Procalcitonin kinetics in pediatric patients with systemic inflammatory response after open heart surgery

AACC Guidance Document on the Clinical Use of Procalcitonin

BACKGROUND

Procalcitonin (PCT), a peptide precursor of the hormone calcitonin, is a biomarker whose serum concentrations are elevated in response to systemic inflammation caused by bacterial infection and sepsis. Clinical adoption of PCT in the United States has only recently gained traction with an increasing number of Food and Drug Administration-approved assays and expanded indications for use. There is interest in the use of PCT as an outcomes predictor as well as an antibiotic stewardship tool. However, PCT has limitations in specificity, and conclusions surrounding its utility have been mixed. Further, there is a lack of consensus regarding appropriate timing of measurements and interpretation of results. There is also a lack of method harmonization for PCT assays, and questions remain regarding whether the same clinical decision points may be used across different methods.

CONTENT

This guidance document aims to address key questions related to the use of PCT to manage adult, pediatric, and neonatal patients with suspected sepsis and/or bacterial infections, particularly respiratory infections. The document explores the evidence for PCT utility for antimicrobial therapy decisions and outcomes prediction. Additionally, the document discusses analytical and preanalytical considerations for PCT analysis and confounding factors that may affect the interpretation of PCT results.

SUMMARY

While PCT has been studied widely in various clinical settings, there is considerable variability in study designs and study populations. Evidence to support the use of PCT to guide antibiotic cessation is compelling in the critically ill and in some lower respiratory tract infections but is lacking in other clinical scenarios, and evidence is also limited in the pediatric and neonatal populations. Interpretation of PCT results requires guidance from multidisciplinary care teams of clinicians, pharmacists, and clinical laboratorians.

Utility of Procalcitonin as a Biomarker for Sepsis in Children

Sepsis is a complex process defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. It is associated with significant morbidity and mortality rates in both adults and children, and emphasis has been placed on its early recognition and prompt provision of antimicrobials. Owing to limitations of current diagnostic tests (i.e., poor sensitivity and delayed results), significant research has been conducted to identify sepsis biomarkers. Ideally, a biomarker could reliably and rapidly distinguish bacterial infection from other, noninfectious causes of systemic inflammatory illness. In doing so, a sepsis biomarker could be used for earlier identification of sepsis, risk stratification/prognostication, and/or guidance of antibiotic decision-making. In this minireview, we review one of the most common clinically used sepsis biomarkers, procalcitonin, and its roles in sepsis management in these three areas. We highlight key findings in the adult literature but focus the bulk of this review on pediatric sepsis. The challenges and limitations of procalcitonin measurement in sepsis are also discussed.

The value of procalcitonin in systemic inflammatory response syndrome after open-heart surgery for CHD

BAKGROUND

Systemic inflammatory response syndrome, which is marked by fever, is a possible complication after open-heart surgery for CHD. The inflammatory response following the use of cardiopulmonary bypass shows similar clinical signs with sepsis. Therefore serial measurements of procalcitonin, an early infection marker, can be helpful to differentiate between sepsis and systemic inflammatory response syndrome.

OBJECTIVES

To evaluate serial levels of procalcitonin in children who underwent open-heart surgery for cyanotic and acyanotic CHD, and identify factors associated with elevated level of procalcitonin.

METHODS

Children and infants who had open-heart surgery and showed fever within 6 hours after surgery were recruited. Procalcitonin levels were serially measured along with leukocyte and platelet count. Other data were also recorded, including diagnosis, age, body weight, axillary temperature, aortic clamp time, bypass time, duration of mechanical ventilation, risk adjustment for congenital heart surgery score-1, and length of stay in Cardiac ICU. The patients were categorised into cyanotic and acyanotic CHD groups.

RESULTS

High mean of procalcitonin level suggested the presence of bacterial infection. Cyanotic CHD group had significantly higher mean of procalcitonin level compared to acyanotic CHD group in the first two measurements. Both groups had no leukocytosis, though platelet count results were significantly different between the two groups. There was no significant difference of procalcitonin level observed in culture results and adverse outcomes.

