The effect of lymphatic fluid protein concentration on lymphatic resistance

Abstract

Edema, increased tissue fluid volume, may be caused by impaired lymphatic system return. This edema formation inhibits organ function. We hypothesized that increased lymphatic fluid protein concentration would cause increased resistance to flow through lymphatic vessels. Mesenteric lymphatic vessels in anesthetized sheep were catheterized at both ends and connected to polyethylene tubing that functioned as inflow and outflow ports. Outflow pressure and, thus, the end-to-end pressure gradient were manipulated by altering the height of the outflow port. Two fluids - lactated Ringers solution and 6% albumin in lactated Ringers solution - were introduced alternately into the vessels. Flow through the vessel was determined for several pressure gradients. We calculated the resistance for each solution using the inverse of the slope of the flow-pressure gradient relationship. The calculated resistance for the Lactated-Ringers solution was 1.796 ± 0.213 mmHgṁin/ml while the resistance for the 6% albumin solution was 1.911 ± 0.154 mmHgṁin/ml. The resistance calculated for the 6% albumin solution was greater in all experiments, however the difference in resistance between the two solutions was not statistically significant (P = .201). We conclude that the number of experiments included in this study was insufficient to resolve the nature of the relationship between protein concentration and resistance in lymphatic vessels.