Increased interleukin-6 after cardiac surgery predicts infection

Early diagnosis and treatment of infection after cardiac surgery with cardiopulmonary bypass (CPB) improves outcome. Conventional laboratory tests, such as C-reactive protein and white blood cell count can not distinguish patients with early infection from those with systemic inflammatory response syndrome but without infection. After CPB, there is a systemic release of proinflammatory and antiinflammatory cytokines, including tumor necrosis factor-a, interleukin (IL)-6, and IL-10. We investigated the predictive ability of these variables for infection after cardiac surgery. Forty-six patients with impaired left ventricular ejection fraction (< 60%), scheduled for cardiac surgery, were included. Plasma samples were drawn 1 day before and immediately before surgery, on admission to the intensive care unit, and on days 1, 3, and 7 after surgery. Infection was identified according to the criteria of the Centers for Disease Control and Prevention. After surgery 13 patients developed an infection. In patients with infection, confirmed a median of 4 days after surgery, all measurements of IL-6, and IL-10 on postoperative day 3 were significantly increased. Tumor necrosis factor-a, leukocytes, and C-reactive protein were not increased in these patients. Immediately after surgery blood glucose was significantly increased in patients with infection. Increased IL-6 after CPB is predictive of infection after cardiac surgery in patients with impaired left ventricular function.