The effect of positive end expiratory pressure on thoracic duct lymph flow during controlled ventilation in anesthetized dogs

Abstract

Changes in thoracic duct lymph flow were measured in 8 anesthetized dogs during ventilation with positive end expiratory pressure (PEEP) (15cm H2O). Central venous pressure, intrapleural pressure, heart rate, and arterial pressure were also measured. Lymph flow decreased during PEEP (from a control value of 0.55 ± 0.15 ml/min to 0.17 ± 0.17 ml/min). Following release of PEEP, lymph flow rates were higher than the control value (0.55 ± 0.15 ml/min to 1.29 ± 0.45 ml/min) and returned to control value after 30 min. The authors conclude that PEEP obstructs lymph return and hypothesize that lymph may accumulate in the extrathoracic interstitium. Further, they postulate that this accumulation may contribute to water retention with prolonged PEEP.