Acid-Base Balance in Hemofiltration

Abstract

Dietary intake and metabolism provide a number of potential sources of acid. Sulfur in the sulfur-containing amino acids is oxidized to sulfuric acid, phosphorus in proteins and phospholipids is converted to phosphoric acid, and organic acids may be produced in excess of the capacity to metabolize them. Since none of these products can exist in the body fluids as free dissociated acid, the hydrogen must react with the buffers of the body. Most of the extracellular buffering occurs by reaction of the acid with bicarbonate to yield the corresponding sodium salt and carbonic acid. The carbonic acid is then converted to water and carbon dioxide, the latter being excreted in the lungs. The net result is the replacement in the extracellular fluid of one equivalent of bicarbonate by one anion equivalent of the acid [1]. The buffer capacity of the extracellular fluid can be restored if bicarbonate is regenerated. In healthy people, this is accomplished by the Kidney. In patients with chronic renal failure (CRF) on maintenance therapy, bicarbonate regeneration must be achieved by the treatment technique.