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Anesthesia Workload Nationally During Regular Workdays and Weekends

Dexter, Franklin MD, PhD*; Dutton, Richard P. MD, MBA; Kordylewski, Hubert PhD; Epstein, Richard H. MD, CPHIMS

doi: 10.1213/ANE.0000000000000773
Economics, Education, and Policy: Research Report

BACKGROUND: We analyze data from the American Society of Anesthesiologist’s (ASA) Anesthesia Quality Institute (AQI) to report the U.S. anesthesia workload by time of day and day of the week. We consider the extent to which first case starts, rather than durations of workdays and weekend cases, influence the number of anesthesia providers nationally.

METHODS: The ASA AQI data were from all the U.S. anesthesia groups that submitted cases to the National Anesthesia Clinical Outcomes Registry (NACOR) for all 12 months of 2013. For each of the n = 2,075,188 cases, we identified the local date and time of the start of anesthesia care, duration of anesthesia care, and the local time zone. Anesthesia workload was measured as the time from the start to the end of continuous anesthesia care. Data are reported as mean ± SEM with 95% confidence intervals (CIs).

RESULTS: Half (53.0% ± 0.6%) of the ASA AQI–reported weekly anesthesia workload was completed by 1:00 PM, local time, on regular workdays. The busiest 8-hour interval was from 7:30 AM to 3:30 PM and accounted for 70.3% ± 0.7% of anesthetic minutes. Although most facilities completed the majority of their weekly anesthesia workload in the mornings of regular workdays (P < 0.0001; 62.3%; CI, 58.6%–66.1%), just 24.4% of the University and large community hospitals did so (P = 0.0008 relative to half; CI, 13.8%–38.4%).

CONCLUSIONS: The results are inconsistent with widespread use of surgical facilities (i.e., anesthesia providers) in mornings only, especially at University and large community hospitals. The observed national work hours match with what would be expected if most anesthesiologists work at least 8 hours on regular workdays. Opportunity for greater use of the capital (building and equipment) probably would involve the use of additional anesthesia providers representing a second shift or use of weekends.

Published ahead of print April 28, 2015

From the *Division of Management Consulting, Department of Anesthesia, University of Iowa, Iowa City, Iowa; Anesthesia Quality Institute, American Society of Anesthesiologists, Schaumburg, Illinois; and Department of Anesthesiology, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, Pennsylvania.

Accepted for publication March 5, 2015.

Published ahead of print April 28, 2015

Funding: Departmental.

The authors declare no conflicts of interest.

Some of the data presented in this article were presented at the International Anesthesia Research Society meeting in Montreal, Quebec, May 19, 2014.

An abstract describing this work was submitted to the American Society of Anesthesiologist’s Practice Management 2015 conference in Atlanta, GA, January 2015.

Reprints will not be available from the authors.

Address correspondence to Franklin Dexter, MD, PhD, Division of Management Consulting, Department of Anesthesia, University of Iowa, 200 Hawkins Dr., 6JCP, Iowa City, IA 52242. Address e-mail to Franklin-Dexter@UIowa.edu or www.FranklinDexter.net.

In this article, we analyze data1 from the American Society of Anesthesiologist’s (ASA) Anesthesia Quality Institute (AQI) to report the U.S. anesthesia workload by time of day and day of the week. The percentages of anesthetizing locations with >8 hours of cases differ among facilities nationally2–4 and among services and days of the week at individual facilities.5 The extent to which first case starts, rather than durations of workdays and weekend cases, drive the number of anesthesia providers nationally is unknown.6 Understanding the determinants of perioperative efficiency nationwide is important. Opportunities to reduce health care costs include greater use of fixed (capital) costs (e.g., >$1 million per operating room [OR] for capital and equipment).a The Triple-R model for transforming ambulatory surgical care includes expanded facility hours to 18 hours per day 7 days per week.b

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METHODS

The University of Iowa IRB determined that this work is not human subjects research.

The AQI data were from all U.S. anesthesia groups that submitted cases to the National Anesthesia Clinical Outcomes Registry (NACOR) for all 12 months of 2013 (Fig. 1). The n = 2,075,188 cases’ times were compared using Central Time (i.e., the time zone of the headquarters of the ASA and AQI)c for use in our companion paper of a call center providing real-time support to anesthesia providers nationwide.7 Anesthesia workload was measured as the time from the start to the end of continuous anesthesia care for each case (i.e., turnover times and delays were not included).

