A normal platelet count at admission in acute meningococcal disease does not exclude a fulminant course

Blood platelets and sepsis pathophysiology: A new therapeutic prospect in critically [corrected] ill patients?

Beyond haemostasis, platelets have emerged as versatile effectors of the immune response. The contribution of platelets in inflammation, tissue integrity and defence against infections has considerably widened the spectrum of their role in health and disease. Here, we propose a narrative review that first describes these new platelet attributes. We then examine their relevance to microcirculatory alterations in multi-organ dysfunction, a major sepsis complication. Rapid progresses that are made on the knowledge of novel platelet functions should improve the understanding of thrombocytopenia, a common condition and a predictor of adverse outcome in sepsis, and may provide potential avenues for management and therapy.

Invited review: Neisseria meningitidis lipopolysaccharides in human pathology

Neisseria meningitidis causes meningitis, fulminant septicemia or mild meningococcemia attacking mainly children and young adults. Lipopolysaccharides (LPS) consist of a symmetrical hexa-acyl lipid A and a short oligosaccharide chain and are classified in 11 immunotypes. Lipid A is the primary toxic component of N. meningitidis . LPS levels in plasma and cerebrospinal fluid as determined by Limulus amebocyte lysate (LAL) assay are quantitatively closely associated with inflammatory mediators, clinical symptoms, and outcome. Patients with persistent septic shock, multiple organ failure, and severe coagulopathy reveal extraordinarily high levels of LPS in plasma. The cytokine production is compartmentalized to either the circulation or to the subarachnoid space. Mortality related to shock increases from 0% to > 80% with a 10-fold increase of plasma LPS from 10 to 100 endotoxin units/ml. Hemorrhagic skin lesions and thrombosis are caused by up-regulation of tissue factor which induces coagulation, and by inhibition of fibrinolysis by plasminogen activator inhibitor 1 (PAI-1). Effective antibiotic treatment results in a rapid decline of plasma LPS (half-life 1—3 h) and cytokines, and reduced generation of thrombin, and PAI-1. Early antibiotic treatment is mandatory. Three intervention trials to block lipid A have not significantly reduced the mortality of meningococcal septicemia.

von Willebrand factor activation, granzyme-B and thrombocytopenia in meningococcal disease

SUMMARY BACKGROUND

During invasive meningococcal disease, severe thrombocytopenia is strongly associated with a poor outcome.

OBJECTIVES

In order to elucidate the pathophysiological mechanism behind the development of thrombocytopenia, we studied the role of von Willebrand factor (VWF) in meningococcal disease.

PATIENTS/METHODS

Thirty-two children with severe meningococcal disease admitted to our university hospital were included in this study. VWF and related parameters were measured and results were correlated with the development of shock and thrombocytopenia.

RESULTS

At admission, all patients had increased levels of (active) VWF and VWF propeptide. The highest VWF propeptide levels were observed in patients with shock, indicating acute endothelial activation. Although VWF propeptide levels in patients with shock, with or without thrombocytopenia, were similar, increased active VWF was significantly lower in patients with thrombocytopenia as compared with patients without thrombocytopenia. ADAMTS13 was moderately decreased. However, the VWF multimeric pattern was minimally increased. We assume that these findings are explained by VWF consumption and perhaps by granzyme B (GrB). In vitro experiments showed that GrB is able to cleave VWF multimers in plasma, whereas GrB was high in patients with shock, who developed thrombocytopenia.

CONCLUSIONS

Our results demonstrate that consumption of VWF, derived from endothelial cells, could be a key feature of meningococcal disease and primary to the development of thrombocytopenia during shock.

Implications of thrombocytopenia and platelet course on pediatric intensive care unit outcomes

INTRODUCTION

Thrombocytopenia has been shown to be an independent predictor of mortality and prolonged hospital length of stay in critically ill adults. Studies are lacking in the pediatric intensive care unit population. We evaluated the relationship between platelet counts at admission, platelet course, and outcomes.

HYPOTHESES

1) Thrombocytopenia at the time of admission to the pediatric intensive care unit is a risk factor for increased mortality and prolonged length of stay. 2) Thrombocytopenia at any point during pediatric intensive care unit stay is associated with increased mortality and length of stay. 3) Falling platelet counts during a pediatric intensive care unit course are associated with greater mortality and longer length of stay.

METHOD

Prospective observational study.

STUDY POPULATION

All patients admitted to a multidisciplinary tertiary care pediatric intensive care unit in a University Hospital over the course of a year. ANALYSIS OF DATA: Data were analyzed using logistic and linear regression.

