CPR, or cardiopulmonary resuscitation, involves compressions at a faster rate of 100-120 compressions/minute, which is equivalent to nearly 2 compressions per second. The depth of compression should be 4-6cm, which refers to the frequency and depth of compression for adult CPR. Pressure position in the sternum in the middle of the sternum upper 2/3 and lower 1/3 junction, the palm of the hand on the chest wall and the other palm overlap, vertical downward pressure. Clinical resuscitation of patients, a little weak nurses or girls, press 1-3 minutes or so feel tired, so CPR is physical work.