Pressure within the thoracic duct modulates lymph composition.

The amount of lymph received by the thoracic duct depends on each contributing organ's ability to produce interstitial fluid and generate a pressure differential moving lymph into the central lymphatic circulation. It has been reported that varying the pressure within the thoracic duct could alter each organ's contribution to thoracic duct flow. The thoracic duct above the diaphragm was cannulated to obtain lymph from the liver, gut, and lower body. Pressure within the thoracic duct was elevated serially by increasing the lymphatic cannula outflow height. This caused lymph protein concentration to increase while chyle concentration (measured by absorbance) decreased. The data demonstrate that as thoracic duct pressure increases, the percentage contribution of gut lymph flow (as represented by chyle concentration) decreases while the contribution of lymph originating within the liver (as indicated by higher protein concentration) increases. We conclude that pressure variation within the central lymphatic system affects the amount of lymph or edema fluid leaving any given organ.