[Hydrogen ion metabolism and parenteral alimentation]

The necessity of using solutions and emulsions in parenteral nutrition of solutions directly utilisable by the cell has led to the manufactur of substances with a composition and physico-chemical nature which greatly alters H+ ions balance. Theoretical calculation and various experimental protocois have shown that the production of H+ ions may be multiplied by 3 or 4. This explains the complications of metabolic acidosis seen in association with prolonged parenteral nutrition. There are two main sources : lipid emulsions and amino-acid solutions. One litre of lipid emulsion may provide 37 to 60 mEq of H+ ions. According to their formula, amino acid solutions may consume, or more often provide, large amounts of H+ ions (up to 20 mEq/gram of nitrogen). These physiopathological concepts should be taken into consideration in defining the compositions of fluids for parenteral nutrition, in particular when renal function is impaired.