Managers at Washington Hospital Center and the nurses union are bracing for a planned strike Friday at the region's largest hospital, with managers flying in replacement nurses from all across the country and nurses seeking support from city officials. The nurses' contract expired last spring, and the two sides have been engaged in a rancorous dispute over wages, benefits, staffing and patient safety. The union represents about 1,600 nurses. If a strike takes place, the 926-bed hospital will be fully staffed, with all units open, according to an e-mail sent to hospital physicians Wednesday by Janis Orlowski, MD, the CMO at the facility. The job action is supposed to last a day, from 7 a.m. Friday to 7 a.m. Saturday. But hospital officials said they will lock out striking nurses for five days, meaning that they will not be allowed back to work until Wednesday and will not get paid for those days. Hospital officials said they are doing so because they are obligated to pay 600 replacement nurses for a minimum of 60 hours of work, typically five 12-hour shifts.