INCREASED ABDOMINAL LYMPH FLOW INCREASES LUNG LYMPHATIC OUTFLOW PRESSURE IN SHEEP

Abstract

We tested the hypothesis that increasedlymph flow from the abdominal organs wouldincrease the pressure within the thoracic ductat the thoracic duct-lung lymphatic junction.Cannulas were placed into the thoracic ductvia the caudal mediastinal (lung) node efferentlymphatics in 4 sheep. After the sheeprecoveredfrom the surgery, we monitored thethoracic duct pressure with pressuretransducers. To increase lymph flow from thelower body, we infused Ringers solution (59 ±19 [mean ± SD] mllkg body weight in 30 min.)intravenously into the sheep and we inflated aballoon in the inferior vena cava. Thistechnique causes substantial increases inlymph flow from the lower body (mainly fromthe liver and intestines) through the thoracicduct. During the infusions, the thoracic ductpressure increased significantly from 4.1 ± 2.9cm Hp (baseline) to 6.8 ± 1.7 cm Hp. Theneck vein pressure (pressure at the outflow ofthe thoracic duct) did not increase frombaseline (3.0 ± 2.6 cm H20). Thus our resultssupport the hypotheses that increased flowthrough the thoracic duct causes increasedthoracic duct pressure.