In this month's issue, Sessler et al.1 show absence of an association between the time of day at which scheduled (elective) general surgery and orthopedic procedures start and both 30-day risk-adjusted mortality and incidence of in-hospital complications. For start times between 7:00 AM and 5:00 PM, the confidence intervals for the odds ratios were narrow (i.e., unlikely that absence of an association was attributable to a type II error). These results are especially important because they differ from recent findings in gastrointestinal endoscopy.2–5 Sessler et al.1 also show no difference in patient outcome between July and August, when there are new trainees, and other months.
In this Editorial, we review research in operating room (OR) management to help readers apply the results obtained by Sessler et al. to managerial decision-making. We apply the authors' findings to the various decisions that may be made, from decisions made on the day of surgery to decisions made several months before surgery.
On the day of surgery, urgent (add-on) cases are scheduled. The findings by Sessler et al.1 do not apply in this setting, because they studied scheduled cases. There may be provider fatigue and/or resource availability late at night affecting patient outcome, as detected for some transplantation procedures.6,7
Weeks to days before the day of surgery, cases are scheduled into allocated OR time.8–10 The decision is made rationally by not scheduling a case into overutilized OR time unless there is insufficient remaining allocated time for the case.8–10 Issues regarding patient outcome related to the time of day do not arise in the decision.8
A few months before the day of surgery (e.g., before staff scheduling is done), allocated OR time is calculated based on forecasted workload.10–12 This decision is made based on the total workload, not case start times.10–12 The results of Sessler et al.1 do not apply to this decision either.
Several months before the day of surgery, surgeons' block times can be readjusted (e.g., days of the week that they operate).13 Because such decisions do not change mean start times or numbers of first case starts, these decisions too are unaffected by the Sessler et al. results.
Several months before the day of surgery, additional block time may be planned for one or more surgeons in the hope of future growth in the surgeon's OR workload.14–17 That decision frequently does change the duration of the workday (e.g., cases scheduled up to 6:00 PM instead of up to 3:30 PM) and could be influenced by the findings of Sessler et al. However, in practice, the decision should not be affected. Sessler et al.1 pooled procedures (see the authors' Fig. 1). Their confidence intervals for odds ratios were narrow when pooled, unlike what the result would be for each specified procedure and/or surgeon. Although quality can be built into the contribution margin per OR hour analysis, either as increased utility (revenue) or as reduced cost, the resulting confidence intervals by surgeon for contribution margin per OR hour would be impractically wide.14,18 The potential incremental increase in margin from increasing block time to one specified surgeon would thus be offset by a large increase in risk that the realized contribution margin per OR hour would be significantly different from the expected value.19 The analysis would result in the surgeon not being allocated additional block time, in lieu of the alternative (salvage) decision to allocate the additional block time as first-come, first-scheduled unblocked open OTHER overflow time.16,17
Several months before the day of surgery, the decision may be made to open another such OTHER flexible OR. This is the decision to which the results of Sessler et al.1 do apply. Opening such an OR at a facility with many cases starting beyond an 8-hour workday will result in fewer cases starting that late. The value of the findings of Sessler and colleagues is in showing that patient outcome is unlikely to be affected by this decision. Therefore, the decision to run longer days versus more ORs can be made balancing (a) the cost of longer days, (b) the cost of opening one or more OR(s), and (c) the reduction in surgeons' waiting times from scheduled start times achieved by adding first case starts.20
Facilities tend to decide to add an additional OR when the upper (e.g., 80%) prediction limit for the hours of elective cases and turnovers per OR per workday is approximately 8 hours.21,22 For the mean to be 8 hours, some ORs will have cases totaling 9 to 10 hours, and some for 6 to 7 hours. The matching of these times to the start times in the study by Sessler et al.1 shows the usefulness of their findings to the management decision.
Provided there are at least 8 hours of elective cases per room per workday, the addition of these open ORs reduces tardiness from scheduled start times20,23 and reliably increases anesthesia providers' and surgeons' productivity,24 without reducing institutional operating margin.25,26 Because it is economically irrational for ORs without specialized equipment (e.g., robotics) to be bottlenecks to surgical workload, the increase in productivity should not represent more ORs to accommodate queued (available) surgical cases.10,15–12,27 Rather, productivity is increased because surgeons choose to schedule more cases, at least partly because they perceive that the durations of their personal workdays will not suffer.25,28–30 How the ORs are used and arranged on the day of surgery has relatively small effect on the increased productivity, as long as decisions are made to use the extra OR to reduce overutilized time on the day of surgery.9,24 Consequently, the lack of details of the case scheduling at the Cleveland Clinic in the Sessler et al.1 paper is irrelevant. The month when the additional OR(s) is added is unlikely to influence patient outcome, which we know not only from the findings of Sessler et al.,1 but also from national data for a few, common procedures.31 We are fortunate to have the findings obtained by Sessler et al.1 to guide this common and important OR management decision.
