A medical emergency is a medical condition that poses an immediate threat to someone's life of health if not treated quickly. A common example is the heart attack (myocardial infarction).
Emergency medicine is a specialization itself, dealing with these medical emergencies, and specialists are trained to handle such conditions, both inside and outside a clinic. Due to their nature, medical emergencies require very quick actions to be taken.
The first thing to be done, if possible, is activating the emergency medical services or calling a local emergency response service, if available. Many countries have such emergency response services that can be contacted by telephone -- the well know 911 in the US, for example, but also 999 in UK or 112 in many European countries.
Operators will demand some data such as:
- state of consciousness,
- name of the caller,
- name of the patient if known, etc.
Those who have no training for handling medical emergencies should take no medical action unless instructed to do so. The best they can do is usually to keep their calm and stay with the person requiring medical assistance. Crowding is usually to be avoided, unless the presence of more people is required. Evacuation requires expertise so it should be left to professionals, unless there is no other solution (for example, if the medical emergency occurs in the wild). Self transport should only go as far as the nearest emergency room.
In general, staff able to deal with average emergency situations exists in every hospital. Emergency medicine physicians are trained for dealing with most medical emergencies, maintaining ACLS and CPR certifications. In special cases like disasters, hospitals usually maintain protocols to allow them to gather their medical staff quickly enough.
Regardless of the nature of the medical emergencies, there is a protocol (the Advanced Cardiac Life Support) that is always respected. These protocols ensure that the proper actions are taken, by setting various guidelines referring to how interventions should be made.