Loss of consciousness is judged by tapping the patient’s shoulders and calling out loudly. Secondly, to determine the respiratory condition, some patients have a complete interruption of respiration in cardiac arrest, and some patients may show sigh-like jaw breathing. Third, to determine the loss of large arterial pulsations, including the carotid, radial, brachial or femoral arteries, the most commonly palpated is the carotid artery, which is located in the depression between the cricoid cartilage and the sternocleidomastoid muscle. If there is trauma to the neck and the carotid artery cannot be palpated, then consider palpating other parts of the great arterial vessels. The diagnosis of cardiac arrest can be satisfied by quickly determining the above three conditions within ten seconds.