Early detection and markers of sepsis

[The diagnosis of sepsis]

The early diagnosis of sepsis is mandatory for the further reduction of mortality due to sepsis. Current findings exist that accentuate the role of the time factor, comparable with acute myocardial infarction or with ischemic stroke. On the other hand, there are no generally accepted diagnostics for sepsis, realizing the demands of early diagnosis and based on the physician's experience.The diagnostics start with the recognition of the inflammatory reaction caused by infection (at least 2 of 4 criteria of inflammatory reaction have to be fulfilled). This definition has high sensitivity, but remarkably lower specificity and it leads either to too frequent admissions or only to hospitalization in case of a complicating organ failure. Making a careful history and knowledge about sepsis are essential for the out-patient department physicians. In addition to the varying pictures of sepsis, the clinicians have laboratory findings available, most of all procalcitonin. Patients have to be considered as septic with a serum PCT level higher than 1 ng/ml particularly when clinical signs do not exclude sepsis and in cases of positive blood cultures. Initially PCT is a product of macrophages if the defense reaction starts, but it becomes an infection marker, when the serum PCT level declines less than the half life falls.

Die Diagnose der Sepsis

Die frühe Diagnostik der Sepsis ist das Nadelöhr für die weitere Senkung der Sepsissterblichkeit. Inzwischen liegen Befunde vor, dass, vergleichbar mit akutem Myokardinfarkt und Schlaganfall, dem Faktor Zeit eine wichtige Rolle zukommt. Demgegenüber gibt es keine allgemein akzeptierte Sepsisdiagnostik, die der Forderung nach früher Diagnose und der Unabhängigkeit vom Erfahrungsstand des jeweiligen Arztes Rechnung tragen könnte.

Prognostic determinants of acute respiratory distress syndrome in adults: impact on clinical trial design

OBJECTIVE

The objective of this study was to review known clinical predictors and biologic markers of adverse clinical outcomes in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) that might be used as selection criteria in clinical trials of novel therapies for ALI/ARDS.

DATA SOURCE

Published studies on clinical predictors and biologic markers of adverse outcomes in ALI/ARDS.

MAIN RESULTS

In large epidemiologic studies, a number of clinical factors have been identified consistently as independent predictors of mortality in ALI/ARDS. These include age, comorbidities, including chronic liver disease and immunosuppression, severity of illness scores, and the degree of multisystem organ failure. Several biologic markers of mortality have also been identified in large studies, including von Willebrand factor antigen, surfactant protein D, protein C, plasminogen activator inhibitor-1, interleukins 6 and 8, and the TNF receptors. The Pao2/Fio2 ratio at the onset of ALI/ARDS does not predict clinical outcome but may be more useful after the first day of ALI/ARDS. A persistently low Pao2/Fio2 ratio is associated with worse outcomes and may be a marker of failure to respond to conventional therapy. Changes in IL-6, IL-8, TNF receptors, and SP-D over the first 3 days of ALI/ARDS are also associated with adverse clinical outcomes. The use of a combination of clinical factors and biologic markers is a promising strategy that needs to be prospectively validated.

CONCLUSIONS

The design of clinical trials for new therapies for ALI and ARDS is a complex problem that ultimately will have a major impact on both trial outcome and generalizability. A number of clinical factors and biologic markers can be used to differentiate groups of patients at highest risk for adverse clinical outcomes. Whether enriching study populations with these sicker patients will increase or decrease the likelihood of a treatment effect for a given therapy is unknown.

Lower tidal volume ventilation and plasma cytokine markers of inflammation in patients with acute lung injury*

OBJECTIVES

To evaluate the association between interleukin-6, interleukin-8, and interleukin-10 and clinical outcomes including mortality in patients with acute lung injury and to determine whether lower tidal volume ventilation was associated with a decrease in plasma cytokines in patients with acute lung injury.

DESIGN

Multiple-center, randomized trial.

SETTING

Intensive care units in ten university centers.

PATIENTS

The study included 861 patients enrolled in the National Heart, Lung and Blood Institute Acute Respiratory Distress Syndrome Clinical Network trial of lower tidal volumes compared with traditional tidal volumes for acute lung injury.

INTERVENTIONS

Patients were randomized to a 6 mL/kg or a 12 mL/kg tidal volume strategy that has been previously described.

MEASUREMENTS AND MAIN RESULTS

Baseline plasma levels of interleukin-6, interleukin-8, and interleukin-10 were each associated with an increased risk of death in both logistic regression analyses controlling for ventilator group (odds ratio 1.63 per log-10 increment, 95% confidence interval 1.33-1.98; odds ratio 2.33 per log-10 increment, 95% confidence interval 1.79-3.03; odds ratio 2.02 per log-10 increment, 95% confidence interval 1.47-2.76, respectively) and multivariate analyses controlling for ventilation strategy, Acute Physiology and Chronic Health Evaluation III score, Pao2/Fio2 ratio, creatinine, platelet count, and vasopressor use (odds ratio 1.63 per log-10 increment, 95% confidence interval 0.93-1.49; odds ratio 1.73 per log-10 increment, 95% confidence interval 1.29-2.34; odds ratio 1.23 per log-10 increment, 95% confidence interval 0.86-1.76, respectively). Interleukin-6 and interleukin-8 levels were also associated with a significant decrease in ventilator free and organ failure free days. Patients with sepsis had the highest cytokine levels and the greatest risk of death per cytokine elevation. By day 3, the 6 mL/kg strategy was associated with a greater decrease in interleukin-6 and interleukin-8 levels. There was a 26% reduction in interleukin-6 (95% confidence interval, 12-37%) and a 12% reduction in interleukin-8 (95% confidence interval, 1-23%) in the 6 mL/kg group compared with the 12 mL/kg group.

