Implantable Peritoneal Ultrafiltration Device: A Novel Fluid Decongestion Approach

Background: Diuretic therapies aiming to enhance fluid removal in chronic HF are limited due to diuretic resistance in about 30% of the patients. Intravenous diuretics and ultrafiltration as alternatives are associated with side effects, multiple visits and cost. We suggest a novel continuous peritoneal ultrafiltration approach, in which extracellular fluids are slowly prompted through the peritoneal membranes by a fully implantable device towards the urinary system. This work tested long term performance and scalability of the concept.

Methods: A flat disk shaped absorption chamber covered by semi-permeable membrane was implanted intraperitoneally in twelve rats (405±33 gr.). Two control rats where implanted with peritoneal dialysis catheter. Extracorporeal drainage and sampling of fluids by induction of intermittent hydrostatic vacuum were conducted for 4-6 weeks followed by histopathological analysis.

Large model was tested with a fully implantable device in 4 pigs (69±4.5kg) up to 6 weeks. At sacrifice, drainage rate at congestion was assessed in one animal by induction of acute venous overload.

Results: In rats, isotonic extracellular fluid was drained at an average rate of 3.2±0.5 cc/kg/hour during follow up period. Unlike designated membrane based chambers, catheters drained 25 folds less per square centimeter. In pigs, the average drainage rate after follow-up was 8±1.6 ml/hr and 210±109 ml/day throughout follow-up period. Overloading CVP acutely from 7 to 16mmHg has doubled drainage rate.

Conclusions: Implantable absorption chamber enables durable systemic extracellular fluids removal through the peritoneal membranes, suggesting of a novel non-aggressive therapy for congested HF patients.