The Clinical Value of Procalcitonin and Neopterin in Predicting Sepsis and Organ Failure After Major Trauma

Prognostic Value of Serum Procalcitonin Based Model in Moderate to Severe Traumatic Brain Injury Patients

Objective

Procalcitonin (PCT) is an acknowledged marker of systemic inflammatory response. Previous studies have not reached agreement on the association between serum PCT and outcome of traumatic brain injury (TBI) patients. We designed this study to confirm the prognostic value of PCT in isolated TBI and those with extracranial injury, respectively.

Methods

Patients hospitalized in our hospital for moderate-to-severe TBI between March 2015 and December 2019 were included. Logistic regression analysis was performed to validate the association between PCT and in-hospital mortality in these patients. AUC (area under the receiver operating characteristics curve) of PCT and constructed model were calculated and compared.

Results

Among the included 211 patients, 81 patients suffered a poor outcome, with a mortality rate of 38.4%. Non-survivors had a higher level of serum PCT (2.73 vs 0.72, p<0.001) and lower GCS (5 vs 7, p<0.001) on admission than survivors. AUC of single PCT for predicting mortality in isolated TBI and those with extracranial injury were 0.767 and 0.553, respectively. Multivariate logistic regression showed that GCS (OR=0.744, p=0.008), glucose (OR=1.236, p<0.001), cholesterol (OR=0.526, p=0.002), and PCT (OR=1.107, p=0.022) were independently associated with mortality of isolated TBI. The AUC of the prognostic model composed of GCS, glucose, cholesterol, and PCT was 0.868 in isolated TBI.

Conclusion

PCT is an efficient marker of outcome in isolated moderate-to-severe TBI but not those with extracranial injury. A prognostic model incorporating PCT is useful for clinicians to make early risk stratification for isolated TBI.

Procalcitonin Assay Has No Role in the Routine Assessment of Severe Trauma Patients at Admission to the Emergency Department

Introduction A key challenge in emergency departments (ED) is the early recognition of sepsis or the potential for sepsis in patients. Appropriate and accurate ED triage will ensure improved case management. This study analysed the association between ED findings at admission and outcomes in patients presenting with severe trauma. Methods This was a prospective study conducted at a tertiary level ED and included severely injured adult patients who presented to the ED within 24 hours of injury. Data collected included clinical findings and imaging reports at initial assessment, serum procalcitonin (PCT), length of ICU and hospital stay, the incidence of bloodstream and other infections, and patient outcome as discharge from care or death. Multiple logistic regression was used to assess the association between outcome variables and independent variables. Results A total of 155 patients were included in the study. Head and neck (61.9%), extremity (58%), and chest (45%) were more commonly injured. Injury Severity Score (ISS) >25, Glasgow Coma Scale (GCS) score <8, head and neck injuries, and extremity injuries were found to be significantly associated with mortality. Bloodstream infections were more common in the presence of lung contusions, abdominal injury, operative management, and blood transfusions. PCT levels at admission did not have a significant predictive value for mortality, bloodstream infections, other infectious complications, or length of ICU stay. Conclusions Head injuries were the most common cause of mortality in our study. In addition to the anatomical region involved, ISS and GCS have a significant association with mortality. PCT levels at ED admission do not have any prognostic value and need not be routinely analysed.

Procalcitonin in special patient populations: Guidance for antimicrobial therapy

PURPOSE

Procalcitonin (PCT) is an endogenous hormone that increases reliably in response to bacterial infection, and measurement of serum PCT levels is recommended to help guide antimicrobial therapy. The utility of PCT assessment in special patient populations (eg, patients with renal dysfunction, cardiac compromise, or immunocompromised states and those undergoing acute care surgery) is less clear. The evidence for PCT-guided antimicrobial therapy in special populations is reviewed.

SUMMARY

In the presence of bacterial infection, nonneuroendocrine PCT is produced in response to bacterial toxins and inflammatory cytokines, resulting in markedly elevated levels of serum PCT. Cytokine induction in nonbacterial inflammatory processes activated by acute care surgery may alter the interpretation of PCT levels. The reliability of PCT assessment has also been questioned in patients with renal dysfunction, cardiac compromise, or immunosuppression. In many special populations, serum PCT may be elevated at baseline and increase further in the presence of infection; thus, higher thresholds for diagnosing infection or de-escalating therapy should be considered, although the optimal threshold to use in a specific population is unclear. Procalcitonin-guided antimicrobial therapy may be recommended in certain clinical situations.

CONCLUSION

Procalcitonin may be a reliable marker of infection even in special populations with baseline elevations in serum PCT. However, due to unclear threshold values and the limited inclusion of special populations in relevant clinical trials, PCT levels should be considered along with clinical criteria, and antibiotics should never be initiated or withheld based on PCT values alone. Procalcitonin measurement may have a role in guiding de-escalation of antibiotic therapy in special populations; however, the clinician should be aware of disease states and concomitant therapies that may affect interpretation of results.

Procalcitonin in clinical practice: from diagnosis of sepsis to antibiotic therapy

A diagnostic algorithm that allows for the rapid identification of sepsis and possibly guides the appropriate antimicrobial therapy application is the cornerstone to obtaining effective treatment and better results. The use of emerging surrogate markers could significantly improve clinical practice, but the validity and clinical utility have been proved only for very few of them, and their availability in clinical routine is limited. For this purpose, numerous scientific evidence has indicated procalcitonin as a marker linked to sepsis and its evolution. This review aims to retrace the main evidence relating to the use of procalcitonin in sepsis. We analyzed the primary studies in the literature and the existing meta-analysis evaluating the behavior of procalcitonin as a marker of bacterial sepsis, its prognostic power, and its ability to influence antibiotic therapy. Recent evidence has suggested that procalcitonin could be an efficient marker for diagnosing sepsis and its therapeutic management in many types of patients. The choice of the appropriate timing to initiate and suspend antibiotic therapy, with obvious clinical advantages, the favorable effects could also include reducing health costs, both avoiding the administration of inappropriate antibiotic therapies, and reducing the duration of hospitalization. Moreover, limited studies reported high procalcitonin levels in coronavirus disease 2019 patients with a worse prognosis. Despite the considerable evidence in favor of the potential of procalcitonin as an index for managing septic patients, there are conflicting data that deserve specific and detailed studies.

Oxidative stress and immune cell activation quantification in sepsis and non-sepsis critical care patients by neopterin/7,8-dihydroneopterin analysis

Introduction: Neopterin and 7,8-dihydroneopterin are used as biomarkers of oxidative stress and inflammation, but the effect of kidney function on these measurements has not been extensively explored. We examine the levels of oxidative stress, inflammation and kidney function in intensive patients and compare them to equivalent patients without sepsis.

Methods: 34 Intensive care patients were selected for the study, 14 without sepsis and 20 with. Both groups had equivalent levels of trauma, assessed by SAPS II, SOFA, and APACHE II and III scores. Plasma and urinary neopterin and total neopterin (neopterin + 7,8-dihydroneopterin) values were measured.

Results: Neopterin and total neopterin were significantly elevated in urine and plasma for multiple days in sepsis versus non-sepsis patients. Plasma neopterin and total neopterin have decreasing relationships with increased eGFR (p<0.008 and p<0.001, respectively). Plasma/urinary neopterin and total neopterin ratios demonstrate that total neopterin flux is more influenced by eGFR than neopterin, with significantce of p<0.02 and p<0.0002 respectively.

Conclusion: Sepsis patients present with greater levels of oxidative stress and immune system activation than non-sepsis patients of equal levels of trauma, as measured by neopterin and total neopterin. eGFR may need to be taken into account when accessing the level of inflammation from urinary neopterin measurements.

