Continuous arteriovenous hemofiltration: an alternative to hemodialysis.

An introduction to the procedure of continuous arteriovenous hemofiltration (CAVH) for management of acute renal failure, as well as a review of hemodialysis, is presented. Initially developed for the management of hemodynamically unstable patients with acute renal failure, CAVH now is also used for management of fluid overload and acid-base disturbances resulting from conditions such as acute pulmonary edema, congestive heart failure, septic shock, and oliguric states in which pharmacologic or parenteral nutrition therapy necessitates administration of large volumes of fluids. CAVH, in contrast to hemodialysis, does not typically involve use of blood pumps but uses the patient's own mean arterial pressure to generate a driving force across the hemofilter membrane. CAVH, like hemodialysis, can remove excess fluid and uremic toxins; however, fluid removal by CAVH is characterized by the slow, continuous process of ultrafiltration and thus avoids the risk of hypotension, muscle cramps, or disequilibrium syndrome. Furthermore, CAVH does not require fluid restriction, allowing for increased administration of parenteral nutrition and intravenous medications; neither does it require expensive equipment or highly trained personnel. Although CAVH membrane materials may differ, they all permit the removal of plasma water and non-protein-bound solutes with molecular weights less than 10,000. To prevent blood from clotting in the hemofilter, most patients will require administration of heparin, which in some patients may increase the possibility of hemorrhaging. CAVH also can remove pharmacologic agents from the blood; however, only the non-protein-bound fraction of the drug has the potential to be cleared from the bloodstream by CAVH.(ABSTRACT TRUNCATED AT 250 WORDS)