The economy class syndrome--a survey of 19 cases.

BACKGROUND: Thromboembolic events during or immediately after long-distance flights (economy class syndrome--ECS) are gaining more importance due to the rapidly increasing number of flights. Systematic data on haemostatic parameters in these patients are not available yet. PATIENTS AND METHODS: We were therefore analyzing the anamnestic, laboratory and clinical findings in 19 patients (17 males, 2 females, aged 33-75 years) with the final clinical diagnosis ECS. RESULTS: Symptoms commenced either immediately or up to 93 hours after disembarkation (mean 42.3 hours). In the great majority (84.2%) myocardial infarction was the initial diagnosis. No defect in the coagulation and/or prostaglandin system was discovered in either of the patients. Prevalence of smoking (26.3%) was even lower than in the normal population. No predisposing factors were found. Apparent anamnestic similarities were flu and fever (47.4%) while 4 of the patients (26.3%) had severe diarrhoea and dehydration before the flight. Almost all the patients (78.9%) were drinking alcohol during the flight and not actively moving their legs (84.2%). ECS occurred also in business and first class passengers. CONCLUSION: Surprisingly the onset of ECS is definitely not associated with haemostatic defects and not necessarily associated with the clinical risk factors reported.

Hereditary and acquired antithrombin deficiency.

Antithrombin (AT) is the most important inhibitor of activated coagulation enzymes. Deficiency of this protein can be a congenital defect. Different types have been described with a diminution of the entire molecule as well as diminution of activity only with normal concentration and normal activity and concentration but with a decreased sensitivity to heparin. There exist also different types of acquired deficiency due to a diminished production, an increased loss or an increased consumption of the inhibitor. Because AT deficiency is the cause of an increased thrombotic tendency in many cases the therapeutic and prophylactic possibilities are described. Since highly purified concentrates became available, substitution was attempted in cases of AT deficiency. It was found to be of greatest importance in cases of disseminated intravascular coagulation (DIC) which is a frequent consequence of septic or traumatic shock. In such cases an adequate AT-substitution can even be lifesaving as could be shown in different trials.

Therapeutic use of antithrombin concentrate in sepsis.

Sepsis and its associated complications of disseminated intravascular coagulation (DIC) and multiple organ dysfunction syndrome (MODS) continue to be a major cause of morbidity and mortality. Improved detection of all forms of DIC is essential to assure earlier diagnosis. Studies already indicate that the therapeutic use of antithrombin (AT) concentrate may produce a more positive outcome for sepsis-associated DIC. If DIC could be identified earlier and AT concentrate could then be given earlier in the sepsis continuum, study results for the use of AT concentrate in humans might reveal a statistically significant difference versus placebo, and the efficacy of AT concentrate for this syndrome is more likely to be proved. Fixed-bolus doses of AT concentrate based on body weight are currently preferred, but improved, user-friendly assays for plasma AT levels would permit more rapid turnaround time for AT results and could help fine-tune the use of AT concentrate to the specific needs of each patient. Clinical trials involving the therapeutic use of AT concentrate in sepsis should continue, and it can be hoped that their design will reflect the concepts and conclusions offered by this panel of investigators.

Efficacy and safety of a low-molecular-weight heparin and standard unfractionated heparin for prophylaxis of postoperative venous thromboembolism: European multicenter trial.

A randomized, double-blind multicenter trial was performed to compare the safety and efficacy of a new low-molecular-weight heparin (LMWH) (LU 47311, Clivarine) and standard unfractionated heparin for the prophylaxis of postoperative venous thromboembolism. Altogether 1351 patients scheduled to undergo abdominal surgery were included. Main outcome measures included the incidence of thromboembolic events (deep vein thrombosis, pulmonary embolism, or both) and bleeding complications, including wound hematoma. A total of 655 patients received 1750 anti-Xa IU of LMWH plus a placebo injection daily; 677 patients received 5000 IU of unfractionated heparin (UFH) twice a day. Both drugs were found to be equally effective, as 4.7% of patients in the LMWH group and 4.3% in the UFH group developed postoperative thromboembolic complications. However, the incidence of bleeding complications was significantly reduced in the LMWH group: 55 (8.3%) patients in the LMWH group and 80 (11.8%) in the UFH group developed bleeding complications, a relative risk (RR) of 0.70 (95% CI 0.51-0.97;p = 0.03); wound hematoma occurred in 29 (4.4%) of the LMWH group compared with 55 (7.7%) in those in the UFH group for an RR of 0.57 (95% CI 0.37-0.88;p = 0.01). This study confirmed that a very low dose of 1750 anti-Xa IU daily of this new LMWH is as effective as 10,000 IU of UFH for preventing postoperative deep vein thrombosis. At this dose its administration is associated with a significant reduction in the risk of bleeding including wound hematoma.

