Mixed acid-base disturbances.

Mixed acid-base disturbances, defined as the simultaneous presence of two or more acid-base disorders, are commonly observed in hospitalized patients, especially those in critical care units. Certain clinical settings are commonly associated with mixed acid-base disorders, including cardiorespiratory arrest, sepsis, drug intoxications, diabetes mellitus, and organ failure (especially renal, hepatic, and pulmonary failure). As a general rule, the symptoms and signs of the underlying disease that gives rise to the observed mixed acid-base disorder dominate the clinical picture. The basic principles underlying the diagnosis of mixed acid-base disorders are identical to those required for the identification of simple acid-base disturbances. The management of mixed acid-base disturbances is aimed at restoring the altered acid-base status by reversing all the elemental components present, thus it encompasses the therapy of each simple acid-base disorder.