Comparison of a rapid platelet function assay--Verify Now Aspirin--with whole blood impedance aggregometry for the detection of aspirin resistance.
Explore the source record for details and available documents.
Adult↗
Biomedical subjects
Ravindra Sarode
Publications and source records attributed to Ravindra Sarode.
Blood bank issues associated with red cell exchanges in sickle cell disease.
Sickle cell disease (SCD) patients are prone to develop complications that include stroke, acute chest syndrome, and other crises. Some of these complications require chronic transfusion therapy or red cell exchange (RCE), either for therapeutic or prophylactic reasons. Due to a discrepancy of red cell antigens between African Americans and Caucasians (majority blood donors), the incidence of alloantibody formation is very high, which makes it difficult to find compatible red cell units, especially for urgent RCE. Some of the above conditions require immediate oxygen delivery to the tissues. Thus, SCD patients undergoing RCE should receive red blood cells with special attributes that include matching for Rh and Kell blood group antigens; RBCs should be fresh in order to provide (1) immediate oxygen delivery and (2) longer surviving cells to reduce the interval between RCE. Also, these units should be pre-storage leukoreduced to prevent febrile non-hemolytic reactions and screened for sickle cell traits to avoid transfusing red cells containing HbS. This requires a concerted effort between the apheresis unit, the local blood bank, and the central blood supplier.
2,3-Diphosphoglycerate↗
Should plasma be transfused prophylactically before invasive procedures?
PURPOSE OF REVIEW: Plasma transfusion to correct abnormal coagulation test results prior to an invasive procedure is a common clinical practice; however, there are no evidence-based guidelines. This review aims to analyze the most recent publications to either support or disprove such practice. RECENT FINDINGS: Due to heightened awareness of transfusion-related acute lung injury and volume overload in susceptible patients, clinicians are increasingly questioning the validity of prophylactic plasma transfusion. Recently, several articles, reviews and clinical studies (although small and poorly designed) have shown no benefit of prophylactic plasma transfusion in either correcting abnormal coagulation tests or reducing perceived risk of hemorrhage. SUMMARY: The use of sensitive reagents (especially for prothrombin time) has resulted in increased incidence of abnormal preprocedure coagulation screening test results - tests that are not designed to assess risk of bleeding in patients without a history of bleeding. Transfusion of plasma prior to an invasive procedure to correct mild to moderate abnormal test results neither corrects the abnormality nor reduces the perceived bleeding risk.
Blood Coagulation Disorders↗
Poor correlation of supratherapeutic international normalised ratio and vitamin K-dependent procoagulant factor levels during warfarin therapy.
Patients with a supratherapeutic international normalised ratio (ST-INR) are at risk for bleeding. ST-INR is corrected by withholding warfarin therapy and often by supplementing vitamin K or providing vitamin K-dependent factors; the exact therapeutic decision is based on the extent of the prolonged INR. Currently, ST-INRs are frequently observed in clinical practice due to the use of sensitive recombinant tissue thromboplastin reagents and automation. However, there are scant data correlating an ST-INR with various vitamin K-dependent factors. This prospective cohort study, set in a large tertiary care teaching hospital for the University of Texas Southwestern Medical Center at Dallas, defined the relationship between ST-INR (>5.0) and measured vitamin K-dependent procoagulant factors. Prothrombin time, INR and vitamin K-dependent factors II, VII, IX and X were measured in 78 patients with an INR > 5.0 (ST-INR) who were on warfarin therapy for more than 2 months. There was no significant relationship between the ST-INR and levels of important vitamin K-dependent factors II and X. These data support the recent guidelines that the management of an INR > 5.0 should be driven by the clinical determinants rather than specific INR values per se.
Adult↗
Approach to the assessment of platelet function: comparison between optical-based platelet-rich plasma and impedance-based whole blood platelet aggregation methods.
Platelet aggregation studies play an important role in the assessment of hereditary and acquired platelet function defects. The first aggregation test introduced into laboratory practice used platelet-rich plasma (PRP) where aggregation was detected by an optical method. The assessment of platelet function using whole blood (WB) aggregation by an impedance method followed up nearly 20 years later. The WB impedance aggregation assay appears to be superior to the optical method because it 1) evaluates platelets in a physiologic milieu in the presence of red and white blood cells, which are known to modulate platelet function; 2) is faster; 3) has higher sensitivity; and 4) does not require centrifugation, thus avoiding injury to platelets and loss of giant thrombocytes. These two assays were compared. Clearly, the WB impedance aggregation methodology has many advantages over the optical PRP assay for the assessment of the hyperactive platelet syndrome and the effects of anti-platelet drugs.
Adolescent↗
Relapsed thrombotic thrombocytopenic purpura presenting as an acute cerebrovascular accident.
Thrombotic thrombocytopenic purpura (TTP) is an uncommon but severe disorder that classically presents with microangiopathic hemolytic anemia (MAHA), thrombocytopenia, and fluctuating neurological changes. Previously, it was impossible to make a diagnosis of TTP in the absence of thrombocytopenia or microangiopathic hemolysis (MAHA). We describe two cases of relapsing TTP that presented with acute cerebrovascular accident (CVA) without concurrent thrombocytopenia or MAHA after initial classical presentation of TTP. In both cases, the diagnosis of TTP as the cause of the CVA was attributed to severe deficiency of the von Willebrand factor cleaving protease, ADAMTS13 in plasma (11 and 12%, normal 79-127%). Each patient had a dramatic clinical improvement in response to therapeutic plasma exchange. The experience in these two cases suggests that TTP should be considered as a potential cause among patients presenting with a CVA, particularly if the patients have a history of TTP.
