Procalcitonin versus C-reactive protein and immature-to-total neutrophil ratio as markers of infection after cardiopulmonary bypass in children

T-cell lymphopenia is associated with an increased infecting risk in children after cardiopulmonary bypass

BACKGROUND

children who undergo CPB operations are at an elevated risk of infection due to immunosuppression. This study aims to investigate the association between lymphopenia following CPB and early postoperative infection in children.

METHODS

A retrospective analysis including 41 children under 2 years old underwent CPB. Among them, 9 subjects had an early postoperative infection, and 32 subjects were period-matched without infection. Inflammatory cytokines, serum CRP and PCT values were measured in plasma, additionally, circulating total leucocyte and lymphocyte subpopulations were counted.

RESULTS

Infected subjects exhibited significantly higher levels of inflammatory cytokines, including IL-6, IL-8, IL-10, IL-1β and TNF-α, than non-infected subjects after CPB. Additionally, lower absolute number of lymphocyte and their subpopulations CD3+ T cells, CD4+ T-helper cells and CD8+cytotoxic T-cells, were observed in infected subjects. The impairment of T-cells Immune was found to be associated with higher levels of inflammatory cytokines IL-10. The ROC demonstrated that the absolute number of CD3+ T-cells <1934/ul, CD4+ T helper cells <1203/ul and CD8+cytotoxic T-cells <327/ul were associated with early postoperative infection.

CONCLUSION

Higher levels of inflammatory cytokines resulted in T-cells lymphopenia after CPB, which significantly increasing the risk of postoperative infection in infants and young children.

IMPACT

Infection complications after cardiopulmonary bypass (CPB) in pediatric CHD patients are serious issues, identifing the infection from after CPB remains a challenging. CPB can release numerous inflammatory cytokines associated with T cells lymphopenia, which increases the risk of postoperative infection after surgery. Monitoring T cells lymphopenia maybe more beneficial to predict early postoperative infection than C-reactive protein and procalcitonin.

Post-operative kinetics of C-reactive protein to distinguish between bacterial infection and systemic inflammation in infants after cardiopulmonary bypass surgery: the early and the late period

OBJECTIVES

Differentiation between post-operative inflammation and bacterial infection remains an important issue in infants following congenital heart surgery. We primarily assessed kinetics and predictive value of C-reactive protein for bacterial infection in the early (days 0-4) and late (days 5-28) period after cardiopulmonary bypass surgery. Secondary objectives were frequency, type, and timing of post-operative infection related to the risk adjustment for congenital heart surgery score.

METHODS

This 3-year single-centre retrospective cohort study in a paediatric cardiac ICU analysed 191 infants accounting for 235 episodes of CPBP surgery. Primary outcome was kinetics of CRP in the first 28 days after CPBP surgery in infected and non-infected patients.

RESULTS

We observed 22 infectious episodes in the early and 34 in the late post-operative period. CRP kinetics in the early post-operative period did not accurately differentiate between infected and non-infected patients. In the late post-operative period, infected infants displayed significantly higher CRP values with a median of 7.91 (1.64-22.02) and 6.92 mg/dl (1.92-19.65) on days 2 and 3 compared to 4.02 (1.99-15.9) and 3.72 mg/dl (1.08-9.72) in the non-infection group. Combining CRP on days 2 and 3 after suspicion of infection revealed a cut-off of 9.47 mg/L with an acceptable predictive accuracy of 76%.

CONCLUSIONS

In neonates and infants, CRP kinetics is not useful to predict infection in the first 72 hours after CPBP surgery due to the inflammatory response. However, in the late post-operative period, CRP is a valuable adjunctive diagnostic test in conjunction with clinical presentation and microbiological diagnostics.

C-reactive protein and procalcitonin after congenital heart surgery utilizing cardiopulmonary bypass: When should we be worried?

INTRODUCTION

To assess the efficacy of C-reactive protein (CRP) and procalcitonin (PCT) at identifying infection in children after congenital heart surgery (CHS) with cardiopulmonary bypass (CPB).

