A manually-operated external device (a hand-powered pump) designed to be applied to the chest of a patient suffering cardiac arrest so that a healthcare professional or layperson can administer rhythmic compression to the chest in the region of the heart to provide blood flow during cardiopulmonary resuscitation (CPR). It typically consists of central piston, a soft but firm base, (a ring) that contacts the chest, a strong spiralled spring that transfers the users applied force to the piston, and a large handle for the user's hands. The compression force can be adjusted to a pre-set load to achieve equal delivered compressions to prevent damage to the ribs/organs. This is a reusable device.