The pattern of high values of [HCO3-] and pCO2 occurring together suggests either a metabolic alkalosis or a respiratory acidosis (or both). If pCO2 is over 60mmHg, the metabolic alkalosis is either very severe or there is a mixed disorder with a respiratory acidosis.
Metabolic alkalosis is suspected if one of the known causes of the disorder is present especially vomiting, nasogastric suction, pyloric obstruction, excess mineralocorticoid syndromes or diuretic use.
The delta ratio can be a useful adjunct in detecting the presence of a second acid-base disorder in patients with a metabolic acidosis. In patients who have a metabolic acidosis and a chronic metabolic alkalosis the delta ratio has a value greater then 2. Such a high value can also occur in patients with a pre-existing chronic respiratory acidosis because the bicarbonate is also elevated in that disorder as well. Because of potential errors, the delta ratio should be assessed cautiously.