Delta gap changes should guide therapy in different cases of metabolic acidosis

ABSTRACT

Metabolic acidosis is associated with serious morbidities and mortality. Its diagnosis is difficult because it is frequently associated with mixed acid-base disorders and its clinical manifestations are often non specific or subclinical, which means that its diagnosis is made from laboratory and other diagnostic tests. The aim of this study was to use the delta gap for accurate interpretation of normal anion gap [AG] acidosis, high AG acidosis and if there was a coexisted metabolic disorders associated with the metabolic acidosis. Such diagnosis is beneficial in the management of each type of these metabolic disorders. Forty hundred and seventy nine measurements of acid-base changes were drawn from 479 ICU critically ill patients and patients with metabolic acidosis were selected. They were divided according to the aetiology of their acidotic condition into a renal failure group [n = 23] and a sepsis group [n= 26]. Arterial blood gases [ABG] were analyzed and the anion gap [AG] was calculated by arterial blood gas analyzer. In the renal failure group the incidence of metabolic acidosis was normal AG acidosis 9%, mixed [normal and high] AG acidosis 48% and high AG acidosis 43%, but there was no associated metabolic alkalosis. In sepsis group, 23% of the patients had normal AG acidosis, 42% of patients had mixed [normal and high] AG acidosis, 12% of patients had high AG acidosis and the remaining cases [23%] had an associated metabolic alkalosis. In conclusion, AG is important for differential diagnosis between normal and high AG metabolic acidosis. Delta gap is an important tool for diagnosing the mixed acid-base disorders associated with the metabolic acidosis. Such diagnosis is important as a guide to know when to use bicarbonates [HCO[3]] to treat metabolic acidosis