Hyperchloraemic metabolic acidosis during plasma volume replacement

Objectives: Review of the physiological and clinical consequences of hyperchloraemic acidosis observed during plasma volume replacement using crystalloids and colloids. Data sources: Data were searched in the Medline(R) database after 1990 using the following key words: metabolic acidosis, crystalloids, colloids, albumin, gelatin, hydroxyethyl starch. Data extraction: Publications before 1990 were selected for their historical value. Most of articles published after 1990 and all types including case report were accepted. Data synthesis: Large volume infusion of isotonic solution can cause hyperchloraemic acidosis. Colloid plasma substitutes using saline solvent may be responsible for the same kind of acidosis with acidaemia. The anion gap is not modified in this case because of chloride increase. Physiological mechanism may be described using the Henderson-Hasselbach equation or the strong ion difference decrease (Stewart concept). Excessive chloride infusion is a major factor in this acid-base disorder and the term hyperchloraemic acidosis should be preferred to dilutional acidosis. When perioperative acidosis occurs, careful and complete analysis of acid-base disturbance should be made. The association of a normal anion gap, normal lactatemia, hyperchloraemia and acidaemia does not need specific treatment. Acidosis corrects spontaneously and slowly following chloride normalization. But any factor that may increase acidosis should be avoided. Conclusion: The use of balanced solution like lactated-Ringer solution instead of isotonic saline solution for fluid resuscitation, except for specific contra-indication as intracranial hypertension, may avoid hyperchloraemic acidosis. Potential risk of this acidosis led to the conception of a new colloid using balanced crystalloids solution as the solvent (Hextend(R)). (C) 2002 Editions scientifiques et medicales Elsevier SAS.