[Usefulness of procalcitonin for the diagnosis of infection in cardiac surgical patients].

OBJECTIVE

To determine the value of procalcitonin (PCT) as an early marker of postoperative infection after cardiac surgery with cardiopulmonary bypass (CPB).

METHODS

A retrospective study was conducted. Patients with systemic inflammatory response syndrome (SIRS) after cardiac surgery with CPB admitted to intensive care unit (ICU) of Peking Union Medical College Hospital from November 2014 to January 2017 were enrolled. The cardiac surgery types and intraoperative conditions, the treatments in ICU, postoperative 28-day mortality and hospital mortality of the patients; the levels of plasma PCT measured at ICU admission, postoperative 1, 3, and 5 days were collected. According to whether patients with postoperative infection or not, they were divided into infection group and non-infection group. Receiver operating characteristic curve (ROC) was used to analyze the predictive value of plasma PCT levels at different time points in patients with infection.

RESULTS

Eighty-two patients were included in this study, 25 (30.5%) had microbiological evidence of pneumonia. The levels of plasma PCT were increased with a peak 1 day after cardiac surgery in all patients, then significantly decreased 5 days after operation. Compared with patients without infection, the levels of plasma PCT were significantly increased in patients with infection at immediate and 1, 3, 5 days post operation in ICU [μg/L: 10.0 (6.0, 64.5) vs. 5.0 (1.0, 10.0), 31.0 (10.0, 116.2) vs. 5.0 (1.0, 10.0), 34.7 (10.0, 60.4) vs. 2.9 (0.7, 9.3), 15.8 (7.7, 29.4) vs. 0.7 (0.5, 2.6), all P < 0.01]. The area under the ROC curve (AUC) of the plasma PCT levels at ICU admission, and 1, 3, 5 days thereafter to predict infection for critically ill patients with SIRS after CPB was 0.77, 0.82, 0.86, and 0.91, respectively (all P < 0.01), cut-off values were 6.8, 9.4, 9.2 and 3.9 μg/L, with the sensitivities of 76.0%, 84.0%, 79.2%, and 88.0%, and the specificities of 66.7%, 68.4%, 75.4%, and 78.9%, respectively.

CONCLUSIONS

In the presence of SIRS, elevated plasma PCT levels correlated with evidence of infection in early stage post operation in the ICU patients after cardiac surgery with use of CPB. The level of plasma PCT exceeded the cut-off value in different time points, suggesting infection, and it is helpful to predict the occurrence of infection early after operation.