The Collaborative International Dictionary
Plethysmography
Plethysmography \Pleth`ys*mog"ra*phy\, n. (Physiol.) The study, by means of the plethysmograph, of the variations in size of a limb, and hence of its blood supply.
Wiktionary
plethysmography
n. (context medicine English) The diagnostic use of a plethysmograph.