title: Usefulness of procalcitonin for diagnosis of infection in cardiac surgical patients.
abstract: OBJECTIVE
  To determine the value of procalcitonin (PCT) as a marker of postoperative infection after cardiac surgery.
  
  
  METHODS
  A prospective single institution three phase study.
  
  
  METHODS
  University cardiac surgical intensive care unit (31 beds).
  
  
  METHODS
  Phase 1: To determine the normal perioperative kinetics of PCT, 20 consecutive patients undergoing elective cardiac surgery with cardiopulmonary bypass were included. Phase 2: To determine whether PCT may be useful for diagnosis of postoperative infection, 97 consecutive patients with suspected infection were included. Phase 3: To determine the ability of PCT to differentiate patients with septic shock from those with cardiogenic shock, 26 patients with postoperative circulatory failure were compared.
  
  
  RESULTS
  Phase 1: Serum 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 2: In 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 <1 ng/mL. These eight patients were administered antibiotics previously and serum PCT was measured during a therapeutic antibiotic window. For prediction of infection by PCT, the best cutoff value was 1 ng/mL, with sensitivity 85%, specificity 95%, positive predictive value 96%, and negative predictive value 84%. Serum CRP was high in all patients without intergroup difference. For prediction of infection by CRP, a value of 50 mg/L was sensitive (84%) but poorly specific (40%). Comparing the area under the receiver operating characteristic curves, PCT was better than CRP for diagnosis of postoperative sepsis (0.82 for PCT vs. 0.68 for CRP). Phase 3: Serum PCT concentration was significantly higher in patients with septic shock than in those with cardiogenic shock (96.98 +/- 119.61 ng/mL vs. 11.30 +/- 12.3 ng/mL). For discrimination between septic and cardiogenic shock, the best cutoff value was 10 ng/mL, with sensitivity of 100% and specificity of 62%.
  
  
  CONCLUSIONS
  Cardiac surgery with cardiopulmonary bypass influences serum PCT concentration with a peak on POD 1. In the presence of fever, PCT is a reliable marker for diagnosis of infection after cardiac surgery, except in patients who previously received antibiotics. PCT was more relevant than CRP for diagnosis of postoperative infection. During a postoperative circulatory failure, a serum PCT concentration >10 ng/mL is highly indicative of a septic shock.
authors.affiliation: Service d'Anesthésie-Réanimation and EA 1896 (Université Claude Bernard Lyon I), Hôpital Cardiovasculaire et Pneumologique L. Pradel, France. abdellah.aouifi@vnumail.com
authors.forename: A
authors.initials: A
authors.lastname: Aouifi
authors.forename: V
authors.initials: V
authors.lastname: Piriou
authors.forename: O
authors.initials: O
authors.lastname: Bastien
authors.forename: P
authors.initials: P
authors.lastname: Blanc
authors.forename: H
authors.initials: H
authors.lastname: Bouvier
authors.forename: R
authors.initials: R
authors.lastname: Evans
authors.forename: M
authors.initials: M
authors.lastname: Célard
authors.forename: F
authors.initials: F
authors.lastname: Vandenesch
authors.forename: R
authors.initials: R
authors.lastname: Rousson
authors.forename: J J
authors.initials: JJ
authors.lastname: Lehot
mesh_terms: D000328:Adult; D000368:Aged; D002097:C-Reactive Protein / Q000378:metabolism; D002116:Calcitonin / Q000097:blood*; D015740:Calcitonin Gene-Related Peptide; D003428:Cross Infection / Q000097:blood / Q000175:diagnosis*; D003937:Diagnosis, Differential; D005260:Female; D006331:Heart Diseases / Q000097:blood / Q000601:surgery*; D006333:Heart Failure / Q000097:blood / Q000175:diagnosis; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011498:Protein Precursors / Q000097:blood*; D012770:Shock, Cardiogenic / Q000097:blood / Q000175:diagnosis; D012772:Shock, Septic / Q000097:blood / Q000175:diagnosis; D013530:Surgical Wound Infection / Q000097:blood / Q000175:diagnosis*
chemical_list: C000606589:CALCA protein, human; D011498:Protein Precursors; D002116:Calcitonin; D002097:C-Reactive Protein; D015740:Calcitonin Gene-Related Peptide