A 2020 review on the role of procalcitonin in different clinical settings: an update conducted with the tools of the Evidence Based Laboratory Medicine

Biomarkers to guide antibiotic treatment decisions have been proposed as an effective way to enhancing a more appropriate use of antibiotics. As a biomarker, procalcitonin (PCT) has been found to have good specificity to distinguish bacterial from non-bacterial inflammations. Decisions regarding antibiotic use in an individual patient are complex and should be based on the pre-test probability for bacterial infection, the severity of presentation and the results of PCT serum concentration. In the context of a high pre-test probability for bacterial infections and/or a high-risk patient with sepsis, monitoring of PCT over time helps to track the resolution of infection and decisions regarding early stop of antibiotic treatment. As outlined by the Evidence Based Laboratory Medicine (EBLM), not only the pre-test probability but also the positive likelihood ratio influence the performance of a test do be really diagnostic. This aspect should be taken into account in the interpretation of the results of clinical trials evaluating the performance of PCT in guiding antibiotic therapy.

The prognostic value of serum procalcitonin measurements in critically injured patients: a systematic review

Background

Major trauma is associated with high incidence of septic complications and multiple organ dysfunction (MOD), which markedly influence the outcome of injured patients. Early identification of patients at risk of developing posttraumatic complications is crucial to provide early treatment and improve outcomes. We sought to evaluate the prognostic value of serum procalcitonin (PCT) levels after trauma as related to severity of injury, sepsis, organ dysfunction, and mortality.

Methods

We searched PubMed, MEDLINE, EMBASE, the Cochrane Database, and references of included articles. Two investigators independently identified eligible studies and extracted data. We included original studies that assessed the prognostic value of serum PCT levels in predicting severity of injury, sepsis, organ dysfunction, and mortality among critically injured adult patients.

Results

Among 2015 citations, 19 studies (17 prospective; 2 retrospective) met inclusion criteria. Methodological quality of included studies was moderate. All studies showed a strong correlation between initial PCT levels and Injury Severity Score (ISS). Twelve out of 16 studies demonstrated significant elevation of initial PCT levels in patients who later developed sepsis after trauma. PCT level appeared a strong predictor of MOD in seven out of nine studies. While two studies did not show association between PCT levels and mortality, four studies demonstrated significant elevation of PCT levels in non-survivors versus survivors. One study reported that the PCT level of ≥ 5 ng/mL was associated with significantly increased mortality (OR 3.65; 95% CI 1.03–12.9; p = 0.04).

Conclusion

PCT appears promising as a surrogate biomarker for trauma. Initial peak PCT level may be used as an early predictor of sepsis, MOD, and mortality in trauma population.

Pterins as Diagnostic Markers of Mechanical and Impact-Induced Trauma: A Systematic Review

We performed a systematic review of the literature to evaluate pterins as biomarkers of mechanical and impact-induced trauma. MEDLINE and Scopus were searched in March 2019. We included in vivo human studies that measured a pterin in response to mechanical or impact-induced trauma with no underlying prior disease or complication. We included 40 studies with a total of 3829 subjects. Seventy-seven percent of studies measured a significant increase in a pterin, primarily neopterin or total neopterin (neopterin + 7,8-dihydroneopterin). Fifty-one percent of studies measured an increase within 24 h of trauma, while 46% measured increases beyond 48 h. Pterins also showed promise as predictors of post-trauma complications such as sepsis, multi-organ failure and mortality. Exercise-induced trauma and traumatic brain injury caused an immediate increase in neopterin or total neopterin, while patients of multiple trauma had elevated pterin levels that remained above baseline for several days. Pterin concentration changes in response to surgery were variable with patients undergoing cardiac surgery having immediate and sustained pterin increases, while gastrectomy, liver resection or hysterectomy showed no change. This review provides systematic evidence that pterins, in particular neopterin and total neopterin, increase in response to multiple forms of mechanical or impact-induced trauma.

Simultaneous analysis of neopterin, kynurenine and tryptophan by amine-HPLC shows minor oxidative stress from short-term exhaustion exercise

Introduction: Neopterin, kynurenine and tryptophan can be used to measure activation of monocytes and macrophages during immunological events such as exercise inducing inflammation. Endurance exercise and high-impact sports have shown significant increases in these biomarkers. Measurement is typically conducted by high-performance liquid chromatography (HPLC) using C18 or SCX columns. However, kynurenine and tryptophan are not measured simultaneously to neopterin using these separation systems. Here we have used an amine column for separation and simultaneous determination of neopterin, kynurenine and tryptophan.

Methods: Optimization and validation for the amine-HPLC method was conducted using plasma from 43 participants subjected to a short maximal exercise bicycling regime or rest period. The order of exercise and rest was randomized and separated by a 3-5 week washout period.

Results: Using an amine column developed with ammonium acetate formic acid (33%) and acetonitrile (72%) provided optimal separation and run time for analysis. Neopterin increased significantly post-exercise and subsided to baseline by 30 minutes. Total neopterin remained elevated until 60 minutes following exercise.

Conclusion: Amine-HPLC can be used for simultaneous determination of kynurenine, tryptophan and neopterin in plasma. Short intense exercise causes a significant increase in plasma neopterin suggesting a prolonged activation of monocytes and macrophages.

Metabolomics and Precision Medicine in Trauma: The State of the Field

Trauma is a major problem in the United States. Mortality from trauma is the number one cause of death under the age of 45 in the United States and is the third leading cause of death for all age groups. There are approximately 200,000 deaths per year due to trauma in the United States at a cost of over $671 billion in combined healthcare costs and lost productivity. Unsurprisingly, trauma accounts for approximately 30% of all life-years lost in the United States. Due to immense development of trauma systems, a large majority of trauma patients survive the injury, but then go on to die from complications arising from the injury. These complications are marked by early and significant metabolic changes accompanied by inflammatory responses that lead to progressive organ failure and, ultimately, death. Early resuscitative and surgical interventions followed by close monitoring to identify and rescue treatment failures are key to successful outcomes. Currently, the adequacy of resuscitation is measured using vital signs, noninvasive methods such as bedside echocardiography or stroke volume variation, and other laboratory endpoints of resuscitation, such as lactate and base deficit. However, these methods may be too crude to understand cellular and subcellular changes that may be occurring in trauma patients. Better diagnostic and therapeutic markers are needed to assess the adequacy of interventions and monitor responses at a cellular and subcellular level and inform clinical decision-making before complications are clinically apparent. The developing field of metabolomics holds great promise in the identification and application of biochemical markers toward the clinical decision-making process.

Status and Challenges of Predicting and Diagnosing Sepsis in Burn Patients

Burns are a common form of trauma that account for more than 300,000 deaths each year worldwide. Survival rates have improved over the past decades because of improvements in nutritional and fluid support, burn wound care, and infection control practices. Death, however, remains unacceptably high. The primary cause of death has changed over the last decades from anoxic causes to now predominantly infections and sepsis. Sepsis and septic complications are not only major contributors to poor outcomes, but they further result in longer hospital stay and higher healthcare costs. Despite the importance of infections and sepsis, the diagnosis and prediction remain a major challenge. To date, no clear diagnostic criteria or predictive formula exist that can predict reliably the occurrence of sepsis and infections. This review will highlight and discuss current definitions and criteria for diagnosis as well as predictive biomarkers of sepsis in patients with burns. It will also present the diagnostic tools employed, such as procalcitonin, C-reactive protein, and cytokines. We will discuss the benefits and shortcomings of different treatment modalities in the context of sepsis prevention. Last, we identify new therapeutic strategies for sepsis prediction and present future considerations to prevent sepsis in patients with burns. Minimizing and preventing septic complications through early detection would significantly benefit patients and necessitate continued research to unravel new biomarkers and mechanisms. Subsequent studies need to take a fresh perspective and consider the implementation of patient-centered therapeutic strategies.

