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CRNA Scope of Practice

Written by Dr. Rieka Yu
Published on January 31, 2024
Research Highlights

Missouri requires Certified Registered Nurse Anesthetists (CRNAs) to work collaboratively or with supervision by a physician.


CRNA and anesthesiologist services have similar clinical outcomes.


The impact of expanding CRNA scope of practice on healthcare access and costs is unclear.

States can opt out of CRNA supervision requirements.

CRNAs are advanced practice registered nurses (APRN) certified as a nurse anesthetist by any certifying body allowed by the Board of Nursing (RSMo 335.016). See our Science Note on APRN Scope of Practice for the practice limitations on all APRNs and healthcare shortages in MO. While APRNs are required to work collaboratively with physicians, CRNAs can provide anesthesia services without collaborative practice arrangements if they are supervised by an anesthesiologist, physician, dentist, or podiatrist (RSMo 334.104).


Originally, to participate in Medicare hospitals and surgery centers were required to have physician supervision of CRNAs, but the decision on this requirement was left to the states in 2001 (Missouri Association of Nurse Anesthetists 2014).

  • States can opt-out of this supervision requirement if the Governor consults with state boards of medicine and nursing regarding the access and quality of anesthesia services and if opting-out is in the best interest of citizens.
  • States’ decision to opt-out must be consistent with state law.
  • Twenty-four states have partially or fully opted out of the supervision requirement.
  • MO has not opted-out of the supervision requirement.


One survey found that CRNAs have unfavorable attitudes towards collaboration (Jones & Fitzpatrick 2009). Role conflict, unclear expectations, and limited scope of practice can affect CRNA job satisfaction and stress. CRNAs that practice independently are more likely to be satisfied with their job.


CRNAs provide similar quality of care with and without supervision.

Nationally, there is no difference in the rate of anesthesia complications or mortality between CRNAs and anesthesiologists (Hogan et al. 2010, Negrusa et al. 2016). States that have opted-out of the CRNA supervision requirement show no difference in mortality rates to those that have not opted-out (Dulisse & Cromwell 2010).


In states that opt-out of supervision requirements (Baird et al. 2020):

  • Anesthesiologists spend more time in the operating room and less time monitoring anesthesia care.
  • There is no change in work hours for anesthesiologists nor in earnings.
  • There is no change in time spent by anesthesiologists supervising CRNAs, but there is an increase in time supervising residents.


Independent CRNA practice has mixed effects on access and cost.

CRNAs are more common in the Midwest and South while anesthesiologists are more common on the West and East Coasts (Liao et al. 2015, Cohen et al. 2020). CRNAs are more likely to serve low income, unemployed, Medicaid eligible, rural, and uninsured populations than anesthesiologists. Medicaid eligible populations and rural counties are more likely to utilize CRNAs more than anesthesiologists (Liao et al. 2015). Staffing models that had predominantly CRNAs were not associated with whether a state opted-out of supervision requirements (Coomer et al. 2019). Small hospitals and rural ambulatory surgical centers were more likely to staff predominantly CRNAs (Coomer et al. 2019).


Nationally, less restrictive scope of practice is correlated to greater access of CRNAs, especially in rural areas (Martsolf et al. 2019). However, one study found that opt-out states did not see a change in the percentage of patients that traveled out of their home zip code, nor the distance traveled for a surgery (Sun et al. 2017). From 2012 to 2019, CRNA employment increased by 25%, but this was not correlated with states that opted-out of supervision requirements (Wilson et al. 2020).


Among three options to increase access to healthcare in rural areas, expanding the scope of practices for CRNAs is the most cost-effective option (Table 1). Other analyses of anesthesia models found that independent CRNA practice has the lowest cost and the greatest revenue for hospitals (Hogan et al. 2010, Lewin Group 2016). Intensive anesthesiologist care is less cost efficient and more likely to need hospital subsidization (Hogan et al. 2010). For common oncological surgeries, personnel are the greatest cost (79% of the total cost) and switching from anesthesiologists to CRNAs can lead to a 13-28% decrease in total costs (French et al. 2016). However, some models also showed that in states that opted out of supervision requirements had higher per patient costs for hospitals and fewer procedures at freestanding outpatient facilities (Schneider et al. 2017).


Table 1. The costs and benefits of different strategies to increase rural healthcare access. This table details how much and where funding would be needed for each policy option and the effects for healthcare users, CRNAs, and physicians. Table adapted from Figueroa et al. 2013.



Baird M, O’Donnell JM, & Martsolf GR. (2020). Effects of opting-out from federal nurse anesthetists’ supervision requirements on anesthesiologists work patterns. Health Services Research. 55, 54-62. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6981044/pdf/HESR-55-54.pdf.

