Drotrecogin Alfa (Activated) in an Infant with Gram-Negative Septic Shock

Endothelial Cell Function and Dysfunction in Critically Ill Children

Endothelial cells (ECs) line the lumen of the entire vascular system and actively regulate blood flow; maintain blood fluidity; control water, solute, and macromolecular transfer between blood and tissue; and modulate circulating immune cell recruitment and activation. These vital functions, combined with the broad anatomic distribution of ECs, implicate them in all forms of critical illness. The present article discusses how ECs adapt and break down during the course of critical illness. We first review the biology of ECs, highlighting the vascular segmental differences and their specific roles in the maintenance of homeostasis. We then discuss how ECs acquire new functions to restore local and systemic homeostasis (activation) as well as how breakdowns in EC functions (dysfunction) contribute to local and systemic pathologic responses, with clinical correlations. Lastly, how these processes have been studied in critically ill children is discussed.

Recombinant human activated protein C for severe sepsis in neonates

BACKGROUND

Sepsis is a common problem in preterm and term infants. The incidence of neonatal sepsis has declined, but mortality remains high. Recombinant human activated protein C (rhAPC) possess a broad spectrum of activity modulating coagulation and inflammation. In septic adults it may reduce mortality, but no significant benefit has been reported in children with severe sepsis.

OBJECTIVES

To determine whether treatment with rhAPC reduces mortality and/or morbidity in neonatal sepsis.

SEARCH METHODS

For this update searches were carried out in May 2011 of the Cochrane Central Register of Controlled Trials (The Cochrane Library), MEDLINE, EMBASE, CINAHL, and abstracts of annual meetings of the Pediatric Academic Societies. Doctoral dissertations, theses and the Science Citation Index for articles on activated protein C were searched. No language restriction was applied.

SELECTION CRITERIA

Randomized or quasi-randomized trials, assessing the efficacy of rhAPC compared to placebo or no intervention as an adjunct to antibiotic therapy of suspected or confirmed severe sepsis in term and preterm infants less than 28 days old. Eligible trials should report at least one of the following outcomes: mortality during initial hospital stay, neurodevelopmental assessment at two years of age or later, length of hospital stay, duration of ventilation, chronic lung disease, periventricular leukomalacia, intraventricular haemorrhage, necrotizing enterocolitis, bleeding, and any other adverse events.

DATA COLLECTION AND ANALYSIS

Review authors were to independently evaluate the articles for inclusion criteria and quality, and abstract information for the outcomes of interest. Differences were to be resolved by consensus. The statistical methods were to include relative risk, risk difference, number needed to treat to benefit or number needed to treat to harm for dichotomous and weighed mean difference for continuous outcomes reported with 95% confidence intervals. A fixed effect model was to be used for meta-analysis. Heterogeneity tests, including the I(2) statistic, were to be performed to assess the appropriateness of pooling the data.

MAIN RESULTS

No eligible trials were identified. In October 2011 rhAPC (Xigris®) was withdrawn from the market by Eli Lilly due to a higher mortality in a trial among adults. Xigris® (DrotAA)( rhAPC) should no longer be used in any age category and the product should be returned to the distributor.

AUTHORS' CONCLUSIONS

Despite the scientific rationale for its use, there is insufficient data to use rhAPC for the management of severe sepsis in newborn infants. Due to the results among adults with lack of efficacy, an increase in bleeding and resulting withdrawal of rhAPC from the market, neonates should not be treated with rhAPC and further trials should not be conducted.

The host response to sepsis and developmental impact

Invasion of the human by a pathogen necessitates an immune response to control and eradicate the microorganism. When this response is inadequately regulated, systemic manifestations can result in physiologic changes described as "sepsis." Recognition, diagnosis, and management of sepsis remain among the greatest challenges shared by the fields of neonatology and pediatric critical care medicine. Sepsis remains among the leading causes of death in both developed and underdeveloped countries and has an incidence that is predicted to increase each year. Despite these sobering statistics, promising therapies derived from preclinical models have universally failed to obviate the substantial mortality and morbidity associated with sepsis. Thus, there remains a need for well-designed epidemiologic and mechanistic studies of neonatal and pediatric sepsis to improve our understanding of the causes (both early and late) of deaths attributed to the syndrome. In reviewing the definitions and epidemiology, developmental influences, and regulation of the host response to sepsis, it is anticipated that an improved understanding of this host response will assist clinician-investigators in identifying improved therapeutic strategies.

The effect of activated protein C on plasma cytokine levels in a porcine model of acute endotoxemia

OBJECTIVE

To assess the anti-inflammatory effects of recombinant human activated protein C (rhAPC) in a porcine model of acute endotoxemia.

DESIGN AND SETTING

Animal randomized controlled study at the Laboratory of Clinical Institute, Aarhus University Hospital.

SUBJECTS

Eighteen female landrace pigs (30 kg).

INTERVENTIONS

By pairwise randomization, pigs were given either LPS or LPS and rhAPC. Both groups received a stepwise increasing LPS infusion for 30[Symbol: see text]min; whereafter the infusion continued at a lower rate (300 min LPS in both groups). The LPS+rhAPC group received rhAPC (100 microg/kg per hour) 15 min before the LPS infusion began and throughout the trial period.

RESULTS

While rhAPC showed no modifying effects on peak plasma levels of pro- or anti-inflammatory cytokines (TNF-alpha, IL-6, IL-8, IL-10), TNF-alpha and IL-10 peaked significantly later in the rhAPC-treated animals. The profibrinolytic effects of rhAPC were confirmed by decreased plasminogen activator inhibitor 1 levels, while no differences were found in other coagulation markers, hemodynamic, metabolic, or leukocyte data between the two groups.

