A Code Blue is a hospital-wide alert signaling that a patient is experiencing cardiac or respiratory arrest and requires immediate resuscitation. It's triggered when a patient stops breathing, loses consciousness due to cardiac arrest, or shows no detectable pulse. “Code Blue” is a term used in hospitals and healthcare facilities to indicate a life-threatening emergency situation in which a patient’s heart has stopped beating, he/she may have fallen unconscious or is unresponsive, etc., and they require immediate resuscitation. Learn what the different colors and codes mean in hospital emergencies, and how some states and organizations are adopting plain language alerts for consistency and clarity. Code Blue typically indicates a life-threatening medical emergency, such as cardiac arrest or respiratory failure. When emergencies arise at a hospital, a unique colour coding system is in place to communicate the type of crisis the medical staff should be preparing for. For example, a Code Blue indicates a cardiac arrest, immediately activating the essential responders and protocol required for such an event.