First, Do No Harm (Situational Irony)
Doctors and nurses are bound to do everything they can to help their patients overcome whatever illness they are facing and to help them recover. Charles Cullen neither helped his patients overcome their illnesses nor helped them recover. Instead, he broke the code of ethics for medical professionals and murdered many people.
The Other Hospitals (Dramatic Irony)
When Charles Cullen is hired at his final hospital, readers know that he had a long history of leaving previous hospitals under suspicious circumstances. In fact, in many cases Cullen left the hospitals after he began to arouse suspicion because of the deaths of his patients (in most cases, most started an investigation into Cullen before he quit). The people at the hospital that hired Cullen, however, did not know about Cullen's tumultuous history.
Nursing (Situational Irony)
Most people go into the medical profession so they can help people and heal those who are ill. Charles Cullen went into the medical profession for a very different reason: to satiate his sick desire to hurt and ultimately kill people. A complex man, Cullen went into nursing for horrible, unethical, and evil reasons--reasons which no one would expect.
Hospital Law (Situational Irony)
Hospitals are in the business of making money by helping people recover from their injuries or illnesses. Laws governing hospitals aim for the same thing: to provide guiderails for hospitals so that people stay safe. Yet these laws did not allow some of Cullen's past employers to tell his future employers about their suspicions that he was killing patients, likely causing the death of several hundred people.
The Good Nurse (Verbal Irony)
The title of Charles Graber's book, The Good Nurse, is an example of verbal irony. Charles Cullen murdered over 400 of his patients and was the epitome of a bad, evil nurse--the direct opposite of a "good nurse."
