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Query: UMLS:C0034065 (pulmonary embolism)
14,979 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Prevention of deep venous thrombosis is fundamental in the prevention of pulmonary embolism. Deep venous thrombosis is common after all surgical procedures, but the frequency differs, as does the effectiveness of various methods of prevention. Low-dose heparin, low molecular weight heparin, graduated compression elastic stockings, intermittent pneumatic compression, and oral anticoagulants have a role in the prevention of deep venous thrombosis, depending on the risks of deep venous thrombosis and their demonstrated effectiveness (or lack of effectiveness) in the particular circumstance. The optimal method of prophylaxis is specific to the predisposing condition. Heparin continues to be a mainstay of anticoagulant therapy. Major bleeding is rare in patients treated with low doses of heparin to prevent deep venous thrombosis. With therapeutic doses, however, major bleeding occurs in about 5% of patients. The optimal dose of warfarin and the method of evaluating the anticoagulant effect of warfarin have undergone modifications in recent years. It is now recognized that the prothrombin time ratio depends on the activity of the thromboplastin used for measuring the prothrombin time. An International Normalized Ratio, which relates to a standardized thromboplastin, has been developed, thus avoiding differences of the prothrombin time ratio that occur from batch to batch of thromboplastin reagent from the same manufacturer and that occur with different thromboplastin reagents from different animal sources and different manufacturers. The bedside diagnosis of pulmonary embolism is useful in helping a physician determine the extent to which diagnostic tests should be pursued. A sound bedside impression also contributes strongly to the formulation of a noninvasive diagnosis of pulmonary embolism. The clinical manifestations of pulmonary embolism form a recognizable constellation of findings that often lead to a correct diagnosis or exclusion of pulmonary embolism. Important clues to the diagnosis of pulmonary embolism relate to the initial syndrome. The presentation of pulmonary embolism is most often in the form of the pulmonary hemorrhage-pulmonary infarction syndrome. The next most common presentation is unexplained dyspnea, unaccompanied by pulmonary hemorrhage or infarction. Least common, but most severe, is the syndrome of circulatory collapse. Immobilization, usually caused by surgery, is the most frequent predisposing factor. Most patients with clinically recognizable pulmonary embolism have dyspnea or tachypnea. Dyspnea or tachypnea or pleuritic pain occurs in nearly all patients who have clinically apparent pulmonary embolism (97%). Ordinary tests such as the electrocardiogram and chest radiograph are helpful if the physician is attentive to nonspecific abnormalities.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Acute pulmonary embolism. 807

Current guidelines for heparin therapy in pediatric patients have been extrapolated from trials in adult patients without rigorous evaluation of efficacy and safety. We prospectively monitored consecutive pediatric patients receiving systemic doses of heparin over 10 mo at one institution using a predetermined nomogram to monitor maintenance therapy. Sixty-five consecutive children; 38 males and 27 females, received systemic doses of heparin. Thirty children had deep venous thrombosis and/or pulmonary embolism; 11 had arterial thrombi, most frequently after diagnostic angiography; and the remaining 24 received heparin prophylactically, for congenital heart disease. Twenty-nine (45%) of the 65 patients were less than 1 y of age and 22 (34%) were 10 y or older. Congenital heart disease was the predominant diagnosis under 1 y and deep venous thrombosis in older children. After a bolus dose of 50 U/kg, 39% of children (n = 30) achieved a minimal level activated partial thromboplastin time (APTT). Sixty-eight percent of children achieved a minimal level APTT by 24 h and 81% by 48 h. For all 65 children, APTT values were within the therapeutic range 43% of the time. APTT values outside the therapeutic range were twice as likely to be low as high. The average amount of heparin required to maintain therapeutic APTT values for children was 22 U/kg/h: 28 U/kg/h for infants < 1 y and 20 U/kg/h for the rest. Bleeding was rare (2%) and mild. Documented recurrent thrombotic disease was more common (7%) with associated morbidity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Heparin therapy in pediatric patients: a prospective cohort study. 813 3

