Coagulopathy in malaria

Blood coagulation activation is frequently found in patients with malaria. Clinically apparent bleeding or disseminated intravascular coagulation (DIC) is associated with very severe disease and a high mortality. Protein C, protein S, and antithrombin levels were found to be low in P. falciparum, but were normal in P. vivax infection. Plasma levels of plasminogen activator inhibitor-1 were high in cases of P. falciparum infection whereas tissue plasminogen activator levels were low. Elevated plasma levels of von Willebrand factor (vWF) and vWF propeptide, thrombomodulin, endothelial microparticles have been reported in P. falciparum-infected patients. It has been demonstrated that severe P. falciparum infection is associated with acute endothelial cell (EC) activation, abnormal circulating ultralarge vWF multimers, and a significant reduction in plasma ADAMTS13 function. These changes may result in intravascular platelet aggregation, thrombocytopenia, and microvascular disease. It has also been shown that P. falciparum-parasitized red blood cells (pRBCs) induce tissue factor (TF) expression in microvascular ECs in vitro. Recently, loss of endothelial protein C receptor (EPCR) localized to sites of cytoadherent pRBCs in cerebral malaria has been demonstrated. Severe malaria is associated with parasite binding to EPCR. The cornerstone of the treatment of coagulopathy in malaria is the use of effective anti-malarial agents. DIC with spontaneous systemic bleeding should be treated with screened blood products. Study in Thailand has shown that for patients who presented with parasitemia > 30% and severe systemic complications such as acute renal failure and ARDS, survival was superior in the group who received exchange transfusion. The use of heparin is generally restricted to patients with DIC and extensive deposition of fibrin, as occurs with purpura fulminans or acral ischemia. Antiplatelet agents interfere with the protective effect of platelets against malaria and should be avoided.     

National survey of patients with hemophilia and other congenital bleeding disorders in Thailand

A national survey of patients with hemophilia and other congenital bleeding disorders in Thailand was conducted in the years 2000 to 2002. Questionnaires were sent to physicians working at hospitals throughout the country. Although the overall response rate to the questionnaires was 19%, the two highest rates of 80% and 73.7% were found at university and regional hospitals, respectively, where most of the patients received their diagnosis and treatment. A total of 1,450 patients comprised of hemophilia 1,325 cases, von Willebrand disease, 69 cases, congenital factor VII deficiency, 15 cases, hereditary platelet dysfunction, 22 cases, and undefined causes of congenital bleeding disorders, 19 cases. Most were pediatric patients <15 years of age. Treatment was mainly given on demand for a bleeding episode, while only 8.6% received additional home treatment for early bleeding episodes. Replacement therapy primarily relied on fresh frozen plasma, cryoprecipitate and cryo-removed plasma. Factor concentrate was seldom used because of the high price. As a result, hemophilia care services in Thailand should be strengthened by providing comprehensive education for medical personnel, making available simple laboratory kits to determine hemophilia A and B, ensuring an adequate supply of blood components and affordable factor concentrate, and establishing home care treatment.     

Prevalence of the G1691A mutation in the factor V gene (factor V Leiden) and the G20210A prothrombin gene mutation in the Thai population

We investigated the prevalence of a genetic variation in the factor V gene (G1691A Leiden mutation) and the prothrombin gene (G20210A) using polymerase chain reaction techniques in samples from 500 normal Thai population and among 50 unselected Thai patients with an objectively confirmed history of deep venous thrombosis. The prevalence of factor V Leiden and the prothrombin G20210A gene mutation in a group of 500 healthy controls was 0.2% in both groups (allele frequency of 0.1%). Of the 50 adult patients studied, none was a carrier of factor V Leiden or the prothrombin G20210A gene mutation. Our findings confirm that the prevalence of factor V Leiden and prothrombin G20210A gene mutation is lower among Asians than Caucasians and that the distribution of factor V Leiden is similar to that of the prothrombin G20210A variant. The low prevalence of these two mutations can, at least in part, account for the lower frequency of deep venous thrombosis reported in the Thai population. Screening for factor V Leiden and prothrombin gene mutation is of limited benefit and may not be cost-effective in Thai patients with the first episode of deep venous thrombosis.     

Low prevalence of heparin-induced thrombocytopenia after cardiac surgery in Thai patients

Introduction

Heparin induced-thrombocytopenia (HIT) has been well recognized in Western countries. However, there are no data in the Thai population. We therefore investigated the prevalence of anti-platelet factor 4 (PF4)/heparin antibodies, HIT, and its thrombotic complications in Thai patients undergoing cardiac surgery using unfractionated heparin.

Materials and methods

Seventy-three consecutive patients were prospectively enrolled in this study. Blood samples before operation and week 1, week 2, and week 3 after operation were collected from each patient for HIT antibody screening by enzyme-linked immunosorbent assay using IgG antibody specific to the PF4/heparin complex. Positive samples were further analyzed by ¹⁴C-serotonin release assay. Complete blood count was performed daily during the first week, then weekly for 3 weeks.

