In the process of CPR for patients with sudden respiratory arrest, the frequency and depth of compressions are important. A normal human heartbeat should be 60-100 times per minute, and for a patient in sudden respiratory arrest, the frequency of compressions should be no less than 100 times per minute, because even a formally trained internist or emergency physician can fail to perform some compressions or invalid compressions in the process. Therefore, the number of compressions should be increased appropriately, but not too much, if more than 120 times per minute, the heart does not get enough diastolic contraction, and therefore also belongs to the invalid compressions. On the contrary, if the compression frequency is too low, it will lead to insufficient heartbeat, so that the blood pumped out of the heart can not meet the oxygen supply of the heart, brain, kidneys and other important organs. As for the depth of compression, the previous requirement of 3-5 centimeters, later required more than 5 centimeters, now requires the depth of compression is not less than 5 centimeters, it can be seen that the depth of compression in about 5 centimeters, the patient’s thorax can get the maximum degree of compression, not only to protect the sternal ribs from breaking, but also for the heart can have a good stimulating effect.