Lactate/Pyruvate as a marker of tissue hypoxia

Dr. Perz

Lactate/Pyruvate Ratio as a Marker of Tissue Hypoxia in Circulatory and Septic Shock

Rimachi, R., Bruzzi de Carvahlo, F., Orellano-Jimenez, C., Cotton, F., Vincents, J.L., De Backer, D.  Anesth Intensive Care 2012; 40:427-423.

                This article described a prospective, observational study which measured arterial lactate and pyruvate concentrations within the first four hours of shock and at four hour intervals during the first 24 hours in 26 patients with septic shock and 13 patients with cardiogenic shock.    The basis for this study is based on the fact that several authors have suggested that lactate in itself may not be an accurate measure of hypoxia.  Increased blood lactate concentrations may also, especially in patients with sepsis, result from impaired clearance of lactate, inhibition of pyruvate dehydrogenase, and accelerated aerobic glycolysis due to the activation of the Na/K ATPase by catecholamines.  These authors suggest that lactate should be measured with pyruvate, to attempt to distinguish between hypoxic and non-hypoxic sources of lactate.  In anaerobic conditions, pyruvate is transformed to lactate and thus, the lactate/pyruvate (L/P) ratio increases.  So, this study attempted to use the L/P ratio to assess the contribution of hypoxic and non-hypoxic causes to hyperlactataemia.

The lactate/pyruvate ratio was measured in each of these patients, and several observations were noted.  Blood lactate values were higher at shock onset and remained higher in the non-survivors in relation to the survivors; the lactate/pyruvate ratio at shoch onset was significantly higher in the non-survivors.  All patients with cardiogenic shock had hyperlactataemia at the onset of shock and 69% had a high lactate/pyruvate ratio, and of the septic shock patients, 65% had hyperlactataemia and 76% had a high lactate/pyruvate ratio.  Eighteen percent of patients died during the first 24 hours, thirty one percent of patients died later in the ICU and fifty four percent were discharged alive from the ICU.  Ultimately, the study concluded that the L/P ratio confirms that hyperlactataemia is frequently, but not solely due to hypoxia, especially at the onset of shock.