Circulation external chest compression >High-irequency(100 compressions per min) aortic pressure myocardial perfusion pressurer cardiac outputs T cise survivalrate reduce interrupted compression( compression ventilation ratio simplified to 15: 2 )Compression-only CPR: unwilling or unable to perform mouth to mouth or cardiogenic cardiac arrestCirculation —external chest compression ➢High-frequency（100 compressions per min） aortic pressure ↑myocardial perfusion pressure↑ cardiac outputs ↑ rise survival rate ➢Reduce interrupted compression ( compression – ventilation ratio simplified to 15:2) ➢Compression-only CPR: unwilling or unable to perform mouth to mouth or cardiogenic cardiac arrest