[Procalcitonin in the diagnosis of postoperative complications]

The dynamic changes in levels of procalcitonin (PCT), as well as other cytokines and acute phase proteins (APP) in post-operative stages reflect the systemic immune response, integrating perioperative infectious and non-infectious stimuli. This study evaluates PCT in context of 16 other inflammatory parameters in patients with different types of infectious post-operative complications. It analyses the specificity and sensitivity of PCT, cytokines and APP and their relationships during systemic inflammatory response.

The study involved the following groups of patients: those with confirmed bacterial sepsis, fulfilling the SIRS criteria (N = 28), those with limited infectious site at the wound (N = 16), those with post-operative pneumonia (N = 15) and a control group of N = 25. In 24-hour interval we assessed plasma levels of: PCT, TNF-alpha, IL-1 beta, IL-1ra, IL-6, IL-8, sIL-2R and a spectrum of APP.

PCT in patients with wound infection (1.4 +/- 0.31 ng/ml) and in those with pneumonia (0.7 +/- 0.30 ng/ml) does not rise above levels expected in uncomplicated post-op course (1.7 +/- 0.04 ng/ml), but it differs significantly in comparison to healthy controls (0.2 +/- 0.07 ng/ml). Initial levels of PCT as well as their maximum levels were significantly different in septic patients compared to other groups (p < 0.001). According to specificity and sensitivity tests PCT is the most significant marker for diagnosis of sepsis as opposed to uncomplicated post-operative course (AUC 0.91, CI 0.82-1.0).

Individual inflammatory parameters vary in sensitivity and specificity to causative stimulus. PCT when compared to major cytokines and APP reacts sensitively mainly to systemic stimuli accompanying bacterial infection, notably endotoxin. It is characterized by markedly lower sensitivity to non-bacterial stimuli (trauma of surgery) or localized bacterial inflammations. It is this behaviour that makes it a useful diagnostic tool in post-op courses. Unlike other parameters, PCT allows with sufficient sensitivity and specificity single-test diagnosis of initial sepsis.