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

Presently available data indicate that low-dose heparin will significantly diminish postoperative deep venous thrombosis and pulmonary embolism in patients over the age of 40 subjected to major elective abdomino-thoracic surgery. The schedule is 5,000 USP units of heparin subcutaneously beginning two hours before operation and continued every twelve hours (10,000 units per day) until the patient is discharged. Whether anticoagulent therapy should be continued after discharge should be decided on an individual basis. Preoperative tests for patients on this regimen should include an hematocrit, prothrombin time, partial thromboplastic time, and a platelet count. They should also not be receiving aspirin or other platelet anti-aggregating agents for five days before operation. The efficacy of this regimen is complemented by the fact that it is well tolerated by the patient and requires no laboratory monitoring. However, it does produce a definite but acceptably low frequency of minor intraoperative and postoperative bleeding. This low-dose regimen has not proved effective in open prostatectomy or major orthopedic operations. Data are not available concerning the drug's safety in patients receiving spinal or epidural anesthesia. Nor is it recommended for operations on the eye, brain or in patients who are experiencing an active thrombotic process. More than five million individuals over the age of 40 undergo major general surgical operations annually in this country. One or two out of each thousand of these patients will die postoperatively from pulmonary embolism. If low dose heparin prophylaxis in 80% effective, then the possibility exists of saving 4,000 to 8,000 lives annually. Such an impact might be realized if physicians are prepared to recommend the low-dose heparin regimen as primary prophylaxis for all hemostatically competent patients over the age of 40 who undergo abdomino-thoracic surgery.
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PMID:Prevention of venous thromboembolism in surgical patients by low-dose heparin: prepared by the Council on Thrombosis of the American Heart Association. 83 57

Plasma fibrinopeptide A (FPA) concentrations were measured in clinical blood samples incubated in the collecting syringe for different time periods before addition to heparin and Trasylol, and the rate of in vitro generation of FPA was calculated as the mean increment in FPA concentration per minute over the linear portion of the generation curve. 36 normal individuals had a mean plasma FPA level of 0.64 +/- 0.56 pmol/ml and an FPA generation rate of less than 0.5 pmol/ml per min. Clinical samples with elevated plasma FPA levels manifested slow (less than 1 pmol/ml per min) (28 patients) or rapid FPA generation (greater than 1 pmol/ml per min) (33 patients). Slow FPA generation was found in 10/10 patients with venous thrombosis, in 4/4 with aortic aneurysm, and in several patients with acquired hypofibrinogenemia. In one such patient, addition of fibrinogen resulted in rapid FPA generation whereas thrombin addition was without effect. Rapid FPA generation was generally linear, was usually associated with slower fibrinopeptide B generation and was inhibited by parenteral or in vitro heparin. It is thought to reflect increased thrombin activity and was seen in patients with pulmonary embolism, active systemic lupus erythematosus, renal transplant rejection, and after infusion of prothrombin concentrates. The initial rate of FPA cleavage by thrombin at fibrinogen concentrations from 0.05 to 4 mg/ml showed little change between 2 and 4 mg/ml with a Km of 2.99 muM. At a fibrinogen concentration of 2.5 mg/ml the FPA cleavage rate was 49.2 +/- 1.6 nmol/ml per min per U of thrombin. Exogenous thrombin added to normal blood generated 21.7 nmol/ml per U of thrombin FPA in the first minute with a nonlinear pattern reflecting inactivation of thrombin and the presence of alternative substrates. Hence, the thrombin concentration in the blood cannot be calculated from the FPA generation rate. The FPA generation rates in clinical samples with rapid generation (1-28 pmol/ml per min) could be produced by 2 X 10(-5) to 5.6 X 10(-4) thrombin U/ml acting on purified fibrinogen at physiological conditions of pH, ionic strength, and temperature.
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PMID:The generation of fibrinopeptide A in clinical blood samples: evidence for thrombin activity. 99 37

In an open, randomised controlled study, 101 patients with phlebographically diagnosed deep vein thrombosis of the leg, not extending into more than two thirds of the femoral vein, were randomised to receive Fragmin (a low molecular weight heparin) administered subcutaneously either once or twice daily in doses of 200 U(anti-FXa)/kg/24h or 100 U(anti-FXa)/kg/12h respectively. Prior to Fragmin unfractionated heparin had been administered by continuous iv infusion for not longer than 24h. Warfarin was administered from the first treatment day. Fragmin was administered for at least 5 days or until the prothrombin complex had been within the therapeutic range for at least 2 days. Patients were kept in bed for the first day but thereafter were ambulant. Phlebography was repeated at 5-7 days. Comparison of the phlebograms revealed a similar improvement (reduction in Marder score) in both groups. There were 5 cases of bleeding: 1 major and 3 minor in the twice daily group and 1 minor bleed in the once daily group. There were no cases of clinical pulmonary embolism. It is concluded that Fragmin, administered as a single daily subcutaneous injection, is effective in the treatment of deep vein thromboses, and offers the advantages of reduced costs, despite higher price of the drug, including reduced nursing time.
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PMID:Fragmin once or twice daily subcutaneously in the treatment of deep venous thrombosis of the leg. 133 13

