On the competency of the venous valves and the venous flow in relation to changes in intra-abdominal pressure

In the present series of experiments performed upon dogs, the blood flow in the femoral vein was measured by means of the recording stromuhr, described by the author. 1

During the experiment the intra-abdominal pressure was suddenly raised either by pressure with the hands upon the external surface of the abdomen, or by inflation of the cavity with air.

In both cases a retardation of the venous inflow was noticed, the degree of the slowing of the blood stream being in accordance with the increase in the intra-abdominal pressure. Thus, in one specific instance the intra-abdominal pressure was raised to 70 mm. Hg. The venous pressure increased accordingly from 4.5 mm. to 64.0 mm. Hg, while the blood flow decreased from 1.02 c.c. to 0.08 c.c. per second.

A similar retardation occurred also with the chest widely opened. Raising the intra-abdominal pressure produced no marked influence upon the flow in the external jugular vein.

A more abrupt and decisive slowing of the blood stream occurred, when pressure was exerted with the hands. It then became possible at times to produce not only a stoppage of the flow, but also a slight backward movement, such as can be accounted for by the stretching of the venous valves.