Steps for first aid: First, check the patient’s response. If the patient is unresponsive and is not breathing, or cannot breathe normally, you need to call the emergency number immediately. Then check the pulse, and if the aorta is palpable, perform artificial respiration only, every 5-6 seconds, and check the pulse every two minutes. If the aorta is not touched, then chest compressions and artificial respiration are required, with a frequency of at least one hundred chest compressions per minute and a ratio of compressions to artificial respiration of 30:2.