The Impact of Input and Output Factors on Emergency Department Throughput

Emergency Medicine Division, Washington University School of Medicine, St. Louis, MO, USA.
Academic Emergency Medicine (Impact Factor: 2.2). 04/2007; 14(3):235-42. DOI: 10.1197/j.aem.2006.10.104
Source: PubMed

ABSTRACT To quantify the impact of input and output factors on emergency department (ED) process outcomes while controlling for patient-level variables.
Using patient- and system-level data from multiple sources, multivariate linear regression models were constructed with length of stay (LOS), wait time, treatment time, and boarding time as dependent variables. The products of the 20th to 80th percentile ranges of the input and output factor variables and their regression coefficients demonstrate the actual impact (in minutes) of each of these factors on throughput outcomes.
An increase from the 20th to the 80th percentile in ED arrivals resulted in increases of 42 minutes in wait time, 49 minutes in LOS (admitted patients), and 24 minutes in ED boarding time (admitted patients). For admit percentage (20th to 80th percentile), the increases were 12 minutes in wait time, 15 minutes in LOS, and 1 minute in boarding time. For inpatient bed utilization as of 7 AM (20th to 80th percentile), the increases were 4 minutes in wait time, 19 minutes in LOS, and 16 minutes in boarding time. For admitted patients boarded in the ED as of 7 AM (20th to 80th percentile), the increases were 35 minutes in wait time, 94 minutes in LOS, and 75 minutes in boarding time.
Achieving significant improvement in ED throughput is unlikely without determining the most important factors on process outcomes and taking measures to address variations in ED input and bottlenecks in the ED output stream.

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    ABSTRACT: While emergency department (ED) crowding has myriad causes and negative downstream effects, applying systems engineering science and targeting throughput remains a potential solution to increase functional capacity. However, the most effective techniques for broad application in the ED remain unclear. We examined the hypothesis that Lean-based reorganization of Fast Track process flow would improve length of stay (LOS), percent of patients discharged within one hour, and room use, without added expense. This study was a prospective, controlled, before-and-after analysis of Fast Track process improvements in a Level 1 tertiary care academic medical center with >95,000 annual patient visits. We included all adult patients seen during the study periods of 6/2010-10/2010 and 6/2011-10/2011, and data were collected from an electronic tracking system. We used concurrent patients seen in another care area used as a control group. The intervention consisted of a simple reorganization of patient flow through existing rooms, based in systems engineering science and modeling, including queuing theory, demand-capacity matching, and Lean methodologies. No modifications to staffing or physical space were made. Primary outcomes included LOS of discharged patients, percent of patients discharged within one hour, and time in exam room. We compared LOS and exam room time using Wilcoxon rank sum tests, and chi-square tests for percent of patients discharged within one hour. Following the intervention, median LOS among discharged patients was reduced by 15 minutes (158 to 143 min, 95%CI 12 to 19 min, p<0.0001). The number of patients discharged in <1 hr increased by 2.8% (from 6.9% to 9.7%, 95%CI 2.1% to 3.5%, p<0.0001), and median exam room time decreased by 34 minutes (90 to 56 min, 95%CI 31 to 38 min, p<0.0001). In comparison, the control group had no change in LOS (265 to 267 min) or proportion of patients discharged in <1 hr (2.9% to 2.9%), and an increase in exam room time (28 to 36 min, p<0.0001). In this single center trial, a focused Lean-based reorganization of patient flow improved Fast Track ED performance measures and capacity, without added expense. Broad multi-centered application of systems engineering science might further improve ED throughput and capacity.
    The western journal of emergency medicine 11/2014; 15(7):770-6. DOI:10.5811/westjem.2014.8.21272
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    ABSTRACT: A pathway care model allowing low-risk patients to gain rapid admission to a hospital medical ward¿¿¿a pilot study on ambulance nurses and Emergency Department physicians.Background Patients with non-urgent medical symptoms who nonetheless require inpatient hospital treatment often have to wait for an unacceptably long time at the Emergency Department (ED). The purpose of this study is to evaluate the feasibility and effect on length of delay of a pathway care model for low-risk patients who have undergone prehospital assessment by an ambulance nurse and ED assessment by a physician within 10 minutes of arrival at the ED.Methods The pilot study comparing two low-risk groups took place in western Sweden from October 2011 until January 2012. The pathway model for low-risk patients was used prospectively in the rapid admission group (N¿=¿51), who were admitted rapidly after being assessed by the nurse on scene and then assessed by the ED physician on ED admission. A retrospectively assembled control group (N¿=¿51) received traditional care at the ED. All p-values are age-adjusted.ResultsPatients in the rapid admission group were older (mean age 80 years old) than patients in the control group (mean age 73 years old) (p¿=¿0.02). The median delay from arrival at the patient¿s side until arrival in a hospital medical ward was 57 minutes for the rapid admission group versus 4 hours 13 minutes for the control group (p¿<¿0.0001). However, the median delay time from the ambulance¿s arrival at the patient¿s side until the nurse was free for a new assignment was 77 minutes for the rapid admission group versus 49 minutes for the control group (p¿<¿0.0001). The 30-day mortality rate was 20% for the rapid admission group and only 4% for the control group (p¿=¿0.16).Conclusion The pathway care model for low-risk patients gaining rapid admission to a hospital medical ward shortened length of delay from the first assessment until arrival at the ward. However, the result was achieved at the cost of an increased workload for the ambulance nurse. Furthermore patients who were rapidly admitted to a hospital ward had a high age level and a high early mortality rate. Patient safety in this new model of fast-track assessment needs to be further evaluated.
    Scandinavian Journal of Trauma Resuscitation and Emergency Medicine 12/2014; 22(1):72. DOI:10.1186/s13049-014-0072-0 · 1.93 Impact Factor

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