On the action of a heparan-like glycosaminoglycan (Hemovasal) on the mechanism of haemostasis and fibrinolysis.

Hemovasal produced by Manetti-Roberts, Florence, Italy, is a glycosaminoglycan obtained from porcine intestinal mucosa which belongs to the family of heparan sulfates. The substance was examined On 36 male survivors of myocardial infarction with an interval of at least 6 months after the acute event. No anticoagulants were given and ASA was withdrawn at least 2 weeks before the trial. Hemovasal was administered in 3 different i.m. doses as single injections. A further group received a daily oral dose of 300 mg for one week. A comparable placebo group of patients as well as a group of healthy volunteers was run in parallel. The coagulation profile showed only a slight prolongation of the aPTT, a trace of diminution of Antithrombin III and no activation of Heparin cofactor II. The fibrinolytic system showed an enhancement of the diurnal increase of t-PA without an alteration of the total increase of this activity. There was a considerable and highly significant diminution of the PAI-1 activity. This was dose dependent and could be found after i.m. as well as after oral administration. It was assumed that the thrombolytic effect which was repeatedly described was a consequence of the diminution of PAI-1.

The effect of a long-acting recombinant hirudin (PEG-hirudin) on experimental disseminated intravascular coagulation (DIC) in rabbits.

Reproducible disseminated intravascular coagulation in rabbits was provoked by two intravenous injections 24 hours apart of endotoxin from Salmonella enteritidis. There were mild symptoms of DIC before the second injection which considerably increased thereafter. In detail there was a sharp drop of the platelet count and a considerable diminution of Antithrombin III, of Protein C, Plasminogen and Antiplasmin as well as an appearance of fibrin monomer complexes and an increase of the aPTT. When PEG-hirudin in a single dose of 1 mg/kg BW was given simultaneously with the second injection of endotoxin the following alterations were observed: The drop of the platelet count and of the activities of Antithrombin III, Protein C, Plasminogen and Antiplasmin was significantly less pronounced. The fibrin monomer complexes were lower and the aPTT was less prolonged. The thrombin time, however, as a sign of a direct action of hirudin on thrombin was considerably more prolonged than in the controls. The combined effect of these alterations strongly points in the direction of a favourable influence of PEG-hirudin on the course of DIC. It is of special interest that 6 h after the intravenous injection of PEG-hirudin its full effect on the thrombin time was still detectable. This is apparently due to a longer half-life in circulation of PEG-hirudin than of natural hirudin.

Heparin cofactor II: experimental approach to a new assay and clinical results.

By a series of experiments it could be shown that an activity test of heparin cofactor II (HC II) is only specific after a complete depletion of antithrombin III. Also when dermatan sulfate which does not enhance the action of AT III is used for the activation of HC II there is a considerable influence on the remaining thrombin activity which alters the test results. Furthermore, in a system which contains plasma as well as thrombin the formation of a clot is likely to occur which by its opacity influences photometric results. A chromogenic substrate assay is described which excludes the influence of these variables. This assay was used to examine the activity of HC II in healthy persons as well as in patients. Three members of a family were found who had a heterozygous deficiency of HC II without any history of thrombosis. On the other hand, a total of 16 patients with heterozygous deficiency of HC II suffered from recurrent thromboembolic episodes. For this reason it is assumed that a deficiency of HC II has a certain importance in the occurrence of thrombophilia though it is apparently less thrombogenic than a deficiency of other inhibitors.

