Removal of abdominal sources of caudal mediastinal node lymph in anesthetized sheep

We investigated the conditions for and the quantity of abdominal contributions to caudal mediastinal node (CMN) efferent lymph in 15 anesthetized sheep with open thorax and lung lymph fistulas. Contractions of the diaphragm by phrenic nerve stimulation increased lymph flow by 29%. Adding large volumes (10 ml/kg) of 5% albumin solution to the peritoneal cavity increased lymph flow by 19 and 28% during diaphragm contraction. Tracer albumin specific activity in lymph indicated that about half the lymph flow increment came from the peritoneal liquid. Raising hepatic vein pressure 19 cmH2O increased CMN lymph flow 178%. Lymph protein concentration also increased markedly, from 0.72 to 0.91 of the plasma concentration. We devised a simple procedure to cauterize across the pleural surface of the diaphragm to destroy the aberrant lymphatics. This procedure markedly diminished both abdominal cavity and portal system contributions.