RESULTS

Thrombocytopenia (platelet count <150 x 10/L) was present in 17.3% of pediatric intensive care unit patients on admission. Mortality was higher in thrombocytopenic patients (17.6% vs. 2.47%, p < 0.001). The median length of stay in the thrombocytopenia and nonthrombocytopenia groups was 4 days vs. 1.6 days, respectively (p < 0.001). The pediatric intensive care unit patients (25.3%) were thrombocytopenic at some point in their stay. They had higher mortality (17.1% vs. 0.9%, odds ratio [OR] 23.8, 95% confidence interval [CI] 5.2-108.6, p < 0.0005) and longer length of stay (median 6.6 days vs. 1.5 days, p < 0.0005) compared with those who were never thrombocytopenic. For every 10% fall in platelet count from the time of admission, the OR for mortality was 1.4 (95% CI 1.1-1.8) and the length of stay was longer (p < 0.0005). Patients with normal platelet counts at admission who later developed thrombocytopenia had increased mortality (OR 18.6, 95% CI 3.2-107.3) and longer length of stay (p < 0.0005) compared with those who did not develop thrombocytopenia.

CONCLUSION

Thrombocytopenia and falling platelet counts are associated with increased risk of mortality and length of stay in the pediatric intensive care unit.

Pre-admission clinical course of meningococcal disease and opportunities for the earlier start of appropriate intervention: a prospective epidemiological study on 752 patients in the Netherlands, 2003-2005

To improve the timeliness of health care delivery to patients with meningococcal disease, the early disease evolution and clinical manifestation at admission were studied in all 752 patients with invasive meningococcal disease in the Netherlands in 2003-2005. Eighty-eight percent (88%) had serogroup B disease. The case fatality rate (CFR) was 6.7% overall, but reached 16% among adults over 50 years of age. The CFR was similar for serogroups B (6.3%) and C (5.2%). Admission followed 17 h (median) after the onset of symptoms. The CFR in patients admitted within 12 h, 12-18 h, 18-36 h or >36 h after the first symptoms was 10.2, 7.8, 3.5 and 2.2%, respectively. Only 60% of patients had skin lesions, and admission followed 2 h (median) later. Earlier recognition can be achieved when non-petechial clues are included in the diagnosis. A short duration of disease before admission is a simple tool in the recognition of patients with severe disease.

Early differentiation between dengue and septic shock by comparison of admission hemodynamic, clinical, and laboratory variables: a pilot study

OBJECTIVE

To compare the clinical, hemodynamic, and laboratory variables, treatment, and outcome in dengue shock syndrome (DSS) and septic shock (SS), with an aim to permit early differentiation at presentation to the emergency department.

DESIGN

Retrospective chart review.

SETTING

A tertiary care pediatric emergency and critical care unit.

PATIENTS

Thirty-two patients (16 DSS and 16 SS) between June 2004 and December 2005 who were treated in the emergency department and intensive care using protocols.

INTERVENTIONS

None.

RESULTS

There were no differences between groups in terms of age, number with decompensated shock, and Pediatric Risk of Mortality III scores. Differences between DSS and SS were found in heart rate, 120 +/- 39 beats per minute versus 158 +/- 35 beats per minute (P < 0.01); pulse pressures, 25 +/- 8 mm Hg versus 43 +/- 8 mm Hg (P < 0.01); presence of systemic inflammatory response syndrome, 9/16 versus 15/16 (P < 0.05); Glasgow Coma Score, 13 +/- 3 versus 10 +/- 4 (P < 0.05); hematocrit, 42 +/- 6 versus 29 +/- 7 (P < 0.01); and median platelet count, 29,000/mm3 (interquartile range, 20,500-57,500/mm3) versus 115,500/mm3 (interquartile range, 91,750-182,250/mm3 in SS) (P < 0.01). Patients with SS were more likely to require greater than 40 mL/kg of fluid for initial resuscitation, ventilation, and vasoactive support for shock compared with those with dengue. In the fluid and catecholamine refractory patients, 6 of 16 SS versus 0 of 16 DSS patients were treated with steroids (P < 0.05). The outcome was similar in both groups, with 2 of 16 deaths among children with SS and 1 of 16 in those with DSS.

CONCLUSIONS

Dengue shock syndrome is likely a distinct entity from SS with some overlapping features. The DSS patients are significantly less likely to have systemic inflammatory response syndrome, be tachycardic, and have a narrower pulse pressure at admission when compared with SS patients. Mental status is better preserved, and spontaneous clinical bleeding is more common in children with DSS compared with those in SS. These likely results from the predominantly vasodilatory state in SS versus vasoconstrictory state that is the initial response in DSS.

Coagulation, coma, and outcome in bacterial meningitis--an observational study of 38 adult cases

OBJECTIVES

The purpose of this study was to evaluate the epidemiology of intravascular coagulation in bacterial meningitis and to recognise the associations with disease severity and outcome.

