Volume changes in forearm and hand following release of obstruction to venous return

Observations were made on the changes that occur in the volume of the forearm and hand following the release of an obstruction to the venous return. The presence of three phases has been confirmed: a) a rapid primary decrement (P.D.) followed occasionally by b) an increase in volume (Hump), and finally c) a secondary decrement (S.D.) as the limb volume gradually returned to normal. It is suggested that the primary decrement in limb volume (P.D.) is largely venous in origin and is probably due to the rapid initial ejection of blood from the limb as the large veins recover their normal size and calibre. An index of venous distensibility is suggested which might provide a means of indirectly measuring venous tone.(AU)