Is lactate an energy substrate in the intensive care unit?

Abstract

Glucose is an energy substrate because its total oxidation to CO₂ and H₂O allows the synthesis of adenosine triphosphate (ATP). Glucose is converted to pyruvate and lactate during its metabolism. If not oxidized by the mitochondria to produce ATP, pyruvate and lactate leave the cell. They can then spread to other cells where they are converted into glucose or oxidized in the mitochondria. From a biochemical point of view, pyruvate and lactate are thus carbohydrates perfectly usable for energy metabolism. Compared to glucose, lactate is easily metabolized by all tissues even in situations of insulin resistance. It requires no activation step by ATP and prevents the deleterious effects of hypoglycemia. In addition, sodium lactate is an alkalizing solute with anti-edematous properties. Furthermore, hypertonic sodium lactate solutions have good capacity for intravascular volume expansion. This review attempts to promote lactate and its use in the intensive care unit.