EMS: a facet of ambulatory care.
D000553:Ambulatory Care; D001294:Attitude to Health; D003695:Delivery of Health Care; D003710:Demography; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D006760:Hospitalization; D007878:Legislation as Topic; D011320:Primary Health Care; D012959:Socioeconomic Factors; D014481:United States; D014505:Urban Population