Active pumping in postnodal lymphatic vessels is an important factor i
nfluencing lymph flow. However, the output of the lymphatic PumP also
depends on the rate of flow into the pump. This arrangement is similar
to the blood circulation where cardiac output depends on the rate of
blood flow through the veins into the heart (venous return) and on the
pumping characteristics of the heart itself (cardiac function curves)
. One common way to analyze the blood circulation rate is to interrela
te venous return and cardiac function curves. In this study, we used a
similar technique to analyze lymph flow. We used lymphatic flow vs. o
utflow pressure (passive flow) relationships for nonpumping lymphatics
to represent the inflow of lymph to the lymphatic pump. We used data
on the pumping characteristics of postnodal lymphatic vessels to gener
ate relationships between lymphatic pump outflow and pump inflow press
ure (pump function curves), and then interrelated these curves. The re
sults were not only similar to previously measured lymph flow data obt
ained from experimental animals, but also support the observation that
under normal circumstances lymph flow is periodic and in surges (acti
ve pumping) but in edematogenic states lymph flows more continuously (
i.e., passively).