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County-Level Effects of Prehospital Regionalization of Critically Ill Patients: A Simulation Study*

Seymour, Christopher W. MD, MSc1,2; Alotaik, Osama MS3; Wallace, David J. MD, MPH1,2; Elhabashy, Ahmed E. MS4; Chhatwal, Jagpreet PhD5; Rea, Thomas D. MD, MPH6,7; Angus, Derek C. MD, MPH2,8; Nichol, Graham MD, MPH9; Kahn, Jeremy M. MD, MSc2,8

doi: 10.1097/CCM.0000000000001133
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Objective: Regionalization may improve critical care delivery, yet stakeholders cite concerns about its feasibility. We sought to determine the operational effects of prehospital regionalization of nontrauma, nonarrest critical illness.

Setting: King County, Washington.

Design: Discrete event simulation study.

Patients: All 2006 hospital discharge data, linked to all adult, eligible patients transported by county emergency medical services agencies.

Interventions: We simulated active triage of high-risk patients to designated referral centers using a validated prehospital risk score; we studied three regionalization scenarios: 1) up triage, 2) up and down triage, and 3) up and down triage after reducing ICU beds by 25%. We determined the effect on patient routing, ICU occupancy at referral and nonreferral hospitals, and emergency medical services transport times.

Measurements and Main Results: A total of 119,117 patients were hospitalized at 11 nonreferral centers and 76,817 patients were hospitalized at three referral centers. Among 20,835 emergency medical services patients, 7,817 patients (43%) were eligible for up triage and 10,242 patients (57%) were eligible for down triage. At baseline, mean daily ICU bed occupancy was 61% referral and 47% at nonreferral hospitals. Up triage increased referral ICU occupancy to 68%, up and down triage to 64%, and up and down triage with bed reduction to 74%. Mean daily nonreferral ICU occupancy did not exceed 60%. Total emergency medical services transport time increased by less than 3% with up and down triage.

Conclusions: Regionalization based on prehospital triage of the critically ill can allocate high-risk patients to referral hospitals without adversely affecting ICU occupancy or prehospital travel time.

Supplemental Digital Content is available in the text.

1Department of Critical Care and Emergency Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA.

2Clinical Research, Investigation, and Systems Modeling of Acute Illness Center, Department of Critical Care, University of Pittsburgh, Pittsburgh, PA.

3Department of Industrial Engineering, University of Pittsburgh, Pittsburgh, PA.

4Production Engineering Department, Alexandria University, Alexandria, Egypt.

5Department of Health Services Research, The University of Texas MD Anderson Cancer Center, Houston, TX.

6Department of Medicine, University of Washington School of Medicine, Seattle, WA.

7King County MedicOne, King County Emergency Medical Services, Seattle, WA.

8Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA.

9University of Washington-Harborview Center for Prehospital Emergency Care, Seattle, WA.

*See also p. 2018.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s website (

Supported, in part, by a Vision Grant from the Society of Critical Care Medicine.

Dr. Seymour received support for article research from the National Institutes of Health (NIH; 1K23GM104022-01) and consulted for Beckman Coulter. His institution received grant support from the Society of Critical Care Medicine and the NIH. Dr. Wallace received support for article research from the NIH (K12-HL109068). His institution received grant support from the National Heart, Lung and Blood Institute K12-HL109068. Dr. Chhatwal’s institution received grant support from the NIH (KL2TR000146). Dr. Kahn has disclosed nonfinancial research support from the Cerner Corporation (Kansas City, MO). His institution received grant support from the U.S. National Institutes of Health and the U.S. Health Resources and Services Administration. The remaining authors have disclosed that they do not have any potential conflicts of interest.

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