METHODS

Thirty-eight consecutively admitted adult patients with microbiologically proven bacterial meningitis were observed prospectively for platelets count (PLT), platelets-decline (dPLT), prothrombin ratio (PTr), INR, and D-dimer levels during the first three days in relation to disease severity (Glasgow Coma Scale--GCS, APACHE-III) and outcome (Glasgow Outcome Scale--GOS).

RESULTS

The prevalence of activated coagulation measured by abnormal laboratory results varied respectively: PTr--30%, INR--36%, PLT--38%, dPLT--50%, and D-dimer--88%. Patients with GCS <9 at admission presented with laboratory results suggesting triggered coagulation: dPLT 48 vs. 15%/day (p=0.0246), INR 1.6 vs. 1.12 (p=0.0014), PTr 76 vs. 93% (p=0.0020). An unfavourable outcome (GOS 1-4) was observed in 42% of patients and was associated with: PLT <170 or >265 G/L (OR--24.4; p=0.0006), PTr <82% (OR--5.00; p=0.0388), INR >1.1 (OR--5.04; 0.0336), and D-dimer >850 ng/ml (OR--24.0; p=0.0033).

CONCLUSIONS

Coagulation was activated in a majority of patients with bacterial meningitis and related to coma and unfavourable outcome.

Time course of platelet counts in critically ill patients

BACKGROUND

Although thrombocytopenia in the intensive care unit (ICU) is associated with a poorer outcome, the precise relationship between the time course of platelet counts and the mortality rate has not been well defined.

OBJECTIVE

To describe the time course of the platelet count in relation to the mortality rate in critically ill patients.

DESIGN

Substudy of a prospective, multicenter, observational cohort analysis.

SETTING

Forty ICUs in 16 countries from Europe, America, and Australia.

PATIENTS

Data were collected from all ICU admissions in a 1-month period, excluding patients younger than 12 yrs old and those who stayed in the ICU for <48 hrs after uncomplicated surgery. A total of 1,449 critically ill patients were enrolled, including 257 who stayed in the ICU for >2 wks.

INTERVENTIONS

None.

MEASUREMENTS

Platelet counts were collected daily throughout the ICU stay, together with other measures of organ dysfunction. Thrombocytopenia was defined as a platelet count of <150 x 103/mm3. A relative increase in platelet count was defined as a 25% increase above the admission value, together with an absolute platelet count of > or =150 x 103/mm3.

MAIN RESULTS

For the entire population, the platelet count was lower in the 313 nonsurvivors than in the 1,131 survivors throughout the ICU course. Of the 257 patients who stayed in the ICU for >2 wks, 187 (64%) survived. The platelet count decreased significantly in the first days after admission to reach a nadir on day 4 in both survivors and nonsurvivors. In the survivors, the platelet count returned to the admission value by the end of the first week and continued to rise to become significantly greater than the admission value by day 9. In the nonsurvivors, the platelet count also returned to the admission value after 1 wk, but there was no subsequent increase in platelet count. A total of 138 (54%) patients had thrombocytopenia on day 4, and these patients had a greater mortality rate than the other patients (33% vs. 16%; p <.05). On day 14, 51 (20%) patients had thrombocytopenia, and these patients had a greater mortality rate than the other patients (66% vs. 16%; p <.05). Thrombocytopenia was less common on day 14 than on day 4 (20% vs. 54%; p <.05), but the mortality rate was greater in the thrombocytopenic patients on day 14 than those who were thrombocytopenic on day 4 (66% vs. 33%; p <.05). The ICU mortality rate of nonthrombocytopenic patients on day 14 was also significantly lower in patients with, than without, a relative increase in platelet count on day 14 (11% vs. 30%; p <.05).

CONCLUSION

Platelet count changes in the critically ill have a biphasic pattern that is different in survivors and nonsurvivors. Late thrombocytopenia is more predictive of death than early thrombocytopenia. A relative increase in platelet count after thrombocytopenia was present in survivors but not in nonsurvivors. Although a single measured platelet count is of little value for predicting outcome, changes in platelet count over time are related to patient outcome.

Thrombocytopenia and prognosis in intensive care

OBJECTIVE

To study the incidence and prognosis of thrombocytopenia in adult intensive care unit (ICU) patients.

DESIGN

Prospective observational cohort study.

SETTING

The medical ICU of a university hospital and the combined medical-surgical ICU of a regional hospital.

PATIENTS

All patients consecutively admitted during a 5-month period.

INTERVENTIONS

Patient surveillance and data collection.

