ECONOMICS AND HEALTH SYSTEMS RESEARCH SECTION EDITOR RONALD D. MILLER An Operating Room Scheduling Strategy to Maximize the Use of Operating Room Block Time: Computer Simulation of Patient Scheduling and Survey of Patients’ Preferences for Surgical Waiting Time Franklin Dexter, MD, PhD, Alex Macario, MD, MBA, Rodney D. Traub, PhD, Margaret Hopwood, PhD, and David A. Lubarsky, MD Department of Anesthesia, University of Iowa, Iowa City, Iowa Determining the appropriate amount of block time to allocate to surgeons and selecting the days on which to schedule elective cases can maximize operating room (OR) use. We used computer simulation to model OR scheduling. Inputs in the computer model included dif- ferent methods to determine when a patient will have surgery (on-line bin-packing algorithms), case dura- tions, lengths of time patients wait for surgery (2 wk is the median longest length of time that the outpatients [n = 367] surveyed considered acceptable), hours of block time each day, and number of blocks each week. For block time to be allocated to maximize OR utiliza- tion, two parameters must be specified: the method used to decide on what day a patient will have surgery and the average length of time patients wait to have surgery. OR utilization depends greatly on, and in- creases as, the average length of time patients wait for surgery increases. Implications: Operating room utili- zation can be maximized by allocating block time for the elective cases based on expected total hours of elec- tive cases, scheduling patients into the first available date provided open block time is available within 4 wk, and otherwise scheduling patients in “overflow” time outside of the block time. (Anesth Analg 1999;89:7–20) T he single largest cost to a hospital delivering surgical care is incurred in the operating room (OR) (1). Salaries of OR staff account for most OR costs (2), particularly at hospitals with salaried nurse anesthetists and/or anesthesiologists. Consequently, in many hospitals, an OR manager or a governing body has the authority to organize care for surgical patients at the least cost. To have an important impact on costs of patient care in the OR suite, OR managers must try to maximize “labor productivity” by using the least number of staff necessary to care for the patients. At such OR suites, labor costs are fixed be- cause staffing does not change from day to day ac- cording to the number of patients cared for. Thus, to care for patients while employing as few staff as pos- sible, the OR manager must maximize OR utilization. Utilization equals the time an OR is used (occupan- cy plus setup and cleanup) divided by the length of time an OR is available and staffed. For example, if patient care in an OR starts at 7:00 am and finishes at 1:00 pm, and if the regularly scheduled period of elective cases extends from 7:00 am to 3:00 pm, then there are 2 h of unused OR time. OR utilization equals 75% (6 h used/8 h staffed). In a previous study in which we used computer simulation to model how the OR suite functions, we evaluated the impact of different interventions that might be im- plemented to increase OR utilization (3). Using OR suite data from the University of Iowa, we found that large increases in OR utilization are unlikely to occur even by (i) improving scheduling accuracy such that all errors in predicting durations of cases are eliminated, (ii) eliminating variability in turn- over times, or (iii) eliminating day to day variation in number of hours of add-on cases. Instead, the computer analysis of OR utilization suggested that the most effective strategy to maximize OR time utilization is to select the days on which to perform elective cases so as to best match the OR caseload This work was presented in part at the 1998 annual meeting of the Association of Anesthesia Clinical Directors, Orlando, FL. Accepted for publication March 5, 1999. Address correspondence and reprint requests to Franklin Dexter, Department of Anesthesia, University of Iowa, Iowa City, IA 52242. Address e-mail to franklin-dexter@uiowa.edu. ©1999 by the International Anesthesia Research Society 0003-2999/99 Anesth Analg 1999;89:7–20 7