Local activation of the tissue factor-factor VIIa pathway in patients with pneumonia and the effect of inhibition of this pathway in murine pneumococcal pneumonia

OBJECTIVE

The tissue factor (TF)-factor VIIa (FVIIa) complex not only is essential for activation of blood coagulation but also affect the inflammatory response during sepsis. The objective of this study was to determine the role of TF-FVIIa in pneumonia caused by Streptococcus pneumoniae, the most important causative organism in community-acquired pneumonia and a major cause of sepsis.

DESIGN

A controlled, in vivo laboratory study.

SETTING

Research laboratory of a health sciences university.

PATIENTS AND SUBJECTS

Patients with unilateral community-acquired pneumonia and female BALB/c mice.

INTERVENTIONS

Bilateral bronchoalveolar lavage was performed in patients with community-acquired pneumonia. In mice, pneumonia was induced by intranasal inoculation with S. pneumoniae with or without concurrent inhibition of TF-FVIIa by subcutaneous injections of recombinant nematode anticoagulant protein (rNAPc2).

MEASUREMENTS AND MAIN RESULTS

Patients with unilateral community-acquired pneumonia demonstrated elevated concentrations of FVIIa, soluble TF, and thrombin-antithrombin complexes in bronchoalveolar lavage fluid obtained from the infected site compared with the uninfected site. Mice with S. pneumoniae pneumonia displayed increased TF expression and fibrin deposits in lungs together with elevated thrombin-antithrombin complex levels in bronchoalveolar lavage fluid; inhibition of TF-FVIIa by rNAPc2 attenuated the procoagulant response in the lung but did not affect host defense, as reflected by an unaltered outgrowth of pneumococci and an unchanged survival.

CONCLUSIONS

These data suggest that TF-FVIIa activity contributes to activation of coagulation in the lung during pneumococcal pneumonia but does not play an important role in the antibacterial host defense in this murine model.

Hyperglycemia stimulates coagulation, whereas hyperinsulinemia impairs fibrinolysis in healthy humans

Type 2 diabetes and insulin resistance syndromes are associated with an increased risk for cardiovascular and thrombotic complications. A disturbed balance between coagulation and fibrinolysis has been implicated in the pathogenesis hereof. To determine the selective effects of hyperglycemia and hyperinsulinemia on coagulation and fibrinolysis, six healthy humans were studied on four occasions for 6 h: 1) lower insulinemic-euglycemic clamp, 2) lower insulinemic-hyperglycemic clamp, 3) hyperinsulinemic-euglycemic clamp, and 4) hyperinsulinemic-hyperglycemic clamp. In the hyperglycemic clamps, target levels of plasma glucose were 12 versus 5 mmol/l in the normoglycemic clamps. In the hyperinsulinemic clamps, target plasma insulin levels were 400 versus 100 pmol/l in the lower insulinemic clamps. Hyperglycemia exerted a procoagulant effect irrespective of insulin levels, as reflected by mean twofold rises in thrombin-antithrombin complexes and soluble tissue factor, whereas hyperinsulinemia inhibited fibrinolysis irrespective of glucose levels, as reflected by a decrease in plasminogen activator activity levels due to a mean 2.5-fold rise in plasminogen activator inhibitor type 1. The differential effects of hyperglycemia and hyperinsulinemia suggest that patients with hyperglycemia due to insulin resistance are especially susceptible to thrombotic events by a concurrent insulin-driven impairment of fibrinolysis and a glucose-driven activation of coagulation.

The relationship between inflammation and the coagulation system

Inflammation and coagulation play pivotal roles in host defence. As phylogenetically old responses, there is extensive cross-talk between inflammation and coagulation in enabling an adequate immune response against potentially injurious stimuli. Immune cells are important in the initiation of coagulation pathways, while various inflammatory mediators are capable of altering haemostasis. Vice versa, coagulation proteases have significant immunomodulatory effects. Understanding the mechanisms involved in the crosstalk between inflammation and coagulation may yield new therapeutic strategies for human diseases.

Tissue factor in infection and severe inflammation

In the pathogenesis of vascular disease, inflammation and coagulation play a pivotal role. Increasing evidence points to an extensive cross-talk between these two systems, whereby inflammation not only leads to activation of coagulation, but coagulation also considerably affects inflammatory activity. Tissue factor (TF) plays an important role at the crossroad of coagulation and inflammation, as the principal initiator of coagulation and an important modulator of inflammation. Proinflammatory cytokines can induce TF expression on mononuclear cells and endothelial cells and thereby commence pathways that lead to thrombin generation. Simultaneously, TF may bind to cellular receptors, which may affect the production and release of inflammatory mediators. There is increasing experimental evidence that TF inhibition may have beneficial effects in disease states in which the combination of coagulation and inflammation plays a prominent role.

