A Physicochemical Acid-Base Approach for Managing Diabetic Ketoacidosis

Diabetic ketoacidosis (DKA) is one of the most serious acute metabolic complications of diabetes. It is characterized by the biochemical triad of hyperglycemia, ketonemia/ ketonuria, and an increased anion gap (AG) metabolic acidosis. Unless it is relatively mild, DKA is usually managed in the intensive care unit (ICU), and treatment involves a continuous infusion of intravenous (IV) insulin, correction of water and electrolytes deficits, and treatment of the underlying precipitating factors. Patients are commonly discharged from the ICU when criteria of DKA resolution are met (glucose < 200 mg/dl, serum bicarbonate ≥ 18 mEq/l, venous pH > 7.3 and calculated AG ≤ 12 mEq/l) and an IV insulin infusion is no longer necessary. However, serum bicarbonate levels have serious limitations as a surrogate of underlying metabolic disturbances (due to an interdependence with pCO 2 and it does not reveal, per se, the main acid responsible for the acidosis). Because hyperchloremic acidosis is a frequent complication of the treatment of DKA, it is not surprising that hyperchloremia retards the increase in bicarbonate and pH and, consequently, tends to prolong IV insulin infusion time and ICU stay. Taking a physicochemical approach to acid-base disorders could be useful in this setting because this approach allows for the quantification of circulating, unmeasured anions as well as the strong ion difference (SID). As a result, it becomes easier to detect the moment that DKA has been resolved and the magnitude of hyperchloremic acidosis (see below). We describe the case of a young female patient admitted to our ICU with DKA and demonstrate how useful the physicochemical approach was in the management of her case.