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Five Key Anesthesia Metrics

April 20, 2024

BY JODY LOCKE, MA, Vice President of Anesthesia and Pain Practice Management Services, Anesthesia Division, Coronis Health, Jackson, MI

Five years in, the long-term effects of the COVID-19 pandemic are still present in our industry. Ever since the second quarter of 2021—when surgical case volume dropped precipitously—most anesthesia providers have been asking the same two questions: when would things return to normal, and what would normal look like? Now that we are already in 2024, we have a much better perspective on the impact of the pandemic and the state of the specialty.

To identify the most significant trends, we reviewed the data from 12 Coronis Health anesthesia clients from across the country. Practice data for activity from January through October was compiled for 2022 and 2023. Surgical and obstetric data included case counts, units billed, collections and payor mix. Because the intent was to identify trends, the data represented postings by month, based on date of entry (DOE). The sample represented 591,737 surgical and obstetric (OB) cases from 2022 and 637,263 total cases from 2023, which we determined to be meaningful and representative. The objective was to identify trends that would be useful in assessing broad indications and potential concerns. 

Our analysis has focused on five key management metrics that all anesthesia practices should be tracking as they plan for the future. These metrics define the current economic realities of the specialty.

  1. Percentage change in case volume 
  2. Percentage change in acuity of case (units per surgical case) 
  3. Percentage change in DOE collections (OR versus OB) 
  4. Yield per unit (surgical cases) 
  5. Yield per hour 


As a practical matter, it is always useful to distinguish surgical from obstetric activity. There are many compelling reasons for this. Surgical cases typically represent the majority of practice activity and the most significant percentage of practice revenue. Most payer contracts are based on the surgical payment model, where payment represents a per-unit payment for base and time units. Obstetric care is often the most challenging aspect of practice economics. It is not uncommon for the obstetric population to have a much higher rate of Medicaid patients, which usually results in much less revenue per shift. Most practices typically develop two distinct staffing models.

The good news is that most practices experienced a significant increase in overall surgical case volume from 2022 to 2023. As indicated in Table 1, the average growth rate of this sample was eight percent while obstetric case volume remained essentially flat. As Table 1 indicates, some practices experienced a significant growth in surgical volume. While it is true that most hospitals saw an increase in case volume from one year to the next, the bulk of this increase came as a result of the addition of new venues. The largest practices aggressively pursued surgery centers.


While it is true that most anesthesia providers tend to measure their production in cases performed, this is not exactly the best way to measure the economic potential of the practice. Anesthesia is unique in relying on base and time units to determine payment. Because of these changes in the acuity of care, the average units billed per case can have a significant impact on the overall revenue potential of the practice. 

The migration from inpatient surgical venues to outpatient venues—especially those dedicated to endoscopy—can gradually erode the billing potential. Although the drop in average units per case may appear small, the overall impact can be significant. 

Conventional wisdom has held that there is an inverse relationship between the average units per case and the payer mix. In other words, inpatient facilities with a higher Medicare population tend to generate more units per case, but the average yield per unit is less. The notion that payment for cases performed in an outpatient facility nets more per unit is not always true, as will be explored below. 


Obviously, what matters most to every practice is the amount of money collected. Table 3 indicates the percentage change in Date of Entry (DOE) collections from 2022 to 2023. Most practices have an expectation of what should be deposited each month. When collections reach or exceed this number, they are happy. When it falls short, they want to know why. It is a common paradigm. Based on the past few years, most practices are ecstatic to see total collections represent a seven percent increase.

When it comes to assessing the impact of strong collections, we are at an interesting juncture. The impact of the COVID-19 pandemic was dramatic and was still being felt to some extent into 2022. Positive collection trends this year raise hopes that this growth is the new normal. Let us hope this is the case, but history tells us that the future is never guaranteed.