CONCLUSIONS

We found no significant effect of rhAPC on plasma levels of either pro- or anti-inflammatory cytokines in this porcine model of acute endotoxemia. However, TNF-alpha and IL-10 peaked significantly later in the rhAPC-treated animals.

Recombinant human activated protein C for severe sepsis in neonates

BACKGROUND

Sepsis is a common problem in both preterm and term infants. Although the overall incidence of neonatal sepsis has declined over the past decade, mortality remains high. Recombinant human activated protein C (rhAPC) has been shown to possess a broad spectrum of activity modulating coagulation and has been shown in septic adults to reduce mortality. In septic children, an open label study has shown similar pharmacokinetics, adverse reaction profile and frequency as in adults with severe sepsis.

OBJECTIVES

To determine whether treatment with rhAPC will reduce mortality and/or morbidity in neonates with severe sepsis.

SEARCH STRATEGY

Searches were carried out in July 2005 by the review authors independently of MEDLINE (1966 to July 2005), EMBASE (1980 to July 2005), CINAHL (1982 to July 2005), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 3, 2005), abstracts of annual meetings of the Pediatric Academic Societies and Society for Pediatric Research which were published in Pediatric Research from 1980, and contacts were made with subject experts. Doctoral dissertations, theses and the Science Citation Index for articles on activated protein C were searched from 1980. No language restriction was applied.

SELECTION CRITERIA

Studies were included if they were randomized or quasi-randomized trials, assessing the efficacy of rhAPC compared to placebo or no intervention as an adjunct to antibiotic therapy of suspected or confirmed severe sepsis in term and preterm infants less than 28 days old. Eligible trials were required to report treatment effects on at least one of the following outcomes: all cause mortality during initial hospital stay, neurological development and neurodevelopmental assessment at two years of age or later, length of hospital stay, duration of ventilation, chronic lung disease in survivors, periventricular leukomalacia, intraventricular hemorrhage, necrotizing enterocolitis, bleeding, and any other adverse events.

DATA COLLECTION AND ANALYSIS

Both review authors independently evaluated the papers for inclusion criteria and quality, and abstracted information for the outcomes of interest. Differences were resolved by mutual discussion. The statistical methods were to include relative risk, risk difference, number needed to treat to benefit or number needed to treat to harm for dichotomous and weighed mean difference for continuous outcomes reported with 95% confidence intervals. A fixed effects model was to be used for meta-analysis. Heterogeneity tests, including the I(2) statistic, were to be performed to assess the appropriateness of pooling the data.

MAIN RESULTS

No eligible trials were identified.

AUTHORS' CONCLUSIONS

Despite the scientific rationale for its use, there are insufficient data to support the use of rhAPC for the management of severe sepsis in newborn infants. There is a need for large well-designed trials to elucidate the effectiveness of rhAPC to reduce mortality and adverse outcomes in neonates with severe sepsis. The results of such trials would guide clinical practice. Currently, a cautious approach to the use of rhAPC is warranted due to the high incidence of bleeding with its use; especially as severe sepsis in preterm infants is commonly associated with bleeding problems and intraventricular hemorrhage. Its use is not recommended outside of randomized controlled trials.

Pediatric hemostasis and use of plasma components

Indications for fresh frozen plasma (FFP), once used routinely in the support of critically ill infants and children, have become more specific as evolving evidence has confirmed or disproved the efficacy of plasma in various circumstances. FFP is currently indicated to treat the coagulopathies of massive hemorrhage, liver failure and disseminated intravascular coagulation and sepsis. Whole blood reconstituted from FFP and packed red cells is the product of choice for exchange transfusion, as well as for circuit priming. In the US, FFP remains the only approved source of factors V, XI, protein C, protein S and plasminogen. Cryoprecipitate is used chiefly as a source of fibrinogen, factor VIII and factor XIII in consumptive coagulopathy; recombinant or viral inactivated plasma derivatives are preferred for congenital deficiencies of factor VIII and von Willebrand factor. Recombinant and highly purified, viral inactivated, plasma-derived proteins are preferred over FFP for congenital and acquired deficiencies. This chapter reviews evidence to support the use of plasma and plasma derivatives for pediatric patients.

Recombinant human activated protein C, heparin and melagatran in umbilical cord versus adult plasma

AIM

We investigated the anticoagulant effects of recombinant human activated protein C (rhAPC), unfractionated heparin (UH) and melagatran (a new direct thrombin inhibitor [DTI]), when administered individually and in combinations of rhAPC with either UH or melagatran, in umbilical cord and adult plasma. rhAPC is a promising candidate treatment to improve the outcome of severe sepsis in neonates and adults; the DTI melagatran represents a potential advance in antithrombotic therapy.

METHODS

The anticoagulant efficacy of these drugs was measured using the standard coagulation assays activated partial thromboplastin time (aPTT) and prothrombin time (PT).

RESULTS

Administered individually, rhAPC, UH and melagatran dose-dependently prolonged aPTT to a significantly greater extent in umbilical cord than in adult plasma. Melagatran alone, but not rhAPC or UH alone, dose-dependently prolonged the PT in both umbilical cord and adult plasma. Combining rhAPC with either UH or melagatran significantly augmented aPTT prolongation in both umbilical cord and adult plasma.

CONCLUSION

Our results, which facilitate estimation of rhAPC and melagatran dose requirements in umbilical cord plasma, may be of benefit in critically sick newborns with severe sepsis.