Initial postoperative serum lactate levels predict survival in children after open heart surgery

Abstract

Objective: To evaluate the relationship between postoperative serum lactate levels and outcome in children undergoing open heart surgery.

Design: Prospective, noninterventional study.

Setting: Pediatric intensive care unit (PICU) of a university hospital.

Patients: 41 nonconsecutive children who had had cardiopulmonary bypass for repair of congenital heart disease.

Interventions: None.

Measurements and results: Serum lactate levels were measured on admission to the PICU immediately after open heart surgery. Lactate levels were correlated with bypass and cross clamp times, estimated intraoperative blood loss, lowest temperature on bypass, admission Pediatric Risk of Mortality score, anion gap, and measures of postoperative morbidity. Mean lactate levels on admission to the PICU were 6.86 +/- 0.79 mmol/l for nonsurvivors (n = 7) and 2.38 +/- 0.13 mmol/l for survivors (n = 34) (p < 0.0001), and 4.87 +/- 0.7 mmol/l and 2.35 +/- 0.19 mmol/l, for patients with (n = 11) and without (n = 30) multiple organ system failure, respectively (p < 0.0001). Admission lactate levels correlated with all measurements of postoperative morbidity. A serum lactate level of greater than 4.2 mmol/l had a positive predictive value of 100% and a negative predictive value of 97% for postoperative death.

Conclusions: Initial postoperative serum lactate levels after pediatric open heart surgery may be predictive of outcome. Lactate levels are also higher in patients who go on to develop multiple organ system failure. Elevated postoperative lactate levels may reflect intraoperative tissue hypoperfusion, and measures aimed at increasing oxygen delivery, with normalization of lactate, may improve patient outcome.