A doctor, who was leading the treatment of a 50-year-old man who jumped to his death at Princess Margaret Hospital on Monday night, met the bereaved family yesterday to explain how the man was being treated. The man, who suffered from chronic lung disease, had complained about the attitudes of the nurses and a malfunction of his oxygen hood before he jumped out of a window. A spokeswoman for the hospital said the duty nurse was taking care of another patient when the man jumped.