High-tech emergency departments, staffed with doctors and nurses but often miles from a hospital, are increasing rapidly nationwide. In addition to convenience for patients, these stand-alone ERs can ease overcrowding in nearby hospitals. But critics question their limited services, their ability to decrease the overall burden for area hospitals and their impact on healthcare spending. The number of such facilities owned by hospitals or entrepreneurial doctors grew 23% from 2005 to 2006, according to the American Hospital Association. Currently, about a dozen are opening or in the planning stages in states such as Florida, Minnesota and Texas.