Procalcitonin and Postoperative Outcome After Open-heart Surgery

The cardiopulmonary bypass (CPB) causes an inflammatory response secondary to the activation of cytokine systems in the whole body. The causes of this inflammation have been discussed extensively in the literature. As a concise summary the causes can be listed as; 1- the surgical stress, 2- the recognition of bypass circuit as an artificial surface by the blood components, 3- ischemia-reperfusion injury, 4- endotoxemia. After open-heart surgery with CPB, the development of several postoperative complications including myocardial dysfunction, respiratory failure, renal and neurologic dysfunction, bleeding disorders, altered liver function, and, multiple organ failure has been demonstrated to be related to the inflammatory response. Procalcitonin (PCT), is a 116-amino-acid protein that is produced in the liver and peripheral mononuclear cells and the normal serum PCT value is below 0.1 ng/mL in patients without signs of systemic inflammation. Serum PCT levels increase postoperatively after open-heart surgery and a peak level of 0.5 to 7.0 ng/mL is reported at 24 hours after the operation and serum PCT values decrease to normal values within seven days. Serum C-reactive protein (CRP) values are often abnormally elevated after open-heart surgery as a result of an inflammatory response and it has not been found to be a useful prognostic marker due to its prolonged elevation after cardiac surgeries. In the literature, there are studies showing that serum PCT levels are consistently higher in patients with postoperative complications, however, a cutoff point for serum PCT to determine the risk of possible poor outcome has not been well studied. A recent study demonstrated that after CPB, serum PCT increased in patients with poor outcome especially in those who developed renal and hepatic dysfunction in addition to respiratory and circulatory insufficiency. This study demonstrated a cut off value of 2 ng/mL to predict postoperative complications. In another study, a PCT level of 2.8 ng/mL was found to be a cut off value to predict 28-day mortality in patients after coronary artery bypass grafting (CABG) however, it has been pointed out that there is a need for further studies. The aim of our study was to investigate a relation between serum values of CRP, PCT, and lactate and development of postoperative complications (circulatory failure, pneumonia, respiratory insufficiency, sepsis, reoperation, hemorrhage, tamponade, need of inotropic support, myocardial infarction, acute kidney injury), in patients undergoing open-heart surgery with CPB. A sample size of 72 patients would have a power (1-ß) of 80% to detect a difference in serum PCT level of 10% (1 standard deviation) difference between patients with postoperative complications (n=36) and without postoperative complications (n=36) using 2-sided significance and an α=0.05.