Diaphragmatic lymph vessel drainage of the peritoneal cavity

We have studied the drainage of peritoneal fluid through the diaphragmatic lymph vessels in sheep. To measure the lymphatic flow rate, we cannulated the lymphatic vessels and timed the flow from the cannula. After we infused Escherichia coli endotoxin into awake sheep, the diaphragmatic lymph flow rate increased substantially. However, we found no increase in lymph flow in anesthetized acutely operated sheep. This indicates that studies in anesthetized animals may yield underestimates of diaphragmatic lymph flow. In sheep, many of the diaphragmatic lymph vessels drain to the caudal mediastinal lymph node. We cannulated an efferent vessel from that node in 5 sheep. Several days later we infused 100 ml/kg of Ringer's solution into the abdominal space of each awake sheep. In response, the lymph flow rate increased from 0.15 +/- 0.16 ml/min (mean +/- SD) to 0.50 +/- 0.17 ml/min. Our results are important because they demonstrate that diaphragmatic lymph flow increases substantially after fluid infusions into the abdominal space.