If cardiac arrest is detected during CPR, you should immediately begin cardiopulmonary resuscitation, which is an emergency rescue measure mainly used to maintain blood supply to vital organs such as the brain and heart in the event of cardiac arrest, as well as to promote gas Exchange to restore heartbeat, breathing and consciousness as quickly as possible.

First, you should perform chest compressions. The compression site is usually at the intersection of the middle and lower 1/3 of the sternum and the front midline, which is the midpoint of the line connecting the two nipples (sometimes not applicable to female patients), or the two transverse fingers above the xiphoid process (the lower half of the sternum). Touch the pressing point with the heel of your left hand (or right hand), overlap your right hand (or left hand), and press with both hands perpendicular to the chest wall. When pressing, lean your upper body forward, straighten your wrists, elbows, and shoulder joints. Use the hip joint as the fulcrum, press vertically downward, and use the gravity of your upper body to press. The depth of each compression should be 5 to 6 centimeters, and the frequency of compressions should be 100-120 times per minute. When compressing, observe the patient's complexion and reaction. The time of each compression and relaxation should be roughly equal to allow the chest to fully rebound, and the compression interruption time should not exceed 10 seconds.

Secondly, after completing 30 heart compressions, you need to start opening the airway and perform artificial respiration. Open the airway so that the line between the tip of the mandible and the ears and lips is perpendicular to the ground, then pinch the patient's nasal cavity, fully wrap the patient's lips, blow hard for more than one second, and blow a second time after an interval of one second. Seeing the patient's chest rise and fall indicates that the insufflation was successful. After two artificial respirations, continue 30 heart compressions, and repeat until medical professionals arrive or the patient returns to spontaneous circulation.

Throughout the process, stay calm and perform CPR steps quickly and accurately. At the same time, call the emergency number as early as possible so that professional medical personnel can rush to the scene as soon as possible. Remember, CPR is an emergency rescue measure. It can win valuable rescue opportunities for patients, but it cannot completely replace professional medical treatment. Therefore, during CPR, it is necessary to continuously observe the patient's condition and be ready to take further first aid measures at any time.