[Metabolic alkalosis on the surface but metabolic acidosis in depth].
Our purpose in writing this article is to emphasize the acid-base consequences and total body imbalances which follow the selective depletion of HCl. The initial body balance is an equimolar deficit of chloride and gain of bicarbonate. Within a short period of time, body balance changes; the net deficits are closer to equimolar losses of potassium and chloride. Since the loss of potassium occurred without the simultaneous loss of existing body anions (chloride or phosphate), this negative balance of potassium is accompanied by an equimolar gain of hydrogen ions. Thus when the negative balance is that of KCl, acid-base balance is present but there is a surplus of bicarbonate in the extracellular fluid (ECF) together with an equal surplus of hydrogen ions in another compartment (the intra-cellular fluid (ICF)). Moreover, if the ECF volume is contracted, a more severe degree of acidosis of the ICF may occur due to a higher PCO2 in venous blood. Given the acid-base balance and a deficit of KCl, one should not view this disorder as being "corrected" by saline at any time other than in the acute phase before a large potassium deficit occurs. Sodium chloride should be restricted to repair a deficit of sodium chloride. The emphasis on therapy is obviously to replace the deficit of KCl.