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

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.