Methods for evaluation of medical terminological systems--a literature review and a case study

OBJECTIVES

The usability of terminological systems (TSs) strongly depends on the coverage and correctness of their content. The objective of this study was to create a literature overview of aspects related to the content of TSs and of methods for the evaluation of the content of TSs. The extent to which these methods overlap or complement each other is investigated.

METHODS

We reviewed literature and composed definitions for aspects of the evaluation of the content of TSs. Of the methods described in literature three were selected: 1) Concept matching in which two samples of concepts representing a) documentation of reasons for admission in daily care practice and b) aggregation of patient groups for research, are looked up in the TS in order to assess its coverage; 2) Formal algorithmic evaluation in which reasoning on the formally represented content is used to detect inconsistencies; and 3) Expert review in which a random sample of concepts are checked for incorrect and incomplete terms and relations. These evaluation methods were applied in a case study on the locally developed TS DICE (Diagnoses for Intensive Care Evaluation).

RESULTS

None of the applied methods covered all the aspects of the content of a TS. The results of concept matching differed for the two use cases (63% vs. 52% perfect matches). Expert review revealed many more errors and incompleteness than formal algorithmic evaluation.

CONCLUSIONS

To evaluate the content of a TS, using a combination of evaluation methods is preferable. Different representative samples, reflecting the uses of TSs, lead to different results for concept matching. Expert review appears to be very valuable, but time consuming. Formal algorithmic evaluation has the potential to decrease the workload of human reviewers but detects only logical inconsistencies. Further research is required to exploit the potentials of formal algorithmic evaluation.

Immunohistochemical expression of CD10 antigen in uterine adenosarcoma

Uterine adenosarcoma (UAS) is microscopically characterized by a biphasic growth pattern. By definition, the epithelial component is benign, whereas the stromal component typically has the appearance of a low-grade sarcoma, usually an endometrial stromal sarcoma. CD10 acts by reducing cellular response to peptide hormones and is currently regarded as a specific marker for endometrial stromal tumors. In this international multicenter study, we further explored CD10 immunoreactivity in 30 UASs. We encountered CD10 positivity of the sarcomatous component in 18/20 (90%) of UASs, in five of eight (63%) of UASs with sarcomatous overgrowth as well as in both cases of recurrent UAS. The epithelial component stained negative in all cases. These findings suggest that CD10 can be used to differentiate UAS from cellular leiomyoma, or in case endometrial stromal cells exhibit muscle differentiation. Furthermore, CD10 positivity in recurrent UAS might guide the pathologist toward an endometrial stromal origin.

Recombinant nematode anticoagulant protein c2, an inhibitor of tissue factor/factor VIIa, attenuates coagulation and the interleukin-10 response in human endotoxemia

The tissue factor-factor (F)VIIa complex (TF/FVIIa) is responsible for the initiation of blood coagulation under both physiological and pathological conditions. Recombinant nematode anticoagulant protein c2 (rNAPc2) is a potent inhibitor of TF/FVIIa, mechanistically distinct from tissue factor pathway inhibitor. The first aim of this study was to elucidate the pharmacokinetics and pharmacodynamics of a single intravenous (i.v.) dose of rNAPc2. The second aim was to study its effect on endotoxin-induced coagulation and inflammation. Initially, rNAPc2 was administered to healthy volunteers in three different doses. There were no safety concerns and the pharmacokinetics were consistent with previous studies, in which rNAPc2 was administered subcutaneously. rNAPc2 elicited a dose-dependent reduction of the endogenous thrombin potential and a selective prolongation of prothrombin time. Subsequently, the effect on endotoxin-induced coagulation and inflammation was studied. The administration of rNAPc2 completely blocked the endotoxin-induced thrombin generation, as measured by plasma prothrombin fragment F1+2. The endotoxin-induced effect on fibrinolytic parameters such as plasmin-antiplasmin complexes and plasminogen activator inhibitor type 1 was not affected by rNAPc2. The administration of rNAPc2 attenuated the endotoxin-induced rise in interleukin (IL)-10, without affecting the rise in other cytokines. In conclusion, rNAPc2 is a potent inhibitor of TF/FVIIa, which was well tolerated and could safely be used intravenously in this Phase I study in healthy male volunteers. A single i.v. dose rNAPc2 completely blocked endotoxin-induced thrombin generation without affecting the fibrinolytic response. In addition, rNAPc2 attenuated the endotoxin-induced rise in IL-10, without affecting the rises in other cytokines.

[Intensive care medicine in the Netherlands, 1997-2001. I. Patient population and treatment outcome]

OBJECTIVE

To describe the patients admitted to intensive care units (ICUs) in the Netherlands between 1997-2001 and the treatment outcome.

DESIGN

Descriptive.

METHOD

For the years 1997-2001, prospective admission and discharge data as well as all data necessary for calculating prospective severity of illness scores (e.g. APACHE II and SAPS II) were collected for all patients that were admitted to 18 ICUs participating in the Dutch National Intensive Care Evaluation (NICE). Outcome measures were ICU mortality and hospital mortality, length of hospital and ICU admission, and standardised mortality ratio (SMR).

RESULTS

Data from 55,016 admissions were registered. The median APACHE II score was 15 (P25-P75: 10-20) and the median SAPS II score was 29 (19-43). The median ICU length of admission for individual ICUs varied between 0.86 and 2.76 days. The occupied ICU capacity of individual ICUs varied between 220 and 1260 days per 100 patients admitted for non-cardiosurgical patients and between 110 and 330 days per 100 patients admitted for cardiosurgical patients. The ICU mortality and hospital mortality were 9.0% and 12.9% respectively. The mean SMR according to APACHE II was 0.95 (95% CI: 0.93-0.98). The SMR of the individual participating hospitals varied between 0.55 (95% CI: 0.37-0.80) and 1.20 (1.13-1.28).