MATERIALS AND METHODS

Systematic review of the literature was conducted to identify studies with data regarding CRP and/or PCT after CHS with CPB. The primary variables identified to be characterized were CRP and PCT at different timepoints. The main inclusion criteria were children who underwent CHS with CPB. Subset analyses for those with and without documented infection were conducted in similar fashion. A p value of less than .05 was considered statistically significant.

RESULTS

A total of 21 studies were included for CRP with 1655 patients and a total of 9 studies were included for PCT with 882 patients. CRP peaked on postoperative Day 2. A significant difference was noted in those with infection only on postoperative Day 4 with a level of 53.60 mg/L in those with documented infection versus 29.68 mg/L in those without. PCT peaked on postoperative Day 2. A significant difference was noted in those with infection on postoperative Days 1, 2, and 3 with a level of 12.9 ng/ml in those with documented infection versus 5.6 ng/ml in those without.

CONCLUSIONS

Both CRP and PCT increase after CHS with CPB and peak on postoperative day 2. PCT has a greater statistically significant difference in those with documented infection when compared to CRP and a PCT of greater than 5.6 ng/ml should raise suspicion for infection.

The diagnostic accuracy of procalcitonin in infectious patients after cardiac surgery: a systematic review and meta-analysis

Cardiac surgery with cardiopulmonary bypass (CPB) induces an acute inflammatory response that may lead to a systemic inflammatory response syndrome. The interest in procalcitonin (PCT) in the diagnosis of bacterial infection in patients after cardiac surgery remains less defined. The aim of this meta-analysis is to prospectively examine the discriminatory power of PCT as markers of infection in hospitalized patients with after cardiac surgery. The bivariate generalized nonlinear mixed-effect model and the hierarchical summary receiver operating characteristic model were used to estimate the pooled sensitivity, specificity and summary receiver operating characteristic curve. The pooled sensitivity and specificity were 0.81 (95% CI 0.75-0.87) and 0.78 (95% CI 0.73-0.83), respectively. The pooled positive likelihood ratio, and negative likelihood ratio of PCT were 3.74 (95% CI 2.98-4.69) and 0.24 (95% CI 0.17-0.32), respectively. The pooled area under the summary receiver operating characteristic curve of PCT using the HSROC method was 0.87 (95% CI 0.84- 0.90). This study indicated that PCT is a promising marker for the diagnosis of sepsis for those patients who undergo cardiac surgery.

Invasive Bacterial and Fungal Infections After Pediatric Cardiac Surgery: A Single-center Experience

BACKGROUND

Discrimination of infectious and noninfectious complications in children with inflammatory signs after cardiac surgery is challenging. Given the low prevalence of infectious complications after heart surgery, there might be a risk of excessive antibiotic usage. We performed this study to determine the rate of invasive bacterial or fungal infections in children after cardiac surgery at our institution and to evaluate our postoperative management.

METHODS

This single-center retrospective observational cohort study included children 16 years of age or younger who underwent cardiac surgery at our institution between January 2012 and December 2015.

RESULTS

We analyzed 395 surgical procedures. Thirty-five postoperative invasive bacterial or fungal infections were detected in 29 episodes (7%, 0.42 per 100 admission days). Among bacterial infections, the most common infection sites were bacteremia and pneumonia, accounting for 37% (13/35) and 23% (8/35) of infections respectively. The rate of postoperative infections was associated with surgical complexity score and length of postoperative pediatric intensive care unit (PICU) stay. In 154 (43%) of 357 episodes without microbiologically documented infection, uninterrupted postoperative antibiotic administration was continued for more than 3 days and in 80 (22%) for more than 5 days.

CONCLUSIONS

The rate of postoperative bacterial or fungal infection at our institution is comparable to current literature. High surgical complexity score and prolonged length of PICU stay were risk factors for bacterial or fungal infections in this patient population.

Prognostic value of biomarkers after cardiopulmonary bypass in pediatrics: The prospective PANCAP study

Objective

To assess the usefulness of procalcitonin, pro-adrenomedullin and pro-atrial natriuretic peptide as predictors of need for mechanical ventilation and postoperative complications (need for inotropic support and bacterial infection) in critically ill pediatric patients after cardiopulmonary bypass.

Design

A prospective, observational study

Setting

Pediatric intensive care unit.

Patients

Patients under 18 years old admitted after cardiopulmonary bypass.