MEASUREMENTS AND MAIN RESULTS

The primary outcome measure was ICU mortality. Data of 329 patients were analyzed. Overall ICU mortality rate was 19.5%. A total of 136 patients (41.3%) had at least one platelet count <150 x 10(9)/L. These patients had higher Multiple Organ Dysfunction Score (MODS), Simplified Acute Physiology Score (SAPS) II, and Acute Physiology and Chronic Health Evaluation (APACHE) II scores at admission, longer ICU stay (8 [4-16] days vs. 5 [2-9] days) (median [interquartile range]), and higher ICU mortality (crude odds ratio [OR], 5.0; 95% confidence interval [CI], 2.7-9.1) and hospital mortality than patients with daily platelet counts >150 x 10(9)/L (p < .0005 for all comparisons). Bleeding incidence rose from 4.1% in nonthrombocytopenic patients to 21.4% in patients with minimal platelet counts between 101 x 10(9)/L and 149 x 10(9)/L (p = .0002) and to 52.6% in patients with minimal platelet counts <100 x 10(9)/L (p < .0001). In all quartiles of admission APACHE II and SAPS II scores, a nadir platelet count <150 x 10(9)/L was related with a substantially poorer vital prognosis. Similarly, a drop in platelet count to < or =50% of admission was associated with higher death rates (OR, 6.0; 95% CI, 3.0-12.0; p < .0001). In a logistic regression analysis with ICU mortality as the dependent variable, the occurrence of thrombocytopenia had more explanatory power than admission variables, including APACHE II, SAPS II, and MODS scores (adjusted OR, 4.2; 95% CI, 1.8-10.2).

CONCLUSIONS

Thrombocytopenia is common in ICUs and constitutes a simple and readily available risk marker for mortality, independent of and complementary to established severity of disease indices. Both a low nadir platelet count and a large fall of platelet count predict a poor vital outcome in adult ICU patients.

Update on meningococcal disease with emphasis on pathogenesis and clinical management

The only natural reservoir of Neisseria meningitidis is the human nasopharyngeal mucosa. Depending on age, climate, country, socioeconomic status, and other factors, approximately 10% of the human population harbors meningococci in the nose. However, invasive disease is relatively rare, as it occurs only when the following conditions are fulfilled: (i) contact with a virulent strain, (ii) colonization by that strain, (iii) penetration of the bacterium through the mucosa, and (iv) survival and eventually outgrowth of the meningococcus in the bloodstream. When the meningococcus has reached the bloodstream and specific antibodies are absent, as is the case for young children or after introduction of a new strain in a population, the ultimate outgrowth depends on the efficacy of the innate immune response. Massive outgrowth leads within 12 h to fulminant meningococcal sepsis (FMS), characterized by high intravascular concentrations of endotoxin that set free high concentrations of proinflammatory mediators. These mediators belonging to the complement system, the contact system, the fibrinolytic system, and the cytokine system induce shock and diffuse intravascular coagulation. FMS can be fatal within 24 h, often before signs of meningitis have developed. In spite of the increasing possibilities for treatment in intensive care units, the mortality rate of FMS is still 30%. When the outgrowth of meningococci in the bloodstream is impeded, seeding of bacteria in the subarachnoidal compartment may lead to overt meningitis within 24 to 36 h. With appropriate antibiotics and good clinical surveillance, the mortality rate of this form of invasive disease is 1 to 2%. The overall mortality rate of meningococcal disease can only be reduced when patients without meningitis, i.e., those who may develop FMS, are recognized early. This means that the fundamental nature of the disease as a meningococcus septicemia deserves more attention.

Update on meningococcal disease with emphasis on pathogenesis and clinical management

The only natural reservoir of Neisseria meningitidis is the human nasopharyngeal mucosa. Depending on age, climate, country, socioeconomic status, and other factors, approximately 10% of the human population harbors meningococci in the nose. However, invasive disease is relatively rare, as it occurs only when the following conditions are fulfilled: (i) contact with a virulent strain, (ii) colonization by that strain, (iii) penetration of the bacterium through the mucosa, and (iv) survival and eventually outgrowth of the meningococcus in the bloodstream. When the meningococcus has reached the bloodstream and specific antibodies are absent, as is the case for young children or after introduction of a new strain in a population, the ultimate outgrowth depends on the efficacy of the innate immune response. Massive outgrowth leads within 12 h to fulminant meningococcal sepsis (FMS), characterized by high intravascular concentrations of endotoxin that set free high concentrations of proinflammatory mediators. These mediators belonging to the complement system, the contact system, the fibrinolytic system, and the cytokine system induce shock and diffuse intravascular coagulation. FMS can be fatal within 24 h, often before signs of meningitis have developed. In spite of the increasing possibilities for treatment in intensive care units, the mortality rate of FMS is still 30%. When the outgrowth of meningococci in the bloodstream is impeded, seeding of bacteria in the subarachnoidal compartment may lead to overt meningitis within 24 to 36 h. With appropriate antibiotics and good clinical surveillance, the mortality rate of this form of invasive disease is 1 to 2%. The overall mortality rate of meningococcal disease can only be reduced when patients without meningitis, i.e., those who may develop FMS, are recognized early. This means that the fundamental nature of the disease as a meningococcus septicemia deserves more attention.