CONCLUSION

Serial procalcitonin measurement can be helpful to determine the cause of fever. Meanwhile other conventional markers such as leukocyte and platelet should be assessed thoroughly.

Procalcitonin Concentration Measured Within the First Days of Cardiac Surgery Is Predictive of Postoperative Infections in Neonates: A Case-Control Study

Increased procalcitonin concentration (PCT) is known to be reliable for the identification of infections even in the presence of the non-specific systemic inflammatory response seen after cardiopulmonary bypass (CPB), whereas increased C-reactive protein concentration (CRP) is not. The present work explored the ability of neonate PCT measured early after cardiac surgery to identify postoperative infections. This was a retrospective case-control study, where PCT was matched between patients with and without infections according to the patient's age, the CPB length, the use of deep hypothermic circulatory arrest (DHCA), and the postoperative day (POD). The accuracy in the prediction of infections was ascertained and cutoff thresholds were identified. 144 neonates were eligible, and 89 pairs of measurements from 94 patients were analyzed. PCT was a good predictor of infections within POD4, and was a better predictor when compared with CRP at POD1 and POD2. The sum of PCT (pg mL^-1) and CRP (mg L^-1) > 33 on POD1 or POD2 predicted infections with a 0.68 sensitivity and a 0.82 specificity, and a sum  > 49.36 on POD3 or POD4 predicted infections with a 0.82 sensitivity and a 0.93 specificity. In patients with DHCA, PCT was higher than in those without DHCA, and was not predictive of infections. The accuracy of PCT to identify infections after neonatal cardiac surgery is better than that of CRP when measured within 48 h of surgery. The sum of the two markers measured early after surgery is an excellent predictor of postoperative infections.

Early Kinetics of Procalcitonin in Predicting Surgical Outcomes in Type A Aortic Dissection Patients

BACKGROUND

In cardiac surgery, elevation of procalcitonin (PCT) could be observed postoperatively in the absence of any evidence of infection and also seems to be a prognostic marker. PCT levels measured in patients undergoing Type A aortic dissection (TAAD) were used to determine prognostic values for complications and surgical outcomes.

METHODS

Measurements of PCT, C-reactive protein (CRP), and leukocyte count were observed in TAAD surgery patients (n = 251; average age: 49.02 ± 12.83 years; 78.5% male) at presurgery (T0) and 24 h (T1), 48 h (T2), and 7 days (T3) postsurgery. PCT clearance (PCTc) on days 2 and 7 was calculated: (PCTday1- PCTday2/day7)/PCTday1 × 100%. Endotracheal intubation duration, length of stay (LOS) in the Intensive Care Unit (ICU)/hospital, and complications were recorded.

RESULTS

PCT peaked 24 h postsurgery (median 2.73 ng/ml) before decreasing. Correlation existed between PCT levels at T1 and duration of cardiopulmonary bypass (P = 0.001, r = 0.278). Serum PCT concentrations were significantly higher in nonsurvivor and multiple organ dysfunction syndrome groups on all postoperative days. PCT levels at T1 correlated with length of time of ventilation support and ICU/hospital LOS. Comparing PCT values of survivors versus nonsurvivors, a PCT cutoff level of 5.86 ng/ml at T2 had high sensitivity (70.6%) and specificity (74.3%) in predicting in-hospital death. PCTc-day 2 and 7 were significantly higher in survivor compared with nonsurvivor patients (38% vs. 8%, P= 0.012, 83% vs. -39%, P< 0.001). A PCTc-day 7 cutoff point of 48.7% predicted survival with high sensitivity (77.8%) and specificity (81.8%).

CONCLUSIONS

PCT level and PCTc after TAAD surgery might serve as early prognostic markers to predict postoperative outcome. PCT measurement may help identify high-risk patients.