The accuracy of a first-order pharmacokinetic model for determining initial heparin infusion rates was studied, and factors that could affect the accuracy of the method were investigated. Patients who received an i.v. infusion of heparin for at least 24 hours for treatment of deep-vein thrombosis, pulmonary embolism (PE), or myocardial infarction were identified by retrospective chart review. A therapeutic dosage of heparin was defined by an activated partial thromboplastin time of 45-75 seconds. Heparin dosages were calculated by using estimated blood volume as the heparin volume of distribution, a desired steady-state heparin concentration of 0.30 units/mL, and an elimination rate constant of 0.832 hr-1. The difference between the calculated dosage and the actual therapeutic dosage was calculated. The differences for various patient subgroups were compared, and the estimated dosages were regressed against the actual dosages to determine their predictive value. Data for 49 patients were analyzed. The mean +/- S.E. difference between the actual and calculated dosages was 29.2 +/- 37.1 units/hr. No significant differences were evident according to sex or indication for therapy. Smokers and nonsmokers differed, as did obese and lean patients. The equation appeared to be more accurate in nonsmokers than smokers. The addition of 200 units/hr to the calculated dosage for patients with PE resulted in minor improvement in the predictive capacity of the equation. Moderate agreement was observed between the actual and calculated heparin dosages in non-smokers of various body weights.
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PMID:Accuracy of a first-order model for estimating initial heparin dosage. 822 24

The objective was to retrospectively study the initiation of anticoagulant therapy in inpatients of the two major teaching hospitals in Tasmania, Australia. The medical records of a random sample of patients with an admission diagnosis of deep venous thrombosis (DVT) or pulmonary embolism (PE) during the period February 1992 to June 1994 were studied, to examine therapeutic issues including (i) the time taken after commencing heparin to achieve a therapeutic activated partial thromboplastin time (APTT), (ii) when warfarin was commenced, (iii) the time taken after commencing warfarin to achieve a therapeutic International Normalized Ratio (INR), and (iv) the degree of anticoagulant control at the time of discharge from hospital. The medical records of 99 patients (median age: 65 years and range: 16-93 years; 52 females) were studied. Heparin was generally commenced within 4 h of admission to hospital. The median duration of heparin therapy was 5 days (range: 2-26 days). The median number of APTTs performed per patient was 6 (range: 1-24), with most results (60%) being below the optimum range. Warfarin was commenced from day 1 of hospitalization in only 34% of patients. The INR was within the therapeutic range in only 29% of cases when heparin was ceased. The median time taken to achieve a therapeutic INR after starting warfarin was 3 days (range: 1-15 days).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Review of the initiation of anticoagulant therapy. 855 86

Plasma levels of selected coagulation and fibrinolytic parameters (activated partial thromboplastin time, prothrombin time, fibrinogen, antithrombin III, protein C, thrombin-anti-thrombin III complexes (TAT), plasminogen activator inhibitor-1 (PAI-1), plasminogen, alpha 2-plasmin inhibitor) were evaluated in 90 patients with clinical suspicion of pulmonary embolism (PE). Plasma levels of fibrinogen, PAI-1 and TAT were significantly higher in patients than in controls (p < 0.01): evaluation of TAT displayed a sensitivity of 96.1% and specificity of 30.8%, and positive and negative predictive values of 64.5 and 85.7%, respectively. The number of nonperfused lung segments correlated directly with TAT levels (p < 0.01) and inversely with arterial pO2 values (p < 0.01). No significant difference was found in the other parameters between patients and controls. Our results suggest that the finding of normal TAT plasma levels can help to exclude PE in patients with clinically suspected PE.
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PMID:Thrombin-antithrombin III complexes as an additional diagnostic aid in pulmonary embolism. 869 74

All patients at moderate to high risk for the development of venous thromboembolism should receive prophylaxis. The approaches of proven value include low dose heparin, low molecular weight heparin, oral anticoagulants and intermittent pneumatic compression. The use of one of the cited heparin nomograms will ensure that all patients are rapidly brought within the therapeutic range. Because of the varying sensitivities of thromboplastins, each laboratory should establish a therapeutic range using the activated partial thromboplastin time (APTT) which will correspond to 0.2 to 0.4 U/ml of heparin. Constant vigilance and a high level of suspicion are necessary to establish the clinical diagnosis of heparin-induced thrombocytopenia, and to institute appropriate therapy. Physicians should be aware of the sensitivity of the thromboplastin being used in the performance of the International Normalised Ratio (INR). Care must be taken to ensure that patients are maintained within the target therapeutic range for INR (in most cases 2 to 3) by frequent determination of the INR and appropriate adjustments of warfarin dosage. Low molecular weight heparin is the recommended approach to the initial management of venous thromboembolism where these agents are available. Patients with an acute episode of venous thromboembolism should receive warfarin therapy for at least 3 months. At the present time it is reasonable to treat the first recurrence with oral anticoagulants for a period of 12 months and indefinitely for more than 1 recurrence. For selected patients with acute massive pulmonary embolism, thrombolytic therapy with one of the available agents is recommended. However, the role of thrombolytic therapy in patients with proximal venous thrombosis remains unclear. In selected patients with acute venous thromboembolism who have contraindications to anticoagulant therapy or who-have objectively documented recurrent disease while on adequate therapy, the insertion of an inferior vena cava filter is recommended.
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PMID:Prevention and treatment of venous thromboembolism. 879 86

