Effect of an emergency department (ED) managed acute care unit on ED overcrowding and emergency medical services diversion.

OBJECTIVE To determine the impact of an inpatient, emergency department (ED)-managed acute care unit (ACU) on ED overcrowding and use of ambulance diversion. METHODS Descriptive observational study with prospectively collected data from a 14-bed ACU recently opened remote from the main ED. Rates of patients who left without being seen (LWBS) and ambulance diversion frequency and duration were adjusted for ED patient volumes and compared with those for the period immediately before the ACU was opened and with those for a matching time period during the previous year. RESULTS There were 1,589 patients seen in the ACU during the first ten weeks of operation, representing about 14.5% of the ED volume (10,871). About 33% could be classified as post-ED management, 20% as admission processing, and the rest as primary evaluation. The number of patients who LWBS decreased from 10.1% of the ED census two weeks prior to opening of the ACU, and from 9.4% during the previous year, to 5.0% (range 4.2%-6.2%) during the ensuing ten weeks post opening. Ambulance diversion was a mean of 6.7 hours per 100 patients before the unit opened and 5.6 hours per 100 patients during the same time in the previous year, and decreased to 2.8 hours per 100 patients after the unit opened (p < 0.05, respectively). A six-month pre- and two-month post-examination revealed that the mean monthly hours of ambulance diversion for the ED decreased by 40% (202 hours vs 123 hours) (p < 0.05) in contrast to a mean increase of 44% (186 hours vs 266 hours) (p < 0.05) experienced by four proximate hospitals. CONCLUSIONS An ED-managed ACU can have significant impact on ED overcrowding and ambulance diversion, and it need not be located proximate to the ED.