It is very important to estimate significance of preoperative clinical and demographic data and risk factors in prediction of short-term mortality in this patients, because patients with only two of large palette of preoperative risk factors significant higher short-term mortality.

Hospital–acquired infections are infections that occur in hospital environment more than 48 hours after hospital admission, more frequent in immuno-compromised patients. The way of spreading micro-organisms in hospital-conditions, is both primary and secondary, as well as endogenous and exogenous.