New method of extracorporeal concentration of ascitic fluid as a treatment of refractory ascites.

A new piece of equipment for the treatment of ascites is described. Ascitic fluid is drained by gravity in a unit consisting of an Amicon D-30 ultrafilter and a bag used as transit reservoir placed below the patient. When the bag is full, it is raised to a height sufficient to let the fluid flow back through the filter to the peritoneal cavity. Mainly during this step ultrafiltration of ascitic fluid occurs through the membrane of the filter. Ultrafiltration is enhanced by the negative pressure created in the filtrate compartment due to the height difference between filter unit and filtrate drainage bag placed at the bottom of the machine. Proteins in the ascitic fluid are retained and returned to the abdominal cavity. The machine cycle is automatically repeated as many times as necessary to achieve the scheduled patient weight loss. 17 patients have been treated for a total of 1.94 sessions/patient with reinfusion of the fluid in the abdominal cavity. In all patients a significant reduction of the amount of ascitic fluid and of its rate of formation have been achieved. The treatment was well tolerated and no side effects were observed. After treatment the diuresis and the sodium excretion increased significantly in all patients. The system is safe and reliable for the treatment of refractory ascites without major complications.