Procalcitonin in the Early Course Post Pediatric Cardiac Surgery

OBJECTIVE

Procalcitonin has emerged as a promising infection marker, but previous reports from small-sized studies suggest nonspecific elevation of procalcitonin after pediatric heart surgery. As procalcitonin is increasingly used as a marker for infection in the PICU, the aim of this study was to identify factors associated with postoperative procalcitonin elevation and to investigate the role of procalcitonin as an early marker of outcome after cardiac surgery.

DESIGN

Prospective observational study.

SETTING

Single, tertiary referral PICU.

PATIENTS

Patients aged 0-16 years following cardiac surgery with or without cardiopulmonary bypass.

INTERVENTIONS

Procalcitonin was measured in all patients at admission to PICU, and on postoperative day 1 and 2. Outcome variables included major adverse event, length of stay in PICU, postoperative renal failure requiring temporary dialysis, duration of mechanical ventilation and duration of inotropic support. A major adverse event was defined as cardiac arrest, need for postoperative extracorporeal life support or death within 3 months of cardiac surgery.

MEASUREMENTS AND MAIN RESULTS

In 221 included patients who underwent 232 operations, procalcitonin at admission to PICU was significantly associated with mechanical ventilation prior to surgery (p = 0.001), preoperative myocardial dysfunction (p = 0.002), duration of cardiopulmonary bypass (p < 0.001), intraoperative cross-clamp time (p = 0.015), and serum lactate at admission (p < 0.001). Patients suffering a major adverse event and patients with postoperative renal failure had significantly higher procalcitonin levels at admission to PICU (p = 0.04 and 0.01, respectively). Furthermore, procalcitonin levels at admission correlated significantly with the length of stay in the PICU (p = 0.005), time on mechanical ventilation (p = 0.03), and duration of inotropic support (p = 0.02).

CONCLUSIONS

Elevated levels of procalcitonin in the early phase after pediatric cardiac surgery are a marker for increased risk for major adverse events and postoperative renal failure and increased postoperative morbidity.

Procalcitonin as a biomarker of bacterial infection in pediatric patients after congenital heart surgery

Background:

Bacterial infection (BI) after congenital heart surgery (CHS) is associated with increased morbidity and is difficult to differentiate from systemic inflammatory response syndrome caused by cardiopulmonary bypass (CPB). Procalcitonin (PCT) has emerged as a reliable biomarker of BI in various populations.

Aim:

To determine the optimal PCT threshold to identify BI among children suspected of having infection following CPB.

Setting and Design:

Single-center retrospective observational study.

Materials and Methods:

Medical records of all the patients admitted between January 2013 and April 2015 were reviewed. Patients in the age range of 0-21 years of age who underwent CHS requiring CPB in whom PCT was drawn between postoperative days 0-8 due to suspicion of infection were included.

Statistical Analysis:

The Wilcoxon rank-sum test was used for nonparametric variables. The diagnostic performance of PCT was evaluated using a receiver operating characteristic (ROC) curve.

Results:

Ninety-eight patients were included. The median age was 2 months (25th and 75th interquartile of 0.1-7.5 months). Eleven patients were included in the BI group. The median PCT for the BI group (3.42 ng/mL, 25th and 75th interquartile of 2.34-5.67) was significantly higher than the median PCT for the noninfected group (0.8 ng/mL, 25th and 75th interquartile 0.38-3.39), P = 0.028. The PCT level that yielded the best compromise between the sensitivity (81.8%) and specificity (66.7%) was 2 ng/mL with an area under the ROC curve of 0.742.

Conclusion:

A PCT less than 2 ng/mL makes BI unlikely in children suspected of infection after CHS.