Low haemoglobin in haemophilia children is associated with chronic immune activation.

Anaemia is a frequent complication in patients with human immunodeficiency virus type 1 (HIV-1) infection. We tested 14 children with severe haemophilia (9 HIV-1 antibody seropositive CDC stage IIA, 5 seronegative) for haemoglobin and urinary neopterin concentrations and found a negative correlation between neopterin and haemoglobin (rs = -0.745, p = 0.007; Spearman's rank correlation). This finding suggests that chronic immune activation, possibly along with the release of specific cytokines such as interferon gamma and tumor necrosis factor alpha may be involved in the pathogenesis of anaemia.

Autologous platelet-labeling in thrombocytopenia.

Field studies performed with peripheral platelets obtained from 6 male volunteers aged 23 to 29 years revealed an extraordinary dependence of labeling efficiency on incubation time and platelet concentration after 111In-oxine platelet labeling. Since the monitoring of in vivo-platelet function in patients with thrombocytopenia may cause problems due to insufficient labeling results and homologous platelets may show a different in vivo behaviour to autologous ones, we have searched for the minimal amount of platelets necessary to allow appropriate labeling and imaging in patients with thrombocytopenia. In 15 patients with untreated thrombocytopenia aged 14 to 79 years demonstrating a mean peripheral platelet count of 2.509 +/- 1.45 x 10(4) cells/microliters autologous 111In-oxine platelet labeling was performed. The results indicate that approximately 1 x 10(8) (concentrated) platelets/ml are necessary to obtain an adequate labeling efficiency and recovery. This platelet concentration can be easily achieved by drawing one more Monovette of whole blood per each 5 x 10(4) platelets/microliter peripheral platelet count less than 2 x 10(5)/microliter. It is concluded, that calculation of the required number of platelets in advance, variation of the blood volume drawn and the volume of incubation buffer allow informative, qualitative and quantitative results using autologous platelets. The method presented effectively circumvents the requirement of homologous platelets for radiolabeling in thrombocytopenia.

Prophylaxis of thromboembolism in general surgery: comparison between standard heparin and Fragmin.

In a double blind randomized trial on 250 patients undergoing elective abdominal surgery the effect of Fragmin was compared with heparin. Patients over 40 years of age except appendectomy and herniotomy were included. The dose of heparin was 5,000 IU b.i.d. whilst Fragmin was given in a dose of 2,500 U once per day and the second injection was a placebo. Prophylaxis started 2 h preoperatively and was maintained for 7 days. The fibrinogen uptake test was used as a screening method for thrombosis which was confirmed by phlebography. 124 patients were in the heparin group and 126 in the Fragmin group. Comparability between groups was found in: age, sex, Broca index, amount and type of risk factors, type of surgery. Thromboembolism was found in 10 cases in each group. Blood transfusions on the postoperative days 1 to 6 were required in 2 Fragmin and in 12 heparin patients. The total amount of blood given during that time was 6 units in the Fragmin and 37 units in the heparin group. These differences were significant.

[Risk factors for venous thromboembolism]. / Risikofaktoren für venöse Thromboembolien.

In addition to the well known general risk factors for thromboembolic events certain alterations of the clotting system are of considerable importance and are, therefore, described in detail. Such preexisting alterations should be suspected when spontaneous thrombosis is found in patients under 40 years of age and when there is also a history of thrombosis in the patient's family.

Antithrombotic therapy in patients with known risk factors for thromboembolism.

