title: Mathematical modeling to define optimum operating room staffing needs for trauma centers.
abstract: BACKGROUND
  Level II trauma centers may be verified (1999, American College of Surgeons Committee on Trauma) with an on-call operating room team if the performance-improvement program shows no adverse outcomes. Using queuing and simulation methodology, this study attempted to add a volume guideline.
  
  
  METHODS
  Data from 72 previously verified trauma centers identified multiple demographic factors, including specific information about the first trauma-related operation that was done between 11:00 PM and 7:00 AM each month for 12 consecutive months.
  
  
  RESULTS
  The annual admissions averaged 1,477 for 37 Level I trauma centers, 802 for 28 Level II trauma centers, 481 for 4 Level III trauma centers, and 731 for 3 pediatric trauma centers. The annual admissions correlated with the number of operations done between 11:00 PM and 7:00 AM (p < 0.001). These 946 operations were performed by general surgery (39%), neurosurgery (8%), orthopaedic surgery (33%), another specialty (9%), or multiple services (10%). Admission to operation time was within 30 minutes for 12.1% of patients (2.6% for blunt and 24.1% for penetrating injuries). The probability of operation within 30 minutes of arrival varied with the number of admissions and with the percentage of penetrating versus blunt injuries. The likely number of operations from 11:00 PM to 7:00 AM would be 19 for 500 annual admissions, 26 for 750 annual admissions, and 34 for 1,000 annual admissions, with 5.83, 7.98, and 10.13 patients, respectively, going to operation within 30 min. The probability that two rooms would be occupied simultaneously was 0.14 and 0.24 for centers admitting 500 and 1,000 patients, respectively.
  
  
  CONCLUSIONS
  Trauma centers performing fewer than six operations between 11:00 PM and 7:00 AM per year could conserve resources by using an immediately available on-call team, with responses monitored by the performance-improvement program.
authors.affiliation: Department of Surgery, Wayne State University, Detroit, MI, USA.
authors.forename: C E
authors.initials: CE
authors.lastname: Lucas
authors.forename: K J
authors.initials: KJ
authors.lastname: Buechter
authors.forename: R L
authors.initials: RL
authors.lastname: Coscia
authors.forename: J M
authors.initials: JM
authors.lastname: Hurst
authors.forename: J W
authors.initials: JW
authors.lastname: Meredith
authors.forename: J D
authors.initials: JD
authors.lastname: Middleton
authors.forename: C R
authors.initials: CR
authors.lastname: Rinker
authors.forename: D
authors.initials: D
authors.lastname: Tuggle
authors.forename: A L
authors.initials: AL
authors.lastname: Vlahos
authors.forename: J
authors.initials: J
authors.lastname: Wilberger
mesh_terms: D017408:Guidelines as Topic; D006302:Health Services Research; D006801:Humans; D016014:Linear Models; D015233:Models, Statistical; D020380:Needs Assessment / Q000458:organization & administration; D009873:Operating Rooms / Q000706:statistics & numerical data*; D010343:Patient Admission / Q000706:statistics & numerical data; D010562:Personnel Staffing and Scheduling Information Systems; D011237:Predictive Value of Tests; D011795:Surveys and Questionnaires; D013598:Systems Theory; D013997:Time Factors; D017749:Total Quality Management / Q000458:organization & administration*; D014193:Trauma Centers; D014481:United States / Q000453:epidemiology; D000078329:Workforce; D014949:Wounds, Nonpenetrating / Q000453:epidemiology / Q000601:surgery; D014950:Wounds, Penetrating / Q000453:epidemiology / Q000601:surgery