What is the role of procalcitonin (PCT) in managing postoperative infections in patients after recent surgery?

From the Guidelines

Procalcitonin (PCT) is a valuable biomarker for diagnosing and managing bacterial infections in postoperative patients, and its levels should be measured as part of the initial workup, with levels >0.5 ng/mL suggesting bacterial infection and levels >2.0 ng/mL strongly indicating sepsis, as supported by recent studies 1.

Key Points to Consider

• PCT levels increase in bacterial infections, rising early in the course of infection, making it a useful biomarker for decision making regarding initiation of antibiotic therapy and management of sepsis when the results of blood culture are not available 1.
• Serial PCT measurements are recommended every 24-48 hours to monitor treatment response, with declining levels (ideally by >80% from peak) indicating effective antimicrobial therapy 1.
• PCT testing complements but does not replace clinical judgment, as levels may be transiently elevated (typically <2 ng/mL) for 24-48 hours after surgery due to surgical stress alone 1.
• PCT is particularly useful in distinguishing bacterial infections from non-infectious inflammatory conditions or viral infections, helping to guide appropriate antibiotic use, with its production being attenuated by interferon-gamma during viral infections, making it relatively specific for bacterial infections 1.

Clinical Application

• For optimal clinical application, PCT results should always be interpreted alongside clinical assessment, other laboratory findings, and imaging studies 1.
• The use of PCT can help guide the duration and cessation of antibiotic therapy in critically ill patients, with some studies suggesting that it may be useful in shortening antibiotic duration 1.
• However, it is essential to consider the limitations of PCT, including its expense compared to other biomarkers like CRP and WBC, and its potential to falsely rise in cases of acute respiratory distress syndrome, chemical pneumonitis, and severe falciparum malaria 1.

Recommendations

• PCT levels should be used in conjunction with clinical judgment to guide antibiotic therapy in postoperative patients with suspected bacterial infections 1.
• Serial PCT measurements should be used to monitor treatment response and guide the duration of antibiotic therapy 1.
• PCT results should be interpreted alongside other laboratory findings, clinical assessment, and imaging studies to ensure optimal clinical application 1.

From the Research

Role of Procalcitonin in Managing Postoperative Infections

• Procalcitonin (PCT) is a biomarker that has been studied for its potential in detecting postoperative infections in patients after recent surgery 2, 3, 4, 5, 6.
• The level of PCT can be influenced by the type of surgery, with higher levels observed after major surgeries such as intestinal surgery and thoracic surgery 2, 4.
• PCT has been shown to be a reliable diagnostic parameter for detecting postoperative infections, especially in patients at higher risk of infection 2.
• However, the accuracy of PCT in diagnosing postoperative infection can be affected by renal dysfunction, and different thresholds may need to be applied depending on the patient's renal function 3.
• The diagnostic accuracy of PCT for postoperative infection has been found to be moderate, with pooled sensitivity and specificity of 72% and 62%, respectively 5.
• Other biomarkers such as interleukin-6 (IL-6) have also been studied, and IL-6 has been found to have a higher diagnostic accuracy than PCT for postoperative infection 5.
• The monitoring of PCT kinetics after surgery may help guide rational antimicrobial use, but none of the biomarkers studied can reliably distinguish between infection and postoperative inflammatory reaction within 3 days of infection 6.

Factors Influencing Procalcitonin Levels

• Type of surgery: PCT levels can be influenced by the type of surgery, with higher levels observed after major surgeries such as intestinal surgery and thoracic surgery 2, 4.
• Renal dysfunction: Renal dysfunction can affect the accuracy of PCT in diagnosing postoperative infection, and different thresholds may need to be applied depending on the patient's renal function 3.
• Postoperative inflammatory reaction: PCT levels can be elevated after surgery due to postoperative inflammatory reaction, making it challenging to distinguish between infection and non-infectious causes of inflammation 6.

Clinical Applications of Procalcitonin

• Diagnostic tool: PCT can be used as a diagnostic tool to detect postoperative infections, especially in patients at higher risk of infection 2.
• Monitoring: PCT kinetics can be monitored after surgery to guide rational antimicrobial use and to distinguish between infection and postoperative inflammatory reaction 6.
• Risk stratification: PCT levels can be used to stratify patients according to their risk of postoperative infection, allowing for targeted interventions and improved patient outcomes 2, 3, 4, 5, 6.