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PubMed1975

Retinal hemorrhage associated with thrombasthenia.

A healthy 20-year-old man presented with a spontaneous unilateral retinal hemorrhage. Because of a history of easy bruisability, we obtained hematologic studies and diagnosed thrombasthenia, a hereditary hemorrhagic disorder. The association of retinal hemorrhage and thrombasthenia is rare. Thrombasthenia and other platelet functional disorders are becoming better defined as tests for these abnormalities become more reliable and available. Patients with apparent spontaneous retinal hemorrhages of unknown origin should be questioned about hemorrhagic tendencies, and the various tests for hemorrhagic disorders should be obtained. The hematologic survey should include the more sophisticated tests of platelet function. Patients with thrombasthenia should avoid aspirin intake.

Adenosine Diphosphate↗
PubMed1990

Preservation of platelet function during trimethaphan infusion.

The effect of trimethaphan (Arfonad) infusion on platelet function was prospectively evaluated in 38 (n = 38) patients (28 patients receiving trimethaphan, ten control patients) undergoing elective cardiac surgery. Any patient with a positive history for the ingestion of medication known to interfere with platelet function was excluded from the study. Following induction of anesthesia with fentanyl (and prior to cardiopulmonary bypass) 28 patients (n = 28) received trimethaphan as clinically indicated to maintain a mean blood pressure of 80 mmHg. The infusion rate and total dose of trimethaphan delivered was recorded for each patient. The evaluation of platelet function was performed via adenosine diphosphate (ADP) and epinephrine-induced platelet aggregation tests. The administration of trimethaphan failed to result in any detrimental effect on platelet function as assessed via these aggregation studies. Template bleeding times were also performed on all study patients. Bleeding time measurements performed in patients following trimethaphan administration were unchanged from baseline values. Platelet aggregation studies and bleeding time performed in control group following the administration of fentanyl (30 micrograms/kg) plus enflurane (inspired concentration 0.5-1%) did not reveal any deviation from baseline values. These results are in contrast to a previous study that demonstrated a negative effect upon platelet function following sodium nitroprusside administration (at clinically acceptable doses). These data demonstrate that trimethaphan provides control of arterial pressure with preservation of platelet function.

Aged↗
PubMed1992

[Effect of leukocyte depleting polyester filters on thrombocytapheresis concentrates].

We studied platelet loss, leukocyte depletion, T/B cell ratio, platelet morphology and platelet function (aggregation, hypotonic shock reaction, retention and retraction) prior to and after filtration through two different polyester filters (Sepacell PL-5A, Pall PL100) as well as the posttransfusional platelet increment 1 h after transfusion in 8 pairs of single-donor platelet concentrates (Cobe Spectra, Fresenius AS 104). Leukocyte depletion was effective (>99.9%) and platelet loss acceptable in both filters, all tests showing no indication of a diminished platelet function by filtration.

Blood Component Transfusion↗
PubMed1973

Effect of intravenous prostaglandin E 2 on platelet function, coagulation, and fibrinolysis.

Prostaglandin E(2) (PGE(2)) was infused intravenously to eight women for the termination of pregnancy and tests of platelet function: coagulation and fibrinolysis were studied before and during the infusion.Platelet adhesiveness, as measured by a cellophane membrane test-cell system, was significantly diminished by PGE(2), a change which was not noted by the glass-bead column technique. The administration of PGE(2) caused more rapid platelet disaggregation following ADP-induced aggregation but had no effect on the platelet count, collagen-induced aggregation, or platelet factor 3 activity. An increase in plasma antithrombin concentration and euglobulin lysis activity was also noted. These results support the concept that prostaglandin E(2) might have a role in the prevention of thrombosis.

Abortion, Induced↗
PubMed2001

Comparison between different laboratory tests for the detection and prevention of heparin-induced thrombocytopenia.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is a possible complication of heparin therapy that can evolve with life-threatening thromboembolism, for which early diagnosis is essential. However, the specific laboratory approach to the diagnosis of HIT is still controversial. METHODS: Sera from 13 patients with HIT, from 15 patients with non-HIT thrombocytopenia, and from 10 normal subjects were used to compare nonfunctional and functional methods to detect anti-heparin:PF-4 antibodies and platelet activation. We used three enzyme-linked immunosorbent assays (ELISAs) and the particle gel immunoassay as nonfunctional tests, and platelet aggregometry, CD62p (p-selectin) phenotypical expression, and Annexin V binding as functional assays. RESULTS: CD62p expression was positive in 85% of the cases and Annexin V was positive in 40% of the HIT cases examined. Aggregometry gave variable results that depend strongly on the donor. CONCLUSION: Functional tests for platelet activation are more reliable for HIT diagnosis than the nonfunctional tests. We conclude that the phenotypical expression of p-selectin detected by flow cytometry on activated platelets appears to be a good functional marker for the diagnosis of HIT and its possible thromboembolic complications.

Adult↗
PubMed2004

Aspirin resistance in stroke: 2004.