Short-term and long-term mortality in very elderly patients admitted to an intensive care unit

OBJECTIVE

To report short-term and long-term mortality of very elderly ICU patients and to determine independent risk factors for short-term and long-term mortality

DESIGN AND SETTING

Retrospective cohort study in the medical/surgical ICU of a tertiary university teaching hospital.

PATIENTS

578 consecutive ICU patients aged 80 years or older.

RESULTS

Demographic, physiological, and laboratory values derived from the first 24h after ICU admission. ICU mortality of unplanned surgical (34.0%) and medical patients (37.7%) was higher than that of planned surgical patients (10.6%), as was post-ICU hospital mortality (26.5% and 29.7% vs. 4.4%). Mortality 12 months after hospital discharge, including ICU and hospital mortality, was 62.1% in unplanned surgical and 69.2% in medical patients vs. 21.6% in planned patients. Only median survival of planned surgical patients did not differ from survival in the age- and gender-matched general population. Independent risk factors for ICU mortality were lower Glasgow Coma Scale score, higher SAPS II score, the lowest urine output over 8 h, abnormal body temperature, low plasma bicarbonate levels, and higher oxygen fraction of inspired air. High urea concentrations and admission type were risk factors for hospital mortality, and high creatinine concentration was an independent risk factor for 12-month mortality.

CONCLUSION

Mortality in very elderly patients after unplanned surgical or medical ICU admission is higher than after planned admission. The most important factors independently associated with ICU mortality were related to the severity of illness at admission. Long-term mortality was associated with renal function.

Dobutamine does not influence inflammatory pathways during human endotoxemia*

OBJECTIVE

Catecholamines have anti-inflammatory and anticoagulant properties. Dobutamine is a synthetic catecholamine frequently used in patients with septic myocardial dysfunction. The objective was to determine whether a continuous infusion of dobutamine exerts immunomodulatory effects in healthy volunteers challenged with endotoxin.

DESIGN

Prospective, open-label study.

SETTING

Clinical research unit of a university hospital.

PARTICIPANTS

Sixteen male healthy volunteers.

INTERVENTIONS

Volunteers received a constant infusion with dobutamine (10 microg.kg.min, n = 8) or physiologic saline (n = 8). All participants were challenged with a bolus injection of endotoxin prepared from Escherichia coli (4 ng/kg). Dobutamine infusion was commenced 1 hr before endotoxin challenge and was continued until 3 hrs thereafter.

MEASUREMENTS AND MAIN RESULTS

Dobutamine infusion was associated with an increase in mean arterial blood pressure (peak 122 +/- 5 mm Hg) and heart rate (peak 84 +/- 4 beats/min, both p < .05 vs. saline). Endotoxin injection induced the systemic release of cytokines (tumor necrosis factor-alpha, interleukins-6, -8, and -10) and secretory phospholipase A2, endothelial cell activation (increase in the plasma levels of soluble E-selectin and von Willebrand factor), activation of coagulation (increased plasma levels of soluble tissue factor, F1 + 2 prothrombin fragment, and thrombin-antithrombin complexes), and activation with subsequent inhibition of fibrinolysis (increased plasma concentrations of tissue-type plasminogen activator, plasminogen activator inhibitor type I, and plasmin-alpha2-antiplasmin complexes). None of these responses were influenced by dobutamine.

CONCLUSIONS

Dobutamine, infused in a clinically relevant dose, does not influence inflammatory and coagulant pathways during human endotoxemia.

The relationship between inflammation and the coagulation system

Inflammation and coagulation play pivotal roles in host defence. As phylogenetically old responses, there is extensive cross-talk between inflammation and coagulation in enabling an adequate immune response against potentially injurious stimuli. Immune cells are important in the initiation of coagulation pathways, while various inflammatory mediators are capable of altering haemostasis. Vice versa, coagulation proteases have significant immunomodulatory effects. Understanding the mechanisms involved in the crosstalk between inflammation and coagulation may yield new therapeutic strategies for human diseases.