Figure 1

Figure 1

Days with atypically low workloads nationally (e.g., holidays) were identified by using the counts of general anesthetics nationwide on each Monday through Friday.8 The date at the 5th percentile was a U.S. federal holiday. Thus, dates with caseloads of the ≤5th percentile were treated as holidays.8

We summed minutes of anesthesia time nationwide on regular workdays from 7:30 AM to 3:30 PM in the local time zones. Batches of 13 four-week periods were created for each hour interval (Fig. 2). The percentage of minutes for each period that was from 7:30 AM to 3:30 PM regular workdays was calculated. Student’s one-group 1-sided t test was used to calculate SEs (n = 13).9–16 Because the briefest anesthesia workday (in terms of times of direct patient care) may at some facilities start sooner than 7:30 AM (e.g., 7:00 AM), sensitivity analyses considered other intervals (Table 1). Sensitivity analyses limited analyses to general anesthetics. Sensitivity analyses tested whether few (<10%) minutes of anesthesia time nationwide occurred on weekends.17

Table 1

Table 1

Figure 2

Figure 2

We also performed analyses by studied facility (n = 656). For each, we calculated the total annual number of minutes and the total number of those minutes in the mornings of regular workdays (i.e., before 12 noon local time zone). The summary statistic for each facility was whether the minutes in the mornings of regular workdays ≥50% of the facility’s total. By using the method of Blyth-Still-Casella, we calculated an exact CI on the percentage of facilities having most of its minutes of cases over the year in the mornings of regular workdays (StatXact-9, Cytel Inc., Cambridge, MA). The 2-sided binomial test compared the percentage to half (i.e., “most”) facilities. Sensitivity analyses limited analyses to general anesthetics. In addition, sensitivity analyses limited analyses to the n = 45 facilities reported as University and large community hospitals. The cases are from self-reported medium-sized (100–500 beds) community hospitals (34.8% of cases; 25.3% of facilities), unlisted (missing value) (27.5%; 30.0%), freestanding surgery centers (9.1%; 20.3%), University hospitals (8.3%; 2.3%), attached surgery centers (4.7%; 7.2%), small (<100 beds) community hospitals (4.1%; 3.9%), specialty hospitals (1.6%; 3.5%), and offices (0.4%; 2.7%).

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RESULTS

Half (53.0% ± 0.6%) of the ASA AQI–reported weekly anesthesia workload was completed by 1:00 PM, local time, on regular workdays. The busiest 8-hour interval was from 7:30 AM to 3:30 PM, and it accounted for 70.3% ± 0.7% of anesthetic minutes (Table 1 and Fig. 2). That 7:30 AM to 3:30 PM interval (using local times) accounted for 74.2% ± 0.7% of the workload on regular workdays. The corresponding interval relevant to staffing of national call centers (6:30 AM to 6:30 PM Central Time) accounted for 82.2% ± 0.7% of anesthetic minutes (Fig. 3). Less than 10% of anesthetic minutes occurred on weekends (P < 0.0001, 5.2% ± 0.1%).

Figure 3

Figure 3

Although most facilities completed the majority of their weekly anesthesia workload in the mornings of regular workdays (P < 0.0001, 62.3%, 58.6%–66.1%), just 24.4% of the University and large community hospitals did so (P = 0.0008 relative to half; 13.8%–38.4%).

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DISCUSSION

Slightly more than half of the U.S. national OR workload is completed slightly after noon of regular workdays. Anesthesia providers providing direct OR clinical care 5 days per week from 7:30 AM to 3:30 PM would result in an average time of 11:30 AM (i.e., by noon). Thus, the results likely indicate longer workdays than previous analyses of 2004 and 2006 Medical Group Management Association data.6,d

Even though many hospitals have nearly every anesthetizing location in use >8 hours daily, most facilities nationwide complete most of their weekly anesthesia minutes by noon of regular workdays. Thus, the results match the tendency of U.S. facilities to open additional OR(s) when the sum of the hours of cases and turnovers per OR per workday is nearly 8 hours.18–20 Opportunity for greater use of the capital (building and equipment) probably would involve the use of additional anesthesia providers representing a second shift or use of weekends. However, scheduling cases <8 hours has the benefit of reducing patient and surgeon waiting on the day of surgery,21–24 although such limitation in scheduled hours of surgery does not reduce complication rates or mortality.19,25 Rather than the traditional full day in a large hospital caring for surgical inpatients having major procedures, shorter hours may provide what many patients want21: morning surgical start times to facilitate outpatient and short-stay procedures1,22–24,26 that provide the most predictable experience for patients and surgeons.