Kinetics of interleukin-6, procalcitonin, and C-reactive protein after pediatric liver transplantation

In the early phase after pediatric liver transplantation (pLT) several concomitant factors may reduce the performance of established sepsis markers. To date, their clinical interpretation is hindered by a lack of information on their postoperative kinetics. To gather more information on the postoperative course and their changes in bacterial sepsis, we prospectively studied C-reactive protein (CRP), interleukin-6 (IL-6), and procalcitonin (PCT) on 9 perioperative days in 25 consecutive pLTs. After an initial postoperative peak, IL-6 and CRP levels significantly re-increased in patients with bacterial sepsis (P < .001). In contrast, PCT had very high postoperative levels; therefore severe infection was a comparatively inferior trigger for PCT elevation compared with the initial operation. The area under the receiver operating characteristic curve to diagnose postoperative sepsis for PCT was only 0.52, compared with 0.95 for IL-6 and 0.89 for CRP. None of the studied biomarkers were depressed by poor graft function. In conclusion, PCT performs poorly as a biomarker for sepsis in the early phase after pLT. With a rapid decline of initially elevated levels, IL-6 provides the best kinetics for detection of postoperative bacterial sepsis.

Markedly elevated procalcitonin in early postoperative period in pediatric open heart surgery: a prospective cohort study

Background

We encountered markedly elevated procalcitonin (PCT) among pediatric patients during the early postoperative period of open heart surgery. The purpose of this study is to investigate what factors are associated with the PCT elevation.

Methods

Fifty-two pediatric patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) were enrolled. Plasma PCT, aspartate aminotransferase/alanine aminotransferase (AST/ALT), creatinine, lactate, and C-reactive protein (CRP) were measured on admission to ICU and during the postoperative period. The patients were categorized into high (group H) and low (group L) groups according to their peak PCT levels. Aorta cross-clamp (ACC), CPB time, ICU stay, mechanical ventilation period, peak AST/ALT, creatinine, lactate, and CRP levels were compared.

Results

ACC and CPB times, ICU stay period, and mechanical ventilation period were significantly longer in group H compared with group L (118.7 ± 51.6 vs. 49.4 ± 43.5 min, 244.5 ± 65.7 vs. 122.9 ± 63.0 min, 7.9 ± 4.6 vs. 4.0 ± 4.5 days, and 6.3 ± 4.1 vs. 2.9 ± 4.2 days, respectively; p < 0.01). Peak AST and creatinine were significantly higher in group H compared with group L (999.0 ± 1,990.3 vs. 88.3 ± 43.0 U/l and 0.84 ± 0.77 vs. 0.41 ± 0.17 mg/dl, respectively; p < 0.05).

Conclusions

ACC and CPB time-related perioperative stress is associated with elevated PCT; an association between ICU stay and mechanical ventilation period, liver enzymes, and creatinine levels was observed. PCT may be a good predictor of postoperative severity and organ dysfunction.

Kinetics of procalcitonin and C-reactive protein and the relationship to postoperative infection in young infants undergoing cardiovascular surgery

BACKGROUND

The utility of procalcitonin (PCT) and C-reactive protein (CRP) as infectious biomarkers following infant cardiothoracic surgery is not well defined.

METHODS

We designed a prospective cohort study to evaluate PCT and CRP after infant cardiothoracic surgery. PCT and CRP were drawn preoperatively and 24/72 h postoperation or daily in delayed sternal closure patients. Presence of infection within 10 d of surgery, vasoactive-inotropic scores at 24 and 72 h, and length of intubation, intensive care unit stay, and hospital stay were documented.

RESULTS

PCT and CRP were elevated at 24 h. PCT then decreased while CRP increased in patients undergoing delayed sternal closure or cardiopulmonary bypass. In the delayed sternal closure group, PCT was significantly higher on postoperative days 2-5 in patients who ultimately developed infection. Higher PCT was independently associated with increased vasoactive-inotropic score at 72 h. CRP did not correlate with infection or postoperative support.

CONCLUSION

PCT rises after cardiothoracic surgery in infants but decreases by 72 h while CRP remains elevated. Sternal closure may affect CRP but not PCT. PCT is independently associated with circulatory support requirements at 72 h postoperation and with development of infection. PCT may have greater utility as a biomarker in this population.

