After studying the idea for more than a year, the city of New Orleans is negotiating to buy Methodist Hospital and open an emergency room that would serve residents of neighborhoods deprived of critical health services since Hurricane Katrina. State Sen. Ann Duplessis, whose district includes eastern New Orleans, said the city hoped first to re-establish emergency services at the hospital, which has stood vacant since Katrina flooding. Residents of the east have had to travel far during medical emergencies, distances that could prove catastrophic for those in critical condition.