Procalcitonin Levels in Survivors and Nonsurvivors of Sepsis: Systematic Review and Meta-Analysis

Procalcitonin (PCT) is an acute-phase reactant that has been used to diagnose and potentially track the treatment of sepsis. Procalcitonin values rise initially as the infection sets in and eventually fall with resolution. Its level has been reported to be significantly higher in potential nonsurvivors of a septic episode than among survivors. However, there is also a significant amount of evidence against this. We thus conducted a meta-analysis to pool data from all the available studies regarding PCT levels in survivors and nonsurvivors of sepsis. An extensive literature search was conducted using the key words "procalcitonin," "sepsis," and "prognosis." The references of the relevant studies were also scanned. The data from the eligible studies were extracted and analyzed for any significant pooled mean difference between survivors and nonsurvivors both on days 1 and 3. The mean difference in the day 1 PCT values between survivors and nonsurvivors was found to be statistically significant (P = 0.02). The mean difference on day 3 was also statistically significant (P = 0.002). However, in a subgroup consisting of studies on patients with severe sepsis and septic shock, day 1 difference was not found to be significant (P = 0.62). We found heterogeneity of 90% in our study population, which decreased to 62% after exclusion of studies conducted in emergency department patients. Procalcitonin levels in early stages of sepsis are significantly lower among survivors as compared with nonsurvivors of sepsis.

Retrospective study on prognostic importance of serum procalcitonin and amino-terminal pro-brain natriuretic peptide levels as compared to Acute Physiology and Chronic Health Evaluation IV Score on Intensive Care Unit admission, in a mixed Intensive Care Unit population

BACKGROUND

Timely decision making in Intensive Care Unit (ICU) is very essential to improve the outcome of critically sick patients. Conventional scores like Acute Physiology and Chronic Health Evaluation (APACHE IV) are quite cumbersome with calculations and take minimum 24 hours. Procalcitonin has shown to have prognostic value in ICU/Emergency department (ED) in disease states like pneumonia, sepsis etc. NTproBNP has demonstrated excellent diagnostic and prognostic importance in cardiac diseases. It has also been found elevated in non-cardiac diseases. We chose to study the prognostic utility of these markers on ICU admission.

SETTINGS AND DESIGN

Retrospective observational study.

MATERIALS AND METHODS

A Retrospective analysis of 100 eligible patients was done who had undergone PCT and NTproBNP measurements on ICU admission. Their correlations with all cause mortality, length of hospital stay, need for ventilator support, need for vasopressors were performed.

RESULTS

Among 100 randomly selected ICU patients, 28 were non-survivors. NTproBNP values on admission significantly correlated with all cause mortality (P = 0.036, AUC = 0.643) and morbidity (P = 0.000, AUC = 0.763), comparable to that of APACHE-IV score. PCT values on admission did not show significant association with mortality, but correlated well with morbidity and prolonged hospital length of stay (AUC = 0.616, P = 0.045).

CONCLUSION

The current study demonstrated a good predictive value of NTproBNP, in terms of mortality and morbidity comparable to that of APACHE-IV score. Procalcitonin, however, was found to have doubtful prognostic importance. These findings need to be confirmed in a prospective larger study.

Procalcitonin-guided antibiotic therapy for septic patients in the surgical intensive care unit

In critically ill patients, elucidating those patients with the systemic inflammatory response syndrome (SIRS) from an infectious source (sepsis), versus those who have SIRS without infection, can be challenging since the clinical features are the same.

Even with strict monitoring and testing, 39–98 % of patients with SIRS will never have bacteriological confirmation of an infection, and 6–17 % of patients with a documented infection will not show signs of SIRS. Due to this overlap, an extensive amount of research has been performed to investigate ways of determining and separating SIRS from infection, compared to SIRS due to trauma, surgical stress, or other non-infectious causes. This review article will discuss the recommended and peer-approved use of procalcitonin in septic patients in the intensive care unit and its use as a guide to antibiotic initiation and termination. The article will focus on the prospective randomized trials (Level 1 evidence) that have been conducted, and lesser levels of evidence will be referenced as needed to substantiate a conclusion.

The literature documents multiple benefits of using procalcitonin as a guide to cost savings and appropriate termination of antibiotics by its use as a new objective marker of bacteremia that was previously not available. This article will show that antibiotics should be terminated when the procalcitonin level falls below 0.5 ng/mL.

The diagnostic accuracy of procalcitonin for bacteraemia: a systematic review and meta-analysis

The diagnostic use of procalcitonin for bacterial infections remains a matter of debate. Most studies have used ambiguous outcome measures such as sepsis instead of infection. We performed a systematic review and meta-analysis to investigate the diagnostic accuracy of procalcitonin for bacteraemia, a proven bloodstream infection. We searched all major databases from inception to June 2014 for original, English language, research articles that studied the diagnostic accuracy between procalcitonin and positive blood cultures in adult patients. We calculated the area under the summary receiver-operating characteristic (SROC) curves and pooled sensitivities and specificities. To minimize potential heterogeneity we performed subgroup analyses. In total, 58 of 1567 eligible studies were included in the meta-analysis and provided a total of 16,514 patients, of whom 3420 suffered from bacteraemia. In the overall analysis the area under the SROC curve was 0.79. The optimal and most widely used procalcitonin cut-off value was 0.5 ng/mL with a corresponding sensitivity of 76% and specificity of 69%. In subgroup analyses the lowest area under the SROC curve was found in immunocompromised/neutropenic patients (0.71), the highest area under the SROC curve was found in intensive-care patients (0.88), sensitivities ranging from 66 to 89% and specificities from 55 78%. In spite of study heterogeneity, procalcitonin had a fair diagnostic accuracy for bacteraemia in adult patients suspected of infection or sepsis. In particular low procalcitonin levels can be used to rule out the presence of bacteraemia. Further research is needed on the safety and efficacy of procalcitonin as a single diagnostic tool to avoid taking blood cultures.

Diagnosis of infection in critical care

Sepsis is the primary cause of death in the intensive care unit. The prevention of sepsis complications requires an early and accurate diagnosis as well as the appropriate mon itoring. A deep knowledge of the immunologic basis of sepsis is essential to better understand the scope of incorporating a new marker into clinical practice. Besides revising this theoretical aspect, the current available tools for bacterial iden tification have been briefly reviewed as well as a variety of new markers showing either well-recognized or potential usefulness for diagnosis and prognosis of infections in crit ically ill patients. Particular conditions such as community acquired pneumonia, pedi atric sepsis, or liver transplantation, among others, have been separately treated, since the optimal approaches and markers might be different in these special cases.

Prediction of sepsis in trauma patients

Trauma is one of the leading causes of death worldwide. Approximately 39.5% of deaths occur in the hospital, and the mortality rate of delayed death caused by septic complications is still high. Early prediction of the development of sepsis can help promote early intervention and treatment for patients and contribute to improving patient outcomes. Thus so far, biomarkers, patient demographics and injury characteristics are the main methods used for predicting sepsis in trauma patients. However, studies that verify their predictive value are limited, and the results are still controversial. More work should be conducted to explore more efficient and accurate ways to predict post-traumatic sepsis.

Biomarkers predicting sepsis in polytrauma patients: Current evidence

INTRODUCTION

Major trauma still represents one of the leading causes of death in the first four decades of life. Septic complications represent the predominant causes of late death (45% of overall mortality) in polytrauma patients. The ability of clinicians to early differentiate between systemic inflammatory response syndrome (SIRS) and sepsis is demonstrated to improve clinical outcome and mortality. The identification of an "ideal" biomarker able to early recognize incoming septic complications in trauma patients is still a challenge for researchers.

AIM

To evaluate the existing evidence regarding the role of biomarkers to predict or facilitate early diagnosis of sepsis in trauma patients, trying to compile some recommendations for the clinical setting.

METHODS

An Internet-based search of the MEDLINE, EMBASE and Cochrane Library databases was performed using the search terms: "Biomarkers", "Sepsis" and "Trauma" in various combinations. The methodological quality of the included studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies Checklist (QUADAS). After data extraction, the level of evidence available for each bio-marker was rated and presented using the "best-evidence synthesis" method, in line with the US Agency for Healthcare Research and Quality.

