The kinetics of ultrafiltration during peritoneal dialysis: the role of lymphatics.

Net ultrafiltration was measured directly during hypertonic peritoneal dialysis exchanges in rats. Simultaneously, lymphatic absorption was measured by monitoring the disappearance of albumin in the instilled dialysis solution from the peritoneal cavity. The albumin method for measuring lymphatic absorption was also tested in rats absorbing Lactated Ringer's solution from the peritoneal cavity where absorption rate could also be measured directly. The findings suggest the following: 1.) lymphatic absorption rate is similar with both hypertonic dialysis solutions and Lactated Ringer's solution; 2.) lymphatic absorption is substantial and net ultrafiltration is well below true transcapillary ultrafiltration; and 3.) in our model, lymphatic absorption occurs at a relatively constant rate over six hours of dwell time.