CONCLUSION

Hospital mortality for ICU-admitted patients in the NICE registration was 12.9%. For patients who could be evaluated with the APACHE II model, actual hospital mortality was lower than predicted by this model. Significant differences in length of admission, hospital mortality and SMR were found between individual hospitals.

[Intensive care medicine in the Netherlands, 1997-2001. II. Changes over time and differences between hospitals]

OBJECTIVE

To describe efficacy (mortality) and efficiency (length of admission) of intensive care (IC) treatment after admission due to a prior cardiothoracic operation or pneumonia, based on data from the Dutch National Intensive Care Evaluation (NICE) foundation.

DESIGN

Descriptive.

METHOD

Data for the period 1 January 1997-31 December 2001 were extracted from the NICE databank for patients admitted after cardiothoracic surgery and for patients admitted with pneumonia. The variables changes in time, risk factors for mortality, and differences between hospitals were analysed.

RESULTS

There were 25,463 admissions to 5 hospitals following cardiothoracic surgery and 1408 admissions to 18 hospitals due to pneumonia. An increase in valve surgery was noted in the cardiothoracic surgery group: from about 10% to about 25%. In the group undergoing valve operations, there was an increase in the average age of the patients and in the number of patients with comorbidity. No significant differences in mortality between hospitals were detected. However, the length of ICU treatment differed. Hospital mortality in the pneumonia group was 33.9%. Differences between hospitals with respect to mortality (both crude mortality and severity-of-illness adjusted mortality) and length of ICU admission were found.

CONCLUSION

With the NICE registration it is possible to detect differences and trends. This is a valuable tool for indicating where and how quality and efficiency in intensive care medicine can be improved.

[The value of the pulmonary-artery catheter: not ruled out, but not proven either]

A number of prospective, randomized trials have recently been published on the effects of using the pulmonary artery (Swan-Ganz) catheter in the peri-operative management of high-risk patients and in the treatment of critically ill patients on the intensive-care unit. These studies show that using the pulmonary-artery catheter does not lead to increased survival. It cannot be excluded that more beneficial effects would have been found with other treatment goals, or if different populations had been studied. However, based on the present evidence from the literature, the routine use of the pulmonary-artery catheter can no longer be defended.

Drotrecogin alfa Eli Lilly

Drotrecogin alfa (Xigris, recombinant activated protein C) is an anticoagulant developed and launched by Eli Lilly & Co for the treatment of sepsis [333781], [339372], [430133], [436271]. The FDA and the EMEA accepted the brand name Xigris for drotrecogin alfa in June 2001. This trade name had been proposed by Lilly in place of the previous brand name, Zovant, which was deemed unacceptable by the EMEA due to concerns that the name could be confused with hospital-based drugs [412512]. Filings for sepsis were made in the US, EU and Australia in February 2001 [398514], [447870] and in March 2001, the US FDA assigned drotrecogin alfa Priority Review status [403435]. The FDA extended the action date from July 27 to October 27, 2001 for completion of its review of the biologics license application (BLA) for drotrecogin alfa to assess further supplementary data submitted by Lilly [412512]. At the October 16, 2001 meeting (postponed from September 12), the FDA Advisory Committee on Anti-Infective Drugs split 10 to 10 over whether to recommend approval [425873], [425940]. In late October 2001, Lilly received an approvable letter from the FDA for the treatment of severe sepsis. Approval was contingent upon successful negotiation of labeling, agreement on post-approval clinical trials, and successful completion of manufacturing inspections [427301]. In November 2001, the FDA approved drotrecogin alfa for the reduction of mortality in adult patients with severe sepsis who have a high risk of death [430133]; the product was launched onto the US market days later [436271]. Following the FDA committee's split decision in October 2001, Credit Suisse First Boston, which expected mid-2002 approval but with restrictive labeling, revised its predictions from $1.265 billion in 2004 sharply downwards to $543 million [425929].

Prevalence of pre-cancerous lesions and cervical cancer in South Africa--a multicentre study

OBJECTIVES

To describe the age-specific prevalence rates of cancer of the cervix in South African women presenting for screening.

DESIGN

A multicentre prevalence survey in 10 geographically defined areas following a common core protocol. Services were located in existing service sites, with the exception of KwaZulu-Natal which used a mobile service. Women aged 20 years and above were eligible for inclusion.

OUTCOME MEASURES

Age-specific cervical cytologically diagnosed abnormality rates according to the Bethesda classification.

RESULTS

During the study 20,603 women participated. Eighty per cent of the sample had never had a Pap smear before and just over 91% had not had a Pap smear in the last 5 years. In this study population 468 women screened (2.42%) were found to have low-grade squamous intra-epithelial lesions (LSIL) and the average age of these women was 33.1 years; 366 (1.8%) had high-grade SIL (HSIL) and these women were statistically significantly older at 37.97 years of age; and 92 women (0.47%) were found to have cytologically diagnosed invasive cancer. These women were significantly older, with an average age of 51.3 years. A clear relationship was found between age and LSIL, with younger women having a high rate of LSIL which decreases with increasing age. A similar but inverse relationship between age and invasive cancer is described, with the rate being low in young women and increasing with increasing age. A clear relationship between HSIL and age is not described in these data. The adequacy rate (satisfactory and satisfactory but limited) of the slides was 95%, and just under 92% of the study sample received their results. Not all women were appropriately referred and it was not possible to assess if women referred for treatment received it.

CONCLUSIONS

These data indicate that cancer of the cervix is a common disease and that, similar to other countries, it is a disease of older women. These data give some positive indicators for future screening--older women will present for screening and the majority of women received their results. However, improvements in health system functioning are needed. A uniform national cytology reporting system is required as well as clear guidelines for providers on what action to take based on cytology reports. Linkage between the site of screening and treatment centre is inadequate and requires urgent attention in order to decrease cervical cancer mortality.