RESULTS

Thirty studies were eligible for the final analysis: 13 case-control studies and 17 cohort studies. The "strong evidence" available demonstrated the potential use of procalcitonin as an early indicator of post-traumatic septic complications and reported the inability of c-reactive protein (CRP) to specifically identify infective complications. Moderate, conflicting and limited evidence are available for the other 31 biomarkers.

CONCLUSION

Several biomarkers have been evaluated for predicting or making early diagnosis of sepsis in trauma patients. Current evidence does not support the use of a single biomarker in diagnosing sepsis. However, procalcitonin trend was found to be useful in early identification of post-traumatic septic course and its use is suggested (Recommendation Grade: B) in clinical practice.

The efficacy of procalcitonin as a biomarker in the management of sepsis: slaying dragons or tilting at windmills?

BACKGROUND

Sepsis is defined as systemic inflammatory response syndrome (SIRS) in the context of an underlying infectious process, and is associated with high rates of morbidity and mortality, particularly when initial therapy is delayed. Numerous biomarkers, including but not limited to cytokines (interleukins-2 and -6 [IL-2, IL-6] and tumor necrosis factor-α [TNF-α]), leukotrienes, acute-phase proteins (C-reactive protein [CRP]), and adhesion molecules, have been evaluated and rejected as unsuitable for the diagnosis of sepsis, predicting its severity, and guiding its treatment. Most recently, procalcitonin (PCT) has been suggested as a novel biomarker that may be useful in guiding therapeutic decision making in the management of sepsis. This article assesses critically the published literature on the clinical utility of PCT concentrations for guiding the treatment of sepsis in adult patients.

METHODS

A comprehensive search of all published studies of the use of serum concentrations of PCT to guide the treatment of sepsis in adult patients (1996 to 2011) was conducted with PubMed and Google Scholar. The search focused on the value of PCT concentrations to guide the diagnosis, prognosis, monitoring, and escalation and de-escalation of antbiotic therapy in these patients. Keywords searched included "procalcitonin," "sepsis," "sepsis biomarker," "sepsis diagnosis," "sepsis prognosis," "sepsis mortality," "antibiotic escalation," "antibiotic de-escalation," "antibiotic duration," and "antimicrobial stewardship."

RESULTS

Forty-six trials evaluating the efficacy of PCT concentrations in diagnosing sepsis have been published, with 39 of these trials yielding positive results and 7 yielding negative results. Wanner et al. published the largest study (n=405) demonstrating that peak PCT concentrations occur early after injury in both patients with sepsis and those with multiple organ dysfunction syndrome (MODS). Among 17 trials assessing the prognostic value of PCT concentrations with regard to clinical outcome and morbidity, 12 trials yielded positive results and five showed negative or equivocal results. Reith et al. published the largest study of the prognostic use of PCT concentrations (n=246), demonstrating that median PCT values on post-operative days (POD) one, four, and 10 were predictive of mortality in patients with abdominal sepsis (p<0.01). Among 14 trials of the utility of PCT concentrations for establishing an infectious cause of sepsis, 13 yielded positive results and only one yielded negative results. The largest study of this use of PCT concentrations, conducted by Baykut et al. (n=400), evaluated these concentrations in post-operative patients with infection, and demonstrated that concentrations of PCT remained elevated until POD 4, with a second increase observed between POD 4 and POD 6. In uninfected patients, PCT concentrations began to decrease on POD 2. Only a single study has assessed the utility of PCT concentrations in guiding the escalation of antibiotic therapy, and its results were negative. Specifically, Jensen et al. (n=1,200) compared a PCT-guided antibiotic escalation strategy with the standard of care for sepsis and found no difference in outcomes. They also found that the PCT group had a longer average stay in the intensive care unit (ICU), greater rates of mechanical ventilation, and a decreased estimated glomerular filtration rate (eGFR). Among four trials focusing on PCT concentrations and antibiotic de-escalation, all showed positive results with the measurement of PCT concentrations. The largest such study, by Bouadma et al. (n=621), demonstrated a four-day decrease in antibiotic duration when PCT concentrations were used to guide therapy relative to the study arm given the standard of care, with no increase in mortality (p=0.003).

CONCLUSIONS

The diagnostic value of serum PCT concentrations for discriminating among SIRS, sepsis, severe sepsis, and septic shock remains to be established. Although higher PCT concentrations suggest a systemic bacterial infection as opposed to a viral, fungal, or inflammatory etiology of sepsis, serum PCT concentrations do not correlate with the severity of sepsis or with mortality. At present, PCT concentrations are solely investigational with regard to determining the timing and appropriateness of escalation of antimicrobial therapy in sepsis. Nevertheless, serum PCT concentrations have established utility in monitoring the clinical response to medical and surgical therapy for sepsis, and in surveillance for the development of sepsis in burn and ICU patients, and may have a role in guiding the de-escalation of antibiotic therapy.

Procalcitonin in the recognition of complications in critically ill surgical patients

BACKGROUND

Procalcitonin (PCT) is a relatively new, promising indirect parameter for infection. In the intensive care unit (ICU) it can be used as a marker for sepsis. However, in the ICU there is a need for reliable markers for clinical deterioration in the critically ill patients. This study determines the clinical value of PCT concentrations in recognizing surgical complications in a heterogeneous group of general surgical patients in the ICU.

MATERIAL AND METHODS

We prospectively collected PCT concentration data from April 2010 to June 2012 for all general surgical patients admitted to the ICU. Both the relationships between PCT levels and events (diagnostic and therapeutic interventions) as well as between PCT levels and surgical complications (abscesses, bleeding, perforation, ischemia, and ileus) were studied.

RESULTS

PCT concentrations were lower in patients who developed complications than those who did not develop complications on the same day, although not significant (P = 0.27). A 10% increase in PCT levels resulted in a 2% higher complication odds, but again this was not significant (odds ratio [OR], 1.020; 95% confidence interval [CI], 0.961-1.083; P = 0.51). Even a 20% or 30% increase in PCT concentrations did not result in higher complication probability (OR, 1.039; 95% CI, 0.927-1.165 and OR, 1.057; 95% CI, 0.897-1.246). Furthermore, an increase in PCT levels did not show an increase or a reduction in the number of diagnostic and therapeutic interventions.

CONCLUSIONS

An increase in PCT levels does not help to predict surgical complications in critically ill surgical patients.

A pilot study on neopterin levels and tryptophan degradation in zinc-exposed galvanization workers

Hot-dip galvanization is a zinc-coating process to protect the metal items from corrosion. Zinc oxide nanoaerosol fume rising from hot metal bath surface in nano dimensions contains the greatest risk for workers in galvanization process. In the present study, it was evaluated whether inhalation of zinc causes any alteration in cellular immunity and tryptophan degradation by measuring neopterin, tryptophan, kynurenine, and zinc levels in 63 male galvanization workers and 23 male office personnel as controls. Serum and urinary zinc levels were found as 102.43 ± 4.74 and 0.66 ± 0.05 μg/dL in workers while 75.45 ± 4.24 and 0.80 ± 0.08 μg/dL [corrected] in controls, respectively (both, p < 0.05). Similarly, the mean urinary neopterin levels and serum neopterin and kynurenine levels were found to be statistically higher in galvanization workers than the controls (all, p < 0.05). Significant correlations were found between urinary neopterin levels and kynurenine to tryptophan ratio or serum zinc levels. The results indicated cellular immune activation by occupational zinc exposure. It was estimated that neopterin, in parallel with kynurenine pathway, could reflect occupational exposure to zinc nanoaerosols and might be useful in early diagnosis of immune alterations due to nano-scale exposures.