In about 50% of the cases of spontaneous deep vein thrombosis a congenital deficiency of an inhibitor of coagulation or an insufficient fibrinolytic mechanism can be detected. In arterial thromboembolism a connection with hyperactive platelets or with a diminished availability of tissue plasminogen activator can be found in about 70%. However, in these cases the defect which provokes thrombosis is mostly acquired and is connected with hyperlipidemia and/or with atherosclerotic alterations of the vessel wall. A study on patients with thromboembolic tendency and detectable risk factors was carried out. A total of 470 patients could be observed for 2 years under an adequate antithrombotic prophylaxis. The occurrence of thromboembolic episodes 2 years prior to prophylaxis and 2 years under prophylaxis was compared. In venous cases thrombosis could be controlled almost completely by coumarins when the underlying cause was a deficient plasmatic inhibitor. In patients with diminished fibrinolysis there was only a partial effect of oral anticoagulants. A better result could be obtained when pentosan polysulfate was administered. In arterial thromboembolism the results of prophylaxis were less convincing. The efficacy of ASA in patients with an increased platelet function was only moderate. In addition, ASA hat to be discontinued in about 20% of the patients because of gastrointestinal problems. Pentosan polysulfate in patients with a diminished fibrinolytic capacity had a fairly good effect and resulted in a 60% reduction of thromboembolic manifestations. It is shown that an exact diagnosis of the underlying deficiency which is likely to cause thrombosis can also improve the efficacy and the specificity of prophylaxis.

[Use of antithrombin III concentrates]. / Einsatz von Antithrombin-III-Konzentraten.

Concentrates of antithrombin III (AT III) have been applied in congenital as well as in acquired AT III deficiency. Congenital defects only require substitution during surgery and in the case of pregnancy. Otherwise prophylaxis of thrombosis can be successfully carried out with oral anticoagulants. In acquired AT III deficiency substitution was found to be useful in cases of advanced DIC. When AT III activity was constantly kept around 100% the duration of DIC could be considerably shortened. No beneficial effect of additional administration of heparin was found. In cases of DIC due to septic shock the survival rate could be increased from an average of 20% without substitution to over 70% with AT III substitution as could be shown by different authors.

Immunological status and HIV antibodies in patients with haemophilia--a longitudinal study.

Various immunological parameters were investigated in 12 children suffering from severe haemophilia A or B receiving substitution therapy over a follow-up period of 3 1/2 years. At the beginning of the study, the therapy was changed to heat-treated concentrates of factors VIII or IX. Antibodies to HIV were found in 9 out of these patients. There were no AIDS-related clinical symptoms, but HIV antigen was detectable in one case. Abnormalities of immunological parameters were found independently of HIV infection, but were more pronounced in anti-HIV seropositive patients. Elevated levels of immunoglobulins gave evidence of polyclonal B-cell activation whilst increased levels of neopterin indicated activated T-cells and macrophages. There was no close association between these two types of activation. However, peak activation of both immune compartments was found approximately 1 year after changing the therapy. Thereafter a continuous tendency towards normalization of neopterin levels was observed. At the final visit immunoglobulin levels also tended to decrease. The HIV antigen seropositive child showed the highest neopterin levels during the whole study period. Our data indicate that the primarily high risk of developing AIDS in anti-HIV-seropositive haemophiliacs is declining.

Basics and practice in evaluating plasminogen.

There exist different ways of assays of plasminogen which give information about different properties of this proenzyme. The concentration of plasminogen can be determined by its antigenicity. Since the normal concentration of plasminogen in plasma is between 15 and 25 mg/dl the test can be carried out by simple methods such as radial immunodiffusion on Partigen plates. The possibility of errors is small and there is no need of special apparatus. The disadvantages are the lapse of 24 h until the result is available and the fact that the knowledge of the concentration does not give any information about the activity. The activity can be measured by different coagulation tests. A typical assay would involve activation of plasminogen to plasmin, addition of plasminogen-free thrombin and measuring of the lysis time. The result is however, dependent on more than one variable. Plasmin is rapidly inhibited by alpha-2-antiplasmin (APL) and there is also a dependence of the lysis time on the amount of clottable fibrinogen in the test system. Better results can be obtained by the use of diluted test plasma and addition of a constant amount of plasminogen-free fibrinogen. A different way would be the use of the euglobulin fraction instead of plasma. This has however, the possible disadvantage of incomplete precipitation of plasminogen. Instead of coagulation tests the activity can also be determined when diluted activated plasma is placed on plasminogen-free fibrin plates and the amount of lysis in the plate is recorded. All assays of this group also depend on the method of activation of plasminogen.(ABSTRACT TRUNCATED AT 250 WORDS)