The amount a practice collects per surgical unit is a function of the practice’s payer mix. In general terms, providers understand that public payer units (Medicare, Medicaid, Workers’ Compensation, Champus and VA) are significantly discounted. At $20 or so per unit, the Medicare rate is often less than 25 percent of the average commercial contract rate. One way to monitor the impact of public payer rates is to track payer mix. 

The good news is that the overall average of public payers for this sample of practices has not changed from 2022 to 2023 as shown in the table below. We find that 48 percent of surgical units are getting billed to public payers in both years. This is a significant percentage. The problem is that this does not tell the whole story.

The bad news is that a practice really needs to generate 50 ASA units per location per day at a rate of $40 per unit to generate enough revenue to cover the cost of providers at current market rates. As Table 5 clearly indicates, only two practices meet this requirement of a net yield of $40 per unit (Practice 9 and Practice 10). The others must rely on hospital support to cover their costs. 

Three factors have led to the need for financial support from facilities: the impact of public payers, inefficient operating room utilization and the increasing cost of anesthesiologists and CRNAs. As the market becomes increasingly competitive, many practices have either sold out to larger entities or become hospital employees. This information is a critical component of an effective management strategy.


Ultimately, the true value of management information comes down to profitability. As more and more practices have come to rely on hospital support to close the gap between the revenue generated from clinical activity and the cost of providing the care, the negotiation of subsidies requires a detailed understanding of the actual revenue potential of each venue. While most of the management information provided by billing staff is actual production data, which is not normalized, it is normalized metrics that allow for an objective comparison to market data. The yield per unit is one example of normalized data, but two other metrics tend to be more relevant and useful for determining profitability: the average yield per hour of care provided and the average yield per clinical day. For purposes of this discussion, the average yield per hour of care is relatively easy to calculate while the yield per clinical day requires detailed coverage information.

Looking at Table 6, $286.27 is the average yield per hour of care. In Chart 6 above, seven of the 12 practices yield more than the average. This number is a reasonable benchmark for purposes of assessing a practice’s yield. From a staffing perspective, this means that each practice should strive to minimize the cost of care through a judicious use of physicians and CRNAs to target a reasonable cost given the payer mix and market for the practice. 


For most practices, 2023 has been a good year. The key metrics are generally positive, although there are clearly some outliers. There is a saying that “a rising tide lifts all ships.” There is a lot of truth to this. Strong surgical volume is typically a blessing. It is always better to have too many cases than not enough cases.

While the metrics are generally positive, they are not necessarily stellar. Payer mix is always a challenge. Given the national demographic trends, the Medicare population is growing. Americans over 80 are the fastest growing segment of the American population. Although the sample included here has not seen any dramatic increase in public payers, many practices have been seeing a one percent increase in their Medicare population per year. This is why it is so critical to monitor payer mix and the impact of Medicare and Medicaid over time. It should also be noted that the number of anesthetizing locations continues to increase as cases move from traditional inpatient venues to outpatient facilities. The dramatic increase in the number of anesthetics for endoscopic cases can be profitable for many practices, but it definitely erodes the average units per case without necessarily increasing the yield per unit. 

To avoid the need for financial subsidy from the facility, a practice should ideally generate 50 billable ASA units per location day at a rate of at least $40 per billed unit. The number-one challenge for most practices today is to generate enough revenue to recruit and retain an adequate team of qualified providers. The impact of discounted public payer rates and commercial plans that are becoming ever more reluctant in agreeing to rate increases is a universal challenge. 

It is important to remember that good news today is not always good news tomorrow. As is true in the provision of anesthesia, vigilance is the key to success. One must always be monitoring the evolution of various factors to be able to plan for their ultimate impact.

Jody Locke, MA serves as Vice President of Anesthesia and Pain Practice Management Services for Coronis Health. Mr. Locke is responsible for the scope and focus of services provided to Coronis Health’s largest clients. He is also responsible for oversight and management of the company’s pain management billing team. He is a key executive contact for groups that enter into contracts with Coronis. Mr. Locke can be reached at

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