Measuraments and main results

Serum levels of procalcitonin, pro-adrenomedullin and pro-atrial natriuretic peptide were determined immediately after bypass and at 24–36 hours. Their values were correlated with the need for mechanical ventilation, inotropic support and bacterial infection. One hundred eleven patients were recruited. Septal defects (30.6%) and cardiac valve disease (17.1%) were the most frequent pathologies. 40.7% required mechanical ventilation, 94.6% inotropic support and 15.3% presented invasive bacterial infections. Pro-adrenomedullin and pro-atrial natriuretic peptide showed significant high values in patients needing mechanical ventilation. Cut-off values higher than 1.22 nmol/L and 215.3 pmol/L, respectively for each biomarker, may indicate need for mechanical ventilation with an AUC of 0.721 and 0.746 at admission and 0.738 and 0.753 at 24–36 hours, respectively but without statistical differences. Pro-adrenomedullin and procalcitonin showed statistically significant high values in patients with bacterial infections.

Conclusions

After bypass, pro-adrenomedullin and pro-atrial natriuretic peptide are suitable biomarkers to predict the need for mechanical ventilation. Physicians should be alert if the values of these markers are high so as not to progress to early extubation. Procalcitonin is useful for predicting bacterial infection. This is a preliminary study and more clinical studies should be done to confirm the value of pro-adrenomedullin and pro-atrial natriuretic peptide as biomarkers after cardiopulmonary bypass.

Use of biomarkers in pediatric sepsis: literature review

Despite advances in recent years, sepsis is still a leading cause of hospitalization and mortality in infants and children. The presence of biomarkers during the response to an infectious insult makes it possible to use such biomarkers in screening, diagnosis, prognosis (risk stratification), monitoring of therapeutic response, and rational use of antibiotics (for example, the determination of adequate treatment length). Studies of biomarkers in sepsis in children are still relatively scarce. This review addresses the use of biomarkers in sepsis in pediatric patients with emphasis on C-reactive protein, procalcitonin, interleukins 6, 8, and 18, human neutrophil gelatinase, and proadrenomedullin. Assessment of these biomarkers may be useful in the management of pediatric sepsis.

The utility of procalcitonin in the prediction of serious bacterial infection in a tertiary paediatric intensive care unit

To determine utility of procalcitonin (PCT) for the prediction of bacterial infection in critically ill children, we analysed the relationship between serum PCT, cultures and other laboratory markers of bacterial sepsis or viral infection in a tertiary paediatric intensive care unit (PICU). The outcome measures were levels of PCT in proven bacteraemia, pneumonia and viral respiratory infection; and comparison of PCT to immature to total neutrophil ratio (ITR) in prediction of bacteraemia. In 420 children with suspected sepsis, 1,226 serum PCT levels were analysed. Children with bacteraemia had a higher median PCT (2.03 ng/ml, interquartile range [IQR] 0.67-42.4) than those who did not have bacteraemia (0.82 ng/ml, IQR 0.295-2.87) (P=0.033). PCT was a significant but only moderate predictor of bacteraemia (AUC 0.65). In 866 episodes of suspected sepsis where paired PCT and ITR were performed, the median ITR in children with bacteraemia was 0.19 ng/ml (IQR 0.04-0.35), and the median PCT was 6.5 ng/ml (IQR 0.71-61.8). PCT was a marginally better predictor of bacteraemia (AUC 0.69) than the ITR (AUC 0.66). In children with viral respiratory tract infection only, the median PCT was 1.26 ng/ml (0.35-5.5), and in those with likely bacterial pneumonia the median PCT was 0.80 ng/ml (IQR 0.28-1.70). In a heterogeneous population of children in a tertiary PICU, PCT measured at a single timepoint was a moderate predictor of proven bacteraemia. In our population PCT did not reliably identify localised bacterial infection or distinguish bacterial from viral respiratory infection.

Procalcitonin Is a Better Biomarker than C-Reactive Protein in Newborns Undergoing Cardiac Surgery: The PROKINECA Study

OBJECTIVES

To assess the kinetics of procalcitonin (PCT) and C-reactive protein (CRP) in newborns after cardiothoracic surgery (CS), with and without cardiopulmonary bypass, and to assess whether PCT was better than CRP in identifying sepsis in the first 72 hours after CS.

