Diagnostic Value of Procalcitonin on Early Postoperative Infection After Pediatric Cardiac Surgery

Objectives: Assess the diagnostic value of serial monitoring of procalcitonin levels on early postoperative infection after pediatric cardiac surgery with cardiopulmonary bypass. Design: Prospective, observational study. Setting: A pediatric cardiac surgical ICU (PICU) and pediatric cardiac surgery department at Fuwai Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College. Patients: Patients were 3 years old and below, underwent cardiac surgery involving cardiopulmonary bypass, the Aristotle Comprehensive Complexity score was 8 or higher and free from active preoperative infection or inflammatory disease. Interventions: Blood samples for measurement of procalcitonin, C-reactive protein, and WBC were taken before surgery and daily for 7 days in postoperative period. Clinical, laboratory, and imaging data were collected on enrollment. Procalcitonin, C-reactive protein, WBC levels, and procalcitonin variation were calculated and compared between those with and without infection. Measurements and Main Results: Two hundred and thirty-eight children were enrolled. Presence of infection within 7 days of surgery, length of intubation, and ICU stay were documented. Two independent experts in regard to the complete medical chart determined the final diagnosis of postoperative infection. Infection was diagnosed in 45 patients. Procalcitonin peaked on the first postoperative day. No differences were found on procalcitonin within 3 days after operation between the infected and the noninfected patients, and significant correlation was found between procalcitonin on postoperative days 1-3 and cardiopulmonary bypass duration. Serum procalcitonin concentration was always higher than 1.0 ng/mL within 7 days after surgery and/or procalcitonin variation between postoperative days 4 and 7 was positive in the infected patients. Best receiver operating characteristics curves area under the curve were obtained for procalcitonin and procalcitonin variation from postoperative days 5 to 7. WBC-and C-reactive protein-related receiver operating characteristics curves area under the curve revealed a very poor ability to predict infection. Logistic regression found that only procalcitonin on postoperative day 7 and PICU stay was independently correlated to the infection status. There was no significant correlation between the absolute value of procalcitonin and timing of infection. Conclusions: Procalcitonin was more accurate than C-reactive protein and WBC to predict early postoperative infection, but the diagnostic properties of procalcitonin could not be observed during the first 3 postoperative days due to the inflammatory process related to cardiopulmonary bypass. The dynamic change of procalcitonin is more important than the absolute value to predict postoperative infection. The maintenance of a high level (procalcitonin > 1.0 ng/mL) within 7 days after surgery and/or a second increase in procalcitonin between the fourth and the seventh postoperative day could be used as an indicator of postoperative infection. Continuous procalcitonin monitoring might help to discover infection earlier.