Aspirin is a well-established medication in the treatment of atherothrombotic vascular disease. However, despite aspirin treatment a substantial number of patients experience recurring ischaemic episodes. Aspirin resistance denotes those situations when it is unable to protect individuals from thrombotic complications, or when it fails to produce an anticipated effect in laboratory tests of platelet function. There are various laboratory techniques with which to evaluate the effectiveness of aspirin and other antiplatelet drugs. It has been estimated that in 5-60% of patients, aspirin does not achieve adequate efficacy in various measures of platelet activity. Some studies have revealed that vascular patients shown by laboratory tests to be aspirin-resistant are at an increased risk of major vascular events. The suggested mechanisms of aspirin resistance, among others, include genetic polymorphisms, alternate pathways of platelet activation, aspirin-insensitive thromboxane biosynthesis, drug interactions, or low aspirin dose. An increase in the dosage of aspirin or conversion to clopidogrel or clopidogrel plus aspirin might be beneficial in the management of those patients who are aspirin resistant. Additional work is required to improve and validate laboratory tests of platelet function, so that they may become useful tools for selecting the most appropriate antiplatelet therapy for an individual patient. Improvements in antiplatelet treatment strategies in the future should lead to a reduction in premature vascular events.

Aspirin↗
PubMed1989

Dietary fish oil supplements preserve renal function in renal transplant recipients with chronic vascular rejection.

The effect of dietary fish oil supplements on renal failure and lipid abnormalities was studied in 14 adult renal transplant recipients with chronic vascular rejection. The rate of decline of renal function (assessed by studying the slope of reciprocal plasma creatinine plots) slowed significantly during a 6-month period on fish oil supplements compared with the preceding 6-month control period (slope 1/cr during supplementation -3.6 X 10(-5) mumols/l per month compared with -13.5 X 10(-5) before, the difference in slope being -9.8 X 10(-5), 95% confidence interval (CI) -16.2 X 10(-5), -3.5 X 10(-5), P less than 0.05). Total plasma triglyceride concentrations decreased during supplementation (mean change -1.15 mmol/l, 95% CI -1.84, -0.47, P less than 0.003), but there was no change in total plasma cholesterol concentration or urinary protein excretion. Platelet function was studied in nine patients. Platelet aggregation induced by adrenaline and collagen was reduced by fish oils (median change in per cent aggregation), adrenaline 2 mumols/l, -36% (95% CI -68%, -8%, P less than 0.05), collagen 1 mg/1, -13% (95% CI -44%, -2%, P less than 0.05). Platelet thromboxane A2 release in response to these agents was also significantly reduced. These results demonstrate that fish oils preserve residual function in renal graft failure due to chronic vascular rejection.

Adult↗
PubMed1988

Quantitative platelet disorders.

Thrombocytopenia may be caused by abnormal platelet production, accelerated removal owing to immunologic or nonimmunologic reasons, or sequestration of platelets in the spleen. Bleeding associated with thrombocytopenia usually presents as petechial or ecchymotic hemorrhages or epistaxis. Immunologic and nonimmunologic cases of thrombocytopenia may be diagnosed with routine hematology, bone marrow cytology, and platelet specific tests. Thrombocythemia may also be associated with platelet functional abnormalities, contrasting the normal platelet function noted in reactive thrombocytosis.

Animals↗
PubMed2004

[Platelet reactivity index by Grotemeyer].

In 1974 Wu and Hoak described a method for determining circulating platelet aggregates. This method was modified by Grotemeyer in 1983. The platelet reactivity index (PR) is based on the ratio of platelet aggregates in blood samples obtained in different buffer solutions. Platelet aggregates are resolved, when blood is sampled in EDTA-buffer, but remain fixed when EDTA-formalin-buffer is used. Generally, the PR is preferred, because in vitro manipulations of platelets are not necessary, and the results are estimated automatically. PR values above 1.05 are suspicious for elevated platelet aggregation. PR values above 1.2 indicate pathological changes in platelet aggregation. The PR is inexpensive (4.0 D ) and rapid to perform. PR-values were used successfully to identify non-responders to secondary prophylaxis with acetylsalicylic acid (ASA), i. e. patients suffering from stroke (33%) and after cardiac ischaemia (18%). Furthermore, elevated PR-values correlated significantly with the incidence of arterial thromboembolic complications. The PR correlated well in a own prospective study (drug monitoring) with values received from the retention test Homburg (RT-H) and the platelet function analyser (PFA-100). These data indicate that the values of the PR seems to be highly predictive for the evaluation of the ASA therapy. However, the PR is not suitable for the determination of ASA overdosage.

Blood Platelets↗
PubMed1989

[Spontaneous intrahepatic hemorrhage: a severe complication of the Hellp syndrome. Value of early radiologic diagnosis. Apropos of a case].

One case of spontaneous hepatic hemorrhage during a severe pre-eclampsia and Hellp syndrome (hemolysis, elevated liver function tests, low platelet count) is reported. This serious complication can be detected by ultrasonography and C.T. The normal sonographic appearance of the liver must prompt a new sonographic examination as soon as possible. C.T. of the abdomen confirmes the diagnosis and delineates the lesions more precisely. It is suggested that with the availability of ultrasound and computed tomography to diagnose and stage the hepatic hemorrhage, they have a systematic indication during the Hellp syndrome.

