Anesthesiology and Intensive Care

         Type A lactic acidosis is by far the commonest group and is usually due to tissue hypoxia caused by systemic or local hypoperfusion, increased glycolysis, reduced oxygen carrying capacity of the blood or reduced tissue oxygen delivery . Apart from excessive muscle activity, other causes of type A lactic acidosis are rare. The inadequate oxygen supply slows mitochondrial metabolism and leads to increased production of lactate from pyruvate. As a byproduct, NAD +  is regenerated so that glycolysis can continue. If hypoxaemia is the only factor, it must be severe to overwhelm the compensatory increase in tissue blood flow triggered by low PO 2 .

TREATMENT ALGORITHM OF HYPERLACTATAEMIA click to zoom the image

Anaerobic causes ◆ Macrocirculatory shock. ◆ Microcirculatory shunting. ◆ Carbon monoxide poisoning (carboxyhaemoglobin). Aerobic causes ◆ Increased aerobic glycolysis:     • Catecholamine-stimulated increased Na+–K+-pump activity.     • Cytokine-mediated glucose uptake. ◆ Mitochondrial dysfunction. ◆ Pyruvate dehydrogenase dysfunction:     • Sepsis.     • Thiamine deficiency. ◆ Reduced clearance:     • Liver insufficiency/surgery.     • Sepsis. ◆ Alkalosis. ◆ Malignancy (Warburg effect). ◆ Epileptic seizure (grand mal). ◆ Congenital metabolic diseases. ◆ Drugs and intoxications:     • Nucleoside reverse transcriptase inhibitors.     • Epinephrine.     • Metformin.     • Propofol (propofol infusion syndrome).     • Corticosteroids.     • Cyanide.     • Ethylene glycol.     • Methanol.     • Carbon monoxide po...