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The American Society of Anesthesiologists is an educational, research and scientific association of physicians organized to raise and maintain the standards of the medical practice of anesthesiology and improve the care of the patient.


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January 1, 2013 Volume 77, Number 1
Developing a Staffing Model: Estimating the Number of Anesthesia Providers Your Group Needs – An Update Amr E. Abouleish, M.D., M.B.A. ASA Committee on Practice Management

In 2001, Dr. Zornow and I co-authored an article on estimating staffing needs and included a downloadable Excel workbook(*) that allowed the reader to begin estimating staffing needs.1 This article is an update and discusses some of the underlying challenges of developing a staffing model.

Anesthesiology groups’ primary day-to-day challenge is to meet their clinical care obligations. Because one cannot hire or fire anesthesiologists, residents, CRNAs or anesthesiologist assistants on a day-to-day basis, it is essential for the group to have estimated correctly the number of each type of provider required. In the last decade, the economic reality for almost all academic departments and the majority of private practice groups is that the clinical revenues do not cover the staffing costs. (The underlying causes are beyond the scope of this article, but may include a stagnate or decreasing conversion factor for Medicare and Medicaid, and the requirement to staff more sites without an equivalent increase in surgical volume.)2 In other words, most anesthesiology groups rely on facility financial support to be able to provide enough staff to cover the needs of that facility. Because the facility is paying for staffing costs, it wants to know that the number of staff determined by the anesthesiology group is correct. Therefore, one will need to be able to present a logical and objective way of determining staff numbers. This article, along with the Excel workbook*, will provide you a framework to developing your staffing model.

Limitations: Several limitations of this article and the Excel workbook* need to be noted. Obviously, your staffing model will be more complex and you will need to adjust the Excel workbook to meet your specific setting. In addition, the information is presented with the underlying principle that anesthesiology is the practice of medicine. Therefore, the discussion is limited to staffing models that utilize anesthesiologist personally-performed care or anesthesia care team (medical direction) or a mixture of the two. The discussion will not examine staffing models that rely on medical supervision (more than four sites per anesthesiologist) or staffing with no anesthesiologist involved. The discussion examines a hypothetical academic anesthesiology department because inclusion of many types of services can be illustrated. Finally, a discussion of a cost-effectiveness analysis, O.R. utilization or scheduling efficiency is beyond the scope of this article.

Staffing Parameters: In order to estimate the staffing needs, you need to have a good understanding of the number of clinical sites staffed daily, the medical direction ratio, the amount of vacation and meeting time allotted per provider, and the amount of non-clinical time for each provider. Further, an estimate of potential new hires and departures should be included.


  • Clinical Services: Usually the clinical obligations are found in the hospital service agreement. If it is not clear, then you are gambling that your understanding is the same as the facility administrator’s understanding at this time or in the future. The most difficult situation for any group is the request (sometimes demand) to cover additional sites in the near future (e.g., tomorrow). Further, you should always reconcile your understanding of clinical obligations with the facility’s staffing plan. That is, you should make sure the number of operating rooms and hours of operations that are staffed by nurses and surgical technicians are the same as the number and hours in your service agreement.
  • Medical Direction Ratio: Although Medicare billing rules allow an anesthesiologist to care for up to four patients concurrently, academic departments are limited to a maximum of two rooms by their accreditation rules.3 Whatever staffing ratio your group uses, the reality is that this ratio will be the “max” and not the median. For instance, in academics, 1:2 is the max, but the median number of faculty per anesthetizing sites is 1:1.7 and can range from 1:1.5-1.9.4 In any staffing plan, there will be a need for an anesthesiologist to cover only one site. For example, the anesthesiologist in charge has administrative duties and usually is assigned less than the maximum rooms. Sometimes the patient requires 1:1 staffing due to medical co-morbidity and/or surgical procedure.
  • Odd Number of Sites: For academic groups, odd number of sites results in inefficiency in staffing ratios. Because academic departments must have sufficient staff to not exceed the 1:2 ratio, running a third room in the evening or on weekends leads to increased staff numbers and costs.
  • Remote Sites: Due to distance, there may be remote sites that preclude the ability to safely medically direct another site and also lead to a need to have a 1:1 staffing ratio. Remote sites often result in inefficiencies from a staffing model perspective.
  • Staffing the Additional Site: In the cases of the odd number of sites, remote site or the additional site, it may be less costly to choose anesthesiologist personally-performed care than medical direction.5
  • Non-clinical Time: For academic departments, the faculty must have some academic time to meet the educational needs for the residency program. But this concept of “non-clinical” time for staffing model is more than just academic time. “Non-clinical” time for a staffing model can be defined as days a provider is not available to work clinically for the group. For private practice anesthesiologists, this would include administrative duties and meetings. For CRNAs, if the CRNA works only four days a week (four 10-hour shifts), then the CRNA is only available four of five days and therefore has one of five days “non-clinical” (clinical FTE = 0.8, non-clinical FTE =0.2). That means that you need 1.2 CRNAs (FTE) to cover five days a week. Similarly, residents who are on rotations outside the department are not available to help the department meet clinical needs. Therefore, away rotations are “non-clinical” time for residents.
  • Time Away: The amount of meeting, vacation and sick leave vary from one group or institution to another, but it must be accounted for in the staffing model. In addition, I favor rounding up on the number of staff gone because “time away” is not a constant, but seasonal. Sick leave is very hard to predict and you truly have to “guess-timate” this number in your staffing model.
  • Late-starting Staff: You may have call staff come in late or have late shift staff. These staff are not available to work in the morning and need to be included in your staffing model, but you need to be prepared to justify why this is a necessity and not a luxury. There are legitimate reasons, including, but not limited to, intensity of call work, the amount of evening work, and inability to provide any breaks due to high O.R. throughput and high staffing ratio.