Three groups of patients receiving oral anticoagulation treatment were evaluated. The groups consisted of patients with mechanical heart valve prosthesis (n = 60), patients after coronary bypass graft surgery (n = 60) and patients using oral anticoagulation after deep venous thrombosis or pulmonary embolism (n = 60). The patient groups were subdivided into three groups of 20 patients, each group receiving different levels of oral anticoagulation as indicated by the international normalized ratio (INR). Prothrombin fragment 1 + 2, thrombin-antithrombin III complexes and fibrin monomers were determined as coagulation activation makers. The prothrombin fragments 1 + 2 were INR dependent in all groups whereas the thrombin-antithrombin III values were only INR dependent in the group of patients with mechanical heart valve prosthesis. For fibrin monomers no correlation with the INR levels could be found. These results indicate that prothrombin fragment 1 + 2 is the only laboratory quantity of the three, which provides a suitable index of low thrombin activity during anticoagulation therapy.
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PMID:Comparison of markers of coagulation activation in patients under oral anticoagulation at different levels. 144 59

This study was designed to identify those total arthroplasty patients at high risk for embolism even while on a proven warfarin prophylactic regimen and to identify the measure of anticoagulation that would be most efficacious in the prevention of pulmonary embolism (PE). A series of 2348 total arthroplasty patients had a preoperative perfusion scan and a postoperative ventilation/perfusion scan. All patients were placed on a low-dose warfarin protocol. Eighty-one patients were identified as having a PE by pulmonary arteriography (incidence of 3.4%). Of these, 89% were asymptomatic and no case was fatal. A control group of 159 patients without PE was used for comparison. Patients older than 65 years of age with a history of genitourinary infection were identified as being at higher risk of PE while on a proven warfarin prophylactic program. These patients may need additional prophylactic measures to reduce the risk of PE. In contrast, patients with a history of phlebitis, PE, obesity, or varicosities were not at excess risk for PE while on warfarin prophylaxis; therefore, no additional prophylactic measures are required. All prothrombin time profiles were within the prophylactic range. Therefore, the actual prothrombin time may not be the critical determinant of the level of anticoagulation or prophylaxis achieved.
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PMID:Pulmonary embolism in total hip and knee arthroplasty. Risk factors in patients on warfarin prophylaxis and analysis of the prothrombin time as an indicator of warfarin's prophylactic effect. 151 7

During the acute phase of myocardial infarction, the generation of thrombin is reflected in the sudden rise of fibrinopeptide A (FPA) and the thrombin-antithrombin III (TAT) complex in blood. We have systematically determined the FPA and TAT plasma concentrations over a period of 14 days after acute myocardial infarction in 100 patients. Mean levels of both thrombin markers were the highest on admission, remained elevated over the following few days, and then gradually declined after day 5. Still, by the end of the first week two thirds of the patients had distinctly elevated TAT and FPA levels, and by the end of the second week such an abnormality was present in half of them. Continuous intravenous heparin infusion at a dose of 20,000 units/day, administered for 1 week to patients who had either received (n = 21) or not received (n = 17) streptokinase, led to a significant depression (p less than 0.05) of thrombin markers over the first 48 hours, an effect that did not persist over the subsequent days of treatment. In patients not assigned to heparin treatment, those in heart failure had significantly (p less than 0.05) higher mean TAT and FPA values on days 3, 5, and 7 compared with patients in whom heart failure was absent. Infarct extension, pulmonary embolism, and death were also associated with a rise in one or both thrombin markers, often preceding the onset of clinical symptoms. Thrombinogenesis was not accompanied by changes in mean plasma concentrations of prothrombin, antithrombin III, or alpha 2-macroglobulin.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Persistent generation of thrombin after acute myocardial infarction. 157 16

Postoperative orthopaedic patients remain at risk for venous thromboembolism (VTE) after hospital discharge. Therefore, the authors designed and implemented a program for prevention of VTE that included outpatient adjusted-dose warfarin using twice-weekly prothrombin time (PT) determinations, a dedicated telephone line for PT results, and vigilant nurse-physician supervision to administer prophylaxis to 125 postoperative orthopaedic patients against VTE for an average of 31.4 days after discharge. PT was maintained between 13.2 and 18.3 seconds (1.1-1.5 x control) in the average patient. There was a failure rate of 3.2% and 0.8% for clinically suspected and radiologically confirmed deep venous thrombosis (DVT) and pulmonary embolism (PE), respectively. The rate of bleeding complications was 3.2%, but none of these patients required transfusion or hospital readmission for hemorrhage. The authors conclude that the described program for VTE prevention is a safe, effective, and practical program to administer prophylaxis to postoperative orthopaedic patients against clinically evident VTE for the first month after hospital discharge.
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PMID:Program for the prevention of venous thromboembolism in high-risk orthopaedic patients. 177 65