Our results were limited to the study of cases and minutes of OR anesthesia, as needed for our companion paper exploring the timing of activity at a national call center.7 Planning remote expert “knowledge consultation”27 for guiding medical decisions depends on the timing of calls during the week, as provided by Figure 3. Such consultation can be, for example, to support telemedicine services to anesthesia providers facing unfamiliar clinical scenarios such as managing rare diseases.7 The cases and minutes of OR anesthesia do not reveal other activities, clinical (e.g., obstetrics, critical care, and acute and chronic pain medicine), non-clinical (management, education, and research),28 and availability for clinical work.8 For example, although 5.2% ± 0.1% of minutes of care were performed on weekends, anesthesia providers needed to be scheduled to be available during these 28.6% minutes of calendar time (i.e., 2 of 7 days).

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DISCLOSURES

Name: Franklin Dexter, MD, PhD.

Contribution: This author helped design the study, conduct the study, analyze the data, and write the manuscript.

Attestation: Franklin Dexter has approved the final manuscript.

Name: Richard P. Dutton, MD, MBA.

Contribution: This author helped conduct the study and prepare the manuscript and is the archival author.

Attestation: Richard P. Dutton approved the final manuscript.

Name: Hubert Kordylewski, PhD.

Contribution: This author helped conduct the study.

Attestation: Hubert Kordylewski has approved the final manuscript.

Name: Richard H. Epstein, MD, CPHIMS.

Contribution: This author helped conduct the study and write the manuscript.

Attestation: Richard H. Epstein has approved the final manuscript.

RECUSE NOTEDr. Franklin Dexter is the Statistical Editor and Section Editor for Economics, Education, and Policy for Anesthesia & Analgesia. This manuscript was handled by Dr. Steven L. Shafer, Editor-in-Chief, and Dr. Dexter was not involved in any way with the editorial process or decision.

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FOOTNOTES

a http://FDshort.com/CostBuildSmallASC. Accessed November 27, 2014.
Cited Here...

b Feryal Erhun, Wednesday, November 12, 2014, WC40 INFORMS 2014 Meeting in San Francisco, CA. Available at: http://FDshort.com/INFORMSascTripleR. Accessed November 27, 2014.
Cited Here...

c The times in the AQI database were stored in the local time zone. They were converted to Central Time based on the zip code of the location of the case and the date of the start of the case. We used Central Time, as a matter of convenience, because the geographic center of population of the U.S. is Central Time. The American Society of Anesthesiologists and AQI are in Chicago, Illinois, which follows Central Time. The Central Time zone is Coordinated Universal Time (UTC) minus 6 hours during Standard Time and minus 5 hours during Daylight Savings Time. Available at: http://en.wikipedia.org/wiki/Mean_center_of_the_United_States_population, www.timetemperature.com/tzmo/plato.shtml, and www.timetemperature.com/tzil/chicago.shtml. Accessed April 1, 2014.
Cited Here...

d Abouleish A, Evenson TB. The fallacy of the field of dreams business plan: a downward trend in anesthesiology productivity. ASA Newslett 2007;71:30–2.
Cited Here...

