Separate thoracic and abdominal lymph flow in the dog.

We present results from an improved dog model, in which lymph flows from the thorax and abdomen are separated. The effect of increased alveolar pressure on lymph flows was studied by the application of positive end expiratory pressure (PEEP). Mean (+/- SD) thoracic lymph flow in 10 dogs was 4.1 ml/h (+/- 2.9) before, and 27.0 ml/h (+/- 17) after the induction of lung damage with oleic acid. Thoracic lymph flow was depressed by 50% with the application of a PEEP of 1.0 kPa (10 cm H2O), both before and after lung damage, thus impeding the drainage of the lung tissue. Abdominal lymph flow increased from 57 +/- 29 ml/h to 111 +/- 65 ml/h with the application of a PEEP of 1.0 kPa. These simulated events in a surgical area demonstrate the risk of causing excessive edema with PEEP. We conclude that if the application of PEEP in a clinical situation is necessary then the additional risk factors (increased extravascular lung water, increased edema in surgical areas) that have been presented should be taken into consideration.