The flow and composition of pulmonary and systemic lymph in dogs with edema

In animals with edema, pulmonary and systemic lymphatics may function to remove accumulated extravascular fluid in addition to responding to events as they occur in the exchanging vessels. We tested this hypothesis by measuring the flow rate and composition of thoracic duct and right duct lymph in anesthetized dogs made edematous by rapid fluid infusion. During a fluid challenge equivalent to 30% of body weight, thoracic and right duct lymph flow rates increased 30- and 60-fold, respectively. After the infusion, lymph flow rates rapidly decreased even though the dogs were edematous. During the postinfusion period, the decrease in right duct lymph flow rate was directly related to a decrease in estimated net pulmonary fluid filtration pressure. We conclude that lymph flow rate and composition reflect events occurring in the microvasculature whether or not edema is present.