Role of lactate in critically ill children.

Lactic acidosis is a common finding in critically ill patients. It has been used as a prognostic marker of the outcome in Pediatric Intensive Care Unit patients. Lactic acid is produced as a product of anaerobic glycolysis and is reversibly converted to pyruvate in the presence of favorable metabolic environment. All the body tissues can produce and consume lactate with few having predominant function of production and others of consumption. Liver is a major organ for lactate consumption and it is the liver, which metabolizes the increased lactic acid produced in regional tissue beds. The lactate levels can be done on arterial, venous, or mixed venous blood and can be measured by various methods. Serial lactate concentrations and the difference in arterial and mixed venous lactate levels or between the arterial and regional blood lactate levels like jugular venous lactate levels have been shown to have better correlation with the outcome. High initial blood lactate levels and persistently high lactate levels have been correlated with poor outcome. There are various causes of lactic acid overproduction, which may produce either hyperlactatemia or lactic acidosis. High blood lactate levels are found in critically ill patients with shock of any etiology and sepsis due to various reasons, which include increased catecholamine induced glucose flux apart from the tissue hypoperfusion and hypoxia. Various other illnesses can cause an increase in blood lactate levels like acute lung/liver injury, severe asthma, poisoning, post cardiac surgery etc. Treating the underlying disease leading to lactic acidosis is the best measure to control lactic acidosis. Some therapeutic choices are available to neutralize the effect of lactic acid on cell function, but none has stood the test of time and are tried only in desperate situations. [ABSTRACT FROM AUTHOR]