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From the Division of Management Consulting, Departments of Anesthesia and Health Management and Policy, University of Iowa, Iowa City, Iowa.
Address correspondence and reprint requests to Franklin Dexter, Division of Management Consulting, Department of Anesthesia, University of Iowa, Iowa City, IA 52242. Address e-mail to Franklin-Dexter{at}UIowa.edu.
When renaming this section of Anesthesia & Analgesia "Economics, Education, and Policy," we were not aware of four papers (1–4) being handled by the former Section Editor and Editor-in-Chief, Ronald D. Miller, MD. Acceptance of these papers has provided a welcome opportunity to highlight the interrelationship of economics, education, and policy.
The authors examined the preincision operating room (OR) time, which includes the anesthesia release time (ART), defined as "the time at which the patient had a sufficient level of anesthesia established to begin the surgical preparation of the patient and the remaining anesthesia tasks did not preclude positioning and surgical preparation of the patient" (1). The ART differed significantly depending on the anesthetic technique and monitoring used (e.g., whether a pulmonary artery catheter was placed) (1). The attending anesthesiologists were, on average, quite good at forecasting ART (Spearman correlation coefficient 0.77) (4). The implication is that once the anesthetic plan is known, ART can be estimated and used to improve the prediction of case duration. One of the two questions that we address is how to quantify and achieve an economic benefit from estimating ART.
Teaching resulted in a mean increase of time to incision of 4.5 min (2). This statistically significant, but small, value was similar to that obtained using a different methodology at another academic hospital (5). Cases with new residents had induction times that averaged 3.5 min longer than those done solo by anesthesiologists (5). The second question we answer is how to quantify the OR cost of teaching and how to expand teaching without increasing OR costs.
More accurate estimation of ART, or longer times to incision due to education, are unlikely to affect the choice of the OR in which each case is performed. Alterations of 5 min to 15 min per case are rarely long enough to affect such decisions (6–8). Thus, the discussion can focus on understanding the importance of the relationship between small changes in case durations and variability in the length of the workday in a given OR.
Suppose that three hip replacements are performed in the same OR every Monday. Each procedure takes exactly 2 h 20 min of OR time. A turnover robot cleans and sets up for the next case in precisely 30 min. Staffing should then be planned for exactly 8 h, where 8 h = 3 x (2 h 20 min) + 2 x (30 min). The OR nurses and anesthesia provider could expect to finish after precisely 8 h without any under- or overutilized OR time. They could schedule revenue-producing activities (e.g., seeing patients in a clinic) or personal activities (e.g., picking up their children) based on finishing at precisely 8 h.
On one Monday, the absence of a technician causes a 5 min increase in ART for each case, resulting in a 15 min increase in OR time (i.e., 15 min of overutilized OR time). What is the incremental cost of the increase in ART?
The increase of 5 min per case might be considered minimal, because it is only a 3.6% increase, where 3.6% = 5 min ÷ (2 h 20 min). However, this percentage approach ignores the fact that the OR has run 15 minutes longer than the length of the workday. Nurses would have to be paid overtime wages. Children would be picked up 15 min late. Patients in clinics would wait for 15 min.
Instead, the analysis could be based on multiplying 5 min per case by the cost per minute of OR time (e.g., $15 per minute). Such an analysis would be valid, based on each hip replacement taking precisely 2 h 25 min instead of 2 h 20 min. However, the scenario is unrealistic. Every hip replacement does not take exactly the same amount of time. When case durations cannot be predicted with certainty, a different analysis is required. The incremental cost of finishing an OR day 15 min late cannot be estimated accurately by assuming a fixed cost per minute of OR time.
Actual surgical times often differ from scheduled surgical times (9,10). Because of that unpredictability, staffing can never be matched precisely to case durations (10), even if the cases to be scheduled are known in advance. Total staffing costs will be lower, on average, if some staff are scheduled to work later than needed (11). It is less expensive to have idle staff some of the time than to have overutilized OR time, and pay overtime to some staff, when the workday extends later than expected (7,8,11).
Thus, staffing should be planned based on the assumption that cases sometimes finish late due to lack of predictability in surgical times. The standard deviations of surgical times for specific procedures are, in most instances, much larger than the changes in mean ART resulting from more accurate predictions (1,4,12,13). Likewise, the standard deviations of surgical times for given procedures are usually much larger than the mean increase in ART from teaching (2). Therefore, the incremental reductions in cost are small from estimating the ART more accurately, as are the increases in costs from lengthening the ART due to teaching (12).
The preceding analysis still overestimates the change in OR costs from small changes in the ART. At many facilities, imprecision of surgical times is not the largest source of variability in the length of the workday. In fact, the amount of under and overutilized OR time can be insensitive to the use of scheduled rather than actual case durations (14). The incremental reduction in cost from having perfect knowledge of case durations has been quantified at an academic hospital’s two surgical suites (7,8,10). The ambulatory surgery center had a mean case duration of 1.6 h. Overutilized OR time was just 1.0 ± 0.1 min (SE) per OR per workday relative to perfect knowledge of case durations (7,8,10). At the tertiary suite, with a mean case duration of 3.6 h, overutilized time per OR per workday was just 5.4 ± 0.3 min (7,8,10).
The reason for the preceding results was that a large source of variability in the length of the workday in a given OR was variability among days in the total hours of cases scheduled into the OR. For example, suppose a surgeon schedules cases from 7 am to 3 pm on half of Mondays and from 7 am to 5 pm the other half, but unpredictably. When staff are scheduled months in advance, staffing should be planned each Monday for 7 am to 5 pm instead of 7 am to 3 pm, because having some underutilized OR time is less expensive than an equal amount of overutilized OR time (11,15).
The preceding arguments still have not considered one of the most important factors. Many hospitals and outpatient facilities have too few hours of cases per OR per day for small changes in ART, or perfect knowledge of ART, to alter overutilized OR time. They would have no overutilized OR time even with only 8 h of staffing per OR. Eleven community anesthesiology groups in the United States had an average of 6.0 h of anesthesia time per OR per day (16). Eight community hospitals in the United States had an average of 5.5 h of OR time per OR per day in their ORs used for knee or hip replacement surgery (17). At academic facilities, many of the ORs had much less than 8 h of cases per OR per day (18,19).
Thus, the impact of understanding factors that affect ART, and the impact of increasing time to incision due to teaching, can be economically small. Policies to reduce costs should focus elsewhere.
The papers in this month’s issue of Anesthesia & Analgesia (1–4) are important because, once the anesthetic plan is known for each patient, more accurate predictions of ART can be used on the day of surgery to provide updated estimates of case durations (8,10). For example, the information may improve case sequencing the day before surgery, thereby reducing surgeon and patient waiting times. Both surgeons and patients may be able to engage in other activities, such as clinic appointments or a preanesthesia workup. In addition, anesthesia staff may be notified when a particular OR is unlikely to have overutilized OR time. They may then feel more comfortable using OR time for education without increasing health care costs. Papers such as these, that provide decision-support on the day of surgery, may serve to increase anesthesia education. That may be increasingly important in the future, because having anesthesiologists medically direct more ORs can not only reduce costs (20), but can also result in less time spent teaching (2).
Footnotes
Accepted for publication July 25, 2006.
Financial disclosure: F.D. is Director of the Division of Management Consulting of the University of Iowa. He receives no funds personally other than his salary from the State of Iowa, including no travel expenses or honorarium, and has tenure with no incentive program.
REFERENCES
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