PATIENTS AND METHODS

This is a prospective study of newborns admitted to the neonatal intensive care unit after CS.

INTERVENTIONS

PCT and CRP were sequentially drawn 2 hours before surgery and at 0, 12, 24, 48, and 72 hours after surgery.

RESULTS

A total of 65 patients were recruited, of which 14 were excluded because of complications. We compared the kinetics of PCT and CRP after CS in bypass and non-bypass groups without sepsis; there were no differences in the PCT values at any time (24 hours, P = 0.564; 48 hours, P = 0.117; 72 hours, P = 0.076). Thirty-five patients needed bypass, of whom four were septic (11.4%). Significant differences were detected in the PCT values on comparing the septic group to the nonseptic group at 48 hours after cardiopulmonary bypass (P = 0.018). No differences were detected in the CRP values in these groups. A suitable cutoff for sepsis diagnosis at 48 hours following bypass would be 5 ng/mL, with optimal area under the curve of 0.867 (confidence interval 0.709–0.958), P < 0.0001, and sensitivity and specificity of 87.5% (29.6–99.7) and 72.6% (53.5–86.4), respectively.

CONCLUSION

This is a preliminary study but PCT seems to be a good biomarker in newborns after CS. Values over 5 ng/mL at 48 hours after CS should alert physicians to the high risk of sepsis in these patients.

Avoidance of Hospital-Acquired Infections in Pediatric Cardiac Surgical Patients

OBJECTIVES

The objectives of this review are to discuss the prevalence and risk factors associated with the development of hospital-acquired infections in pediatric patients undergoing cardiac surgery and the published antimicrobial prophylaxis regimens and rational approaches to the diagnosis, prevention, and treatment of nosocomial infections in these patients.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSION

Hospital-acquired infections remain a significant source of potentially preventable morbidity and mortality in pediatric cardiac surgical patients. Through improved understanding of these conditions and implementation of avoidance strategies, centers caring for these patients may improve outcomes in this vulnerable population.

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.

Culture Negative Stent Infection in an Infant with Hypoplastic Left Heart and Persistent Fever

We present an infant with hypoplastic left heart with persistent fever despite two courses of antibiotics and repeatedly negative blood cultures. He eventually underwent surgical extraction of two stents. The stent cultures became positive; he was treated with 4 weeks of antibiotics and the fever resolved.

Procalcitonin Biomarker Kinetics to Predict Multiorgan Dysfunction Syndrome in Children With Sepsis and Systemic Inflammatory Response Syndrome

Background:

Procalcitonin (PCT) kinetics is a good prognosis marker in infectious diseases, but few studies of children sepsis have been performed.

Objectives:

The aim of our study was to examine kinetics of procalcitonin, to evaluate its relationship with severity and to analyze its usefulness in the prediction of multiorgan dysfunction syndrome (MODS).

Patients and Methods:

Prospective observational study in an 8-bed pediatric intensive care unit of a university hospital. Sixty-two children aged 0-19 years with systemic inflammatory response syndrome or septic states. The degree of severity was evaluated according pediatric logistic organ dysfunction (PELOD) score. Blood tests to determine levels of PCT were taken if the patients had the criteria of systemic inflammatory response syndrome or sepsis. The serum to determine levels of PCT in control group has been taken from patients undergoing elective surgery.

Results:

Higher values of PCT were identified in patients with PELOD score 12 and more compared to those with PELOD < 12 (P = 0.016). Similarly, higher PCT values were found in patients who developed MODS in contrast to those without MODS (P = 0.011). According to ROC analysis cut-off value of 4.05 ng/mL was found to best discriminate patients with PELOD < 12 and PELOD ≥ 12 with AUC = 0.675 (P = 0.035). Effect of procalcitonin levels on mortality was not demonstrated.

Conclusions:

Levels of procalcitonin from day 1 to day 5 are related to the severity and multiorgan dysfunction syndrome in children.

Procalcitonin to predict bacterial coinfection in infants with acute bronchiolitis: a preliminary analysis

OBJECTIVE

The aim of this study was to conduct a preliminary analysis of serum procalcitonin (PCT) to predict bacterial coinfection in infants with acute bronchiolitis.