Procalcitonin in pediatrics

Over the past two decades, the body of literature on the clinical usefulness of procalcitonin (PCT) in adults has grown rapidly. Although this approach has led to increased insight, it has also prompted debate regarding its potential use in diagnosis and management of severe infection. Clinicians, however, are less familiar with the use of PCT in pediatric populations. In this review, we examine PCT as a marker of severe clinical pediatric conditions including its role in systemic inflammation, infection, and sepsis.

Procalcitonin: a useful biomarker to discriminate infection after cardiopulmonary bypass in children

OBJECTIVE

To determine whether procalcitonin discriminates between postcardiopulmonary bypass inflammatory syndrome and infectious complication in children better than does C-reactive protein.

DESIGN

Prospective study of children admitted to the intensive care unit after cardiopulmonary bypass.

PATIENTS

Classified according to a diagnosis of systemic inflammatory response syndrome and bacterial infection or systemic inflammatory response syndrome but no bacterial infection. Two hundred thirty-one cases were recruited.

MEASUREMENT AND MAIN RESULTS

Procalcitonin, C-reactive protein, and leukocyte count were measured daily from surgery until day 3. Twenty-two patients were infected (9.5%). Significant differences were detected in the procalcitonin values of the infected group vs. the noninfected group, especially at day 2 (p = .000). There were no differences in the C-reactive protein values. The optimal cutoff for procalcitonin was >2 ng/mL at day 1 and above 4 ng/mL at the day 2. There was a greater sensitivity and specificity than with C-reactive protein as an infection predictor.

CONCLUSION

Procalcitonin is useful in the diagnosis of bacterial infection after cardiopulmonary bypass. Because procalcitonin kinetics are different in postcardiopulmonary bypass patients, the cutoff to diagnose infection should be different from the normal cutoff.

Procalcitonin level as an aid for the diagnosis of bacterial infections following pediatric cardiac surgery

PURPOSE

The aim of the present study was to determine if blood procalcitonin can serve as an aid to differentiate between bacterial and nonbacterial cause of fever in children after cardiac surgery.

MATERIALS AND METHODS

A nested case-control study of children who underwent open cardiac surgery in critical care units of fourth-level pediatric hospital was performed. Blood samples for procalcitonin level were collected 1 day before operation; 1 hour postoperation; on postoperative days 1, 2, and 5; and on the day of fever, when it occurred.

RESULTS

Of 665 children who underwent cardiac bypass surgery, 126 had a febrile episode postoperatively, 47 children with a proven bacterial infection and 79 without bacterial infection. Among the 68 children in whom fever developed within the first 5 postoperative days, procalcitonin level at fever day was significantly higher in those with bacterial infection (n = 16) than in those without infection (n = 52). Similarly, among the 58 children in whom fever developed after day 5 postoperation, a significant difference was found in procalcitonin level at fever day between those with (n = 31) and without (n = 27) bacterial infection.

CONCLUSION

During the critical early and late periods after cardiac surgery in children, procalcitonin level may help to differentiate patients with bacterial infection from patients in whom the fever is secondary to nonbacterial infectious causes.

Procalcitonin as a marker of bacterial infection in children undergoing cardiac surgery with cardiopulmonary bypass

BACKGROUND

Owing to systemic inflammatory response syndrome, the diagnosis of post-operative infection after cardiopulmonary bypass is difficult to assess in children with the usual clinical and biological tools. Procalcitonin could be informative in this context.

METHODS

Retrospective study in a paediatric intensive care unit. Blood samples were collected as soon as infection was clinically suspected and a second assay was performed 24 hours later. Using referenced criteria, children were retrospectively classified into two groups: infected and non-infected.