Regulatory role of cytokines in disseminated intravascular coagulation

Disseminated intravascular coagulation (DIC) can complicate a number of diseases. DIC in the setting of sepsis is considered to result from strong activation of the coagulation system and concurrent inhibition of fibrinolysis and other anticoagulant pathways. Cytokines have been implicated as important mediators in these hemostatic alterations. This article summarizes recent insights into which cytokines are likely to be involved in the procoagulant response to systemic infection.

Anticoagulant factor concentrates in disseminated intravascular coagulation: rationale for use and clinical experience

Natural inhibitors of coagulation, in other words, antithrombin (AT), the protein C system, and tissue factor pathway inhibitor (TFPI), play an important role in controlling the activation of coagulation during disseminated intravascular coagulation (DIC). Furthermore, they may not only influence coagulation but also attenuate inflammatory responses during sepsis. Low circulating levels of AT and protein C have been associated with poor outcome. Replacement therapy with AT, activated protein C (APC), and TFPI has been shown to attenuate thrombin generation and to reduce mortality in experimental sepsis models. Experience with AT and APC in patients is promising. Data from large phase III trials of AT and APC as treatment of patients with severe sepsis will soon be available. Recombinant TFPI is currently in phase II clinical trials for severe sepsis.

Advances in the understanding of the pathogenetic pathways of disseminated intravascular coagulation result in more insight in the clinical picture and better management strategies

Disseminated intravascular coagulation (DIC) is a syndrome characterized by systemic intravascular activation of coagulation leading to widespread deposition of fibrin in the circulation. There is ample experimental and pathological evidence that the fibrin deposition contributes to multiple organ failure. The massive and ongoing activation of coagulation may result in depletion of platelets and coagulation factors, which may cause bleeding (consumption coagulopathy). Recent knowledge on important pathogenetic mechanisms that may lead to DIC has resulted in novel preventive and therapeutic approaches to patients with DIC. DIC is not a disease in itself but is a complication of a variety of disorders. However, the pathogenesis of DIC follows similar pathways in almost all of these situations, with a pivotal role of proinflammatory cytokines. The cornerstone of the management of DIC is the specific and vigorous treatment of the underlying disorder. Strategies aimed at the inhibition of coagulation activation may theoretically be justified and have been found to be beneficial in experimental and initial clinical studies. These strategies comprise inhibition of tissue factor-mediated activation of coagulation and restoration of physiological anticoagulant pathways by means of the administration of (activated) protein C concentrate or antithrombin concentrate.

Decreased circulating levels of von Willebrand factor after intravenous administration of a rapidly degradable hydroxyethyl starch (HES 200/0.5/6) in healthy human subjects

OBJECTIVE

Impairment of haemostasis has been described with slowly degradable medium molecular weight hydroxyethyl starch (MMW-HES), whereas rapidly degradable MMW-HES is generally considered to have no important effects on blood coagulation. This study was undertaken to investigate the effects of a rapidly degradable MMW-HES plasma substitute on primary haemostasis and blood coagulation in human subjects.

DESIGN

Randomised, cross-over study.

SETTING

Research unit of a university hospital.

PARTICIPANTS

Nine healthy, adult male volunteers.

INTERVENTIONS

A 60-min intravenous infusion of 1 l HES 200/0.5/6 (HAES-steril 6%) or 4% albumin (control).

MEASUREMENT AND RESULTS

The infusion of HES resulted in decreased circulating levels of von Willebrand factor antigen (from 85+/-8% to 59+/-6% after HES vs from 80+/-7% to 69+/-8% after albumin, p<0.05) and ristocetin cofactor activity (from 93+/-4 to 67+/-4% after HES vs from 79+/-5 to 75+/-5% after albumin, p<0.01). This was associated with an impairment of in vitro platelet function as determined with the PFA-100 platelet function analyser (closure time with collagen/epinephrine from 120+/-7 to 159+/-14 s after HES vs from 121+/-7 to 137+/-10 s after albumin, p<0.05; with collagen/ADP from 88+/-3 to 116+/-9 s and from 103+/-4 to 114+/-7 s after HES and albumin, respectively, p=0.01).

CONCLUSIONS

The infusion of 1 l of HES 200/0.5/6 in healthy human subjects results in moderately decreased plasma levels of von Willebrand factor associated with impairment of platelet function.

Rationale for restoration of physiological anticoagulant pathways in patients with sepsis and disseminated intravascular coagulation

OBJECTIVE

In the pathogenesis of disseminated intravascular coagulation, dysfunctional natural anticoagulant pathways appear to play a pivotal role. In this article, we will address the mechanisms that contribute to this defect in the regulation of coagulation activation. Furthermore, we will explore the experimental and clinical evidence that restoration of these anticoagulant pathways results in clinical improvement.

DATA SOURCES

We have searched and reviewed published articles on experimental studies of disseminated intravascular coagulation models in animals and clinical studies in patients with disseminated intravascular coagulation.

DATA SYNTHESIS

All three major anticoagulant pathways, that is, the antithrombin pathway, the protein C system, and tissue factor pathway inhibitor, are defective in sepsis and disseminated intravascular coagulation. Several mechanisms contribute to this defect. Restoration of these pathways, in principle, by administration of coagulation inhibitor concentrates or recombinant anticoagulant factors, appears to ameliorate the coagulation disorder and, more important, result in improvement of clinically relevant outcomes, such as a reduction of organ failure and mortality.

CONCLUSIONS

Restoration of disrupted physiologic anticoagulant pathways in disseminated intravascular coagulation is not only a logical point of impact in patients with sepsis and an activated coagulation system, but also is associated with an improved outcome in experimental and (initial) clinical studies.