Procalcitonin as a diagnostic marker for sepsis: a systematic review and meta-analysis

BACKGROUND

Procalcitonin is a promising marker for identification of bacterial infections. We assessed the accuracy and clinical value of procalcitonin for diagnosis of sepsis in critically ill patients.

METHODS

We searched Medline, Embase, ISI Web of Knowledge, the Cochrane Library, Scopus, BioMed Central, and Science Direct, from inception to Feb 21, 2012, and reference lists of identified primary studies. We included articles written in English, German, or French that investigated procalcitonin for differentiation of septic patients--those with sepsis, severe sepsis, or septic shock--from those with a systemic inflammatory response syndrome of non-infectious origin. Studies of healthy people, patients without probable infection, and children younger than 28 days were excluded. Two independent investigators extracted patient and study characteristics; discrepancies were resolved by consensus. We calculated individual and pooled sensitivities and specificities. We used I(2) to test heterogeneity and investigated the source of heterogeneity by metaregression.

FINDINGS

Our search returned 3487 reports, of which 30 fulfilled the inclusion criteria, accounting for 3244 patients. Bivariate analysis yielded a mean sensitivity of 0 · 77 (95% CI 0 · 72-0 · 81) and specificity of 0 · 79 (95% CI 0 · 74-0 · 84). The area under the receiver operating characteristic curve was 0 · 85 (95% CI 0 · 81-0 · 88). The studies had substantial heterogeneity (I(2)=96%, 95% CI 94-99). None of the subgroups investigated--population, admission category, assay used, severity of disease, and description and masking of the reference standard--could account for the heterogeneity.

INTERPRETATION

Procalcitonin is a helpful biomarker for early diagnosis of sepsis in critically ill patients. Nevertheless, the results of the test must be interpreted carefully in the context of medical history, physical examination, and microbiological assessment.

FUNDING

Ministry of Education and Research, the Deutsche Forschungsgemeinschaft, Thuringian Ministry for Education, Science and Culture, the Thuringian Foundation for Technology, Innovation and Research, and the German Sepsis Society.

The utility of procalcitonin in critically ill trauma patients

BACKGROUND

Procalcitonin (PCT), the prohormone of calcitonin, has an early and highly specific increase in response to systemic bacterial infection. The objectives of this study were to determine the natural history of PCT for patients with critical illness and trauma, the utility of PCT as a marker of sepsis versus systemic inflammatory response syndrome (SIRS), and the association of PCT level with mortality.

METHODS

PCT assays were done on eligible patients with trauma admitted to the trauma intensive care unit (ICU) of a Level I trauma center from June 2009 to June 2010, at hours 0, 6, 12, 24, and daily until discharge from ICU or death. Patients were retrospectively diagnosed with SIRS or sepsis by researchers blinded to PCT results.

RESULTS

A total of 856 PCT levels from 102 patients were analyzed, with mean age of 49 years, 63% male, 89% blunt trauma, mean Injury Severity Score of 21, and hospital mortality of 13%. PCT concentration for patients with sepsis, SIRS, and neither were evaluated. Mean PCT levels were higher for patients with sepsis versus SIRS (p < 0.0001). Patients with a PCT concentration of 5 ng/mL or higher had an increased mortality when compared with those with a PCT of less than 5 ng/mL in a univariate analysis (odds ratio, 3.65; 95% confidence interval, 1.03-12.9; p = 0.04). In a multivariate logistic analysis, PCT was found to be the only significant predictor for sepsis (odds ratio, 2.37; 95% confidence interval,1.23-4.61, p = 0.01).

CONCLUSION

PCT levels are significantly higher in ICU patients with trauma and sepsis and may help differentiate sepsis from SIRS in critical illness. An elevated PCT level was associated with increased mortality.

Anaesthesia during Carotid Endarterectomy and Urinary Neopterin

Recent systematic reviews of randomized controlled trials show that the rate of postoperative complications after carotid endarterectomy (CEA) was not significantly different between operations performed under general anesthesia (GA) or local anesthesia (LA). However, these studies were not large enough to draw meaningful conclusions about any difference in mortality. This study therefore aimed to compare a surrogate endpoint of postoperative mortality between GA and LA by using urinary neopterin. 68 consecutive patients admitted electively for CEA were studied. Urinary neopterin levels were assayed preoperatively, immediately postoperatively (PO), 4, 6, 12, and 24 hrs PO. This study compared the level of urinary neopterin between GA and LA. Of the 68 CEAs, 48 operations were performed under GA. Urinary neopterin concentration in LA group increased PO and reached a peak at 6 hrs PO. At this point, the urinary neopterin levels in the GA group (85.3 μmol/mol creatinine) were significantly lower than those under the LA group (123.4 μmol/mol creatinine) (P=0.02). We found that the level of urinary neopterin level after operation in LA was significantly higher than those under GA. More studies are needed.

Tryptophan degradation and serum neopterin concentrations in intensive care unit patients

Alterations in neopterin concentrations and tryptophan degradation accompany the activation of cellular immune systems. Accordingly, in a variety of diseases, mainly in infections, elevated neopterin levels and tryptophan degradation have been observed. This study aimed to assess serum neopterin levels and tryptophan degradation in intensive care unit (ICU) patients with systemic inflammatory response syndrome (SIRS, n = 9), sepsis (n = 8), septic shock (n = 10), and multiple organ dysfunction syndrome (MODS, n = 7) at the first day of ICU hospitalization. The kynurenine-to-tryptophan (kyn/trp) ratio was used in order to evaluate the degree of tryptophan degradation. The results of each patient group were compared with the control group (n = 30). The differences among the ICU groups and the correlations between APACHE II scores and neopterin concentrations or tryptophan degradation were investigated. All patient groups presented statistically higher kyn/trp and neopterin levels than the controls. The sepsis, septic shock, and MODS group had markedly higher neopterin levels than the SIRS group (all P < 0.05). Additionally, it was found that the survivor group had significantly lower neopterin levels compared with non-survivors (P < 0.05) and lower kyn/trp, but the latter difference was not significant. Neopterin levels and kyn/trp were both correlated with APACHE II score (both P < 0.05). The results indicate that serum neopterin levels and tryptophan degradation correlate well with the severity of the disease in ICU patients, and this was true even at the first day of hospitalization in the unit.

Accelerated tryptophan degradation predicts poor survival in trauma and sepsis patients

Immune system activation and inflammation accompanies immune dysfunction in trauma and sepsis patients. Immunodeficiency may develop in such patients as one consequence of an activated chronic pro-inflammatory response. According to recent data, degradation of L-tryptophan (TRP) via the kynurenine (KYN) pathway by the cytokine-inducible enzyme indoleamine 2,3-dioxygenase (IDO) could represent an important contributor to the deficient responsiveness of immunocompetent cells. Compared to healthy controls, patients post trauma or with sepsis had increasing KYN concentrations and KYN to TRP ratios (KYN/TRP) whereas TRP concentrations decreased. Likewise, concentrations of cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) and of immune activation marker neopterin increased in patients (all p < 0.001). Furthermore in patients KYN/TRP, KYN and neopterin concentrations were further increasing (all p < 0.001), whereas the changes of TRP, TNF-α and IL-6 concentrations were not significant. Compared to the survivors, the non-survivors had a higher concentration of KYN, neopterin, TNF-α and IL-6 as well as a higher KYN/TRP ratio. KYN/TRP correlated with neopterin (p < 0.001) and also with TNF-α (p < 0.01) and IL-6 concentrations (p < 0.05) and inversely with the in vitro response of stimulated monocytes. We conclude that increased TRP degradation in patients post trauma is closely associated with immune activation. Cytokines released during the pro-inflammatory response may induce the activity of IDO and thus accelerate TRP degradation. Thus, increased IDO activity most likely represents a result of host response to pro-inflammation in patients. Data support a possible role of inflammation-induced IDO in the diminished immunoresponsiveness in patients.

