Newswise — Park Ridge, Illinois—New research published online in the journal Anesthesiology confirms the quality and safety of anesthesia provided by Certified Registered Nurse Anesthetists (CRNAs) while raising questions about the role and value of anesthesiologist assistants (AAs) in patient care.

The study, titled “Anesthesia Care Team Composition and Surgical Outcomes,” was funded by the American Society of Anesthesiologists.

 “The value of healthcare professionals is measured in different ways, one of which is the safety and quality of the care they provide,” said Bruce Weiner, DNP, MSNA, CRNA, president of the 52,000-member American Association of Nurse Anesthetists (AANA). “But in today’s healthcare system, other measurable factors that are critically important to meeting the growing patient demand for healthcare services are the cost-effectiveness of the provider and the provider’s ability to ensure patients have access to the care they need.”

According to Weiner, eight research studies published since 2000, including the new study in Anesthesiology, have confirmed that CRNAs are safe providers. In 2010, the landmark RTI study published in Health Affairs showed that anesthesia care is equally safe whether it is provided by a CRNA working solo, an anesthesiologist working solo, or a CRNA working with an anesthesiologist. Three other studies have confirmed that CRNAs are the most cost-effective anesthesia option and ensure patients access to anesthesia services for surgery, labor and delivery, trauma stabilization, and pain management in rural and other medically underserved areas of the United States.

 In the study in Anesthesiology, researchers examined national claims data for more than 443,000 Medicare beneficiaries (2004-2011). CRNAs were involved in more than 421,000 of the cases; AAs assisted in fewer than 22,000 cases. While the researchers concluded that CRNAs and AAs are equally safe providers when working with anesthesiologists, they conceded that a major limitation with the study is that it does not take into consideration supervision ratios between provider types.

 “CRNAs are not required by state or federal laws or regulations to be supervised by—or to even work with—an anesthesiologist, while AAs can only work under the supervision of an anesthesiologist,” Weiner said. “But when an anesthesiologist does supervise multiple CRNAs, it is typical for the anesthesiologist to rarely be present in the operating room, or not present at all, because CRNAs are capable of working safely and effectively without anesthesiologists and do so all the time.”

By comparison, an AA functions as an assistant to an anesthesiologist and is dependent upon the anesthesiologist’s supervision and direction. While the laws vary by state, anesthesiologists are limited in the number of AAs they can supervise and must always be immediately available to the AAs.

“On the basis of this admitted limitation of the study, it is ridiculous to conclude that an AA who must be closely supervised by an anesthesiologist at all times is as safe as a CRNA who doesn’t even need to work with an anesthesiologist, and often does not,” concluded Weiner.  

Access to Care

In the Anesthesiology paper, the researchers observed that CRNAs practice in all 50 states plus the District of Columbia. The researchers also note that 17 states have opted out of the federal physician supervision requirement for CRNAs, which means that in those states supervision by any sort of physician is not required.

AAs, on the other hand, have varying degrees of practice in only 16 states plus the District of Columbia, and only under the supervision and direction of an anesthesiologist. In other words, there are more states that allow CRNAs to practice without physician supervision than states that allow AAs to even practice.

 “Given that AAs cannot practice without an anesthesiologist close by, in what possible way can AAs help solve the access to care issue in large medically underserved areas of the United States where anesthesiologists don’t want to set up shop?” asked Weiner. “The answer is, ‘They can’t.’”

 Cost-Effective Care

Among the study’s eight major limitations cited by the researchers is one that raises questions about the impact of AAs on medical costs. Other research (especially “Cost Effectiveness Analysis of Anesthesia Providers,” Nursing Economic$, 2016) has clearly demonstrated that the most cost-effective anesthesia delivery model is a CRNA working solo, while the most expensive model is an anesthesiologist supervising a single CRNA (1 to 1 ratio).

“Given that an AA, whose average compensation is close to that of a CRNA, must work in tandem with an anesthesiologist, who makes nearly two and a half times more than an AA or CRNA, it’s impossible to see how an anesthesiologist/AA care team would be any more cost-effective than an anesthesiologist/CRNA care team.  On the other hand, it’s easy to see why the researchers didn’t delve into the cost issue,” said Weiner.

“The fact of the matter is the anesthesiologist/AA practice model is an extremely expensive option, and as shown in Anesthesiology, does not improve patient safety,” he said. “Compare this with the study results from Health Affairs and Nursing Economic$ and it becomes clear that CRNAs working solo are the safest, most cost-effective anesthesia delivery model, which is exactly what the U.S. healthcare system needs right now and will need in the years ahead.”

About the American Association of Nurse Anesthetists

Founded in 1931 and located in Park Ridge, Ill., and Washington, D.C., the American Association of Nurse Anesthetists (AANA) is the professional organization representing more than 52,000 Certified Registered Nurse Anesthetists (CRNAs) and student registered nurse anesthetists across the United States. As advanced practice registered nurses and anesthesia specialists, CRNAs administer approximately 43 million anesthetics to patients in the United States each year and are the primary providers of anesthesia care in rural America. In some states, CRNAs are the sole anesthesia professionals in nearly 100 percent of rural hospitals. For more information, visit and