Interleukin-6 levels in serum and lung lavage fluid of children undergoing open heart surgery correlate with postoperative morbidity

Abstract

Objective: To evaluate the relationship of perioperative levels of interleukin 6 (IL-6) in serum and bronchoalveolar fluid with morbidity and mortality in children undergoing cardiopulmonary bypass (CPB). Design: Prospective, noninterventional study. Setting: Operating room and pediatric intensive care unit (PICU) of a university hospital. Interventions: None. Measurements and results: IL-6 levels were measured in serum and lung lavage fluid obtained before, during, and after CPB using the B9.9 bioassay. Alveolar epithelial lining fluid (AELF) volume was calculated using the urea correction method. Mean intraoperative AELF IL-6 levels increased fourfold compared to preoperative levels, and mean serum IL-6 levels increased fivefold after CPB. Mean intraoperative AELF IL-6 levels correlated with intraoperative blood transfusion (r ² = 0.18; p = 0.049) and duration of inotropic support (r ² = 0.29; p = 0.009), mechanical ventilation (r ² = 0.24; p = 0.019), and PICU stay (r ² = 0.29; p = 0.008). Mean serum IL-6 levels 2 h after CPB correlated with intraoperative blood transfusion (r ² = 0.3; p = 0.007), and with Pediatric Risk of Mortality score on postoperative day 3 (r ² = 0.24; p = 0.022), and were higher in patients with massive fluid retention (p = 0.014) and in nonsurvivors (p = 0.003). Conclusions: Serum and alveolar IL-6 levels increase after CPB, and correlate with postoperative morbidity. Serum IL-6 levels also correlate with mortality. They may be useful in assessing the severity of the systemic inflammatory response after CPB.