Early increase of plasma homocysteine in sepsis patients with poor outcome

Moderate hyperhomocysteinemia is a well-established coronary risk factor that develops when dietary supply with folate and/or vitamin B(12) is inadequate. Recently, stimulated peripheral blood mononuclear cells were shown to produce homocysteine. Thus, the stimulated immune system may contribute to moderate hyperhomocysteinemia during certain diseases. Because multiple trauma and sepsis are accompanied by often strong inflammatory responses, we investigated whether hyperhomocysteinemia may develop in patients. Total homocysteine and cysteine concentrations were measured in 83 plasma specimens from 18 patients (14 men, 4 women; 15 posttrauma with sepsis and 3 with sepsis alone) every third day of follow-up. Finally results were compared with concentrations of cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-6, the immune activation marker neopterin and the extent of tryptophan degradation as indicated by the kynurenine-to-tryptophan ratio (kyn/trp). Compared with baseline, average total homocysteine (P < 0.05, d 4-d 10) and cysteine (P < 0.05, d 7-d 13) concentrations increased during follow-up of patients. However, only the increase of homocysteine was related to the survival status: total homocysteine was significantly higher in nonsurvivors (P < 0.05, d 4 and d 10) than in survivors, whereas cysteine concentrations increased in both subgroups. Homocysteine correlated with kyn/trp but not with neopterin concentrations. Increase of total homocysteine is common in patients after trauma with unfavorable outcome. Because all patients received standardized enteral nutrition after the end of hypodynamic shock, inconsistent vitamin supply is unlikely to be the reason for hyperhomocysteinemia in some of the patients; rather, it is associated with a stronger proinflammatory response. Certainly, the number of patients in our study is still small and results can only be regarded as preliminary.

Procalcitonin in sepsis and systemic inflammation: a harmful biomarker and a therapeutic target

The worldwide yearly mortality from sepsis is substantial, greater than that of cancer of the lung and breast combined. Moreover, its incidence is increasing, and its response to therapy has not appreciably improved. In this condition, the secretion of procalcitonin (ProCT), the prohormone of calcitonin, is augmented greatly, attaining levels up to thousands of fold of normal. This hypersecretion emanates from multiple tissues throughout the body that are not traditionally viewed as being endocrine. The serum values of ProCT correlate with the severity of sepsis; they recede with its improvement and worsen with exacerbation. Accordingly, as highlighted in this review, serum ProCT has become useful as a biomarker to assist in the diagnosis of sepsis, as well as related infectious or inflammatory conditions. It is also a useful monitor of the clinical course and prognosis, and sensitive and specific assays have been developed for its measurement. Moreover, it has been demonstrated that the administration of ProCT to septic animals greatly increases mortality, and several toxic effects of ProCT have been elucidated by in vitro experimental studies. Antibodies have been developed that neutralize the harmful effects of ProCT, and their use markedly decreases the symptomatology and mortality of animals that harbour a highly virulent sepsis analogous to that occurring in humans. This therapy is facilitated by the long duration of serum ProCT elevation, which allows for a broad window of therapeutic opportunity. An experimental groundwork has been established that suggests a potential applicability of such therapy in septic humans.

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.

Trauma sepsis

Sepsis is a major cause of mortality and morbidity in the trauma patient. Sepsis following traumatic injury is related to the type of injury, together with the extent of injury and the anatomical location. Burn injuries are associated with the highest risk of sepsis. The diagnosis of sepsis in the trauma patient remains difficult. Interpretation of abnormal results is key to successful diagnosis, particularly in conjunction with clinical findings. This review will consider the specific features of sepsis in the context of trauma relating to epidemiology, risk factors, diagnosis and management.

Procalcitonin Levels as an Early Marker in Patients with Multiple Trauma under Intensive Care

This prospective study investigated the levels of procalcitonin (PCT) and C-reactive protein (CRP) in patients with various types and severity of multiple trauma, and their relationship to trauma-related complications. Adult multiple-trauma patients ( n = 113) admitted to the intensive care unit (ICU) in the first 24 h after trauma were included. The Injury Severity Scores (ISS), and PCT and CRP levels were measured in the first 24 h (day 1), on day 7 and on the final day of their ICU stay. Survival at 30 days was recorded. Mean PCT and CRP levels were both significantly higher on day 7 compared with day 1 and the final assessment day in patients with an ISS > 20. Levels of PCT were significantly higher in cases with sepsis, severe sepsis or septic shock compared with cases who developed systemic inflammatory response syndrome (SIRS), however levels of CRP were significantly higher only in cases with severe sepsis or septic shock, but not in cases with sepsis alone. These data support the view that PCT levels may be a better indicator than CRP levels in the early diagnosis of septic complications in patients with multiple trauma.

Accuracy of procalcitonin for outcome prediction in unselected postoperative critically ill patients

The importance of postoperative procalcitonin (PCT) measurements for outcome prediction is currently controversial. Conflicting results have been obtained for patients after polytrauma, sepsis, peritonitis, or cardiac surgery and may result from incomplete adjustment for important confounders or from nonlinear PCT effects. We retrospectively analyzed the association of PCT concentration with postoperative mortality, morbidity, and length of stay in an unselected series of 220 consecutive patients who required postoperative intensive care unit therapy or surveillance. Biochemical markers were measured on the first day after intensive care unit admission. Results were adjusted for various confounding variables (Acute Physiology and Chronic Health Evaluation II score, underlying disease), and test accuracy was evaluated by receiver operating characteristic statistics. We found a significant nonlinear, logarithmic association between PCT concentration and outcome. After adjustment for relevant covariates, PCT was an independent determinant of mortality, combined mortality/morbidity, and postoperative hospital length of stay in survivors. At mortality analysis, the predictive power of PCT was superior to that of Acute Physiology and Chronic Health Evaluation II score and of IL-6 (optimal cutoff point, 1.44 ng/mL; sensitivity, 80.8%; specificity, 80.4%). The use of PCT was comparable to that of other prognostic markers when combined mortality/morbidity were examined. Our results suggest that PCT may deserve further testing as a prognostic tool in unselected, critically ill, surgical patients.

Validation of postinjury multiple organ failure scores

Most multiple organ failure (MOF) scores were developed over a decade ago, but little has been done in terms of validation and to understand the differences between populations identified by each of them. Given the lack of a gold standard, validation must rely on association with objective adverse outcomes. Thus, we propose to (a) validate two widely accepted MOF scores (Denver and Marshall), examining their association with adverse outcomes in a postinjury population; and (b) compare risk factors, characteristics, and outcomes of patients identified by each score. The Denver MOF score grades (from 0-3) four organ dysfunctions (lung, kidney, liver, and heart) and defines MOF as a total score more than 3. The Marshall score grades, in addition, central nervous system and hematologic dysfunction (total of six organs on a 0- to 4-point scale). Using a prospectively collected data set, MOF was scored daily by both scores for 1,389 consecutive trauma patients with Injury Severity Score of more than 15 admitted from 1992 to 2004. Risk factors, clinical outcomes (death, ventilator-free days), and resource utilization outcomes (mechanical ventilation time, length of stay in the intensive care unit) were evaluated. Both scores were associated with areas under the receiver operating characteristic curves of 80 or greater (ideal value = 100), with values for the Denver score being slightly greater (albeit not significantly) regarding prediction of most outcomes. Values of sensitivity and specificity were more than 70% for death and ventilator-free days (with the Denver score showing a consistent trend toward greater specificity), but either sensitivity or specificity was less than 70% for mechanical ventilation time and length of stay in the intensive care unit, suggesting that these scores are appropriately biased toward clinical outcomes as opposed to resource utilization. Both scores performed well, with the Denver MOF score showing greater specificity, which, coupled with its simplicity, makes it an attractive tool for both the research and clinical environments. Basic concepts of each score can probably be combined to produce an improved MOF score.

