Compressions refer to the act or process of pressing or squeezing something to reduce its size, volume, or space. In a medical context, particularly CPR (cardiopulmonary resuscitation), compressions specifically mean applying pressure on the chest to help restore blood flow when someone's heart has stopped or they are not breathing. For CPR, compressions involve placing the hands on the center of the chest and pushing down hard and fast to a depth of about 2 inches (5 centimeters) for adults, at a rate of 100 to 120 compressions per minute. This is critical to circulate blood to vital organs until normal heart function can be restored or emergency help arrives. Outside medical use, compression generally means pressing or squeezing something to make it smaller or more compact, such as compressing data files or materials.