RESULTS

Out of the 95 children included, 14 were infected. Before the third post-operative day, procalcitonin median concentration was significantly higher in the infected group than in the non-infected group - 20.24 nanograms per millilitre with a 25th and 75th interquartile of 15.52-35.71 versus 0.72 nanograms per millilitre with a 25th and 75th interquartile of 0.28 to 5.44 (p = 0.008). The area under the receiver operating characteristic curve was 0.89 with 95% confidence intervals from 0.80 to 0.97. The best cut-off value to differentiate infected children from healthy children was 13 nanograms per millilitre with 100% sensitivity - 95% confidence intervals from 51 to 100 - and 85% specificity - 95% confidence intervals from 72 to 91. After the third post-operative day, procalcitonin was not significantly higher in infected children - 2 nanograms per millilitre with a 25th and 75th interquartile of 0.18 to 12.42 versus 0.37 nanograms per millilitre with a 25th and 75th interquartile of 0.24 to 1.32 (p = 0.26). The area under the receiver operating characteristic curve was 0.62 with 95% confidence intervals from 0.47 to 0.77. A procalcitonin value of 0.38 nanograms per millilitre provided a sensitivity of 70% with 95% confidence intervals from 39 to 89 for a specificity of 52% with 95% confidence intervals from 34 to 68. After the third post-operative day, a second assay at a 24-hour interval can improve the sensitivity of the test.

CONCLUSIONS

Procalcitonin seems to be a discriminating marker of bacterial infection during the post-operative days following cardiopulmonary bypass in children.

[Kinetics of C-reactive protein and procalcitonin after paediatric cardiac surgery]

INTRODUCTION AND OBJECTIVES

The systemic inflammatory response syndrome developed after cardiac surgery impedes the detection of complications. The aim of our study was to examine the behaviour of C-reactive protein (CRP) and procalcitonin (PCT), as well as to evaluate its relationship with severity and to analyse its usefulness in the identification of complications.

METHODS

A total of 59 children who underwent cardiac surgery with cardiopulmonary bypass were prospectively studied. CRP and PCT were determined after surgery and at 24, 48 and 72 hours. The relationships between both parameters and the clinical severity were analysed (evaluated with PRISM and TISS scoring systems), as well as with the incidence of complications (infectious and haemodynamics).

RESULTS

Serum concentrations of CRP and PCT increased in the first 24 hours after surgery, with a gradual decrease over the following days. There was no association between CRP and severity or development of complications. A moderate correlation was observed between PCT after surgery, at 24 and 48 hours, and PRISM (r=0.548; 0.434 and 0.446) and a low correlation between PCT and TISS. When studying the identification of complications, we obtained cut-off values of PCT>0.17ng/ml (Ss 73.3%; Sp 72.2%) and PCT>1.98ng/ml (Ss 57.1%; Sp 87%) immediately and 48 hours after surgery. No differences were found in CPR and PCT levels among patients with infectious and haemodynamics complications.

CONCLUSIONS

CPR does not correlate with the severity or the incidence of complications after paediatric cardiac surgery. PCT correlates with clinical severity and may be able to detect post-surgical complications.

Procalcitonin as a marker of severe bacterial infection in children in the emergency department

Procalcitonin, the prohormone of calcitonin, is a relatively new and innovative marker of bacterial infection that has multiple potential applications in the pediatric emergency department. In healthy individuals, circulating levels of procalcitonin are generally very low (<0.05 ng/mL), but in the setting of severe bacterial infection and sepsis, levels can increase by hundreds to thousands of fold within 4 to 6 hours. Although the exact physiologic function of procalcitonin has not been determined, the consistent response and rapid rise of this protein in the setting of severe bacterial infection make procalcitonin a very useful biomarker for invasive bacterial disease. In Europe, serum procalcitonin measurements are frequently used in the diagnosis and the management of patients in a variety of clinical settings. To date, the use of procalcitonin has been limited in the United States, but this valuable biomarker has many potential applications in both the pediatric emergency department and the intensive care unit. The intent of this article is to review the history of procalcitonin, describe the kinetics of the molecule in response to bacterial infection, describe the laboratory methods available for measuring procalcitonin, examine the main causes of procalcitonin elevation, and evaluate the potential applications of procalcitonin measurements in pediatric patients.

