Objective: Procalcitonin (PCT) is currently recommended as a suitable parameter to detect and to evaluate the course of bacterial, fungal or parasitic infections. However, recent studies provide evidence that surgical trauma and humoral mediators of inflammation, respectively,may induce PCT synthesis, thereby reducing the validity and reliability of PCT as an "infection-monitoring" parameter. The aim of the present study was to assess and to compare PCT and CRP (C-reactive protein) plasma concentrations in patients presenting without infection following different types of surgery in the absence or presence of a systemic inflammatory response syndrome (SIRS).
Methods: PCT and CRP plasma concentrations were assessed daily on postoperative days 1-5 and maximal values were determined in 94 patients. The patients were allocated to four groups of different types of surgery as follows: A: minor, primarily aseptic surgery, B: major abdominal surgery, C: major vascular surgery and D: thoracic surgery including esophagectomy. All categories were divided into two subgroups representing patients with and without SIRS, respectively. RESULTS. PCT plasma concentrations increased moderately compared to normal values in 21% of patients after minor and aseptic surgery (A), in 27% and 41% after major vascular (C) and thoracic (D) surgery, respectively, and in 65% of patients after major abdominal (B) surgery. The difference between PCT concentrations in patients undergoing major abdominal surgery and the patients after minor, aseptic surgery was significant ( p<0,05: A vs. B). Comparing the patients presenting with or without systemic inflammatory response (SIRS), no significant differences in PCT concentrations between groups could be observed. In the majority of patients PCT values rose to peak levels on the first and second postoperative days, followed by a rapid decline based on the plasma half-life of PCT. In contrast, postoperative CRP plasma concentrations were markedly elevated above normal values in all investigated patients during the whole observation period. Between-categories statistical analysis revealed significant differences comparing patients undergoing minor and aseptic surgery with patients after major vascular, and thoracic surgery, respectively ( p<0,05,A vs.C, D). CRP concentrations were significantly increased in patients with systemic inflammatory response compared to patients with normal postoperative course in surgical categories B, C, and D, respectively ( p<0,05).
Conclusions: Postoperative PCT plasma concentrations in patients presenting without signs of infection are largely influenced by the type of surgical procedure. During the first and second postoperative day PCT concentrations are more frequently elevated in patients after major abdominal, major vascular and thoracic surgery compared to patients undergoing minor, aseptic operations. Thus an "infection monitoring" considering PCT value analysis during the postoperative course may transiently be impeded after major and particularly after intestinal surgery during the first 2 days postoperatively, whereas it appears not to be substantially affected by the presence or absence of systemic inflammatory response.