METHODS

Retrospective cohort chart review of 40 infants admitted with acute bronchiolitis to the pediatric intensive care unit. Logistic regression models were used to determine the association of PCT and white blood count with presence of bacterial coinfection defined by either positive culture or chest radiograph result.

RESULTS

Fifteen (38%) of 40 patients had a diagnosis of bacterial coinfection by positive culture (9/15) or chest radiograph (6/15). Procalcitonin (P < 0.0001) was significantly associated with bacterial coinfection. A cutoff value of 1.5 ng/mL had sensitivity of 0.80, specificity of 1.00, and area under the operating curve of 0.88. White blood count (P = 0.06) was borderline significant with sensitivity of 0.33, specificity of 0.96, and area under the operating curve of 0.67. Three of 15 patients were later found to have bacterial coinfection with initial PCT of less than 1.5 ng/mL. None had follow-up PCT measurements taken. Thirty-five of 40 were prescribed empiric antibiotic therapy, including 20 of 25 patients without evidence of bacterial coinfection. None had a PCT of greater than 1.5 ng/mL. If a PCT cutoff of greater than 1.5 ng/mL had been used, 57% fewer patients would have received antibiotics with a 45% reduction in antimicrobial charges.

CONCLUSIONS

An elevated PCT may assist clinicians in determining presence of bacterial coinfection at admission in infants with acute bronchiolitis. Implementation of a PCT cutoff of 1.5 ng/mL at admission may prevent unnecessary antibiotic use with associated cost savings. Serial PCT levels may increase sensitivity. Further validation is warranted.

Role of biomarkers in sepsis care

Sepsis is one of the leading causes of mortality and morbidity, even with the current availability of extended-spectrum antibiotics and advanced medical care. Biomarkers offer a tool in facilitating early diagnosis, in identifying patient populations at high risk of complications, and in monitoring progression of the disease, which are critical assessments for appropriate therapy and improvement in patient outcomes. Several biomarkers are already available for clinical use in sepsis; however, their effectiveness in many instances is limited by the lack of specificity and sensitivity to characterize the presence of an infection and the complexity of the inflammatory and immune processes and to stratify patients into homogenous groups for specific treatments. Current advances in molecular techniques have provided new tools facilitating the discovery of novel biomarkers, which can vary from metabolites and chemical products present in body fluids to genes and proteins in circulating blood cells. The purpose of this review was to examine the current status of sepsis biomarkers, with special emphasis on emerging markers, which are undergoing validation and may transition into clinical practice for their informative value in diagnosis, prognosis, or response to therapy. We will also discuss the new concept of combination biomarkers and biomarker risk models, their existing challenges, and their potential use in the daily management of patients with sepsis.

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.

Postoperative differences between colonization and infection after pediatric cardiac surgery-a propensity matched analysis

Background

The objective of this study was to identify the postoperative risk factors associated with the conversion of colonization to postoperative infection in pediatric patients undergoing cardiac surgery.

Methods

Following approval from the Institutional Review Board, patient demographics, co-morbidities, surgery details, transfusion requirements, inotropic infusions, laboratory parameters and positive microbial results were recorded during the hospital stay, and the patients were divided into two groups: patients with clinical signs of infection and patients with only positive cultures but without infection during the postoperative period. Using propensity scores, 141 patients with infection were matched to 141 patients with positive microbial cultures but without signs of infection. Our database consisted of 1665 consecutive pediatric patients who underwent cardiac surgery between January 2004 and December 2008 at a single center. The association between the patient group with infection and the group with colonization was analyzed after propensity score matching of the perioperative variables.

Results

179 patients (9.3%) had infection, and 253 patients (15.2%) had colonization. The occurrence of Gram-positive species was significantly greater in the colonization group (p = 0.004). The C-reactive protein levels on the first and second postoperative days were significantly greater in the infection group (p = 0.02 and p = 0.05, respectively). The sum of all the positive cultures obtained during the postoperative period was greater in the infection group compared to the colonization group (p = 0.02). The length of the intensive care unit stay (p < 0.001) was significantly longer in the infection group compared to the control group.

