Hyperchloremic Metabolic Acidosis: Is It Clinically Relevant?

SUMMARY “First, do no harm. ‘These words have been the doctrine of medicine since its inception. The era of evidence‐based medicine now compels us to provide scientific evidence that we indeed do no harm and that the treatments we prescribe have a beneficial effect. The colloid/crystalloid debate continues to evolve and is as hotly contested now as it was a decade ago. There may be some international differences in the use of colloids or crystalloids, but most of us continue to use both. Whatever our preferred choice of intravenous fluid for the treatment of hypovolemia, clinical outcome studies suggest that “when?” and “how much?” are probably more important questions than “what?”. There are now a wide variety of fluids available to the clinician and most differ markedly in their composition. Aside from the gross classification of IV fluids into colloids and crystalloids, they may be subclassified into balanced or unbalanced categories, i.e., those that contain concentrations of electrolytes similar to those in the plasma and those that do not (see Table 1).The very fact that “normal” saline is unphysiological was recognized many years ago. This fact led Alexis Hartmann to develop Hartmann's solution in an attempt to produce an isotonic alkalizing solution. He recognized the need for proportionately more sodium than chloride 1 , which led to a solution very similar to Ringer's original 2 . The existence of hyperchloremic acidosis has been recognized in many areas for some time, e.g., diabetic ketoacidosis and ammonium chloride poisoning, and is generally termed a low‐anion gap acidosis. There is now mounting evidence that the administration of intravenous saline and saline‐based fluids is the commonest avoidable cause of clinically relevant hyperchloremic acidosis.