PULMONARY LYMPH: DEMONSTRATION OF ITS HIGH OXYGEN TENSION RELATIVE TO SYSTEMIC LYMPH.

Summary Po2 in right lymph duct of 15 anesthetized dogs averaged the same as in arterial blood (75 ± 18 mm Hg); Po2 in thoracic duct lymph was close to that in mixed-venous blood (34 ± 20 mm Hg). Allowing for admixture of systemic lymph in the right duct, Po2 in lymph from the respiratory portion of the lung must fall between alveolar gas and arterial blood. The marked difference from thoracic duct lymph P02 (p<.001) supports the concept of lymph as a useful measure of Po2 in interstitial fluid and tissues. Use of mixing equations shows that during air breathing respiratory (i.e., gas-exchanging) tissues contributed at least 53% of right duct lymph flow.