Procalcitonin as a prognostic and diagnostic tool for septic complications after major trauma

OBJECTIVE

The primary aim of this study was to investigate the diagnostic value of procalcitonin (PCT) and C-reactive protein (CRP) in septic complications after major trauma. A secondary aim was to determine whether there was a prognostic value of PCT for severity of injury, organ dysfunction, and sepsis.

DESIGN

Prospective study.

SETTING

Medical/surgical intensive care unit (ICU).

PATIENTS

Ninety-four patients with consecutive trauma >or=16 years who were admitted to the ICU for an expected stay of >24 hours.

INTERVENTIONS

None.

MEASUREMENTS

PCT and CRP were collected at admission and every day thereafter. The American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference definition was used to identify sepsis criteria. The Sequential Organ Failure Assessment score was used to describe the severity of organ dysfunction. We retrospectively analyzed the occurrence of systemic inflammatory response syndrome and sepsis using the collected variables (criteria fulfilled at least during three continuous days).

MAIN RESULTS

Patients with trauma presented an early and significant increase in PCT at the moment of septic complications compared with concentrations measured 1 day before the diagnosis of sepsis: 0.85 vs. 3.32 ng/mL for PCT (p < 0.001) and 135 vs. 175 mg/L for CRP (p = not significant). The areas under the respective curve at admission in the diagnosis of sepsis were 0.787 (p < 0.001) and 0.489 for PCT and CRP, respectively.

CONCLUSION

PCT plasma reinduction marks possible septic complication during systemic inflammatory response syndrome after major trauma. In addition, high PCT concentration at admission after trauma in ICU patients indicates an increased risk of septic complications.

Elevated systemic IL-18 and neopterin levels are associated with posttraumatic complications among patients with multiple injuries: a prospective cohort study

INTRODUCTION

Posttraumatic systemic inflammatory response syndrome (SIRS), sepsis and their subsequent complication, the multiple-organ dysfunction syndrome (MODS), remain major complications following polytrauma. This prospective clinical study aimed at evaluating the association between these and plasma interleukin-18 (IL-18) and neopterin levels.

METHODS

Inclusion in the series required an Injury Severity Score (ISS) >16, age 16-65 years, admission within 6 h of the accident and survival >48 h; 55 patients were enrolled. Over 14 days, plasma neopterin and IL-18 levels and the clinical course regarding MODS, SIRS and sepsis were recorded daily using the Marshall Score for MODS and the ACCP/SCCM criteria for SIRS and sepsis.

RESULTS

Neopterin and IL-18 plasma levels were increased in +MODS cases as compared with -MODS cases over almost the entire observation period. IL-18 concentrations over days 3-6 were significantly increased among participants with sepsis. These increases were all apparent 2-3 days before the clinical diagnosis of sepsis or MODS was made. In contrast, no significant differences in neopterin and IL-18 plasma levels were observed between participants with and without SIRS.

CONCLUSIONS

Determinations of neopterin and IL-18 concentrations might represent early markers for posttraumatic complications such as MODS and sepsis. They might help to differentiate between SIRS and sepsis and thereby guide the timing of the surgery for polytrauma. Neopterin and IL-18 levels should be used together with the clinical status and other inflammatory markers (IL-6, IL-8, etc.) for prediction of posttraumatic complications.

Tryptophan degradation in multiple trauma patients: survivors compared with non-survivors

Immune dysfunction in trauma patients is associated with immune system activation and inflammation. The cytokine-inducible enzyme IDO (indoleamine 2,3-dioxygenase) initiates the degradation of the essential aromatic amino acid tryptophan via the kynurenine pathway and could contribute to deficient immune responsiveness. Activated IDO is indicated by an increased kyn/trp (kynurenine/tryptophan) ratio. The aim of the present study was to investigate whether tryptophan degradation is associated with outcome in patients post-trauma. Tryptophan and kynurenine concentrations were measured by HPLC in serum specimens of 15 patients post-trauma during 12–14 days of follow-up. Up to five samples within this observation period from each patient were included in this analysis, and a total a 69 samples were available. For further comparisons, concentrations of the immune activation marker neopterin were measured. Compared with healthy controls, the average kyn/trp ratio and kynurenine concentrations were increased in patients, whereas tryptophan concentrations were decreased. During follow-up, increased kyn/trp ratio and kynurenine concentrations (all P<0.001) were observed, whereas the changes in tryptophan concentrations were not significant. Non-survivors had higher kyn/trp ratios and kynurenine concentrations compared with survivors. The kyn/trp ratio correlated with neopterin concentrations (rs=0.590, P<0.001). In conclusion, these results imply that increased tryptophan degradation in patients is due to activated IDO, which most probably is a consequence of a host defence response. These findings support a possible role for IDO in the development of immunodeficiency and death in patients.

Time-course of neopterin levels in patients suffering from severe sepsis treated with and without Drotrecogin-alpha (activated)

Neopterin is secreted by activated monocytes/macrophages upon stimulation with interferon-gamma. The release of this pro-inflammatory mediator permits the activation status of cell-mediated immune system to be examined. We assayed neopterin plasma concentrations in septic patients under treatment with (n=10) and without Drotrecogin-alpha (activated) (n=10) on d 1 and 6 of severe sepsis. In septic patients treated with Drotrecogin-alpha (activated), neopterin levels decreased significantly (p=0.027) from d 1 (baseline) (mean 140.8 nmol/l, +/-standard error of mean (SEM) 106.2) to d 6 (mean 68.9 nmol/l, +/-SEM 46.4). In patients not treated with Drotrecogin-alpha (activated) there was no significant (p=0.96) decrease of neopterin levels from d 1 (mean 147.8 nmol/l, +/-SEM 58.4) to d 6 (mean 139.7 nmol/l, +/-SEM 52.6). Furthermore, neopterin levels showed significant correlations with bilirubin in all patient groups on d 1 of severe sepsis (range of correlation coefficient, r: 0.69-0.88; p<0.05). Neopterin levels correlated significantly with creatinine with regard to all patient groups (range of correlation coefficient, r: 0.73-0.92; p<0.05). In conclusion, Drotrecogin- alpha (activated) was associated with a significant decrease of neopterin plasma levels in septic patients. Neopterin concentrations appear to depend on renal function and enterohepatic circulation.

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.

INCREASED PLASMA LEVELS OF SOLUBLE TRIGGERING RECEPTOR EXPRESSED ON MYELOID CELLS 1 AND PROCALCITONIN AFTER CARDIAC SURGERY AND CARDIAC ARREST WITHOUT INFECTION

Soluble triggering receptor expressed on myeloid cells 1 (sTREM-1) and procalcitonin (PCT) are often considered to be specific markers for infection. We evaluated plasma levels of sTREM-1 and PCT in patients with systemic inflammatory response syndrome but no sepsis. Noninfected patients undergoing elective heart surgery with cardiopulmonary bypass (n = 76) and patients admitted after out-of-hospital cardiac arrest (n = 54) were followed up for 3 days. Patients with severe sepsis (n = 55) and healthy volunteers (n = 31) were included as positive and negative controls, respectively. Plasma levels of PCT were higher in sepsis patients than in patients who survived after cardiac arrest or after heart surgery. In contrast, peak plasma levels of sTREM-1 in heart surgery and in cardiac arrest patients overlapped with those measured in patients with sepsis. Both sTREM-1 and PCT were significantly higher in cardiac arrest patients who died of refractory shock than in those who died of neurological failure or survived without major neurological damage. In the cardiac arrest patients with refractory shock, sTREM-1 and PCT levels were similar to those in the patients with severe sepsis. In conclusion, sTREM-1 and PCT are not specific for infection and can increase markedly in acute inflammation without infection.

Sepsis in 2003: are we still in the middle of nowhere?