The low dose heparin regimen (LDH) is not appropriate for prevention of intra- and postoperative thromboembolic complications in high risk patients, especially those undergoing elective hip replacement. Despite LDH prophylaxis, the incidence of deep-vein thrombosis (DVT) remains in a range of 20 to 35%. Adjusted-dose unfractionated heparin prophylaxis is thought to be one of the most effective regimens for thrombosis prophylaxis in this indication, but it requires two or three daily injections as well as precise monitoring of the activated partial thromboplastin time (aPTT). As an attractive alternative, we investigated the efficacy and safety of the low molecular weight heparin (LMWH) certoparin combined with dihydroergotamine (DHE) given once daily. In a randomised, open clinical trial, a total number of 305 patients undergoing total elective hip replacement were enrolled and divided into two groups, either receiving a fixed-dose combination of LMWH (3,000 IU) and DHE (0.5 mg) subcutaneously once daily, or adjusted-dose unfractionated heparin (UFH) subcutaneously every 8 h. The UFH dosage was adjusted daily to keep an aPTT of about 50 s. The aPTT was determined 3 h after the morning injection. During the study, the starting dose (15,000 IU/day) was increased to a plateau value of 28,800 +/- 7,150 IU/day (mean +/- SD) to maintain the aPTT in the prescribed range. The plateau value was achieved after 8 postoperative days. For analysis of efficacy 289 patients were evaluable. The occurrence of deep vein thrombosis was determined by bilateral ascending venography, which was performed on the same day in patients with clinical signs suggesting DVT; and in all remaining patients at the end of the prophylaxis period. Deep vein thrombosis was diagnosed in 17 of 142 patients (12.0%) treated with LMWH/DHE and in 13 of 147 patients (8.8%) treated with adjusted-dose UFH. Combined distalproximal thrombosis was more frequently in patients receiving UFH (n = 5; 3.4%) compared to the LMWH/DHE group (n = 2; 1.4%). These differences are statistically not significant. In the UFH group one case of non-fatal pulmonary embolism occurred. Both prophylaxis regimens were well tolerated; wound bleeding was observed in 8 (5.3%) patients in the LMWH group and in 6 (4.0%) patients in the UFH group. Intraoperative blood-loss volume (mean +/- SD) was 751 +/- 339 mL (LMWH/DHE) and 736 +/- 380 mL (UFH), whereas postoperative drain-loss volume (mean +/- SD) was found to be 523 +/- 333 mL (LMWH/DHE) and 581 +/- 404 mL (UFH). Whole blood transfusion volumes (mean +/- SD) were 570 +/- 202 mL (LMWH/DHE) and 748 +/- 455 mL (UFH). Additionally, red cell replacement volumes (mean +/- SD) were 804 +/- 435 mL (LMWH/DHE) and 720 +/- 328 mL (UHF). Revision of wound or additional drainage were necessary in 3 LMWH/DHE and 7 UFH patients. One patient needed reoperation due to bleeding, 3 (2.0%) had petechia and 1 exhibited an allergic exanthema, all of them in the UFH group. A slight erythema at the injection site was observed in 6 (3.9%) patients receiving LMWH/DHE. During the course of prophylaxis, injection hematomas were documented in 57.9% (LMWH/DHE) and in 61.4% (UFH) of the patients. All differences were statistically not significant. Single daily subcutaneous injections of LMWH/DHE appeared to be safe and efficacious compared to adjusted-dose UFH for prophylaxis of DVT in high-risk patients.
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PMID:A fixed-dose combination of low molecular weight heparin with dihydroergotamine versus adjusted-dose unfractionated heparin in the prevention of deep-vein thrombosis after total hip replacement. 881 69

