QUANTITATION OF LYMPHATIC DRAINAGE OF THE PERITONEAL-CAVITY IN SHEEP - COMPARISON OF DIRECT CANNULATION TECHNIQUES WITH INDIRECT METHODS TOESTIMATE LYMPH-FLOW

Objective: It has been suggested that lymphatics may contribute to ult rafiltration failure in patients on continuous ambulatory peritoneal d ialysis (CAPD) by absorbing dialysate and ultrafiltrate from the perit oneal cavity. In most studies lymphatic drainage has been estimated fr om the disappearance of an instilled tracer from the peritoneal cavity or estimated from the appearance of an intraperitoneally administered tracer in the bloodstream. However, in sheep it is possible to cannul ate several of the relevant lymphatics that drain the peritoneal cavit y and assess lymph drainage parameters directly. The purpose of this s tudy was to estimate lymph drainage from the peritoneal cavity in shee p using the disappearance of tracer from the cavity and the appearance of intraperitoneally instilled tracer in the bloodstream and to compa re these results with those obtained from our previous studies using c annulation techniques. Design: Experiments were performed in anestheti zed and nonanesthetized animals. Volumes of 50 mL/kg of Dianeal 4.25% containing 25 mu Ci of I-125-albumin were infused into the peritoneal cavity. Results: In anesthetized sheep the calculated peritoneal lymph drainage from monitoring the disappearance of tracer from the periton eal cavity over 6 hours was 1.873+/-0.364 mL/kg/hour. Monitoring the a ppearance of tracer in the blood gave significantly lower peritoneal l ymph flow rates of 1.094+/-0.241 mL/kg/hour. Directly measured lymph f low rates from our earlier publication were lower still and ranged fro m 0.156+/-0.028-0.265+/-0.049 mL/hour/kg, depending on how we estimate d the right lymph duct contribution to peritoneal drainage, since we c ould not cannulate this vessel. We repeated these experiments in consc ious sheep. The value for lymph flow estimated from the disappearance of tracer from the peritoneal cavity was 2.398+/-0.617 mL/hour/kg and from the appearance of tracer in the blood, 1.424+/-0.113 mL/ hour/kg. The lymph flow rates monitored from indwelling lymphatic catheters ra nged from 1.021+/-0.186 1.523+/-0.213 mL/hour/kg (again, depending on our estimates for the right lymph duct). Conclusions: Lymph flow rates measured from indwelling lymphatic catheters provided the most conser vative values for lymphatic drainage of the peritoneal cavity under di alysis conditions. Estimates of lymphatic drainage based on the appear ance of tracer in the blood gave values that were on average higher. T he method using the disappearance of tracer from the cavity to estimat e lymph flows overestimated peritoneal lymph drainage. Fluid was lost from the peritoneal cavity, and the estimated proportion of liquid los t through lymphatic drainage depended on the technique used to measure lymph flow rates.