The ABC of first aid is a mnemonic designed to help people remember how to respond to an emergency situation in which someone is injured. There are many other mnemonics and variants, but it is probably the most useful one for lay people to remember. The letters stand for Airway, Breathing, and Circulation, also referred to as the vital signs. If all of the vital signs are monitored and addressed, a patient has a much better chance of surviving until trained help arrives.
Some emergency services prefer the variant DRABC, to remind people to check for danger in a situation before assisting someone. The DR stands for Danger and Response, and means that people should first examine the environment and then the patient to ensure that there is not a source of potential physical danger. For example, an unconscious patient next to a live wire should be treated, but not until the live wire has been turned off or the patient can be moved out of the way, to ensure that the responder is not injured as well.
When using the ABC of first aid, the first thing for a responder to do is check the patient's airway. If the person's throat is blocked, he or she will be unable to breathe. A person who is conscious should be asked to speak; if he or she cannot, then the airway may be obstructed. If the patient is unconscious, the responder should lift his or her chin and tilt the head back carefully, remembering that any rough movements could aggravate unknown spinal and neck injuries. The responder should then sweep the back of the mouth with a finger to check for debris.
Breathing is next. The responder should place his face close to the patient's mouth to listen and feel for breathing, or use an object like a mirror. If the patient is breathing, the breath will condense on the mirror. A patient who is not breathing needs to be treated quickly. When the heart is beating but the patient is not breathing, the responder should administer rescue breathing until the patient is breathing again or help arrives.
Finally, circulation should be checked by monitoring the patient's pulse at the wrist or throat. In addition, the responder should check the patient's color. If he or she is pallid or has splotchy areas of color, it suggests that the circulation may be compromised. The person who is providing treatment should try to keep the patient warm.
If all of the steps of the ABC of first aid are satisfied, responders can move on to a general assessment of the patient, looking at injuries and their severity. Responders constantly check the vital signs while they work on the patient, to ensure that the patient is still stable. At this point, there are a plethora of options, depending on the patient's condition. An untrained individual who is first on the scene should just try to make sure that the patient is breathing and apply pressure to obvious sites of bleeding.