Results

No patient had detectable anti-PF4/heparin antibodies at baseline. Five patients sero-converted during the course of the study for anti-PF4/heparin IgG: 3 (4.1%) at week 1, 4 (5.5%) at week 2, and 5 (6.8%) at week 3 after surgery. However, none of these patients had anti-PF4/heparin antibodies that resulted in ¹⁴C-serotonin release to be considered clinically significant antibodies. Post-operative thrombocytopenia after the operation was found in 35 patients (47.9%), but was not considered to be caused by HIT. Thromboembolic events occurred in 3 patients (4.1%) during follow up; however, none of these patients had positive PF4/heparin antibody tests.

Conclusions

Our study represents the first study to examine Thai patients exposed to heparin in the context of cardiac surgery. We found a lower prevalence of positive anti-PF4/heparin antibodies and clinical HIT than previously published studies.     

Epidemiology of Post-Operative Venous Thromboembolismin Asian Countries

Background In Asia, the prevalence of post-operative venous thromboembolism (VTE) is traditionally thought to be low and the routine use of thromboprophylaxis remains controversial.Methods We performed an exhaustive literature search for published studies on VTE in Asia. Predefined data were extracted from individual studies: country involved, number of patients, type of patient population, type, duration and dose regimens of treatments, if any, method used to detect deep-vein thrombosis (DVT) and pulmonary embolism (PE), and duration of follow-up. The main endpoints were the incidences of systematically detected DVT, and symptomatic DVT or PE. Overall adjusted percentages and 95% confidence intervals (CI) were calculated.Results In clinical studies in patients not receiving thromboprophylaxis, the adjusted incidence of total DVT was 13% (95% CI: 10% to 16%) in general surgery, 16% (95% CI: 13% to 20%) after total hip replacement, 50% (95% CI: 44% to 55%) after total knee replacement and 18% (95% CI: 12% to 24%) in hip fracture surgery. The adjusted incidence of PE was 1% (95% CI: 0% to 2%) in general surgery and 1.4% (95% CI: 1% to 3%) after total hip replacement. In autopsy studies, the incidence of fatal PE ranged from 0.2% to 6.0%, increasing consistently over a period of 30 years in Japan and Hong Kong.Conclusions Post-operative VTE is frequent in Asian general and orthopedic surgery patients and the incidence of autopsy-proven fatal PE is increasing over time. The use of routine prophylaxis in Asian patients undergoing high-risk surgical procedures should be considered.Presented in part at the XVIII Congress of The International Society on Thrombosis and Haemostasis, Paris, France (July 6-12, 2001)*SMART: Surgical Multinational Asian Registry in Thrombosis     

Cancer associated thrombosis in everyday practice: perspectives from GARFIELD-VTE

Journal of Thrombosis and Thrombolysis - Venous thromboembolism (VTE) is common in cancer patients and is an important cause of morbidity and mortality. The Global Anticoagulant Registry in the...     

Nursing roles in orthopaedic joint correction in haemophiliac patients.

The roles of nurses in 16 orthopaedic joint corrections of 14 haemophilia A patients (eight severe, six moderate) are described. The patients' ages ranged from 10 to 37 years with a mean age of 17 years and 4 months. The nursing tasks could be divided into three stages. The first is preoperation, the nurse acting as care provider on a team of experts involved in planning the corrective surgery for the affected joints; and as a counsellor for preparing the patients and family members to cope with the challenging operation. The second is intraoperation, the nurse having the role of care provider, giving factor concentrate either by bolus injection (seven episodes) or continuous infusion (nine episodes). The third is postoperation, as a comprehensive care provider, giving cryoprecipitate and/or factor concentrate and monitoring bleeding doses, and as a trainer, teaching the patients how to dissolve blood components and self-venepuncture with aseptic technique. Home treatment for early bleeding was given for 11 episodes, while 6-month prophylaxis was given for five. The accomplishment of these different roles required good communication and nurturing skills, a well-adjusted personality and a warm and positive attitude. The successful performance of nursing roles allows the haemophiliac patients to have a near-normal quality of life.     

Relationship between hypercoagulable state and erythrocyte phosphatidylserine exposure in splenectomized haemoglobin E/beta-thalassaemic patients

Small pulmonary arterial thromboses can occur following splenectomy of patients with haemoglobin E/beta-thalassaemia (Hb E/beta-thal). We compared plasma markers of coagulation activation in vivo and red blood cell (RBC) markers of procoagulant activity in 15 Hb E/beta-thal patients who were not splenectomized (NS), 15 who had been splenectomized (S), and 15 normal controls (NC). Levels of plasma thrombin-antithrombin III complex (TAT) were significantly higher in the S group than in either the NS or the NC groups, and levels of prothrombin fragment 1.2 (F 1.2) were significantly higher in the S than in the NC group. Diluted Russell's viper venom clotting times were significantly shorter when RBCs from group S patients were added to the assay compared with RBCs from the NC group. Phosphatidylserine (PS) expression (% of annexin V-positive RBCs) on the outer leaflet of RBC membrane of both 'larger'- and 'smaller'-sized RBCs was significantly higher for the S than the NC group. The RBC PS expression of the S and the NS groups, respectively, accounted for 25 x 3% (P = 0 x 174) and 6.3% (P = 0 x 675) of the variation in plasma TAT levels. Our findings indicated that, when compared with NC, splenectomized patients with Hb E/beta-thal were in a chronic low-grade hypercoagulable state associated with increased numbers of circulating PS exposed RBCs. This condition may have a role in the risk of these patients for pulmonary arterial thromboses.