title: Disaster metrics: quantitative benchmarking of hospital surge capacity in trauma-related multiple casualty events.
abstract: OBJECTIVE
  Hospital surge capacity in multiple casualty events (MCE) is the core of hospital medical response, and an integral part of the total medical capacity of the community affected. To date, however, there has been no consensus regarding the definition or quantification of hospital surge capacity. The first objective of this study was to quantitatively benchmark the various components of hospital surge capacity pertaining to the care of critically and moderately injured patients in trauma-related MCE. The second objective was to illustrate the applications of those quantitative parameters in local, regional, national, and international disaster planning; in the distribution of patients to various hospitals by prehospital medical services; and in the decision-making process for ambulance diversion.
  
  
  METHODS
  A 2-step approach was adopted in the methodology of this study. First, an extensive literature search was performed, followed by mathematical modeling. Quantitative studies on hospital surge capacity for trauma injuries were used as the framework for our model. The North Atlantic Treaty Organization triage categories (T1-T4) were used in the modeling process for simplicity purposes.
  
  
  RESULTS
  Hospital Acute Care Surge Capacity (HACSC) was defined as the maximum number of critical (T1) and moderate (T2) casualties a hospital can adequately care for per hour, after recruiting all possible additional medical assets. HACSC was modeled to be equal to the number of emergency department beds (#EDB), divided by the emergency department time (EDT); HACSC = #EDB/EDT. In trauma-related MCE, the EDT was quantitatively benchmarked to be 2.5 (hours). Because most of the critical and moderate casualties arrive at hospitals within a 6-hour period requiring admission (by definition), the hospital bed surge capacity must match the HACSC at 6 hours to ensure coordinated care, and it was mathematically benchmarked to be 18% of the staffed hospital bed capacity.
  
  
  CONCLUSIONS
  Defining and quantitatively benchmarking the different components of hospital surge capacity is vital to hospital preparedness in MCE. Prospective studies of our mathematical model are needed to verify its applicability, generalizability, and validity.
authors.affiliation: Rush University Medical Center, 1653WCongress Pkwy, 177 Murdock Bldg, Chicago, IL 60612, USA. jamil_bayram@rush.edu
authors.forename: Jamil D
authors.initials: JD
authors.lastname: Bayram
authors.forename: Shawki
authors.initials: S
authors.lastname: Zuabi
authors.forename: Italo
authors.initials: I
authors.lastname: Subbarao
mesh_terms: D019985:Benchmarking / Q000379:methods*; D004189:Disaster Planning / Q000379:methods*; D006297:Health Services Accessibility; D006301:Health Services Needs and Demand; D006752:Hospital Planning / Q000379:methods; D006801:Humans; D007087:Illinois; D054527:Mass Casualty Incidents; D017146:Models, Organizational; D008962:Models, Theoretical; D011634:Public Health / Q000379:methods; D055872:Surge Capacity / Q000458:organization & administration*; D013997:Time Factors; D014193:Trauma Centers / Q000458:organization & administration*; D014218:Triage / Q000379:methods; D014481:United States; D014947:Wounds and Injuries