"Code Red," "Code Blue," "Code Black" -- people sometimes wonder what these terms mean, especially if they're fans of TV hospital dramas.
Technically, there's no formal definition for a code, but doctors often use the term as slang for a cardiopulmonary arrest happening to a patient in a hospital or clinic, requiring a team of providers (sometimes called a code team) to rush to the specific location and begin immediate resuscitative efforts.
Each hospital or clinic can decide how it wishes to manage and inform staff of potential emergencies. Many institutions use colors (e.g. Code Red, Code Blue) to identify specific types of emergencies. Code Red and Code Blue are both terms that are often used to refer to a cardiopulmonary arrest, but other types of emergencies (for example bomb threats, terrorist activity, child abductions, or mass casualties) may be given code designations, too. Colors, numbers, or other designations may follow a code announcement to identify the type of emergency that is occurring.
Some hospitals announce emergencies over a public address system, while others just alert the necessary personnel via a pager system. Also, the use of the term "code" to signify that an emergency is occurring is not limited to medical practice. Other institutions, such as office buildings, schools, or government facilities, may use code designations to alert personnel that an emergency is occurring.
There are no standard definitions or conventions for the use of code designations. While code blue does refer to a cardiopulmonary arrest at many hospitals, it doesn't necessarily mean the same thing everywhere. But even if you aren't sure about the meaning of announcements you may hear, keep in mind that every hospital or institution has its own policies and conventions for notification of personnel in the event of emergencies, and the doctors and staff are trained to recognize and respond appropriately to these announcements.