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REFERENCES

1. Bayman EO, Dexter F, Laur JJ, Wachtel RE. National incidence of use of monitored anesthesia care. Anesth Analg. 2011;113:185–9
2. Abouleish AE, Prough DS, Whitten CW, Zornow MH, Lockhart A, Conlay LA, Abate JJ. Comparing clinical productivity of anesthesiology groups. Anesthesiology. 2002;97:608–15
3. Dexter F, Weih LS, Gustafson RK, Stegura LF, Oldenkamp MJ, Wachtel RE. Observational study of operating room times for knee and hip replacement surgery at nine U.S. community hospitals. Health Care Manag Sci. 2006;9:325–39
4. Berry M, Berry-Stölzle T, Schleppers A. Operating room management and operating room productivity: the case of Germany. Health Care Manag Sci. 2008;11:228–39
5. Marcon E, Dexter F. An observational study of surgeons’ sequencing of cases and its impact on postanesthesia care unit and holding area staffing requirements at hospitals. Anesth Analg. 2007;105:119–26
6. Schubert A, Eckhout GV, Ngo AL, Tremper KK, Peterson MD. Status of the anesthesia workforce in 2011: evolution during the last decade and future outlook. Anesth Analg. 2012;115:407–27
7. Dexter F, Rosenberg H, Epstein RH, Semo JJ, Litman RS. Implications of national anesthesia workload on the staffing of a call center: the malignant hyperthermia consultant hotline. A&A Case Reports. 2015;5:43–6
8. Dexter F, Epstein RH. Holiday and weekend operating room on-call staffing requirements. Anesth Analg. 2006;103:1494–8
9. Law AM, Kelton WD Simulation Modeling and Analysis. 19912nd ed. New York McGraw-Hill Inc.:551–3
10. Dexter F, Macario A, Qian F, Traub RD. Forecasting surgical groups’ total hours of elective cases for allocation of block time: application of time series analysis to operating room management. Anesthesiology. 1999;91:1501–8
11. Dexter F, Marcon E, Epstein RH, Ledolter J. Validation of statistical methods to compare cancellation rates on the day of surgery. Anesth Analg. 2005;101:465–73
12. Dexter F, Epstein RH, Marcon E, Ledolter J. Estimating the incidence of prolonged turnover times and delays by time of day. Anesthesiology. 2005;102:1242–8
13. Dexter F, Marcon E, Aker J, Epstein RH. Numbers of simultaneous turnovers calculated from anesthesia or operating room information management system data. Anesth Analg. 2009;109:900–5
14. Ledolter J, Dexter F, Epstein RH. Analysis of variance of communication latencies in anesthesia: comparing means of multiple log-normal distributions. Anesth Analg. 2011;113:888–96
15. Dexter F. High-quality operating room management research. J Clin Anesth. 2014;26:341–2
16. Austin TM, Lam HV, Shin NS, Daily BJ, Dunn PF, Sandberg WS. Elective change of surgeon during the OR day has an operationally negligible impact on turnover time. J Clin Anesth. 2014;26:343–9
17. Epstein RH, Dexter F, Brull SJ. Cohort study of cases with prolonged tracheal extubation times to examine the relationship with duration of workday. Can J Anaesth. 2013;60:1070–6
18. Masursky D, Dexter F, O’Leary CE, Applegeet C, Nussmeier NA. Long-term forecasting of anesthesia workload in operating rooms from changes in a hospital’s local population can be inaccurate. Anesth Analg. 2008;106:1223–31
19. Dexter F, Marco AP. Rationale for anesthesia groups to run additional flexible operating rooms for multiple surgeons who have scheduled more than 8 hours of cases. Anesth Analg. 2011;113:1295–7
20. Sulecki L, Dexter F, Zura A, Saager L, Epstein RH. Lack of value of scheduling processes to move cases from a heavily used main campus to other facilities within a health care system. Anesth Analg. 2012;115:395–401
21. Dexter F, Birchansky L, Bernstein JM, Wachtel RE. Case scheduling preferences of one Surgeon’s cataract surgery patients. Anesth Analg. 2009;108:579–82
22. Smallman B, Dexter F. Optimizing the arrival, waiting, and NPO times of children on the day of pediatric endoscopy procedures. Anesth Analg. 2010;110:879–87
23. Wachtel RE, Dexter F. Influence of the operating room schedule on tardiness from scheduled start times. Anesth Analg. 2009;108:1889–901
24. Wachtel RE, Dexter F. Reducing tardiness from scheduled start times by making adjustments to the operating room schedule. Anesth Analg. 2009;108:1902–9
25. Sessler DI, Kurz A, Saager L, Dalton JE. Operation timing and 30-day mortality after elective general surgery. Anesth Analg. 2011;113:1423–8
26. Kynes JM, Schildcrout JS, Hickson GB, Pichert JW, Han X, Ehrenfeld JM, Westlake MW, Catron T, Jacques PS. An analysis of risk factors for patient complaints about ambulatory anesthesiology care. Anesth Analg. 2013;116:1325–32
27. Kapur PA. Designing the future: insights from current supervisory models. Anesth Analg. 2013;116:749–51
28. Dexter F, Wachtel RE, Todd MM, Hindman BJ. The “fourth mission:” the time commitment of anesthesiology faculty for management is comparable to their time commitments to education, research, and indirect patient care. A&A Case Reports. 2015;5:206–11
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