How many operating rooms are needed to manage non-elective surgical cases? A Monte Carlo simulation study.
BACKGROUND
Patients often wait to have urgent or emergency surgery. The number of operating rooms (ORs) needed to minimize waiting time while optimizing resources can be determined using queuing theory and computer simulation. We developed a computer program using Monte Carlo simulation to determine the number of ORs needed to minimize patient wait times while optimizing resources.


METHODS
We used patient arrival data and surgical procedure length from our institution, a tertiary-care academic medical center that serves a large diverse population. With ~4800 patients/year requiring non-elective surgery, and mean procedure length 185 min (median 150 min) we determined the number of ORs needed during the day and evening (0600-2200) and during the night (2200-0600) that resulted in acceptable wait times.


RESULTS
Simulation of 4 ORs at day/evening and 3 ORs at night resulted in median wait time = 0 min (mean = 19 min) for emergency cases requiring surgery within 2 h, with wait time at the 95th percentile = 109 min. Median wait time for urgent cases needing surgery within 8-12 h was 34 min (mean = 136 min), with wait time at the 95th percentile = 474 min. The effect of changes in surgical length and volume on wait times was determined with sensitivity analysis.


CONCLUSIONS
Monte Carlo simulation can guide decisions on how to balance resources for elective and non-elective surgical procedures.
Department of Astronomy, The Ohio State University, Columbus, OH, USA. joe.antognini@gmail.com.
Joseph M O'Brien
JM
Antognini
Peri-operative Services and the Department of Anesthesiology and Pain Medicine, University of California, Davis, Sacramento, CA, USA. jfantognini@ucdavis.edu.
Joseph F
JF
Antognini
Department of Surgery, University of California, Davis, Sacramento, CA, USA. vpkhatri@ucdavis.edu.
Vijay
V
Khatri
D000368:Aged; D003198:Computer Simulation; D004638:Emergency Treatment / Q000706:statistics & numerical data; D006801:Humans; D009010:Monte Carlo Method; D009873:Operating Rooms / Q000706:statistics & numerical data*; D061646:Operative Time; D013514:Surgical Procedures, Operative / Q000706:statistics & numerical data*; D061665:Time-to-Treatment / Q000706:statistics & numerical data; D014850:Waiting Lists