Mapping the 24-hour emergency department cycle to improve patient flow

Intermountain Healthcare (Salt Lake City), in conjunction with emergency department (ED) staff at LDS Hospital, designed an integrated patient tracking system (PTS) and a specialized data repository (ED Data Mart) that was part of an overall enterprisewide data warehouse. After two years of internal beta testing the PTS and its associated data captures, an analysis of various ED operations by time of day was undertaken.

Real-time data, concurrent with individual ED patient encounters from July 1, 2004 through June 30, 2005 were included in a retrospective analysis.

A number of patterns were revealed that provide a starting point for understanding ED processes and flow. In particular, ED census, acuity, operations, and throughput vary with the time of day. For example, patients seen during low-census times, in the middle of the night, appear to have a higher acuity. Radiology and laboratory utilization were highly correlated with ED arrivals, and the higher the acuity, the greater the utilization.

Although it is unclear whether or not these patterns will be applicable to other hospitals in and out of the cohort of tertiary care hospitals, ED cycle data can help all facilities anticipate the resources needed and the services required for efficient patient flow. For example, the fact that scheduling of most service departments falls off after 5:00 P.M., just when the ED is most in need of those services, illustrates a fundamental mismatch between service capacity and demand.