Plasma and plasma components in the management of disseminated intravascular coagulation

A variety of clinical conditions can cause systemic activation of coagulation that ranges from insignificant laboratory changes to severe disseminated intravascular coagulation (DIC). DIC consists of a widespread systemic activation of coagulation, resulting in diffuse fibrin deposition in small and midsize vessels. There is compelling evidence from clinical and experimental studies that DIC is involved in the pathogenesis of microvascular dysfunction and contributes to organ failure. In addition, the massive and ongoing activation of coagulation can result in depletion of platelets and coagulation factors, which might cause bleeding. Recent insight into important pathogenetic mechanisms that might lead to DIC has resulted in novel preventive and therapeutic approaches to patients with sepsis and derangement of coagulation. Supportive strategies aimed at inhibition of coagulation activation might theoretically be justified and have been found beneficial in experimental and initial clinical studies. These strategies comprise inhibition of tissue factor-mediated activation of coagulation or restoration of physiological anticoagulant pathways.

Two-way interactions between inflammation and coagulation

Activation of inflammatory and coagulation pathways is important in the pathogenesis of vascular disease. There is ample evidence that extensive cross-talk between these two systems exists, whereby inflammation not only leads to activation of coagulation, but coagulation also markedly affects inflammatory activity. The main interfaces linking coagulation and inflammation are the tissue factor pathway, thrombin, the protein C system and the fibrinolytic (or plasminogen-plasmin) system. Proinflammatory cytokines and chemokines can affect all these coagulation mechanisms, and vice versa, activated coagulation proteases and physiological anticoagulants or components of the plasminogen-plasmin system can modulate inflammation by specific cell receptors. The intricate relationship between inflammation and coagulation may not only be relevant for vascular thrombotic disease but also has major consequences in the pathogenesis of microvascular failure and subsequent multiple organ failure in the setting of severe infection. This review focuses on the present understanding of the bidirectional relationship between inflammation and coagulation.

Self-administration of C1-inhibitor concentrate in patients with hereditary or acquired angioedema caused by C1-inhibitor deficiency

BACKGROUND

Administration of C1-inhibitor concentrate is effective for prophylaxis and treatment of severe angioedema attacks caused by C1-inhibitor deficiency. The concentrate should be administered intravenously and hence needs to be administered by health care professionals, which might cause considerable delay in treatment and inconvenience for patients.

OBJECTIVE

The aim of this study was to investigate the feasibility, efficacy, and safety of on-demand and prophylactic self-administration of C1-inhibitor concentrate in patients with frequent attacks of angioedema.

METHODS

Patients with hereditary or acquired C1-inhibitor deficiency who had very frequent angioedema attacks were trained to self-administer C1-inhibitor concentrate. The study consisted of 31 patients using on-demand treatment and 12 patients using prophylaxis with C1-inhibitor concentrate. Mean follow-up was 3.5 years.

RESULTS

All patients were capable of self-administering the concentrate, with technical failure rates of self-injection being less than 2%. Times between the onset of the attack and the initiation of relief or complete resolution of symptoms in the on-demand group were significantly shortened (2.2 hours and 7.9 hours, respectively) compared with the situation before the start of self-administration. In the prophylaxis group self-administration of C1-inhibitor concentrate decreased the angioedema attack rate from 4.0 to 0.3 attacks per month.

CONCLUSION

Intravenous self-administration of C1-inhibitor concentrate is a feasible and safe option and results in more rapid and more effective treatment or prevention of severe angioedema attacks in patients with C1-inhibitor deficiency.

CLINICAL IMPLICATIONS

Self-administration of C1-inhibitor concentrate could be a valuable and convenient treatment modality to prevent or treat angioedema attacks in patients with C1-inhibitor deficiency.

Loss of endothelial glycocalyx during acute hyperglycemia coincides with endothelial dysfunction and coagulation activation in vivo

Hyperglycemia is associated with increased susceptibility to atherothrombotic stimuli. The glycocalyx, a layer of proteoglycans covering the endothelium, is involved in the protective capacity of the vessel wall. We therefore evaluated whether hyperglycemia affects the glycocalyx, thereby increasing vascular vulnerability. The systemic glycocalyx volume was estimated by comparing the distribution volume of a glycocalyx permeable tracer (dextran 40) with that of a glycocalyx impermeable tracer (labeled erythrocytes) in 10 healthy male subjects. Measurements were performed in random order on five occasions: two control measurements, two measurements during normoinsulinemic hyperglycemia with or without N-acetylcysteine (NAC) infusion, and one during mannitol infusion. Glycocalyx measurements were reproducible (1.7 +/- 0.2 vs. 1.7 +/- 0.3 l). Hyperglycemia reduced glycocalyx volume (to 0.8 +/- 0.2 l; P < 0.05), and NAC was able to prevent the reduction (1.4 +/- 0.2 l). Mannitol infusion had no effect on glycocalyx volume (1.6 +/- 0.1 l). Hyperglycemia resulted in endothelial dysfunction, increased plasma hyaluronan levels (from 70 +/- 6 to 112 +/- 16 ng/ml; P < 0.05) and coagulation activation (prothrombin activation fragment 1 + 2: from 0.4 +/- 0.1 to 1.1 +/- 0.2 nmol/l; d-dimer: from 0.27 +/- 0.1 to 0.55 +/- 0.2 g/l; P < 0.05). Taken together, these data indicate a potential role for glycocalyx perturbation in mediating vascular dysfunction during hyperglycemia.

