Hypothermia and Blood Lactate During Cardiopulmonary Bypass in Pediatric Patients

Background: Hypothermic perfusion is widely used in pediatric cardiac surgery units. The present study evaluated the effects of hypothermia severity on the serum levels of lactate during cardiopulmonary bypass (CPB) in the surgical repair of congenital heart defects in children. Methods: A total of 185 pediatric patients candidated for the elective surgical repair of congenital heart diseases were recruited. The patients’ arterial serum lactate, central venous pressure, diuresis, glucose level, and arterial blood gases were measured and recorded at 4 time points: before CPB, in the cooling stage, in the warming stage, and after CPB and upon admission to the intensive care unit (ICU). Results: The mean age of the patients was 28.1 ± 19.6 months. The lactate level was significantly increased more quickly in the patients with hypothermia less than 30 °C than in those with hypothermia of 30 °C or greater (P < 0.001). These 2 groups were significantly different in terms of the duration of CPB (P < 0.001), the duration of cross-clamping (P < 0.001), and the volume of the blood filtered (P < 0.001). No statistically significant difference in the volume of the red blood cell transfused was observed between the 2 groups (P = 0.12). Conclusions: Deep hypothermia is associated with higher blood lactate levels, which may be associated with poor outcomes during and after CPB. It is recommended that normothermia or mild hypothermia be used during CPB in pediatrics. When the use of deep hypothermia is inevitable, patients should be strictly monitored and screened for adverse outcomes associated with hyperlactatemia.