Conclusions

Based on our results, we uncovered independent relationships between the conversion of colonization to infection regarding positive S. aureus and bloodstream results, as well as significant differences between the two groups regarding postoperative C-reactive protein levels and white blood cell counts.

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.

The profile of the systemic inflammatory response in children undergoing ventricular assist device support

OBJECTIVES

Serum C-reactive protein (CRP) has been used as a systemic inflammatory response (SIR) marker in the critical ill, including children after cardiopulmonary bypass surgery. Ventricular assist devices (VAD) have been increasingly used as a bridge support to heart transplantation in children. We aimed to examine the profiles of CRP in children receiving VAD support.

METHODS

Charts of 13 children receiving Berlin Heart EXCOR(®) from 2005 to 2009 were reviewed. The data obtained prior to and during VAD support included: CRP, white blood cells, inotropes and steroid use, VAD mode and duration of VAD support. Ten patients received left VAD (LVAD) and 3 biventricular VAD (BiVAD).

RESULTS

The median duration of VAD support was 59 days (ranged 3-678 days). Pre-VAD CRP was 35 ± 51 mg/l and increased to 109 ± 59 mg/l on days 1-3 after the VAD implantation (P = 0.01), then gradually decreased to 28 ± 28 mg/l by 4 months and normalized by 5 months (P < 0.0001). CRP was higher in BiVAD than in LVAD patients throughout the study period (P = 0.003). CRP positively correlated with the doses of the epinephrine and norepinephrine and the monocyte counts, and negatively correlated with the lymphocyte count. The lymphocyte count was 2.5 ± 0.4 x 10(9)/l prior to implantation, and decreased to 2.1 ± 1.3 x 10(9)/l on days 1-3 (P = 0.5) and then to 0.6 ± 0.1 x 10(9)/l by 6 months (P = 0.08). It tended to be lower in BiVAD patients (P = 0.06).

CONCLUSIONS

SIR exists in children prior to VAD support. VAD implantation is associated with a significant and prolonged increase in CRP and a decrease in lymphocyte count, indicating a suppressed immune function, being more pronounced in BiVAD patients.

Bedside prediction rule for infections after pediatric cardiac surgery

Purpose

Infections after pediatric cardiac surgery are a common complication, occurring in up to 30% of cases. The purpose of this study was to develop a bedside prediction rule to estimate the risk of a postoperative infection.

Methods

All consecutive pediatric cardiac surgery procedures between April 2006 and May 2009 were retrospectively analyzed. The primary outcome variable was any postoperative infection, as defined by the Center of Disease Control (2008). All variables known to the clinician at the bedside at 48 h post cardiac surgery were included in the primary analysis, and multivariable logistic regression was used to construct a prediction rule.

Results

A total of 412 procedures were included, of which 102 (25%) were followed by an infection. Most infections were surgical site infections (26% of all infections) and bloodstream infections (25%). Three variables proved to be most predictive of an infection: age less than 6 months, postoperative pediatric intensive care unit (PICU) stay longer than 48 h, and open sternum for longer than 48 h. Translation into prediction rule points yielded 1, 4, and 1 point for each variable, respectively. Patients with a score of 0 had 6.6% risk of an infection, whereas those with a maximal score of 6 had a risk of 57%. The area under the receiver operating characteristic curve was 0.78 (95% confidence interval 0.72–0.83).

Conclusions

A simple bedside prediction rule designed for use at 48 h post cardiac surgery can discriminate between children at high and low risk for a subsequent infection.

Discriminative value of inflammatory biomarkers for suspected sepsis

BACKGROUND

Circulating biomarkers can facilitate sepsis diagnosis, enabling early management and improved outcomes. Procalcitonin (PCT) has been suggested to have superior diagnostic utility compared to other biomarkers.

STUDY OBJECTIVES

To define the discriminative value of PCT, interleukin-6 (IL-6), and C-reactive protein (CRP) for suspected sepsis.

METHODS

PCT, CRP, and IL-6 were correlated with infection likelihood, sepsis severity, and septicemia. Multivariable models were constructed for length-of-stay and discharge to a higher level of care.

