The use of codes is intended to convey essential information quickly and with minimal misunderstanding to staff while preventing stress and panic among visitors to the hospital.
Such codes are sometimes posted on placards throughout the hospital or are printed on employee identification badges for ready reference.
Other codes, however, only signal hospital staff generally to prepare for the consequences of some external event such as a natural disaster.
When called overhead, the page takes the form of "Code blue, [floor], [room]" to alert the resuscitation team where to respond.
Every hospital, as a part of its disaster plans, sets a policy to determine which units provide personnel for code coverage.
In theory any medical professional may respond to a code, but in practice, the team makeup is limited to those with advanced cardiac life support or other equivalent resuscitation training.
In some hospitals or other medical facilities, the resuscitation team may purposely respond slowly to a patient in cardiac arrest, a practice known as "slow code", or may fake the response altogether for the sake of the patient's family, a practice known as "show code".
[citation needed] "Plan blue" was used at St. Vincent's Hospital in New York City to indicate arrival of a trauma patient so critically injured that even the short delay of a stop in the ER for evaluation could be fatal; "plan blue" was called out to alert the surgeon on call to go immediately to the ER entrance and take the patient for immediate surgery.
[citation needed] "Doctor" codes are often used in hospital settings for announcements over a general loudspeaker or paging system that might cause panic or endanger a patient's privacy.
[citation needed] Specific to emergency medicine, incoming patients in immediate danger of life or limb, whether presenting via ambulance or walk-in triage, are paged locally within the emergency department as "resus" [ri:səs] codes.