In front of a packed room at a Senate hearing on Thursday, longtime nurse Ellen MacInnis recounted working at a Massachusetts hospital owned by Steward Health Care, the nation’s largest for-profit hospital provider. Her voice broke as she remembered the many times she and her colleagues couldn’t give their patients the very best care because Steward insisted on saving money: by laying off staff, cutting resources, and leaving medical supply bills unpaid. During one shift, MacInnis remembered, there were 95 patients in the emergency room and only 11 nurses; that day, she said, an elderly man awaiting chemotherapy treatment suddenly died in the ER.