Abstract
Objective: Lactate is often used as a surrogate marker of inappropriate oxygen delivery. It has been shown that hyperlactatemia is associated with worse clinical outcome in children after cardiac surgery. The purpose of this study is to evaluate the association of hyperlactatemia, low systemic oxygen delivery, and hyperglycemia, in children admitted to the pediatric critical care unit after cardiopulmonary bypass.Design: Secondary analysis of an observational cohort study.Setting: Tertiary pediatric critical care unit (PICU).Patients: Ninety-three patients, aged 6 months to 16 years, undergoing cardiac surgery with cardiopulmonary bypass.Interventions: None.Measurements and Main Results: Metabolic tests (blood glucose, lactate, lactate/pyruvate ratio, and ketones) and oxygen extraction (SaO2-SvO2) were performed before anesthesia, at the end of cardiopulmonary bypass, at PICU admission, and at 4 and 12 h after PICU admission. Four hours after PICU admission, 62% of the patients had hyperlactatemia (>2 mmol/L), of whom 55% had normal oxygen extraction (SaO2-SvO2 < 30%). There was no correlation between lactate and oxygen extraction (R = −0.09, p = 0.41) but there was a moderate correlation between lactate and blood glucose (R = 0.55, p < 0.001). Using a logistic regression model, hyperlactatemia at 4 h after PICU admission was independently associated with hyperglycemia (p = 0.007) and lactate/pyruvate ratio (p = 0.007) at the same timepoint, as well as with lactate at PICU admission (p = 0.002), but not with weight (p = 0.45), severity of the cardiac lesion (p = 0.85), duration of bypass (p = 0.16), or oxygen extraction, as evaluated by SaO2-SvO2 (p = 0.54). At 12 h after PICU admission, there was a very week correlation between lactate and blood glucose (R = 0.27, p = 0.007), but none between lactate and oxygen extraction (R = 0.13, p = 0.20).Conclusion: In children after cardiopulmonary bypass, lactates are not correlated with higher oxygen extraction, but are correlated with hyperglycemia, at both 4 and 12 h after PICU admission. Future research is warranted to better define this relationship.
Highlights
Hyperlactatemia after cardiopulmonary bypass (CBP) in children is a frequent finding [1, 2] and has consistently been identified to be predictive of adverse events during the early postoperative period [3,4,5]
The purpose of this study is to evaluate the association of hyperlactatemia, low systemic oxygen delivery, and hyperglycemia, in children admitted to the pediatric critical care unit after cardiopulmonary bypass
In children after cardiopulmonary bypass, lactates are not correlated with higher oxygen extraction, but are correlated with hyperglycemia, at both 4 and 12 h after pediatric critical care unit (PICU) admission
Summary
Hyperlactatemia after cardiopulmonary bypass (CBP) in children is a frequent finding [1, 2] and has consistently been identified to be predictive of adverse events during the early postoperative period [3,4,5]. Often used as a surrogate marker of a low cardiac output, high blood lactate levels can result from tissue hypoperfusion (type A hyperlactatemia) [6], but may occur in patient with a normal tissue perfusion (type B hyperlactatemia) [7]. In those situations, hyperlactatemia may be related to hyperglycemia [8], increased use of red blood cell transfusions [9] or decreased lactate clearance [10]. Especially hyperlactatemia associated with tissue hypoxia is a major predictor of mortality [11], and differentiating the origin of increased lactates is crucial in the care of children after CPB
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