Tissue Factor Pathway Inhibitor Does Not Influence Inflammatory Pathways during Human Endotoxemia

Activation of coagulation induces a proinflammatory response in in vitro and animal experiments. Inhibition of the tissue factor-dependent pathway of coagulation inhibits cytokine release and prevents death in gram-negative sepsis models in primates. This study investigated the influence of blocking the coagulation system by tissue factor pathway inhibitor (TFPI) on endotoxin-induced inflammatory responses in healthy humans. Eight men were studied in a double-blind, randomized, placebo-controlled cross-over study. They received a bolus intravenous injection of 4 ng/kg of endotoxin, followed by a 6-h continuous infusion of either TFPI (0.2 mg/kg/h after a bolus of 0.05 mg/kg) or placebo. Endotoxin induced-activation of coagulation was prevented completely by TFPI. In contrast, TFPI did not influence leukocyte activation, chemokine release, endothelial cell activation, or the acute phase response. Thus, complete prevention of coagulation activation by TFPI does not influence activation of inflammatory pathways during human endotoxemia.

Effects of different plasma substitutes on blood coagulation: a comparative review

OBJECTIVE

To compare the effects of different colloid plasma substitutes on blood coagulation and postoperative blood loss.

DATA SOURCES

Relevant studies were obtained from the medical literature.

STUDY SELECTION

Articles were selected that provided data on the effects of colloids on hemostasis and postoperative blood loss in humans. Studies comparing different colloids were looked for using MEDLINE and by searching through the references of studies as they were collected.

DATA SYNTHESIS

Articles were reviewed and relevant data were extracted and partly presented in comparative tables.

CONCLUSIONS

Dextran, gelatin, and hydroxyethyl starch (HES) all can induce a specific decrease of von Willebrand factor and factor VIII:c. Blood coagulation is most impaired by dextran and high molecular weight HES, both associated with increased postoperative blood loss. The effects of HES on blood coagulation have been shown to depend on its molecular weight and rate of elimination. Detrimental effects have been shown for high molecular weight HES. Medium molecular weight (MMW)-HES with a high degree of substitution (HES 200/0.62) and MMW-HES with high C2/C6 hydroxyethylation ratio (HES 200/0.5/13) are slowly degradable and have been shown to impair blood coagulation after repeated administration. Rapidly degradable HES 200/0.5/6 and gelatin-based plasma expanders appear not to impair hemostasis. However, based on the reviewed literature, all artificial colloids could potentially induce increased bleeding tendency after infusion of very large volumes and especially when given to patients with even mild forms of von Willebrand disease. In those circumstances, crystalloid solutions or alternatives such as plasma or albumin, although associated with other serious complications, could be considered.

Uterine carcinosarcoma with melanocytic differentiation

A 65-year-old black woman was found to have a 3.0 cm endometrial tumor that was a carcinosarcoma with a major epithelial and a less prominent mesenchymal component. The latter was undifferentiated but one focus of chondroid differentiation was noted. The former showed papillary serous differentiation. Melanin pigment was observed in both epithelial and mesenchymal components. Staining with antisera to S100 protein and HMB-45 confirmed the presence of melanocytes. An endocervical focus of tumor also contained melanin. Electron-microscopic studies showed large tumor cells with an irregularly indented nucleus and abnormal giant cytoplasmic melanosomes. Only one case of uterine carcinosarcoma with melanocytic differentiation has been previously reported.

Up-regulation of HIV coreceptors CXCR4 and CCR5 on CD4(+) T cells during human endotoxemia and after stimulation with (myco)bacterial antigens: the role of cytokines

Concurrent infections in patients with human immunodeficiency virus (HIV) infection stimulate HIV replication. Chemokine receptors CXCR4 and CCR5 can act as HIV coreceptors. The authors hypothesized that concurrent infection increases the HIV load through up-regulation of CXCR4 and CCR5. Using experimental endotoxemia as a model of infection, changes in HIV coreceptor expression were assessed in 8 subjects injected with lipopolysaccharide (LPS, 4 ng/kg). The expression of CXCR4 and CCR5 on CD4(+) T cells was increased 2- to 4-fold, 4 to 6 hours after LPS injection. In whole blood in vitro, LPS induced a time- and dose-dependent increase in the expression of CXCR4 and CCR5 on CD4(+) T cells. Similar changes were observed after stimulation with cell wall components of Mycobacterium tuberculosis (lipoarabinnomannan) or Staphylococcus aureus (lipoteichoic acid), or with staphylococcal enterotoxin B. LPS increased viral infectivity of CD4-enriched peripheral blood mononuclear cells (PBMCs) with a T-tropic HIV strain. In contrast, M-tropic virus infectivity was reduced, possibly because of elevated levels of the CCR5 ligand cytokines RANTES and MIP-1beta. LPS-stimulated up-regulation of CXCR4 and CCR5 in vitro was inhibited by anti-TNF and anti-IFN gamma. Incubation with recombinant TNF or IFN gamma mimicked the LPS effect. Anti-interleukin 10 (anti-IL-10) reduced CCR5 expression, without influencing CXCR4. In accordance, rIL-10 induced up-regulation of CCR5, but not of CXCR4. Intercurrent infections during HIV infection may up-regulate CXCR4 and CCR5 on CD4(+) T cells, at least in part via the action of cytokines. Such infections may favor selectivity of HIV for CD4(+) T cells expressing CXCR4. (Blood. 2000;96:2649-2654)

Reduced ex vivo chemokine production by polymorphonuclear cells after in vivo exposure of normal humans to endotoxin

Monocytes from patients with sepsis have a reduced capacity to produce cytokines, a state referred to as immunoparalysis. To determine whether polymorphonuclear leukocytes (PMNL) can be rendered hyporesponsive, PMNL from 6 healthy volunteers intravenously challenged with lipopolysaccharide (LPS; 4 ng/kg) were stimulated ex vivo with heat-killed bacteria or LPS, and the release of the CXC chemokines interleukin-8, epithelial-derived neutrophil attractant-78, and growth-related oncogen-alpha was measured. At 1 and 2 h after LPS administration in vivo, PMNL produced fewer CXC chemokines after stimulation with bacteria or LPS (all P<.05). Serum obtained 2 h after in vivo administration of LPS did not influence chemokine production by PMNL from 6 healthy volunteers not previously exposed to LPS. Thus, intravenous injection of LPS induces a refractory state of PMNL that is not caused by soluble factors produced in response to in vivo exposure to LPS.