Elevated plantar pressures in neuropathic diabetic patients with claw/hammer toe deformity

Elevated plantar foot pressures during gait in diabetic patients with neuropathy have been suggested to result, among other factors, from the distal displacement of sub-metatarsal head (MTH) fat-pad cushions caused by to claw/hammer toe deformity. The purpose of this study was to quantitatively assess these associations. Thirteen neuropathic diabetic subjects with claw/hammer toe deformity, and 13 age- and gender-matched neuropathic diabetic controls without deformity, were examined. Dynamic barefoot plantar pressures were measured with an EMED pressure platform. Peak pressure and force-time integral for each of 11 foot regions were calculated. Degree of toe deformity and the ratio of sub-MTH to sub-phalangeal fat-pad thickness (indicating fat-pad displacement) were measured from sagittal plane magnetic resonance images of the foot. Peak pressures at the MTHs were significantly higher in the patients with toe deformity (mean 626 (SD 260)kPa) when compared with controls (mean 363 (SD 115) kPa, P<0.005). MTH peak pressure was significantly correlated with degree of toe deformity (r=-0.74) and with fat-pad displacement (r=-0.71) (P<0.001). The ratio of force-time integral in the toes and the MTHs (toe-loading index) was significantly lower in the group with deformity. These results show that claw/hammer toe deformity is associated with a distal-to-proximal transfer of load in the forefoot and elevated plantar pressures at the MTHs in neuropathic diabetic patients. Distal displacement of the plantar fat pad is suggested to be the underlying mechanism in this association. These conditions increase the risk for plantar ulceration in these patients.

[Perioperative thromboprophylaxis--for the immobilisation period, potential extension beyond hospitalisation]

Antithrombotic prophylaxis of venous thromboembolism after surgery, usually by means of subcutaneous administration of(low-molecular-weight) heparin, drastically reduces the incidence of postoperative thrombosis and pulmonary embolism. Therefore, this intervention is advocated in various national and international guidelines. A questionnaire-based study in this issue shows that 99% of surgeons in the Netherlands strictly adhere to these guidelines. Interestingly, the duration of thromboprophylaxis is much less clear and is usually restricted to the duration of hospitalisation. In view of the increasing number of surgical procedures in short-stay or even outpatient settings, it is possible that extended prophylaxis for perioperative thrombosis should be considered, particularly in patients with risk factors for thrombosis, such as the presence of malignant disease.

[Continuous subcutaneous insulin infusion is sometimes a good choice in case of poorly regulated diabetes mellitus type I]

Continuous subcutaneous insulin infusion (CSII) was initiated in 3 patients with diabetes mellitus type I who experienced difficulties with their glucose regulation: a woman aged 26 years and two men aged 56 and 41 years. 2 patients responded very well, while the third, the youngest man, did not benefit. Although interest in CSII has been growing in recent years, considerable uncertainty exists about which patients will benefit from it. In most studies, patients have attained a lower HbA,, and fewer blood glucose fluctuations. Recently, the advantages of CSII have been confirmed in 2 large studies in patients with diabetes mellitus type I. Motivated patients in poor glycaemic control seem to benefit most from CSII. Some questions remain, especially whether these advantages can be confirmed in studies comparing CSII with injection regimens using the new long-acting insulin analogues. Motivated patients in poor control and those with an unpredictable daily life, needing a flexible mode of therapy, should not be denied a trial of CSII.

[Admission of elderly patients to intensive care]

Elderly patients have an increased probability of dying after treatment in an intensive care unit (ICU), compared with younger patients. The risk of dying is largely determined by the admission type (patients with planned admissions have a better prognosis than those with unplanned admissions), severity of illness and functional status prior to admission. Elderly patients surviving ICU often experience a decline in functional status. No data are available on the factors that predict functional outcome. Elderly patients do not necessarily prefer life-sustaining treatment to palliative care. The willingness to undergo ICU treatment depends on the likelihood of survival and beneficial functional outcome. New prognostic models should be developed specifically to predict both survival and functional outcome in individual elderly patients after admission to ICU.