  • Staffing Model: The downloadable Excel workbook* has instructions on the first worksheet. From those instructions, there are overview steps to developing your staffing model. (As an example, a final model is shown in Tables 1-2.)

    1. List all the current staff and the amount of clinical obligations. That is the clinical and non-clinical FTE. Do this separate for each type of provider. You also can then determine the average clinical FTE (needed in Step 6 below).
    2. List all the clinical services required, both anesthetizing sites and non-anesthetizing sites. Don’t forget preoperative clinic, intensive care units, chronic pain management clinic, and now acute pain management/regional block service.
    3. Fill in the staff required for non-anesthetizing sites.
    4. Fill in the in-house call staff starting later in the day, and late shift staff and post-call staff.
    5. Fill in the staff requirements for anesthetizing sites.
    a. The number of CRNAs or AAs will be dependent on how many residents are available after you account for “away rotations,” call and post-call.
    b. Fill in the staff required for anesthetizing sites that are 1:1.
    c. Fill in the staff required for anesthetizing sites using the maximum staffing ratio.
    d. Extra sites. Because academics use a maximum of 1:2, this extra site is the odd number and represents one site. Now you have to decide if these sites will be a lower than maximum ratio (1:1 for academics) or provide care as M.D.-only (personally performed care). In private practice, this may be 1:2 if the group is using a maximum of 1:3.
    6. Non-clinical FTEs for each type of provider. Since an FTE = clinical FTE + non-clinical FTE, you can estimate the number of non-clinical FTE by knowing the average clinical percent for each type of provider and the total number of clinical FTE. (Percent clinical FTE = [number of clinical FTE]/[number of clinical FTE + number of non-clinical FTE].) *
    7. Estimate the away FTE for each type of provider. Using the time away available for each type of provider, you can estimate the number of staff that “should be” away. For example, if an anesthesiologist has six weeks away (vacation and meeting time) per year, then he/she is away 6/52 or 11 percent of the time. If your staffing model finds that the total number of anesthesiologist FTE (the clinical + non-clinical) is 30, then 11 percent of 30 is 3.3, which would be your estimate for away time. As noted earlier, I favor rounding up (in this case to 4) to help with the seasonal nature of away time. Sick leave is a wild card and very difficult to predict. As a rule of thumb, I use one FTE for every 20-30 FTE.
    8. Sum up clinical, non-clinical and away FTE to determine the number of each type of provider you need.
    9. Compare this number with your current staff, expected hires and expected departures.
    10. Rethink some of the parameters based on the number of staff you have. And start again!

    See? 10 easy steps! Reality check – this article only gets you started in thinking about the staffing model and the number of providers you will need to cover your clinical obligations. Good luck.

    Amr E. Abouleish, M.D., M.B.A. is Professor and the Michael T. Phillips Family Chair, Department of Anesthesiology, University of Texas Medical Branch, Galveston.

    1. Abouleish AE, Zornow MH. Estimating staffing requirements: how many anesthesia providers does our group need? ASA Newsl. 2001;65(8):14-16. Published August, 2001. Accessed November 7, 2012.
    2. Abouleish A, Evenson TB. The fallacy of the field of dreams business plan: a downward trend in anesthesiology productivity. ASA Newsl. 2007;71(12):30-31.
    3. ACGME program requirements for graduate medical education in anesthesiology. Accreditation Council for Graduate Medical Education website. Accessed November, 8, 2012.
    4. Abouleish AE, Prough DS, Barker SJ, Whitten CW, Uchida T, Apfelbaum JL. Organizational factors affect comparisons of clinical productivity of academic anesthesiology departments. Anesth Analg. 2003;96(3):802-812.
    5. Abouleish AE, Stead SW, Cohen NA. Myth or fact?: nurse anesthetists cost less than anesthesiologists. ASA Newsl. 2010;74(12):30-34, 51.