ADAM Proteins↗
Presurgical plasma exchange is ineffective in correcting amyloid associated factor X deficiency.
In patients with rare factor deficiencies, for which no factor concentrates are available, plasma exchange (PE) is an option for raising the desired factor level to approximately 80% for surgery. We report a case of acquired factor X (FX) deficiency due to amyloidosis that required urgent surgical repair of an AV fistula aneurysm. This patient had a FX level of 3% at presentation; after 1.5 volume PE with fresh frozen plasma (FFP), his post-exchange FX was only 5%, indicating rapid adsorption of FX to amyloid fibrils. He was managed successfully with FEIBA during surgery.
Amyloid↗
Acquired Glanzmann's thrombasthenia as part of multiple-autoantibody syndrome in a pediatric heart transplant patient.
Although advances in immunosuppressive therapy have allowed prolonged patient survival, immune dysregulation observed in these patients has increased. We report an 11-year-old female heart transplant recipient in whom Glanzmann thrombasthenia was identified as part of a "multiple autoantibody syndrome" manifesting sequentially as autoimmune hemolytic anemia, thrombocytopenia, and neutropenia.
Autoimmune Diseases↗
Rituximab for chronic recurring thrombotic thrombocytopenic purpura: a case report and review of the literature.
Deficiency of von Willebrand factor (VWF) cleaving protease ADAMTS13 has been demonstrated to be the proximate cause of a subset of thrombotic microangiopathic haemolytic anaemias (MAHA) typical for thrombotic thrombocytopenic purpura (TTP). ADAMTS13 gene mutations cause the hereditary form; acquired deficiency has been attributed to presence of an autoantibody, which may represent a specific subset of MAHA best termed 'autoimmune thrombotic thrombocytopenic purpura'. We describe a patient with relapsing TTP because of ADAMTS13 inhibitors, who failed to achieve sustained remission despite therapies with plasma exchange, steroids, vincristine, staphylococcal protein A and splenectomy. The ADAMTS13 inhibitor titre remained elevated and clinical stability was only maintained by plasma exchange every 2-3 d over a period of 268 d. The patient then received rituximab therapy (eight doses of 375 mg/m2 weekly), during which she required five plasma exchanges in the first 10 d, two exchanges in the next 3 weeks, and none thereafter for 450 d and ongoing. The ADAMTS13 inhibitor titre decreased and enzyme activity increased. We compared this case with that of seven previously reported TTP cases also treated with rituximab; experience suggests that rituximab therapy deserves further investigation for patients with either refractory or relapsing TTP caused by ADAMTS13 inhibitors.
ADAM Proteins↗
Ultralarge von Willebrand factor multimers and normal ADAMTS13 activity in the umbilical cord blood.
INTRODUCTION: Recent studies demonstrate that deficiency of ADAMTS13, the metalloprotease that cleaves von Willebrand factor (VWF) in a shear-dependent manner, causes thrombotic thrombocytopenic purpura (TTP). Previously, ultralarge multimers of VWF were detected in the fetuses, the umbilical cords and the newborns. However, the significance of this finding is unknown. MATERIALS AND METHODS: The activity of ADAMTS13 and the multimer pattern of VWF in the cord blood, as well as the VWF antigenic and ristocetin cofactor levels, were analyzed using previously published methods. The presence of ultralarge multimers was determined by densitometric analysis. RESULTS: On the average, the level of VWF antigen and ristocetin cofactor activity are slightly increased in the newborns (mean+/-standard deviation, 1.66+/-0.76 and 1.45+/-0.64 U/ml, respectively). Ultralarge VWF multimers are detected in 11 of 17 umbilical cord plasma samples. However, the ADAMTS13 is normal (0.99+/-0.15 U/ml) in all but one sample in which it is mildly decreased (0.71 U/ml). CONCLUSIONS: Since ADAMTS13 activity is normal, we speculate that the presence of ultralarge multimers in the umbilical cord blood may be due to the low levels of shear stress in the umbilical circulation. These results may have important implications for understanding the manifestation of ADAMTS13 deficiency during the neonatal period.
ADAM Proteins↗
Effect of ABO blood group on the collagen-binding assay for von Willebrand factor.
von Willebrand disease (VWD) is the most common congenital bleeding disorder and is caused by a quantitative or qualitative abnormality of von Willebrand factor (VWF). Ristocetin cofactor (RCoF) assay is used to evaluate VWF activity, but it does not assess collagen-binding activity. Normal values of RCoF and VWF antigen vary with ABO blood group type. The collagen-binding assay (CBA) measures VWF activity; however, its relationship with ABO blood group has not been completely explored. We performed CBA on plasma samples from 131 healthy volunteers to determine if CBA values correlated with blood type. Individuals with blood group O had a mean CBA value of 94 +/- 28%, which was significantly different from the mean of 117 +/- 33% in persons with non-O blood groups (P = 0.0001). Thus, CBA values appear to correlate with ABO blood type in a manner similar to RCoF.
ABO Blood-Group System↗
Allele frequencies of tissue factor pathway inhibitor polymorphisms in African-American, Hispanic and Caucasian populations.
Explore the source record for details and available documents.
Black or African American↗