Usefulness of procalcitonin for diagnosis of infection in cardiac surgical patients

OBJECTIVETo determine the value of procalcitonin (PCT) as a marker of postoperative infection after cardiac surgery. DESIGNA prospective single institution three phase study. SETTINGUniversity cardiac surgical intensive care unit (31 beds). PATIENTSPhase 1To determine the normal perioperative kinetics of PCT, 20 consecutive patients undergoing elective cardiac surgery with cardiopulmonary bypass were included. Phase 2To determine whether PCT may be useful for diagnosis of postoperative infection, 97 consecutive patients with suspected infection were included. Phase 3To determine the ability of PCT to differentiate patients with septic shock from those with cardiogenic shock, 26 patients with postoperative circulatory failure were compared. MEASUREMENTS AND MAIN RESULTSPhase 1Serum samples were drawn for PCT determination after induction of anesthesia (baseline), at the end of surgery, and daily until postoperative day (POD) 8. Baseline serum PCT concentration was 0.17 ± 0.08 ng/mL (mean ± sd). Serum PCT increased after cardiac surgery with a peak on POD 1 (1.08 ± 1.36). Serum PCT returned to normal range on POD 3 and remained stable thereafter. Phase 2In patients with suspected infection, serum PCT was measured at the same time of C-reactive protein (CRP) and bacteriologic samples. Among the 97 included patients, 54 were infected with pneumonia (n = 17), bacteremia (n = 16), mediastinitis (n = 9), or septic shock (n = 12). In the 43 remaining patients, infection was excluded by microbiological examinations. In noninfected patients, serum PCT concentration was 0.41 ± 0.36 ng/mL (range, 0.08–1.67 ng/mL). Serum PCT concentration was markedly higher in patients with septic shock (96.98 ± 119.61 ng/mL). Moderate increase in serum PCT concentration occurred during pneumonia (4.85 ± 3.31 ng/mL) and bacteremia (3.57 ± 2.98 ng/mL). Serum PCT concentration remained low during mediastinitis (0.80 ± 0.58 ng/mL). Five patients with mediastinitis, two patients with bacteremia, and one patient with pneumonia had serum PCT concentrations of