PURPOSE OF REVIEW

Although enthusiasm of intensivists has been raised during the last 2-3 years due to several successful clinical trials, severe sepsis and septic shock still have an increasing incidence with more or less unchanged mortality. Within the last 12 months, the progress in sepsis research covering definitions, epidemiology, pathophysiology, diagnosis, standard and adjunctive therapy, as well as experimental approaches is encouraging. In this review, state-of-the-art publications of 2003 are presented to elucidate the possible impact on clinical routine.

RECENT FINDINGS

The rationale for using a new definition based on the PIRO system has been widely acknowledged, although it is not yet applicable in clinical practice. This includes genomic information for stratifying subgroups of patients, and a broader field of laboratory diagnostics due to clinical studies and basic research on the cellular mechanisms of inflammation and organ dysfunction. Early diagnosis is important for a fast implementation of specific therapies, and it has been confirmed that the time until the start of therapy has an impact on patient outcome. Thorough data analysis of successful trials with activated protein C has revealed encouraging details on long-term outcome and subgroup effects. Together with new findings on low-dose hydrocortisone, this stresses the relevance of adjunctive therapy in severe sepsis and septic shock.

SUMMARY

Scientific progress in areas of sepsis has been continuing throughout 2003, although the challenges are still enormous. The identification of more specific markers and new therapeutic approaches will hopefully improve the diagnosis, monitoring of therapy, and outcome in the septic patient.

The role of procalcitonin in a decision tree for prediction of bloodstream infection in febrile patients

Bloodstream infection (BSI) in febrile patients is associated with high mortality. Clinical and laboratory variables, such as procalcitonin (PCT), may predict BSI and help decision-making concerning empirical treatment. This study compared two models for prediction of BSI, and evaluated the role of PCT vs. clinical variables, collected daily in 300 consecutive febrile inpatients, for 48 h after onset of fever. Multiple logistic regression (MLR) and classification and regression tree (CART) models were compared for discriminatory power and diagnostic performance. BSI was present in 17% of cases. MLR identified the presence of intravascular devices, nadir albumin and thrombocyte counts, and peak temperature, respiratory rate and leukocyte counts, but not PCT, as independent predictors of BSI. In contrast, a peak PCT level of >2.45 ng/mL was the principal discriminator in the decision tree based on CART. The latter was more accurate (94%) than the model based on MLR (72%; p <0.01). Hence, the presence of BSI in febrile patients is predicted more accurately and by different variables, e.g., PCT, in CART analysis, as compared with MLR models. This underlines the value of PCT plus CART analysis in the diagnosis of a febrile patient.

Correlation of procalcitonin and C-reactive protein to inflammation, complications, and outcome during the intensive care unit course of multiple-trauma patients

Background

A comparison of the amount of and the kinetics of induction of procalcitonin (PCT) with that of C-reactive protein (CRP) during various types of and severities of multiple trauma, and their relation to trauma-related complications, was performed.

Methods

Ninety adult trauma patients admitted to the intensive care unit of our tertiary care hospital were evaluated in a prospective case study. During the initial 24 hours after trauma the Injury Severity Score, the Sepsis-related Organ Failure Assessment score, and the Acute Physiology and Chronic Health Evaluation II score were evaluated. PCT, CRP, the sepsis criteria (American College of Chest Physicians/Society of Critical Care Medicine definitions), and the Sepsis-related Organ Failure Assessment score were measured at days 1–7, as well as at days 14 and 21, concluding the observation period with the 28-day survival.

Results

The induction of PCT and CRP varied in patients suffering from trauma. PCT increased only moderately in most patients and peaked at day 1–2 after trauma, the concentrations rapidly declining thereafter. CRP ubiquitously increased and its kinetics were much slower. Complications such as sepsis, infection, blood transfusion, prolonged intensive care unit treatment, and poor outcome were more frequent in patients with initially high PCT (>1 ng/ml), whereas increases of CRP showed no positive correlation.

Conclusion

In patients with multiple trauma due to an accident, the PCT level provides more information than the CRP level since only moderate amounts of PCT are induced, and higher concentrations correlate with more severe trauma and a higher frequency of various complications, including sepsis and infection. Most importantly, the moderate trauma-related increase of PCT and the rapidly declining concentrations provide a baseline value near to the normal range at an earlier time frame than for CRP, thus allowing a faster and more valid prediction of sepsis during the early period after trauma.

Markers for sepsis diagnosis: what is useful?

Timely diagnosis of the different severities of septic inflammation is potentially lifesaving because therapies that have been shown to lower mortality should be initiated early. Sepsis and severe sepsis are accompanied by clinical and laboratory signs of systemic inflammation but patients with inflammation caused by noninfectious causes may present with similar signs and symptoms. It is important to identify markers for an early diagnosis of sepsis and organ dysfunction. This article presents currently interesting sepsis biomarkers. Other novel markers and their potential role are discussed.

Prognostic value of interleukin 6, procalcitonin, and C-reactive protein levels in intensive care unit patients during first increase of fever

To investigate the prognostic value of interleukin 6 (IL-6), procalcitonin (PCT), and C-reactive protein (CRP) in critically ill patients during the first increase of fever, serum levels were measured in 38 patients admitted to intensive care unit of the Department of Medicine, Klinikum Grosshadern, University of Munich, immediately after increase of body temperature more than 38.3 degrees C. Ten healthy controls were also included for comparison. The onset of fever was accompanied by elevated circulating levels of all the 3 markers in comparison with healthy controls. However, only IL-6 levels were significantly higher (P < 0.05) in nonsurvivors (n = 21) compared with survivors. Sensitivity, specificity, positive, and negative predictive values calculated from median levels was higher for IL-6 compared with PCT and CRP. Areas under receiver characteristic operating curves revealed the highest area under the curve for IL-6 in contrast to PCT and CRP. These data suggest that IL-6 rather than PCT or CRP may be an early predictor of mortality in patients with onset of fever and identify patients, who need intensive monitoring to initiate appropriate therapy at an early stage.

Procalcitonin as a diagnostic test for sepsis in critically ill adults and after surgery or trauma: a systematic review and meta-analysis

OBJECTIVE

To quantify the accuracy of serum procalcitonin as a diagnostic test for sepsis, severe sepsis, or septic shock in adults in intensive care units or after surgery or trauma, alone and compared with C-reactive protein. To draw and compare the summary receiver operating characteristics curves for procalcitonin and C-reactive protein from the literature.

DATA SOURCE

MEDLINE (keywords: procalcitonin, intensive care, sepsis, postoperative sepsis, trauma); screening of the literature.

STUDY SELECTION

Meta-analysis of all 49 published studies in medical, surgical, or polyvalent intensive care units or postoperative wards. Children, medical patients, and immunocompromised patients were excluded.

DATA EXTRACTION

Thirty-three studies fulfilled inclusion criteria (3,943 patients, 1,828 males, 922 females; mean age: 56.1 yrs; 1,825 patients with sepsis, severe sepsis, or septic shock; 1,545 with only systemic inflammatory response syndrome); eight studies could not be analyzed statistically. Global mortality rate was 29.3%.

DATA SYNTHESIS

Global odds ratios for diagnosis of infection complicated by systemic inflammation were 15.7 for the 25 studies (2,966 patients) using procalcitonin (95% confidence interval, 9.1-27.1) and 5.4 for the 15 studies (1,322 patients) using C-reactive protein (95% confidence interval, 3.2-9.2). The summary receiver operating characteristics curve for procalcitonin was better than for C-reactive protein. In the 15 studies using both markers, the Q* value (intersection of summary receiver operating characteristics curve with the diagonal line where sensitivity equals specificity) was significantly higher for procalcitonin than for C-reactive protein (0.78 vs. 0.71, p = .02), the former test showing better accuracy.

CONCLUSIONS

Procalcitonin represents a good biological diagnostic marker for sepsis, severe sepsis, or septic shock, difficult diagnoses in critically ill patients. Procalcitonin is superior to C-reactive protein. Procalcitonin should be included in diagnostic guidelines for sepsis and in clinical practice in intensive care units.