Procalcitonin assay in systemic inflammation, infection, and sepsis: clinical utility and limitations

OBJECTIVE

The use of procalcitonin (ProCT) as a marker of several clinical conditions, in particular, systemic inflammation, infection, and sepsis, will be clarified, and its current limitations will be delineated. In particular, the need for a more sensitive assay will be emphasized. For these purposes, the medical literature comprising clinical studies pertaining to the measurement of serum ProCT in various clinical settings was examined.

DATA SOURCE AND SELECTION

A PubMed search (1965 through November 2007) was conducted, including manual cross-referencing. Pertinent complete publications were obtained using the MeSH terms procalcitonin, C-reactive protein, sepsis, and biological markers. Textbook chapters were also read and extracted.

DATA EXTRACTION AND SYNTHESIS

Available clinical and other patient data from these sources were reviewed, including any data relating to precipitating factors, clinical findings, associated illnesses, and patient outcome. Published data concerning sensitivity, specificity, and reproducibility of ProCT assays were reviewed.

CONCLUSIONS

Based on available data, the measurement of serum ProCT has definite utility as a marker of severe systemic inflammation, infection, and sepsis. However, publications concerning its diagnostic and prognostic utility are contradictory. In addition, patient characteristics and clinical settings vary markedly, and the data have been difficult to interpret and often extrapolated inappropriately to clinical usage. Furthermore, attempts at meta-analyses are greatly compromised by the divergent circumstances of reported studies and by the sparsity and different timing of the ProCT assays. Although a high ProCT commonly occurs in infection, it is also elevated in some noninfectious conditions. Thus, the test is not a specific indicator of either infection or sepsis. Moreover, in any individual patient, the precipitating cause of an illness, the clinical milieu, and complicating conditions may render tenuous any reliable estimations of severity or prognosis. It also is apparent that even a febrile septic patient with documented bacteremia may not necessarily have a serum ProCT that is elevated above the limit of functional sensitivity of the assay. In this regard, the most commonly applied assay (i.e., LUMItest) is insufficiently sensitive to detect potentially important mild elevations or trends. Clinical studies with a more sensitive ProCT assay that is capable of rapid and practicable day-to-day monitoring are needed and shortly may be available. In addition, investigations showing that ProCT and its related peptides may have mediator relevance point to the need for evaluating therapeutic countermeasures and studying the pathophysiologic effect of hyperprocalcitonemia in serious infection and sepsis.

Acute-phase reactants after paediatric cardiac arrest. Procalcitonin as marker of immediate outcome

Objective

Procalcitonin (PCT) and C reactive protein (CRP) have been used as infection parameters. PCT increase correlates with the infection's severity, course, and mortality. Post-cardiocirculatory arrest syndrome may be related to an early systemic inflammatory response, and may possibly be associated with an endotoxin tolerance. Our objective was to report the time profile of PCT and CRP levels after paediatric cardiac arrest and to assess if they could be use as markers of immediate survival.

Materials and methods

A retrospective observational study set in an eight-bed PICU of a university hospital was performed during a period of two years. Eleven children younger than 14 years were admitted in the PICU after a cardiac arrest. PCT and CRP plasma concentrations were measured within the first 12 and 24 hours of admission.

Results

In survivors, PCT values increased 12 hours after cardiac arrest without further increase between 12 and 24 hours. In non survivors, PCT values increased 12 hours after cardiac arrest with further increase between 12 and 24 hours. Median PCT values (range) at 24 hours after cardiac arrest were 22.7 ng/mL (0.2 – 41.0) in survivors vs. 205.5 ng/mL (116.6 – 600.0) in non survivors (p < 0.05). CRP levels were elevated in all patients, survivors and non-survivors, at 12 and 24 hours without differences between both groups.

