Effect of haemoperfusion on plasma paraquat concentration in vitro and in vivo

This study was to observe the paraquat (PQ) reduction rate after haemoperfusion (HP) on the groups of a relatively large number: 50 survivors out of 105 patients with acute PQ poisoning. We started off by measuring the clearance of haemodialysis (HD) and HP for the PQ in vitro. At the blood flow of 250 mL/min, the PQ clearance was greater in HP than in HD during the first 90 minutes: 215 versus 175 mL/min at 30 minutes, 213 versus 201 mL/min at 60 minutes, and 199 versus 179 mL/min at 90 minutes. The clearance in HP decreased rapidly after two hours. By the end of the dialysis, however, the final concentration in container decreased to 5.7 microg/mL in HD and 1.5 microg/mL in HP, which implied that although HD was cleared more effectively during the later stages, the overall elimination was greater in HP. Following this preliminary investigation, we performed HP on all the patients in order to assess the extracorporeal elimination. One hundred and five patients who had swallowed one to three mouthfuls of PQ (24.5% w/v) solution were subjected to the in vivo study. The reduction rate of PQ was checked out by measuring the PQ concentration in plasma before and after four hours of HP. Seeing the reduction rate was significantly higher in the survivors group than in the nonsurvivors group (80.3+/-19.9 versus 67.2+/-19.2%, P <0.01), we concluded that adequate HP appears to be an indispensable treatment for patients with acute PQ poisoning.