Novel approaches to the management of disseminated intravascular coagulation

OBJECTIVE

Disseminated intravascular coagulation (DIC) is a syndrome characterized by systemic intravascular activation of coagulation, leading to widespread deposition of fibrin in the circulation. We addressed the issue of whether there is evidence that this fibrin deposition contributes to multiple organ failure. We also explored the current knowledge on the pathogenesis of DIC and reviewed current and future treatment for DIC.

DATA SOURCES

We searched and reviewed published articles on experimental studies of DIC models in animals and clinical studies in patients with DIC.

DATA SYNTHESIS

There is ample experimental and clinical evidence that DIC contributes to morbidity and mortality. Recent knowledge on important pathogenetic mechanisms that may lead to DIC has resulted in novel preventive and therapeutic approaches to patients with DIC. Although the trigger for the activation of the coagulation system may vary depending on the underlying condition, it is usually mediated by several cytokines. Thrombin generation proceeds via the (extrinsic) tissue factor/factor VIIa route and simultaneously occurring depression of inhibitory mechanisms, such as antithrombin III and the protein C-protein S system. Also, impaired fibrin degradation, because of high circulating levels of plasminogen activator inhibitor, type 1, contributes to enhanced intravascular fibrin deposition.

CONCLUSIONS

Although the cornerstone of DIC management is the specific and vigorous treatment of the underlying disorder, strategies aimed at inhibiting coagulation activation may theoretically be justified. Such strategies have been found to be beneficial in experimental and initial clinical studies. These strategies, which follow from our current understanding of the pathophysiology of DIC, involve inhibition of tissue factor-mediated activation of coagulation or restoration of physiologic anticoagulant pathways by means of the administration of antithrombin concentrate or (activated) protein C concentrate. Although no complete evidence from controlled clinical trials is available for most of the proposed therapeutic interventions, these novel strategies are being studied.

Current management of disseminated intravascular coagulation

Both a bleeding and a thrombotic disorder, disseminated intravascular coagulation presents diagnostic and therapeutic challenges. At present, diagnosis requires a set of blood tests; therapy focuses on reversing the underlying disorder and providing supportive treatment. Clinical studies of specific tests and treatments are now under way.

The in vivo kinetics of tissue factor messenger RNA expression during human endotoxemia: relationship with activation of coagulation

Triggering of the tissue factor (TF)-dependent coagulation pathway is considered to underlie the generation of a procoagulant state during endotoxemia. To determine the in vivo pattern of monocytic TF messenger RNA (mRNA) expression during endotoxemia, 10 healthy volunteers were injected with lipopolysaccharide (LPS, 4 ng/kg) and blood was collected before and 0.5, 1, 2, 3, 4, 6, 8, and 24 hours after LPS administration. Total blood RNA was isolated and amplified by NASBA (nucleic acid sequence-based amplification), followed by quantitation of TF mRNA by an electrochemiluminescence (ECL) assay. To compare the pattern of coagulation activation with the kinetics of monocytic TF mRNA expression, we measured plasma levels of markers of thrombin generation, thrombin-antithrombin (TAT) complexes, and prothrombin fragment 1 + 2 (F1 + 2). Baseline value (mean +/- SEM) of the number of TF mRNA molecules per monocytic cell was 0.08 +/- 0.02. A progressive and significant (P <.0001) increase in TF expression was observed after LPS injection (+0.5 hour: 0.3 +/- 0.1, +1 hour: 1.3 +/- 0.9, +2 hours: 4.1 +/- 0.9), peaking at +3 hours (10 +/- 1.9 TF mRNA molecules per monocyte). As TF mRNA levels increased, thrombin generation was augmented. Peak levels of TAT and F1 + 2 were reached later (at t +4 hours) than those of TF mRNA. TF mRNA, TAT, and F1 + 2 levels returned to baseline after 24 hours. In conclusion, we used a NASBA/ECL-based technique to quantify TF mRNA in whole blood during human endotoxemia and observed a 125-fold increase in TF mRNA levels. Our data demonstrate a pivotal role for enhanced TF gene activity in the activation of coagulation after LPS challenge. (Blood. 2000;96:554-559)

Platelets release thrombopoietin (Tpo) upon activation: another regulatory loop in thrombocytopoiesis?

Thrombopoietin is produced at a constant rate by the liver and kidney and is removed from the circulation upon binding and subsequent uptake via the Tpo receptor, c-Mpl, expressed by platelets and mega-karyocytes. Apart from uptake, this study shows that platelets can also function as a storage pool for Tpo. Upon stimulation with various platelet agonists, full-length biologically active Tpo was released by platelets. Platelet fractionation experiments indicated that this Tpo most likely is contained in the granules. When platelets were preincubated with Tpo-peptide mimetic or truncated Tpo prior to maximal activation, a three- to fivefold increment in Tpo release was seen. whereas, the release of other granule proteins such as vWF-propeptide or serotonin remained unchanged. Therefore, the Mpl agonists might compete with Mpl-bound Tpo, thereby releasing Tpo into the platelet supernatant. Intravascular release of Tpo by platelets might occur in patients with massive platelet activation, as occurs in patients with disseminated intravascular coagulation. The Tpo concentration in these patients is elevated (p <0.01) and correlates with markers for thrombin generation, TAT complexes and F1+2(r(p)= 0.8 and 0.9; p <0.01). This suggests that the increment in Tpo concentration was attributed to Tpo release by activated platelets in vivo, which might be instrumental in subsequent stimulation of thrombocytopoiesis.

