The purpose of first aid is to prevent the patient getting worse and this can be performed with some simple, easy skills. Before entering into a rescue scene, the rescuer should perform an initial assessment to ensure that the scene is safe. Next, personal protective equipment should be worn to protect the rescuer. The ABCD concept is designed to give the rescuer a guide of what to do, in what order, during a first aid emergency when the person is unconscious.
First of all, there is "A". This stands for the Airway, which starts at the mouth and nose and ends at the lungs. It is very important that this is not blocked, as it delivers oxygen to the lungs. You can check that it is not blocked by opening the airway. This is done by tilting the head back and lifting the chin. After this, you must check to see if the person is breathing. You need to Look, Listen and Feel for any signs of breathing for 10 seconds. If they are not breathing you must commence CPR and check for Circulation, which is what C stands for. You can do this by checking what is called capillary refill. Gently but firmly push the blood in the thumb towards the body. If the blood returns in 2 seconds then there is adequate circulation.
The next thing the patient needs is "D" - Defibrillation, where an electric shock interrupts a cardiac arrest and hopefully allows the heart to start again.
If alone, the rescuer may need to put the patient into the recovery position, whilst leaving to contact emergency services, if the patient is breathing. If the patient is not breathing, call the EMS and then perform CPR. The recovery position allows the patient to breathe easily, stay safe, whilst removing the risk of them choking, should they vomit.