ABSTRACT
Plethysmography is a term for a set of noninvasive techniques for measuring volume changes in parts of the body, or even the whole body. The more frequently measured volume changes are those caused by breathing (lung and chest expansion), those due to blood’s being forced into arteries, veins and capillaries of the legs, arms, hands and feet by the pumping of the heart, and the volume change of the heart itself as it pumps. It is also possible to measure local volume changes in arms and legs as muscles contract.
