Lactate as a Marker of Hypoperfusion During Cardiac Surgery

Abstract

Background: Tissue hypoperfusion is a major complication during and after cardiac surgery, often associated with increased morbidity, longer ICU stays, and higher mortality. Conventional hemodynamic parameters may not always reflect the adequacy of cellular oxygen delivery, particularly in the context of cardiopulmonary bypass (CPB) where physiological conditions are significantly altered. Among the biochemical indicators of tissue oxygenation, lactate has emerged as a sensitive and dynamic marker of hypoperfusion. Elevated lactate levels often result from anaerobic metabolism due to inadequate oxygen delivery, but they may also reflect stress-induced hypermetabolism, impaired clearance, or microcirculatory dysfunction. Understanding the mechanisms of lactate generation and interpretation in the perioperative setting is essential for timely detection of hypoperfusion and appropriate clinical intervention. This review aims to provide a comprehensive overview of lactate physiology, explore its role as a marker of hypoperfusion in cardiac surgery, and evaluate its diagnostic, prognostic, and therapeutic significance during the perioperative period.