/or anesthesiologists in the Anesthesia Care Team model. The degree of independence or supervision by a licensed provider (physician, dentist, or podiatrist) varies with each state’s law. Some states use the term collaboration to define a relationship where the supervising physician provides medical direction for the Nurse Anesthetist. Other states require the consent or order of a physician or other qualified licensed provider to administer the anesthetic. No state requires supervision specifically by an anesthesiologist.

Anesthesiologist Assistants are allowed to practice in 16 states. Anesthesiologist Assistants can only work under the direction of licensed anesthesiologist, as a member of the Anesthesia Care Team. The AA scope of practice may differ slightly in relation to local practice, and is usually defined by the medically directing anesthesiologist, the hospital’s clinical protocol procedures, the state’s board of medicine, and state regulations.

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