Serum Lactate Level Has Prognostic Significance After Pediatric Cardiac Surgery Murat Basaran, MD, Kenan Sever, MD, Eylul Kafali, MD, Murat Ugurlucan, MD, Omer Ali Sayin, MD, Turkan Tansel, MD, Ufuk Alpagut, MD, Enver Dayioglu, MD, and Ertan Onursal, MD Objective: The determination of postoperative course after cardiac surgery has always been a challenging issue. It is more sophisticated in the pediatric age group. The aim of this investigation was to identify whether in- creased concentrations of lactate in arterial blood has a predictive value for postoperative morbidity and mortality after heart surgery. Methods: From May 2002 to June 2003, 60 infants oper- ated on at the authors’ institution were included in this prospective study. The patients were divided into 2 groups according to their respective postoperative serum lactate values. After the stabilization period in the intensive care unit (first 3 hours postoperatively), samples for serum lac- tate were obtained from arterial blood at 3 (t 1 ), 6 (t 2 ), and 12 hours (t 3 ) postoperatively. The patients were subdivided into 2 groups according to their respective mean serum lactate values. A value of 4.8 mmol/L (3 times the normal upper limit) was choosen as a threshold for serum lactate. The patients with a mean value of greater than 4.8 mmol/L (group 1) were compared with the remaining group of pa- tients (group 2). The relationship between serum mean lac- tate level and intraoperative and postoperative clinical vari- ables was evaluated. Results: Among the patients in this study, 26 (43.3%) had a serum mean lactate level more than 4.8 mmol/L and 34 (56.7%) had a level of 4.8 mmol/L or less. Age, aortic cross- clamping time, cardiopulmonary bypass time, and the low- est hematocrit during cardiopulmonary bypass were signif- icant variables that influenced the postoperative serum mean lactate level. Six patients died in the postoperative period and 54 infants survived. The hospital mortality was significantly higher in group 1 than in group 2 (19.0% v 2.9%; p  0.037, kappa  0.179). Multivariate analysis revealed that serum mean lactate level correlated significantly with inotrope score, intubation time, and intensive care unit stay. Conclusions: Blood lactate concentration of 4.8 mmol/L or higher during the early postoperative hours identifies a group of patients with increased risk of postoperative mor- bidity and mortality. © 2006 Elsevier Inc. All rights reserved. KEY WORDS: lactate, postoperative morbidity and mortal- ity, congenital cardiac disease, pediatric cardiac surgery M ANY CONGENITAL CARDIAC defects can be cor- rected today with acceptable morbidity and mortality rates with the recent refinements in cardiac anesthesia, myo- cardial protection, and postoperative care. However, the inten- sive care unit period of these patients is still a challenging problem for physicians. Although various clinical and bio- chemical parameters are used for the monitoring of these pa- tients, an early objective predictor of morbidity and mortality especially in pediatric population can be very advantageous. Mixed venous oxygen saturation and serum lactate level are the most commonly used parameters for the monitoring of oxygen delivery and consumption. However, the unreliability of mixed venous oxygen saturation in patients with residual intracardiac communication 1 and the technical difficulty encountered while obtaining its serum level have increased the importance of new parameters in clinical practice. Identification of predictors of morbidity and mortality is an important issue for the optimal management of patients with cardiac pathologies. Conventional monitoring of blood gases may detect inadequate tissue oxygenation. Lactate is a product of anaerobic metabolism that reflects tissue hypo- perfusion and might be more sensitive for the detection of an imbalance between oxygen supply and demand. 2-5 Serum lactate levels have been previously used as a prognostic indicator of low cardiac output in adult patients 6,7 ; however, there are limited numbers of reports analyzing the relation- ship between lactate level and mortality risk in the pediatric population. The authors believe that an early elevation of serum lactate level after congenital heart surgery might strongly correlate with an increased risk of morbidity and mortality. The aim of this study was to determine whether serum lactate levels are predictive of morbidity and mortality after congenital cardiac surgery. MATERIALS AND METHODS Sixty patients operated on at the authors’ institution between May 2002 and June 2003 were included in this prospective study. The informed consents were obtained from each family. The diagnoses of the patients were based primarily on transthoracic echocardiography and are given in Table 1. There were 4 patients with prior palliative procedures. The authors established some exclusion criteria to create a more homogenous group that were as follows: body weight less than 2 kg, hemodynamic instability or need of inotropic support before the operation, and the presence of an elevation of any parameters preop- eratively indicating systemic hypoperfusion. Anesthesia was started with 5 mg/kg of intramuscular ketamine. The intravenous anesthesia was performed with 1 mg/kg of ketamine, 1.5 g/kg of fentanyl, and 0.1 mg/kg of pancuronium. Patients’ lungs were ventilated with oxygen, air, and isoflurane, and ventilation was adjusted to maintain normocarbia. The maintenance of the general anesthesia was achieved with an infusion of 5 g/kg/h of fentanyl and isoflurane in 0% to 1% inspiratory concentration. Noninvasive monitoring con- sisting of electrocardiogram, pulse oximetry, and measurements of From the Department of Cardiovascular Surgery, Istanbul Univer- sity, Istanbul, Turkey. Presented at the 52nd International Congress of the European Society for Cardiovascular Surgery, Istanbul, Turkey, November 7-10, 2003. Address reprint requests to Murat Ugurlucan, MD, Department of Cardiovascular Surgery, Istanbul University, Millet Caddesi, Capa/ Fatih, Istanbul 34390, Turkey. E-mail: muratugurlucan@yahoo.com © 2006 Elsevier Inc. All rights reserved. 1053-0770/06/2001-0009$32.00/0 doi:10.1053/j.jvca.2004.10.010 43 Journal of Cardiothoracic and Vascular Anesthesia, Vol 20, No 1 (February), 2006: pp 43-47