RESULTS

Of 336 enrolled subjects, 60% had definite infection, 13% possible infection, and 27% no infection. Of those with infection, 202 presented with sepsis, 28 with severe sepsis, and 17 with septic shock. Overall, 21% of subjects were septicemic. PCT, IL6, and CRP levels were higher in septicemia (median PCT 2.3 vs. 0.2 ng/mL; IL-6 178 vs. 72 pg/mL; CRP 106 vs. 62 mg/dL; p < 0.001). Biomarker concentrations increased with likelihood of infection and sepsis severity. Using receiver operating characteristic analysis, PCT best predicted septicemia (0.78 vs. IL-6 0.70 and CRP 0.67), but CRP better identified clinical infection (0.75 vs. PCT 0.71 and IL-6 0.69). A PCT cutoff of 0.5 ng/mL had 72.6% sensitivity and 69.5% specificity for bacteremia, as well as 40.7% sensitivity and 87.2% specificity for diagnosing infection. A combined clinical-biomarker model revealed that CRP was marginally associated with length of stay (p = 0.015), but no biomarker independently predicted discharge to a higher level of care.

CONCLUSIONS

In adult emergency department patients with suspected sepsis, PCT, IL-6, and CRP highly correlate with several infection parameters, but are inadequately discriminating to be used independently as diagnostic tools.

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.

Biomarker discovery and development in pediatric critical care medicine

OBJECTIVES

To frame the general process of biomarker discovery and development; and to describe a proposal for the development of a multibiomarker-based risk model for pediatric septic shock.

DATA SOURCE

Narrative literature review and author-generated data.

DATA SELECTION

Biomarkers can be grouped into four broad classes, based on the intended function: diagnostic, monitoring, surrogate, and stratification.

DATA EXTRACTION AND SYNTHESIS

Biomarker discovery and development requires a rigorous process, which is frequently not well followed in the critical care medicine literature. Very few biomarkers have successfully transitioned from the candidate stage to the true biomarker stage. There is great interest in developing diagnostic and stratification biomarkers for sepsis. Procalcitonin is currently the most promising diagnostic biomarker for sepsis. Recent evidence suggested that interleukin-8 can be used to stratify children with septic shock having a high likelihood of survival with standard care. Currently, there is a multi-institutional effort to develop a multibiomarker-based sepsis risk model intended to predict outcome and illness severity for individual children with septic shock.

CONCLUSIONS

Biomarker discovery and development are an important portion of the pediatric critical care medicine translational research agenda. This effort will require collaboration across multiple institutions and investigators. Rigorous conduct of biomarker-focused research holds the promise of transforming our ability to care for individual patients and our ability to conduct clinical trials in a more effective manner.

[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.

Biomarkers for pediatric sepsis and septic shock

Sepsis is a clinical syndrome defined by physiologic changes indicative of systemic inflammation, which are likely attributable to documented or suspected infection. Septic shock is the progression of those physiologic changes to the extent that delivery of oxygen and metabolic substrate to tissues is compromised. Biomarkers have the potential to diagnose, monitor, stratify and predict outcome in these syndromes. C-reactive protein is elevated in inflammatory and infectious conditions and has long been used as a biomarker indicating infection. Procalcitonin has more recently been shown to better distinguish infection from inflammation. Newer candidate biomarkers for infection include IL-18 and CD64. Lactate facilitates the diagnosis of septic shock and the monitoring of its progression. Multiple stratification biomarkers based on genome-wide expression profiling are under active investigation and present exciting future possibilities.

Sepsis redefined: the search for surrogate markers

Sepsis is a common and severe medical condition with substantial associated morbidity, mortality and cost. Furthermore, the incidence of sepsis has been rising annually over the past three decades, and morbidity and mortality remain high. The management of sepsis is further complicated by its very heterogeneous nature. This extends not only to the offending pathogens, but also to the nature and severity of the host response as well as its clinical manifestations. Efforts to identify surrogate markers for sepsis have therefore been an ongoing struggle. In this article we present some insights into various sepsis markers through history, presenting advantages and caveats associated with their use and interpretation. We also discuss the state of functional genomics, a relatively recent technological advancement that has already begun to change our understanding of sepsis pathophysiology, and offer new directions in the development of a more sensitive and specific sepsis biomarker.