The indications, efficacy, dosage, administration, and monitoring of heparin and warfarin therapy for acute thromboembolic events are reviewed, with emphasis on recent changes in treatment recommendations. High-dose heparin therapy is indicated for acute deep-vein thrombosis and pulmonary embolism. Heparin therapy as an adjunct to thrombolytic agents for acute myocardial infarction is becoming increasingly accepted. Heparin therapy for acute thromboembolic events consists of a dosage that elevates the activated partial thromboplastin time to 1.5 to 2.0 times the control value; formerly, 1.5 to 2.5 times control was considered therapeutic. The recommended heparin dosage is a bolus dose of 70-100 units/kg followed by an infusion of 15-25 units/kg/hr. To prevent recurrent thromboembolism, most patients require long-term therapy following acute treatment; this typically consists of warfarin, which should be initiated on day 1 or 2 of heparin therapy whenever possible. For most indications, the intensity of warfarin has been reduced to a dosage that elevates the prothrombin time to 1.3 to 1.5 times control. Alternative therapies (low-molecular-weight heparins) and routes (subcutaneous heparin) should be further investigated. Current recommendations for heparin and warfarin therapy of acute thromboembolism include reduced intensity of both drugs and shortened duration of therapy. Since the therapeutic ranges for both heparin and warfarin therapy have been compressed, closer monitoring may be necessary to achieve and maintain adequate anticoagulation.
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PMID:Therapy of acute thromboembolism with heparin and warfarin. 179 18

Seventy-two patients were randomized into a prospective clinical trial to evaluate the effects of epidural (EA) versus general anesthesia (GA) on the incidence of thromboembolic disease (TED) following total knee arthroplasty (TKA). Males received aspirin 650 mg po bid and females low-dose warfarin daily to maintain the prothrombin time at 15 to 16 seconds for pharmacologic prophylaxis against TED. Thirty-four patients had EA and 38 GA for their primary TKA. Contrast venography and ventilation-perfusion scanning were performed on the sixth, seventh, and eighth postoperative days, and these were interpreted in a blinded fashion. The mean age of the 45 males and 27 females was 64 years (range, 42-84 years). There were no significant differences between the two groups with respect to hematocrit, operative time, blood loss, number of units transfused, or hospital stay. Twelve of the 34 patients (35%) receiving an EA and 10 of the 38 patients (26%) receiving GA developed TED, an overall incidence of 31% (p greater than 0.05) Fifty-three percent of the clots were located in the popliteal vein above the trifurcation or more proximal. However, the incidence of proximal vein thrombosis was significantly less in patients receiving an EA (46%) rather than a GA (64%). The incidence and distribution of clots was not affected by the type of pharmacologic prophylaxis, gender, or use of methylmethacrylate. Ten percent of the patients had a positive scan by strict criteria and were thought to have a pulmonary embolism (PE). In patients with a femoral vein clot, the incidence of PE was 67%. One bleeding complication occurred in a patient who took double the appropriate warfarin dose.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Prevention of thromboembolic disease following total knee arthroplasty. Epidural versus general anesthesia. 186 27

Plasma levels of prothrombin fragment 1 + 2 (F 1 + 2), of thrombin-antithrombin III complexes (TAT) and of D-dimers were evaluated at several time intervals in 15 patients affected by acute proximal deep vein thrombosis, complicated or not by pulmonary embolism, and treated by conventional heparin therapy for 9 d. The mean levels of the three markers remained significantly increased throughout the period of observation, except for F 1 + 2 on day 9, when compared to normal values established in a population of normal healthy blood donors. However, whereas heparin significantly decreased the plasma levels of F 1 + 2 and of TAT complexes in less than 3 d. D-dimer levels were not significantly altered. Significant correlations were observed between the plasma levels of the three markers but they were not correlated to the actual intensity of heparin treatment evaluated as the activated partial thromboplastin time prolongation. These results indicate that heparin improves the hypercoagulable state associated with a deep vein thrombosis within the first days of treatment as indicated by TAT and F 1 + 2. They also account for the performances of D-dimer assay for the diagnosis of deep vein thrombosis in patients already receiving heparin, a common situation in routine hospital practice.
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PMID:Prothrombin fragment 1 + 2, thrombin-antithrombin III complexes and D-dimers in acute deep vein thrombosis: effects of heparin treatment. 187 25


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