Continuous hemofiltration/hemodiafiltration in critical care

Continuous hemofiltration and continuous hemodiafiltration (CHF/CHDF) were developed as continuous renal replacement therapy for patients with severe conditons and has come to be widely performed mainly in critical care, taking the place of intermittent hemodialysis. The membrane pore size of a hemofilter used for CHF/CHDF allows passage of substances ranging from 30,000 to 50,000 Da, and the method for solute removal in CHF/CHDF employs the principle of convection, which is advantageous for removing middle- to high-molecular-weight substances. As apheresis therapy to remove pathogenic substances in blood, CHF/CHDF is therefore being investigated for its possible effect on various morbid conditions. It has recently been found that CHF/CHDF removes humoral mediators including cytokines, particularly in severe systemic inflammatory response syndromes such as septic shock and severe acute pancreatitis. CHF/CHDF is thus beginning to be performed for the prevention and treatment of organ dysfunction secondary to septic shock, trauma, or acute pancreatitis. CHF/CHDF is also efficacious as artificial liver support in preventing adverse effects caused by plasma exchange (PE) and for continuous removal of hepatic coma-inducing substances. CHF/CHDF is effective for various morbid conditions not only as renal replacement therapy, but also as apheresis therapy and is expected to be applied more widely in critical care in the future.