Name: Franklin Dexter, MD, PhD.
Contribution: This author helped design the study, conduct the study, and write the manuscript.
Attestation: Franklin Dexter reviewed the analysis of the data and approved the final manuscript.
Name: Alan P. Marco, MD, MMM.
Contribution: This author helped write the manuscript.
Attestation: Alan P. Marco has approved the final manuscript.
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2. Chan MY, Cohen H, Spiegel BM. Fewer polyps detected by colonoscopy as the day progresses at a Veteran's Administration teaching hospital. Clin Gastroenterol Hepatol 2009;7:1217–23
3. Kaneshiro M, Ho A, Chan M, Cohen H, Spiegel BM. Colonoscopy yields fewer polyps as the day progresses despite using social influence theory to reverse the trend. Gastrointest Endosc 2010;72:1233–40
4. Long MD, Martin C, Sandler RS, Herfarth HH, Shaheen NJ, Dellon ES. Reduced polyp detection as endoscopy shift progresses: experience with screening colonoscopy at a tertiary-care hospital. J Clin Gastroenterol 2011;45:253–8
5. Munson GW, Harewood GC, Francis DL. Time of day variation in polyp detection rate for colonoscopies performed on a 3-hour shift schedule. Gastrointest Endosc 2011;73:467–75
6. George TJ, Arnaoutakis GJ, Merlo CA, Kemp CD, Baumgartner WA, Conte JV, Shah AS. Association of operative time of day with outcomes after thoracic organ transplant. JAMA 2011;305:2193–9
7. Lonze BE, Parsikia A, Feyssa EL, Khanmoradi K, Araya VR, Zaki RF, Segev DL, Ortiz JA. Operative start times and complications after liver transplantation. Am J Transplant 2010;10:1842–9
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9. Dexter F, Epstein RD, Traub RD, Xiao Y. Making management decisions on the day of surgery based on operating room efficiency and patient waiting times. Anesthesiology 2004;101:1444–53
10. McIntosh C, Dexter F, Epstein RH. Impact of service-specific staffing, case scheduling, turnovers, and first-case starts on anesthesia group and operating room productivity: tutorial using data from an Australian hospital. Anesth Analg 2006;103:1499–516
11. Strum DP, Vargas LG, May JH, Bashein G. Surgical suite utilization and capacity planning: a minimal cost analysis model. J Med Syst 1997;21:309–22
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14. Wachtel RE, Dexter F. Tactical increases in operating room block time for capacity planning should not be based on utilization. Anesth Analg 2008;106:215–26
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17. O'Neill L, Dexter F. Tactical increases in operating room block time based on financial data and market growth estimates from data envelopment analysis. Anesth Analg 2007;104:355–68
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19. Dexter F, Ledolter J. Managing risk and expected financial return from selective expansion of operating room capacity: mean-variance analysis of a hospital's portfolio of surgeons. Anesth Analg 2003;97:190–5
20. Wachtel RE, Dexter F. Influence of the operating room schedule on tardiness from scheduled start times. Anesth Analg 2009;108:1889–901
21. 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
22. 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
23. Wachtel RE, Dexter F. Reducing tardiness from scheduled start times by making adjustments to the operating room schedule. Anesth Analg 2009;108:1902–9
24. Marjamaa RA, Torkki PM, Hirvensalo EJ, Kirvelä OA. What is the best workflow for an operating room? A simulation study of five scenarios. Health Care Manag Sci 2009;12:142–6
25. Sandberg WS, Daily B, Egan M, Stahl JE, Goldman JM, Wiklund RA, Rattner D. Deliberate perioperative systems design improves operating room throughput. Anesthesiology 2005;103:406–18
26. Smith MP, Sandberg WS, Foss J, Massoli K, Kanda M, Barsoum W, Schubert A. High-throughput operating room system for joint arthroplasties durably outperforms routine processes. Anesthesiology 2008;109:25–35
27. O'Neill L, Dexter F, Wachtel RE. Should anesthesia groups advocate funding of clinics and scheduling systems to increase operating room workload? Anesthesiology 2009;111:1016–24
28. Stahl JE, Egan MT, Goldman JM, Tenney D, Wiklund RA, Sandberg WS, Gazele S, Rattner DW. Introducing new technology into the operating room: measuring the impact on job performance and satisfaction. Surgery 2005;137:518–26
29. Cendan JC, Good M. Interdisciplinary work flow assessment and redesign decreases operating room turnover time and allows for additional caseload. Arch Surg 2006;141:65–9
30. Masursky D, Dexter F, Isaacson SA, Nussmeier NA. Surgeons' and anesthesiologists' perceptions of turnover times. Anesth Analg 2011;112:440–4
31. Englesbe MJ, Fan Z, Baser O, Birkmeyer JD. Mortality in medicare patients undergoing surgery in July in teaching hospitals. Ann Surg 2009;249:871–6