Adult↗
PubMed1990

[Effects of thrombin produced in blood prior to mixing with anticoagulant on the platelet function and blood coagulation tests].

The amount of thrombin produced in the withdrawn blood of healthy donors prior to mixing with anticoagulants was estimated with thrombin-antithrombin III complex (TAT) methods. No samples showed production of thrombin in the blood mixed with anticoagulants within 2 min. After 3 min or more incubation, four donors out of 14 showed elevation of TAT, and a technician could suspect trouble only in a case during taking blood. Although two samples with low thrombin production (5.8, 12 ng/ml, normal: less than 5 ng/ml) showed no changes of APTT or prothrombin time, samples with high thrombin production (74, 98 ng/ml) showed 1.4-2 sec shortening of APTT and 0.8-1 sec shortening of prothrombin time. Platelet counts and platelet volume showed no remarkable changes even when samples with large amount of thrombin were suspended in tubes containing EDTA-2 K. Plasma beta-thromboglobulin concentration was elevated in the blood containing high amount of thrombin and close correlation was observed amount of thrombin in the blood and the amount of plasma beta-thromboglobulin (r = 0.90, P value less than 0.001). Platelet aggregation induced by collagen was not influenced by amount of thrombin produced. ADP-induced aggregation was suppressed in 3 out of 4 cases with thrombin production although no close correlation was observed between maximal aggregation rate and the concentration of thrombin. As improper handling of blood samples including withdrawal of blood leads to misunderstanding of test results. So, blood samples only for these sensitive tests should be taken and mix with anticoagulants within 2 min.

Adolescent↗
PubMed1984

Simultaneous study of platelets and phagocytes in myeloproliferative disorders.

In order to determine the relationship between the anomalies affecting two types of blood cell in myeloproliferative disorders (MPD), a functional study was performed in individuals presenting with such diseases. Thus, platelet function was investigated by means of Ivy's method for bleeding time, platelet retention to glass beads, aggregation with epinephrine and density distribution on a discontinuous sucrose gradient. Simultaneously, three granulocyte functions, i.e. capillary tube random migration, particle ingestion activity and nitroblue tetrazolium dye reduction were studied. This investigation was carried out in 47 patients presenting with chronic myeloproliferative disorders (MPD): chronic granulocytic leukemia (18 cases), polycythemia vera (18 cases), myelofibrosis (6 cases) and essential thrombocythemia (5 cases). The results of the present study indicate that functional abnormalities are more frequent and more strongly marked in platelets than in phagocytes. The tests most affected were platelet density distribution and granulocytic random migration. Simultaneous assessment of platelet and phagocytic functions, though insufficient in itself to determine the type of MPD or to appraise the prognosis of the disease, could be useful in the diagnosis of some atypical cases of myeloproliferative disorders.

Blood Platelets↗
PubMed1992

[Hemostatic disorders in patients with HIV infection].

Impaired hemostasis was studied in 50 adult patients with HIV infection. The blood coagulative potential, the number and functional activity of platelets were examined. Platelet aggregation and secretion were shown to change earlier than thrombocytopenia developed and clinical signs of HIV infection appeared. The disturbance in the plasma section of hemostasis are due to concurrent opportunistic diseases and infections.

Acquired Immunodeficiency Syndrome↗
PubMed2000

A clinical evaluation of platelet function, haemolysis and oxygen transfer during cardiopulmonary bypass comparing the Quantum HF-6700 to the HF-5700 hollow fibre membrane oxygenator.

The continued improvement of oxygenators is an important aspect of patient safety during cardiopulmonary bypass (CPB). The purpose of this study was to compare the Bard William Harvey HF-5700 oxygenator to the upgraded Bard Quantum HF-6700, which has recently been introduced into clinical practice. No clinical evaluation of this device has been published to date. The two oxygenators differ principally in that the Quantum has a smaller priming volume, achieved at the expense of a smaller membrane surface area which could result in sub-optimal gas exchange characteristics, increased haemolysis and increased platelet dysfunction during CPB. Twenty adult patients undergoing elective, first time coronary artery bypass grafting (CABG) were randomly assigned either to the HF-5700 (n=10) or to the HF-6700 (n=10) group. One patient underwent mitral valve repair in addition to CABG and was excluded from further study. There were no statistically significant differences in either preoperative or operative parameters between the two groups. Samples were obtained at the start of CPB, at 30 min, 60 min, at the end of CPB and at 1 h following termination of CPB. No significant differences between the two groups were found in oxygen transfer, haemolysis (plasma haptoglobin levels) or platelet function (a novel platelet activating factor (PAF)-induced platelet activation test) at any of the time points during CPB. It was concluded that the Quantum HF-6700 matches the HF-5700 for the parameters studied, whilst having the advantage of requiring a smaller priming volume.

Aged↗