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Prehosp Disaster Med. 2012 Apr;27(2):130-5. doi: 10.1017/S1049023X12000428. Epub 2012 May 17.

Disaster metrics: quantification of acute medical disasters in trauma-related multiple casualty events through modeling of the Acute Medical Severity Index.

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Department of Emergency Medicine, Johns Hopkins School of Medicine, Baltimore, MD, USA.



The interaction between the acute medical consequences of a Multiple Casualty Event (MCE) and the total medical capacity of the community affected determines if the event amounts to an acute medical disaster.


There is a need for a comprehensive quantitative model in MCE that would account for both prehospital and hospital-based acute medical systems, leading to the quantification of acute medical disasters. Such a proposed model needs to be flexible enough in its application to accommodate a priori estimation as part of the decision-making process and a posteriori evaluation for total quality management purposes.


The concept proposed by de Boer et al in 1989, along with the disaster metrics quantitative models proposed by Bayram et al on hospital surge capacity and prehospital medical response, were used as theoretical frameworks for a new comprehensive model, taking into account both prehospital and hospital systems, in order to quantify acute medical disasters.


A quantitative model called the Acute Medical Severity Index (AMSI) was developed. AMSI is the proportion of the Acute Medical Burden (AMB) resulting from the event, compared to the Total Medical Capacity (TMC) of the community affected; AMSI = AMB/TMC. In this model, AMB is defined as the sum of critical (T1) and moderate (T2) casualties caused by the event, while TMC is a function of the Total Hospital Capacity (THC) and the medical rescue factor (R) accounting for the hospital-based and prehospital medical systems, respectively. Qualitatively, the authors define acute medical disaster as "a state after any type of Multiple Casualty Event where the Acute Medical Burden (AMB) exceeds the Total Medical Capacity (TMC) of the community affected." Quantitatively, an acute medical disaster has an AMSI value of more than one (AMB / TMC > 1). An acute medical incident has an AMSI value of less than one, without the need for medical surge. An acute medical emergency has an AMSI value of less than one with utilization of surge capacity (prehospital or hospital-based). An acute medical crisis has an AMSI value between 0.9 and 1, approaching the threshold for an actual medical disaster.


A novel quantitative taxonomy in MCE has been proposed by modeling the Acute Medical Severity Index (AMSI). This model accounts for both hospital and prehospital systems, and quantifies acute medical disasters. Prospective applications of various components of this model are encouraged to further verify its applicability and validity.

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