Inova HealthPlex at Franconia-Springfield in Northern Virginia differs radically from the ordeal familiar to many Americans who seek treatment in the nation's hospital emergency rooms. HealthPlex's full-service emergency department sees close to 33,000 patients annually. Unlike traditional emergency rooms, it has no inpatient beds. Patients who need hospitalization or surgery are transferred by ambulance to surrounding hospitals. Experts say that HealthPlex, which opened in 2001 and is designed to divert patients from the ERs Inova operates at other Virginia hospitals, is an innovative, patient-friendly response to overcrowded ERs.