Granulocyte colony-stimulating factor receptors on granulocytes are down-regulated after endotoxin administration to healthy humans

Granulocyte colony-stimulating factor (G-CSF) is considered an important mediator of host defense against infection, and recombinant G-CSF is administered to patients with various infections. G-CSF binds to a specific receptor that is expressed on granulocytes and monocytes. To obtain insight about the regulation of the G-CSF receptor after an acute infectious challenge, 8 healthy subjects received an intravenous injection of lipopolysaccharide (LPS; 4 ng/kg), and receptor expression was determined on blood leukocytes by fluorescence-activated cell sorter analysis, both by measurement of saturation binding of recombinant G-CSF and by use of an anti-G-CSF-receptor antibody. LPS induced a transient decrease in granulocyte, but not monocyte, G-CSF-receptor expression. In whole blood in vitro, not only LPS but also gram-positive stimuli and proinflammatory cytokines were capable of down-modulating the G-CSF receptor on granulocytes. Bacterial antigens down-regulate the G-CSF receptor at the surface of granulocytes, which may impair neutrophil functions important for antibacterial host defense.

[Disseminated intravascular coagulation]

Disseminated intravascular coagulation is characterised by systemic activation of blood coagulation, resulting in formation of intravascular thrombi and impaired organ perfusion. Simultaneously, the ongoing consumption of platelets and coagulation factors may lead to bleeding. Disseminated intravascular coagulation is seen in septicaemic infections, trauma, malignancies, obstetrical complications, vascular diseases, toxic and immunological reactions. In summary, the systemic deposition of fibrin is caused by enhanced thrombin generation, simultaneous depression of physiological anticoagulant mechanisms and diminished fibrin degradation due to inhibition of fibrinolysis. The increased insight into the pathogenesis of disseminated intravascular coagulation provides a solid basis for development of improved management strategies for patients with this complication. Therapy may include anticoagulants, platelet and plasma transfusion, concentrates of coagulation inhibitors and antifibrinolytic agents.

Endotoxin down-regulates monocyte and granulocyte interleukin-6 receptors without influencing gp130 expression in humans

Interleukin (IL)-6 is important for host defense against various pathogens. The IL-6 receptor (IL-6R) complex consists of a ligand-binding component (IL-6R) and a signal-transducing component (gp130). In a study designed to obtain insight into the regulation of this receptor complex during inflammation, 8 healthy subjects received an intravenous injection of lipopolysaccharide (LPS; 4 ng/kg), and receptor expression was determined on blood leukocytes by use of fluorescence-activated cell cytometry. LPS induced a transient decrease in monocyte and granulocyte IL-6R expression but did not influence gp130. The plasma concentrations of soluble IL-6R and soluble gp130 did not change after LPS administration. Expression of the receptor for leukemia inhibitory factor, a member of the IL-6R family, remained unaltered after LPS injection. In whole blood in vitro, LPS and gram-positive stimuli and proinflammatory cytokines were capable of down-modulating the IL-6R. Monocytes and granulocytes may down-regulate IL-6R at their surface upon their first interaction with bacterial antigens.

Reduced Th1, but not Th2, cytokine production by lymphocytes after in vivo exposure of healthy subjects to endotoxin

Endotoxin (lipopolysaccharide [LPS]) tolerance is characterized by a reduced capacity of monocytes to produce proinflammatory cytokines upon restimulation in vitro. To determine whether LPS exposure induces a change in lymphocyte cytokine production and whether this results in a shift in the T-helper 1 (Th1)/Th2 balance, whole blood obtained from seven healthy subjects before and after an intravenous injection of LPS (4 ng/kg) was stimulated in vitro with the T-cell stimulus anti-CD3/CD28 or staphylococcal enterotoxin B. Whole-blood production of the Th1 cytokines gamma interferon (IFN-gamma) and interleukin-2 (IL-2) was markedly reduced at 3 and 6 h, while the production of the Th2 cytokines IL-4 and IL-5 was not influenced or was slightly increased. The IFN-gamma/IL-4 ratio was strongly decreased at 6 h. Serum obtained after LPS exposure could slightly inhibit the release of IFN-gamma but increased IL-4 production during stimulation of blood drawn from subjects not previously exposed to LPS. Normal serum also inhibited IFN-gamma production, albeit to a lesser extent. LPS exposure influences lymphocyte cytokine production, resulting in a shift toward a Th2 cytokine response, an effect that may be mediated in part by soluble factors present in serum after LPS administration in vivo.

