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

Abstract

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. King County, Washington. Discrete event simulation study. All 2006 hospital discharge data, linked to all adult, eligible patients transported by county emergency medical services agencies. 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. 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. 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.