Push-pull sorbent based pheresis for treatment of acute hepatic failure: the BioLogic-detoxifier/plasma filter System

The BioLogic-DT (detoxifier) System is an extracorporeal blood treatment device that uses the membranes of a cellulosic plate dialyzer to propel blood in and out through a single lumen access (on a 12 sec cycle) and circulates a suspension of powdered charcoal and cation exchanger through the dialysate spaces to absorb many soluble toxins in the treatment of hepatic failure. The BioLogic-DTPF (detoxifier/plasma filter) System adds two Gambro plasma filters downstream from the plate dialyzer, which allows most of the blood plasma to pass out of the blood, contact powdered charcoal in a suspension, and then return to the blood during each 12 sec cycle (creating push-pull sorbent based pheresis). A roller pump exchanges charcoal suspension between the plasma filter case and a 700 ml bag of powdered charcoal suspension. At a blood flow rate of 150-200 ml/min, 100 ml/min of plasma moves bidirectionally through the plasma filter membranes. Direct contact of plasma with charcoal outside the plasma filter membranes removes creatinine with a clearance rate equal to plasma flow (100 ml/min); clearance of strongly protein bound toxins, such as unconjugated bilirubin, is lower (10-40 ml/min). In this article, the authors explain the mechanisms of operation of this system and present in vitro tests that define its chemical efficiency. Also described are potential problems, tests that indicate the severity of these problems, and monitors and algorithms to detect or avoid these problems in clinical use of the system. The results of the treatment of two patients with acute hepatic failure and coma using the BioLogic-DTPF System are reviewed.