To determine respiratory arrest, there are usually five criteria: First, sudden loss of consciousness, which may be accompanied by convulsions. Second, pallor or cyanosis. Third, breathing becomes sigh-like or stops. Fourth, heart sounds and pulsations of the aorta are absent. Fifth, bilateral pupils are dilated. If in the hospital, the electrocardiogram will show ventricular or atrial fibrillation, ventricular arrest, or inactivity of the heart into a straight line. In order to save life in time, as long as the patient loses consciousness and the pulsation of the large arteries disappears, it can be judged as respiratory cardiac arrest.