Early hyperlactataemia is associated with increased mortality, whereas late-onset hyperlactataemia (4 to 24 hours post-surgery) occurs with preserved cardiac output and no proven mortality increase.
What is the clinical significance of early versus late-onset hyperlactataemia in patients undergoing cardiac surgery?
Differentiating between early and late-onset hyperlactataemia after cardiac surgery is crucial, as late-onset is typically benign and should not delay postoperative progress, unlike early-onset which indicates tissue ischaemia.
Hyperlactataemia and lactic acidosis are commonly encountered during and after cardiac surgery. Perioperative lactate production increases in the myocardium, skeletal muscle, lungs and in the splanchnic circulation during cardiopulmonary bypass. Hyperlactataemia has a bimodal distribution in the perioperative period. An early increase in lactate levels, arising intraoperatively or soon after intensive care unit admission, is a familiar and concerning finding for most clinicians. It is highly suggestive of tissue ischaemia and is associated with a prolonged intensive care unit stay, a prolonged requirement for respiratory and cardiovascular support and increased postoperative mortality. Its presence should prompt a thorough search for potential causes of tissue hypoxia. In contrast, late-onset hyperlactataemia, a less well recognised complication, occurs 4 to 24 hours after completion of surgery and is typically associated with preserved cardiac output and oxygen delivery. Risk factors for late-onset hyperlactataemia include hyperglycaemia, long cardiopulmonary bypass time and elevated endogenous catecholamines. Although patients with this complication may have a longer duration of ventilation and intensive care unit length of stay than those with normolactataemia, an association with increased mortality has not been demonstrated. The discovery of late-onset hyperlactataemia should not delay the postoperative progress of an otherwise stable patient following cardiac surgery.
O’Connor et al. (2012) conducted a review in Perioperative lactate abnormalities in patients undergoing cardiac surgery. Perioperative lactate abnormalities was evaluated. Early hyperlactataemia is associated with increased mortality, whereas late-onset hyperlactataemia (4 to 24 hours post-surgery) occurs with preserved cardiac output and no proven mortality increase.
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