Tissue factor pathway inhibitor dose-dependently inhibits coagulation activation without influencing the fibrinolytic and cytokine response during human endotoxemia

Inhibition of the tissue factor pathway has been shown to attenuate the activation of coagulation and to prevent death in a gram-negative bacteremia primate model of sepsis. It has been suggested that tissue factor influences inflammatory cascades other than the coagulation system. The authors sought to determine the effects of 2 different doses of recombinant tissue factor pathway inhibitor (TFPI) on endotoxin-induced coagulant, fibrinolytic, and cytokine responses in healthy humans. Two groups, each consisting of 8 healthy men, were studied in a double-blind, randomized, placebo-controlled crossover study. Subjects were studied on 2 different occasions. They received a bolus intravenous injection of 4 ng/kg endotoxin, which was followed by a 6-hour continuous infusion of TFPI or placebo. Eight subjects received 0.05 mg/kg per hour TFPI after a bolus of 0.0125 mg/kg (low-dose group), and 8 subjects received 0.2 mg/kg per hour after a bolus of 0.05 mg/kg (high-dose group). Endotoxin injection induced the activation of coagulation, the activation and subsequent inhibition of fibrinolysis, and the release of proinflammatory and antiinflammatory cytokines. TFPI infusion induced a dose-dependent attenuation of thrombin generation, as measured by plasma F1 + 2 and thrombin-antithrombin complexes, with a complete blockade of coagulation activation after high-dose TFPI. Endotoxin-induced changes in the fibrinolytic system and cytokine levels were not altered by either low-dose or high-dose TFPI. The authors concluded that TFPI effectively and dose-dependently attenuates the endotoxin-induced coagulation activation in humans without influencing the fibrinolytic and cytokine response. (Blood. 2000;95:1124-1129)

Pharmacological strategies to decrease excessive blood loss in cardiac surgery: a meta-analysis of clinically relevant endpoints

BACKGROUND

Excessive bleeding may complicate cardiac surgery, and is associated with increased morbidity and mortality. Pharmacological strategies to decrease perioperative bleeding have been investigated in a large number of controlled trials, most of which have shown a decrease in blood loss. However, most studies lacked sufficient power to detect a beneficial effect on clinically more relevant outcomes. We did a meta-analysis of all randomised, controlled trials of the three most frequently used pharmacological strategies to decrease perioperative blood loss (aprotinin, lysine analogues [aminocaproic acid and tranexamic acid], and desmopressin).

METHODS

Studies were included if they reported at least one clinically relevant outcome (mortality, rethoracotomy, proportion of patients receiving a transfusion, or perioperative myocardial infarction) in addition to perioperative blood loss. In addition, a separate meta-analysis was done for studies concerning complicated cardiac surgery.

FINDINGS

We identified 72 trials (8409 patients) that met the inclusion criteria. Treatment with aprotinin decreased mortality almost two-fold (odds ratio 0.55 [95% CI 0.34-0.90]) compared with placebo. Treatment with aprotinin and with lysine analogues decreased the frequency of surgical re-exploration (0.37 [0.25-0.55], and 0.44 [0.22-0.90], respectively). These two treatments also significantly decreased the proportion of patients receiving any allogeneic blood transfusion. By contrast, the use of desmopressin resulted in a small decrease in perioperative blood loss, but was not associated with a beneficial effect on other clinical outcomes. Aprotinin and lysine analogues did not increase the risk of perioperative myocardial infarction; however, desmopressin was associated with a 2.4-fold increase in the risk of this complication. Studies in patients undergoing complicated cardiac surgery showed similar results.

INTERPRETATION

Pharmacological strategies that decrease perioperative blood loss in cardiac surgery, in particular aprotinin and lysine analogues, also decrease mortality, the need for rethoracotomy, and the proportion of patients receiving a blood transfusion.

Current drug treatment strategies for disseminated intravascular coagulation

Disseminated intravascular coagulation (DIC) can be caused by a variety of diseases. Experimental models of DIC have provided substantial insight into the pathogenesis of this disorder, which may ultimately result in improved treatment. Disseminated coagulation is the result of a complex imbalance of coagulation and fibrinolysis. Simultaneously occurring tissue factor-dependent activation of coagulation, depression of natural anticoagulant pathways and shutdown of endogenous fibrinolysis all contribute to the clinical picture of widespread thrombotic deposition in the microvasculature and subsequent multiple organ failure. Cornerstone for the treatment of DIC is the optimal management of the underlying disorder. At present, specific treatment of the coagulation disorders themselves is not based on firm evidence from controlled clinical trials. Plasma and platelet transfusion are used in patients with bleeding or at risk for bleeding and low levels of coagulation factors or thrombocytopenia. The role of heparin and low molecular weight heparin is controversial, but their use may be justified in patients with active DIC and clinical signs of extensive fibrin deposition such as those with meningococcal sepsis. There is some evidence to indicate that low molecular weight heparin is as effective as unfractionated heparin but may be associated with a decreased bleeding risk. Antithrombin III (AT III) replacement appears to be effective in decreasing the signs of DIC if high doses are administered, but effects on survival or other clinically significant parameters are at best uncertain. If AT III supplementation is used, the dosage should be selected to achieve normal or supranormal plasma levels of 100% or higher. Results of studies on protein C concentrate, thrombomodulin or inhibitors of tissue factor are promising, but the efficacy and safety of these novel strategies remains to be established in appropriate clinical trials.

An evaluation of Patient Data Management Systems in Dutch intensive care

OBJECTIVE

To assess the agreement between the functions of seven configurations of Patient Data Management Systems (PDMS) and the Dutch specifications prepared by the users prior to use.

DESIGN

An observational descriptive study with hospital visits of seven configurations of five different PDMS systems including three commercial systems and two locally developed systems.

SETTING

Seven Dutch level I intensive care units in university and teaching hospitals.

MEASUREMENTS AND RESULTS

A substantial disagreement was found between the Dutch specifications and the actual functions of the PDMS configurations tested. Between the PDMS configurations, major differences in key features, including "automated charting", "information and care planning", and "management information", were observed. Automated charting is adequately supported by the three commercial systems. All configurations tested had limited functions supporting care planning. In none of the configurations tested was the required function present to support unit management with reports on resource utilisation and outcome performance. The automatic calculation of prognostic scores was either absent or incorrect. The implementation, the (continuous) configuration and the training required a substantial investment in costs and human resources.

