Objectives: Following surgery, it is difficult to distinguish a postoperative inflammatory reaction from infection. This study examined the predictive value of the biomarkers; procalcitonin, C-reactive protein, lactate, neutrophils, lymphocytes, platelets, and the biphasic activated partial thromboplastin time waveform in diagnosing bacterial infection following cardiac surgery. Design: Prospective, observational study. Setting: A regional, PICU in the United Kingdom. Patients: Three-hundred sixty-eight children under the age of 16 admitted to the PICU for elective cardiac surgery were enrolled in the study. Interventions: All biomarker measurements were determined daily until postoperative day 7. Children were assessed for postoperative infection until day 28 and divided into four groups: bacterial infection, culture-negative sepsis, viral infection, and no infection. We used the Kruskal-Wallis test, chi-square test, analysis of variance, and area under the curve in our analysis. Measurements and Main Results: In total, 71 of 368 children (19%) developed bacterial infection postoperatively, the majority being surgical site infections. In those with bacterial infection, procalcitonin was elevated on postoperative days 1–3 and the last measurement prior to event compared with those without bacterial infection. The most significant difference was the last measurement prior to event; 0.72 ng/mL in the bacterial infection group versus 0.13 ng/mL in the no infection group (for all groups; p < 0.001). Longitudinal profiles of all biomarkers were indistinct in the bacterial infection and nonbacterial infection groups except in those with culture-negative infections who had distinct procalcitonin kinetics on postoperative days 1–4. Children with culture-negative sepsis required longer ventilatory support and PICU stay and were more likely to develop complications than the other groups. Conclusions: None of the biomarkers studied within 3 days of infection distinguished between infection and postoperative inflammatory reaction. However, procalcitonin kinetics peaked on postoperative day 2 and fell more sharply than C-reactive protein kinetics, which peaked at postoperative day 3. The monitoring of procalcitonin kinetics following cardiac surgery may help guide rational antimicrobial use.

AimsThe Systemic Inflammatory Response Syndrome (SIRS) is common after cardiac surgery and cardiopulmonary bypass (CPB), leading to difficulty in distinguishing between a bacterial infection or SIRS. Early diagnosis of post-operative infection is of fundamental importance in order to improve outcomes and reduce antibiotic over use. This study examined the predictive value of the biomarkers procalcitonin (PCT), lactate, neutrophil gelatinase associated lipocalin (NGAL) and the biphasic APTT waveform (bAPTT).MethodsConsecutive children admitted for cardiac surgery at a tertiary paediatric intensive care unit (PICU) were enrolled in the study. None of our patients had a bacterial infection (BI) at admission. Receiver operating curves (ROC) were created to determine the predictive value of the biomarkers to diagnose BI.ResultsIn total, 88/368 children (24%) developed BI. Median PCT in children with BI was 0.16 ng/ml (IQR 0.06–0.98) compared with 0.10 ng/ml (IQR 0.–0.36) in the non-infected group (p=0.03). Median lactate in children with BI was 1.42 mmol/L (IQR 0.93–2.37) compared with 1.20 mmol/L (0.93–1.79) in the non-infected group (p=0.03). The other biomarkers were not significantly different between BI and non-BI groups. The median inotrope score in first 12 hours was 10 (IQR 5–15) in those with BI compared with 7 (5–12) in the non-infected group (p=0.002). Prolonged hospital stay (p=0.001) and increased duration of mechanical ventilation (p=0.001) were more common in children with BI. CPB time was increased in children with BI (median 133 min, IQR 75–183) compared with those without BI (median 101 min, IQR 60–147) (p=0.005).Using ROC curves to predict BI, the AUC for PCT was 0.58, lactate 0.46, inotrope score in the first 12 hours 0.60, CPB 0.60, and circulatory arrest time 0.55 respectively.ConclusionNone of the biomarkers studied demonstrated strong predictive value for BI. The increased health utilisation of postoperative infection is highlighted by increased PICU and hospital stay. Children at higher risk of developing post-operative infection can be identified as those with prolonged bypass and crossclamp times, and those with high inotrope scores in the first 12 hours of admission.