Blood Lactate Levels Differ Significantly Between Surviving and Nonsurviving Patients Within the Same Risk-Adjusted Classification for Congenital Heart Surgery (RACHS-1) Group After Pediatric Cardiac Surgery

Abstract

This study aimed to examine the association between lactate levels in the first hours after surgery for congenital heart defects and the results of Risk-Adjusted Classification for Congenital Heart Surgery (RACHS-1) scoring and to evaluate serial lactate levels over time to determine whether they can serve as a supplementary tool for postoperative assessment within the same RACHS-1 group of patients. A retrospective cohort study was performed using data retrieved from a clinical database of 255 children who had surgery for congenital heart defects between 1999 and 2001 at Sheba Medical Center. Lactate levels were measured postoperatively four times (mg/dL units). The last sample was taken at the end of the surgical procedure, and lactate levels were measured at admission to the pediatrics critical care unit, then 6 and 12 h after admission. The lactate level was measured via arterial blood gases. A total of 27 deaths occurred, yielding a mortality rate of 7.4% when Norwood operations were excluded and 10.16% when they were included. The mean initial postoperative lactate level was significantly lower for survivors (42.2 ± 32.0 mg/dL) than for nonsurvivors (85.4 ± 54.1 mg/dL) (p < 0.01). The serial mean lactate levels decreased progressively for all surviving patients (r (2) = 0.96) compared with nonsurvivors (r (2) = 0.02). The lactate levels correlated with the RACHS-1 subgroups at each time point (r (2) > 0.96 for all). The Pearson correlations between postoperative lactate levels (last lactate measurement taken in the operating room) and cardiopulmonary bypass (CPB) duration (r = 0.549), clamp duration (r = 0.586), and the inotropic score (r = 0.466) (p < 0.001 for all) were significantly positive. The correlations between the maximum lactate levels (during the first 12 postoperative hours) and CPB duration (r = 0.496), clamp duration (r = 0.509), and the inotropic score (r = 0.633) (p < 0.001 for all) were extremely positive. The early elevation of lactate levels in RACHS-1 subgroups 1 to 3 were highly correlated with poor prognosis and death (p < 0.03). In addition, the lactate levels differed significantly between survivors and nonsurvivors within the same RACHS-1 subgroup. The survivors in RACHS-1 subgroups 1 to 3 had lower mean lactate levels than the nonsurvivors in this group (P = 0.011), and this also held true for the survivors and nonsurvivors in RACHS-1 subgroups 4 to 6 (P = 0.026). Lactate levels differed significantly between survivors and nonsurvivors within the same RACHS-1 subgroup. This combination allows the targeting of appropriately intensive interventions and therapies toward the sickest patients.

Correlation between serum lactate levels and outcome in pediatric patients undergoing congenital heart surgery

“…However, the design of these studies was different, as the cut-off lactate levels were calculated as 3-6 mmol/L. [8,[12][13][14] Molina Hazan et al [8] found that maximum lactate levels (within postoperative first 12 hours) were correlated with the duration of CPB, duration of aortic cross-clamp, the RACHS-1 subgroups, and inotropic scores. Maarslet et al [12] reported that young age, low weight, high RACHS-1 scores, prolonged duration of CPB, and inotropic use were risk factors for elevated lactate.…”

“…[3][4][5]8,[17][18][19] Cheifetz et al [3] reported that six of 48 patients who underwent high risk open-heart surgery died. The patients in the group in which the patients died had significantly higher lactate levels in the postoperative period than that of survivors.…”

“…Similar results were found in subgroups of single or double ventricular heart disease and in different groups of RACHS-1. In a retrospective study involving 255 patients, Molina Hazan et al [8] investigated the lactate levels at the end of the operation, at ICU admission, and at postoperative 6 and 12 hours. When the Norwood operations were included, the authors reported that the mortality was 10.16% (n=27).…”

“…[7] High lactate levels have also been shown to correlate with duration of CPB, duration of aortic cross-clamp, inotropic scores, and the Riskadjusted Classification for Congenital Heart Surgery-1 (RACHS-1) subgroups. [8] Lactate elevation is also a risk factor for prolonged intensive care unit (ICU) stay and increased severe postoperative adverse events. [5] However, the methods used in these studies (such as change of lactate level) differ from lactate cut-off values and vary according to surgical procedures.…”

“…Therefore, the correlation between increased serum lactate levels, complications, and mortality still remains unclear. [8,9] In this study, we aimed to investigate the correlation between lactate levels within the first 24 hours, complications, and mortality in pediatric patients with congenital heart disease undergoing open heart surgery.…”