The low molecular weight heparin (LMWH) dalteparin sodium is notable for its improved pharmacokinetic characteristics (chiefly increased bioavailability and plasma elimination half-life) compared with unfractionated heparin (UFH). These properties enable the drug to be given subcutaneously as a single daily dose, compared with the 8- to 12-hourly regimens necessary with UFH. Dalteparin sodium also appears to exert a greater inhibitory effect than UFH on plasma activity of coagulation factor Xa relative to its effects on clotting times [usually expressed as activated partial thromboplastin time (APTT)] and activity of factor IIa. It is not associated with any clinically significant effects on the fibrinolytic system and may have less lipolytic activity than UFH. Extensive clinical studies have been conducted to compare the antithrombotic efficacy of dalteparin sodium with that of UFH in surgical thromboprophylaxis, treatment of established deep vein thrombosis (DVT) and the anticoagulation of patients undergoing haemodialysis and haemofiltration. The majority of trails of patients receiving thromboprophylactic heparin perioperatively have shown similar efficacy of dalteparin sodium and UFH in the prevention of DVT and pulmonary embolism (PE), although 2 groups of investigators reported superior antithrombotic potency for dalteparin sodium. The two types of heparin appear similarly effective in the management of established DVT and the maintenance of the extracorporeal circulation in haemodialysis circuits. Dalteparin sodium has also shown clinical benefit in the management of patients with unstable angina or non-Q-wave myocardial infarction. The overall incidence of haemorrhagic complications observed with daltparin sodium therapy is no greater than that associated with UFH, and data suggest that perioperative transfusion requirements and frequency of bleeding are lower after dalteparin sodium. The antithrombotic efficacy of dalteparin sodium is at least equivalent to that of UFH, although further clinical comparisons with other LMWHs are required. Further studies are also needed to clearly define any advantages of dalteparin sodium over UFH (and other antithrombotics) with regard to the incidence of haemorrhagic complications. The drug has also shown clinical efficacy in the prevention of myocardial infarction and death in patients with unstable coronary artery disease. In addition, there may be cost advantages attached to the once-daily subcutaneous regimen of dalteparin sodium, but this requires further examination. Thus, dalteparin sodium is an effective antithrombotic agent for perioperative thromboprophylaxis, the management of established DVT, and the anticoagulation of patients undergoing haemodialysis.
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PMID:Dalteparin sodium. A review of its pharmacology and clinical use in the prevention and treatment of thromboembolic disorders. 884 43

Optimum anticoagulation with heparin within the first 24 hours of a thrombotic event is critical in preventing a recurrence. We believed that traditional nonweight-based heparin dosing at our institution resulted in delayed anticoagulation. A weight-based heparin nomogram was therefore created and compared to traditional heparin dosing in patients with a diagnosis of acute deep vein thrombosis or pulmonary embolism. Fifty historical control patients were compared to 50 consecutive patients treated prospectively using the weight-based nomogram. The primary outcome assessed was time to achieve therapeutic anticoagulation, defined as an activated partial thromboplastin time (aPTT) of 46-70 seconds (1.5-2.5 times the control aPTT). The weight-based nomogram achieved an aPTT above the therapeutic threshold more rapidly than the control group (10.7 hrs nomogram vs 33.3 hrs control group, p < 0.004). Similarly, the proportion of patients who exceeded the therapeutic threshold at the first aPTT measurement, at 24 hours, and at 48 hours was significantly higher in the nomogram group. There was no difference in the frequency of bleeding complications or recurrent thrombotic events between the two groups. The initial nomogram was revised for patients weighing more than 80 kg owing to a greater frequency of excessive anticoagulation in these patients. Subsequent analysis of 29 patients using the modified nomogram revealed sustained efficacy and a reduced number of supratherapeutic aPTTs. We concluded that a weight-based heparin nomogram is superior to traditional therapy in achieving rapid therapeutic anticoagulation without an increase in adverse outcomes.
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PMID:Comparison of a weight-based heparin nomogram with traditional heparin dosing to achieve therapeutic anticoagulation. 894 81

Intracranial surgery is often complicated by thromboembolic events including the life-threatening pulmonary embolism. After head trauma and in patients with brain tumors disseminated intravascular coagulation (DIC) can occur, characterized by the triggering of the coagulation cascade and the depletion of coagulation factors which ultimately leads to bleeding. The identification of patients at high risk as well as the early diagnosis of hemostatic problems uses routine laboratory parameters such as partial thromboplastin time and prothrombin time reflecting the intrinsic and the extrinsic pathway of the coagulation respectively. Thrombin antithrombin III complexes (TAT) and prothrombin fragment 1 + 2 (F1 + 2) are further indicators of an activation of the coagulation whereas fibrinogen degradation products (FDP) refer to the fibrinolytic system. The basic principles of coagulation and fibrinolysis are summarized as well as the changes of laboratory parameters accompanying DIC, hypercoagulability and hyperfibrinolysis.
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PMID:What the neurosurgeon needs to know about the coagulation system. 898 62

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