Late-onset hyperlactataemia following paediatric cardiac surgery

Objective  To investigate the clinical significance of a late rise in blood lactate concentration, developing after PICU admission, in older children undergoing cardiac surgery. Design  Retrospective, observational study. Setting  Single UK PICU. Patients and participants  A total of 147 children, aged 2–16 years, in 2 cohorts: FONTAN (n = 63) Fontan operation; and MIXED (n = 84) operations of varying complexity. Interventions  None. Measurements and results  Sequential data were collected up to 12 h postoperatively: arterial blood gas, lactate, glucose concentrations; haemodynamic variables; inotropic support; urine output, core-peripheral temperature gradient. Data were collected on clinical outcomes: PICU mortality; length of ventilation, PICU stay; renal and hepatic function. Late-onset hyperlactataemia (LOH) was defined if blood lactate increased to or above 3 mmol/l. Data from the LOH group were compared to a group with a low blood lactate (<3 mmol/l) throughout (No_LOH). LOH occurred in 28 (44%) and 21 (25%) of patients in FONTAN and MIXED cohorts, respectively. A strong association was found between LOH and hyperglycaemia (P < 0.001). No significant difference was found in postoperative urine output, core-peripheral temperature gradient or inotrope requirement in the LOH versus No_LOH groups. No significant differences were found with respect to clinical outcomes in the LOH versus No_LOH groups. All LOH patients were discharged from PICU within 1 day and survived. Conclusions  LOH is common in older children following cardiac surgery. We found no evidence to suggest that it is associated with adverse clinical outcomes. The strong association between LOH and hyperglycaemia supports a metabolic aetiology.