CONCLUSIONS

In patients with acute lung injury, plasma interleukin-6 and interleukin-8 levels are associated with morbidity and mortality. The severity of inflammation varies with clinical risk factor, suggesting that clinical risk factor should be considered when both developing and testing therapeutic interventions. Low tidal volume ventilation is associated with a more rapid attenuation of the inflammatory response.

Mediators and mechanisms of acute lung injury

Since last reviewed in this forum, there have been remarkable advances in our understanding of the acute inflammatory process and how it contributes to the development of ALI. As stated in the beginning of this article, it is not possible to even begin to review all the specific advances that have been made. Instead, the author has focused on concepts that have emerged and improved our ability to study the pathogenesis of ARDS. These include the recognition that patients at risk for and with ARDS represent a heterogeneous population, that mediators or markers of inflammation cannot be considered in isolation, that a balance between proinflammatory mediators and inflammatory modulators may be important, and that there are several genetic factors that could contribute to the susceptibility for the development of ARDS. Hopefully these concepts can be expanded and clarified so that the next review of this topic can report on successful therapeutic interventions for the prevention and the treatment of ARDS.

[Dengue: a new approach]

Previous definition of classic dengue, with or without bleeding, and of dengue hemorrhagic fever (DHF) that may evolve without bleeding and with or without dengue shock syndrome (DSS) are reviewed here. The classical approach to the diagnosis and treatment of dengue, although useful in the past, nowadays breeds confusion and adds a burden to the physician's task of decision-making regarding the treatment of patients with severe forms of the disease. The classification of dengue proposed in this paper, and summarized in a diagram, incorporates new concepts about sepsis, systemic inflammatory response syndrome (SIRS), and acute respiratory distress syndrome (ARDS). This new approach, in our view, is a useful guide to initial evaluation and treatment of the disease. It also approximates the dengue syndrome to other protocols and medical procedures routinely used in intensive care units, making it easier to be followed by the health personnel working in areas subject to epidemic bursts.

Markers for predicting the development of acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) is a relatively common, inflammatory lung disorder that is associated with major morbidity and high mortality. The pathogenesis of ARDS is complex, and unfortunately, the development of ARDS in an individual patient is difficult to anticipate. In this chapter, we outline the rationale for why accurately predicting the development of ARDS would be valuable. We also review the accumulated data on approaches for predicting ARDS and discuss the potential difficulties in establishing predictive markers.

Endothelial cell activity varies in patients at risk for the adult respiratory distress syndrome

OBJECTIVE

The endothelial cell produces many bioactive compounds that are presumed to play important roles in the pathogenesis of the adult respiratory distress syndrome (ARDS). We postulated that individuals with sepsis and trauma-two at-risk diagnoses for the development of ARDS--might demonstrate differences in the degree of endothelial cell activity.

DESIGN

Prospective cohort study.

SETTING

Intensive care unit patients in a tertiary, university-affiliated, city hospital.

PATIENTS

Fifty-five intensive care unit patients (19 with sepsis and 36 trauma patients).

INTERVENTIONS

Plasma measurements of three endothelial cell products--von Willebrand factor antigen, soluble intercellular adhesion molecule-1 (ICAM-1), and soluble E-selectin-were performed within 8 hrs of patients meeting our inclusion criteria, and at the clinical onset of ARDS.

MEASUREMENTS AND MAIN RESULTS

Twenty-six percent of the septic patients and 25% of the trauma patients developed ARDS. The median (and 25% to 75% quartiles) concentrations of all three mediators measured in the sepsis patients (von Willebrand factor antigen 399% [375% to 452%], ICAM-1 573 ng/mL [470 to 980], and soluble E-selectin 180 ng/mL [81 to 340]) were significantly higher (p < .001 for each individual analysis) than in the trauma patients (von Willebrand factor antigen 256% [217% to 310%], ICAM-1 148 ng/mL [113 to 210], and soluble E-selectin 42 ng/mL [31 to 65 ng/ mL]). In addition, neither the ICAM-1 nor soluble E-selectin concentrations measured in the trauma patients were different (p = .17 and p = .24, respectively) from normal controls. In those patients who developed ARDS, the differences in the concentrations of all three endothelial cell mediators between the sepsis and trauma patients persisted (p = .008 for von Willebrand factor antigen, p = .003 for ICAM-1, and p = .003 for E-selectin).

CONCLUSION

These findings suggest that differences in endothelial cell activity exist between sepsis and trauma patients who are at risk for the development of ARDS.