CONCLUSION

Today, none of the PDMSs tested satisfy the Dutch specifications. This can be explained by technical impossibilities of the systems and shortcomings in the actual configuration or in the unit organisation. The PDMS might become a valuable tool in improving the quality of ICU practice, but full implementation of these systems according to the specifications still has a long way to go.

Impaired haemostasis by intravenous administration of a gelatin-based plasma expander in human subjects

The aim of this study was to investigate the effects of a gelatin-based plasma expander on blood coagulation and haemostasis in human subjects. Six healthy men were studied in a randomised, controlled cross-over study to investigate the effects of a 60 min intravenous infusion of either 1 l gelatin-based plasma substitute (Gelofusine) or 0.9% NaCl (control). The infusion of gelatin resulted in a 1.7 fold increase in bleeding time at 60 min and a 1.4 fold increase at 120 min, while saline had no effect (p <0.05). Aggregation studies revealed a significant impairment of ristocetin-induced platelet aggregation (p <0.05), associated with a substantial decrease of vWF:ag (-32% vs. -5%, p <0.05) and ristocetin co-factor (-29% vs. +1%, p <0.05) and without in vitro impairment of the platelet glycoprotein 1b receptor. Gelatin caused a decrease in thrombin-antithrombin complexes (-45% vs. -4%, p <0.05) and F1+2 (-40% vs. +1%, p <0.05). The decrease in circulating levels of vWF:ag, vWF R:Co, thrombin-antithrombin complexes and F1+2 was more than could be expected by the calculated plasma-dilution generated by Gelofusine. Our results demonstrated that the administration of a gelatin-based plasma substitute results in a significant impairment of primary haemostasis and thrombin generation. The defect in primary haemostasis appears to be related to a gelatin-induced reduction in von Willebrand factor, whereas the decreased thrombin generation may be due to the dilution of coagulation factors induced by Gelofusine.

Sclerosing peritonitis complicated by sepsis: a potential cause of portal hypertension

A 27-year-old woman with chronic renal failure, who had been treated with chronic ambulatory peritoneal dialysis and had developed sclerosing peritonitis, was admitted to the hospital with intra-abdominal sepsis. In spite of antibiotic therapy, sepsis recurred and was associated with intrahepatic cholestasis. In addition, over a period of about 4.5 weeks she developed hepatomegaly and portal hypertension unassociated with occlusion of the portal vein or one of its main extrahepatic branches. A wedge biopsy of the liver revealed extensive thick fibrosis of the liver capsule, intrahepatic cholestasis, diffuse swelling of hepatocytes, central veins that were difficult to visualize and small portal tracts. It is suggested that the sepsis was responsible for the intrahepatic cholestasis, swelling of hepatocytes and hepatomegaly. It is also suggested that the rigidity of the fibrotic liver capsule provided resistance to the development of hepatomegaly, with the result that intrahepatic pressure increased (compressing intrahepatic branches of the portal vein as well as portal tracts and central veins) and portal hypertension developed.

Large-scale purification of factor VIII by affinity chromatography: optimization of process parameters

The optimization of a new process for the extraction of human coagulation factor VIII (FVIII) from plasma with the tailor-made affinity matrix dimethylamino-propylcarbamylpentyl-Sepharose CL-4B (C3-C5 matrix) is described. First, plasma is applied to DEAE-Sephadex A-50 anion exchanger in order to separate a number of proteins, including coagulation factors II, IX and X (prothrombin complex), from FVIII. Subsequently, the unbound fraction of the ion exchanger, containing FVIII, is contacted with the C3-C5 affinity matrix. Optimization of the FVIII affinity chromatographic procedure is accomplished in terms of the ligand density of the matrix, adsorption mode (batch-wise versus column-wise adsorption and matrix to plasma ratio), and conditions of pH and conductivity to be applied on washing and desorption. In scale-up experiments, by processing 20 l of plasma, the recovery (340 U VIII:C/kg plasma) and the specific activity (s.a.) (1.2 U VIII:C/mg protein) are better than those obtained by cryoprecipitation (recovery 300 U VIII:C/kg plasma, s.a. 0.3 U VIII:C/mg protein). The newly developed process using the specially designed C3-C5 affinity matrix has potential application in the process-scale purification of FVIII.

Thermal inactivation of human immunodeficiency virus in lyophilised blood products evaluated by ID50 titrations

Inactivation of human immunodeficiency virus (HIV) in lyophilised small pool cryoprecipitate, factor VIII concentrate, prothrombin complex and C1-esterase inhibitor concentrate by prolonged heat treatment (72 h, 60 degrees C) was studied. Plasma products, inoculated prior to lyophilisation, had infectious titres ranging from 10(7) to 10(10.5). Residual infectivity (TCID50) was assessed by multiple titrations on H9 cells in a macro system and subsequent detection of virus replication by determining reverse transcriptase activity. Kinetics of inactivation showed a biphasic pattern: during the first 8 h a variable TCID50 reduction up to 10(4.3) was observed, followed by an additional loss of 10(1)-10(2.7) during the next 64 h. Heat treatment for 72 h resulted in a mean TCID50 reduction of 10(5). It is concluded that prolonged heat treatment may lead to the adequate prevention of HIV transmission by lyophilised plasma products.

Non-electrolyte permeability as a tool for studying membrane fluidity

1. The reflection coefficient for the permeation of thiourea through bilayers of phosphatidylcholine is a function of the fatty-acid composition of the lipid molecules. By means of these reflection coefficients an index for membrane fluidity has been given to each of those lipids, relative to that of egg phosphatidylcholine. 2. The maximum number of water molecules that can copermeate with each molecule of solute by means of solute-solvent interaction is a function of the packing of the lipid molecules in the bilayer. This parameter has been used in this paper for characterizing the fluidity of cholesterol-containing membranes and for membranes with their lipids in the gel state.