workload and resource use

is a growing problem in many health care systems1. Of the 115.3 million ED visit in the United States in 2007 an estimated of 15.5 percent arrived at the ED by ambulance2. Such patients tend to be older than the average ED patients, were more likely to have higher acuity illness, injury or mental health care disturbances, and require more resources, ranging from diag-nostic tests and treatment performed to total time spent in the ED and hospital admission rate3-7. It has been reported that ambulance arrivals seems to be associated with socio economic status, urbanic-ity and time of day7,8. It has been estimated that at currently rate of am-bulance use, the volume of ED ambulance trans-port could grow in the USA until 20.2 million in the next years5. It implicates an increasing in ED workload, crowd-ing and resource use4,6,9, a rising of the ED trans-port per ambulance, a growth of the licensed Emer-gency Medical Services (EMS) vehicles, longer transport times and longer out of service times for individual ambulance5,10. Despite organizative4-6,9-11 and financial12-14 implica-tion related to EMS in the ED, few studies exists to estimate the epidemiology of ED public EMS am-bulance transport related visits and their impact on ED activity2-6. More precise knowdlege of the pattern of ambu-lance arrivals and differences between ambulance and walk in patients could elucidate their respec-tive impacts on the ED crowding, workload and resource use. This study examine some of clinical factors associ-ated with ambulance use as compared to walk in mode of arrival to a medium / large academic ur