Conclusion

Measurement of PCT during the first 24 hours after paediatric cardiac arrest could serve as marker of mortality.

Procalcitonin and C-reactive protein as markers of systemic inflammatory response syndrome severity in critically ill children

OBJECTIVES

To analyse the clinical value of procalcitonin (PCT), C-reactive protein (CRP) and leucocyte count in the diagnosis of paediatric sepsis and in the stratification of patients according to severity.

DESIGN

Prospective, observational study.

SETTING

Paediatric intensive care unit (PICU).

PATIENTS

Ninety-four children.

MEASUREMENT AND RESULTS

Leucocyte count, PCT and CRP were measured when considered necessary during the PICU stay. Patients were classified, when PCT and CRP were measured, into one of six categories (negative, SIRS, localized infection, sepsis, severe sepsis, and septic shock) according to the definitions of the American College of Chest Physicians /Society of Critical Care Medicine. A total of 359 patient day episodes were obtained. Leucocyte count did not differ across the six diagnostic classes considered. Median plasma PCT concentrations were 0.17, 0.43, 0.79, 1.80, 15.40 and 19.13 ng/ml in negative, systemic inflammatory response syndrome (SIRS), localized infection, sepsis, severe sepsis, and septic shock groups, respectively, whereas median plasma CRP concentrations were 1.35, 3.80, 6.45, 5.70, 7.60 and 16.2 mg/dl, respectively. The area under the ROC curve for the diagnosis of septic patients was 0.532 for leucocyte count (95% CI, 0.462-0.602), 0.750 for CRP (95% CI, 0.699-0.802) and 0.912 for PCT (95% CI, 0.882-0.943). We obtained four groups using CRP values and five groups using PCT values that classified a significant percentage of patients according to the severity of the different SIRS groups.

CONCLUSIONS

PCT is a better diagnostic marker of sepsis in critically ill children than CRP. The CRP, and especially PCT, may become a helpful clinical tool to stratify patients with SIRS according to disease severity.

Diagnostic value and prognostic implications of serum procalcitonin after cardiac surgery: a systematic review of the literature

INTRODUCTION

Systemic inflammatory response syndrome is common after surgery, and it can be difficult to discriminate between infection and inflammation. We performed a review of the literature with the aims of describing the evolution of serum procalcitonin (PCT) levels after uncomplicated cardiac surgery, characterising the role of PCT as a tool in discriminating infection, identifying the relation between PCT, organ failure, and severity of sepsis syndromes, and assessing the possible role of PCT in detection of postoperative complications and mortality.

METHODS

We performed a search on MEDLINE using the keyword 'procalcitonin' crossed with 'cardiac surgery,' 'heart,' 'postoperative,' and 'transplantation.' Our search was limited to human studies published between January 1990 and June 2006.

RESULTS

Uncomplicated cardiac surgery induces a postoperative increase in serum PCT levels. Peak PCT levels are reached within 24 hours postoperatively and return to normal levels within the first week. This increase seems to be dependent on the surgical procedure and on intraoperative events. Although PCT values reported in infected patients are generally higher than in non-infected patients after cardiac surgery, the cutoff point for discriminating infection ranges from 1 to 5 ng/ml, and the dynamics of PCT levels over time may be more important than absolute values. PCT is superior to C-reactive protein in discriminating infections in this setting. PCT levels are higher with increased severity of sepsis and the presence of organ dysfunction/failure and in patients with a poor outcome or in those who develop postoperative complications. PCT levels typically remain unchanged after acute rejection but increase markedly after bacterial and fungal infections. Systemic infections are associated with greater PCT elevation than is local infection. Viral infections are difficult to identify based on PCT measurements.

CONCLUSION

The dynamics of PCT levels, rather than absolute values, could be important in identifying patients with infectious complications after cardiac surgery. PCT is useful in differentiating acute graft rejection after heart and/or lung transplantation from bacterial and fungal infections. Further studies are needed to define cutoff points and to incorporate PCT levels in useful prediction models.