A randomized controlled trial to evaluate the effect of sodium bicarbonate versus placebo on renal replacement therapy requirement in critically ill patients with severe metabolic acidosis and acute kidney injury

Metabolic acidosis is defined as a decrease in blood pH below 7.35 due to reduced serum bicarbonate levels with a compensatory fall in arterial carbon dioxide. It is a common finding in critically ill patients with reported incidence ranging from 8 to 64 percent in intensive care units. Persistent acidemia is linked to poor prognosis with mortality rates reaching up to 57 percent when pH remains below 7.20. Management focuses on treating the underlying cause, optimizing tissue perfusion, and supportive strategies including mechanical ventilation and renal replacement therapy. Because acidemia can impair cellular function, intravenous sodium bicarbonate has been considered as a therapeutic option to raise pH and improve outcomes.

Survey data from North America show that more than two thirds of program directors in nephrology or intensive care report using sodium bicarbonate for acidemia with hyperlactatemia. The BICAR ICU trial demonstrated that sodium bicarbonate infusion improved survival and reduced mortality up to day 28 in patients with severe metabolic acidosis with pH at or below 7.20 and acute kidney injury. It also increased days alive without renal replacement therapy. However, no overall benefit was seen in the unselected population. These findings suggest a possible role of sodium bicarbonate in specific subgroups, and further studies are needed to clarify whether this treatment can improve survival in larger cohorts with severe metabolic acidosis.