Cohen C, Baird M, Koirola N, Kandrack R, Martsolf G. (2021). The Surgical and Anesthesia Workforce and Provision of Surgical Services in Rural Communities: A Mixed-Methods Examination. 37(1), 45-54. https://onlinelibrary.wiley.com/doi/full/10.1111/jrh.12417.

Coomer NM, Mills A, Beadles C, Gillen E, Chew R, et al. (2019). Anesthesia Staffing Models and Geographic Prevalence Post-Medicare CRNA/Physician Exemption Policy. Nursing Economics. 37(2), 86-91. https://www.proquest.com/openview/3f55b0d94533f910b7c0c1dc5d7202bc/1?pq-origsite=gscholar&cbl=30765.

Dulisse B, & Cromwell J. (2010). No Harm Found When Nurse Anesthetists Work Without Supervision by Physicians. Health Affairs. 29(8), 1469-1475. https://www.healthaffairs.org/doi/10.1377/hlthaff.2008.0966?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub++0pubmed.

Feyereisen SL, Puro N, McConnell W. (2020). Addressing Provider Shortages in Rural America: The Role of State Opt-Out Policy Adoptions in Promoting Hospital Anesthesia Provision. The Journal of Rural Health. 37(4), 684-691. https://onlinelibrary.wiley.com/doi/full/10.1111/jrh.12487.

Figueroa S. (2013). Policy barriers for advanced practice nurses in rural health care. Health Policy and Technology. 2(4), 196-202. https://www.sciencedirect.com/science/article/abs/pii/S2211883713000531.

French KE, Guzman AB, Rubio AC, Frenzel JC, Feeley TW. (2016). Value Based Care and Bundled Payments: Anesthesia Care Costs for Outpatient Oncology Surgery Using Time-Driven Activity-Based Costing. Healthcare. 4(3), 173-180. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5027066/.

Jones TS, & Fitzpatrick JJ. (2009). CRNA-physician collaboration in anesthesia. American Association of Nurse Anesthetists Journal. 77(6), 431-436. https://pubmed.ncbi.nlm.nih.gov/20108729/.

Hogan PF, Seifert RF, Moore CS, & Simonson BE. (2010). 28(3), 159-169. https://static1.squarespace.com/static/587a829ad2b8579268917db7/.

The Lewin Group. (2016). Update of Cost Effectiveness of Anesthesia Providers. https://www.lewin.com/content/dam/Lewin/Resources/AANA-CEA-May2016.pdf.

Liao CJ, Quaraishi JA, & Jordan LM. (2015). Geographical Imbalance of Anesthesia Providers and its Impact On the Uninsured and Vulnerable Populations. Nursing Economics, 33(5), 263-270. https://nysana.memberclicks.net/assets/Advocacy/Updated-Advocacy-Materials/Research-Articles/geographical unbalance.pdf.

Martsolf GR, Baird M, Cohen CC, & Koirala N. (2019). Relationship Between State Policy and Anesthesia Provider Supply in Rural Communities. Medical Care. 57(5), 341-347. https://www.ingentaconnect.com/.

Missouri Association of Nurse Anesthetists. (2014). Opt-out- What does it mean to Missouri CRNAs? https://moana.org/wp-content/uploads/2020/02/Opt-Out-Missouri-What-does-it-Mean_-Covillo-2014.pdf.

Mo Revisor § 334.104. (2023). https://revisor.mo.gov/main/OneSection.aspx?section=334.104&bid=54241&hl=.

Schneider JE, Ohsfeldt R, Li P, Miller TR, & Scheibling C. (2017). Assessing the impact of state “opt-out” policy on access to and costs of surgeries and other procedures requiring anesthesia services. Health Economics Review. 7(10). https://healtheconomicsreview.biomedcentral.com/articles/10.1186/s13561-017-0146-6.

Mo Revisor § 335.016. (2023). https://revisor.mo.gov/main/OneSection.aspx?section=335.016&bid=53852&hl=.

Negrusa B, Hogan PF, Warner JT, Schroeder CH, & Pang B. (2016). Scope of Practice Laws and Anesthesia Complications. Medical Care. 54(10), 913-920. https://www.jstor.org/stable/pdf/26418238.pdf.

Negrusa S, Hogan P, Jordan L, Hoyem R, Cintina I, Zhou M, Pereira A, Quraishi J. (2021). Work patterns, socio-demographic characteristics and job satisfaction of the CRNA workforce – Findings from the 2019 AANA survey of CRNAs. Nursing Outlooks, 69(3), 370-379. https://www.sciencedirect.com/science/article/abs/pii/S0029655420307193

Sun EC, Dexter F, Miller TR, & Baker LC. (2017). “Opt Out” and Access to Anesthesia Care for Elective and Urgent Surgeries among U.S. Medicare Beneficiaries. Anesthesiology. 126(3), 461-471. https://pubmed.ncbi.nlm.nih.gov/28106610/.


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