In an effort to reverse the trend of people killed because of medical errors, some hospitals like Baptist Children's Hospital in Miami are taking steps to admit grievous mistakes and to learn from them in order to overhaul flawed procedures. That represents a sharp departure from hospitals' traditional response when something goes terribly wrong: Retreating behind a wall of silence to guard against potential lawsuits. Now, some hospitals are hoping to stem the tide of lawsuits by being more open with aggrieved patients and their families.