The role of lymphatic drainage in peritoneal mass transfer

Peritoneal lymphatic drainage has recently been shown to be a contributing factor to both clearance and fluid removal patterns during continuous ambulatory peritoneal dialysis. In this report peritoneal transport equations are derived and compared and contrasted with existing models that ignore this term. It was found that for solutes for which the sieving coefficient may be assumed to equal unity, such as urea and creatinine, the values of the mass transfer area coefficient (KoA) are overestimated by the value of the lymphatic drainage rate. In this instance, corrected KoA may be obtained simply by subtracting lymphatic flow rate from the KoA calculated by traditional methods. For larger solutes, such as beta 2-microglobulin, for which the sieving coefficient may be assumed to equal zero, the value of mass transfer coefficient was underestimated to varying degrees; however, for values of lymphatic drainage rate less than 60 ml/h the effect will not be clinically measurable. A theoretical model is used to plot the dependence of net fluid removal on peritoneal lymphatic flow, glucose KoA, and hydraulic permeability. Reduction in net ultrafiltered volume, and hence estimation of transperitoneal ultrafiltration, is directly proportional to accumulated lymphatic drainage.