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Biomedical subjects

G F Pineo

Publications and source records attributed to G F Pineo.

At least 55 records · Page 3Linked to original sources
PubMed1997

Low-molecular-weight heparin therapy and mortality.

There is ample evidence from clinical trials to justify giving certain low-molecular-weight heparins (LMWHs) subcutaneously rather than administering continuous intravenous unfractionated heparin for the initial treatment of venous thromboembolic disease. The LMWHs given by subcutaneous injection have a predictable anticoagulant response and prolonged duration of action. They can, therefore, be administered once or twice daily to treat venous thrombosis. Furthermore, treatment with these agents does not require laboratory monitoring. Eliminating the need for intravenous therapy and for laboratory monitoring should allow patients to be discharged earlier, and eventually lead to the outpatient treatment of venous thromboembolism. Studies to date indicate that LMWH is safer and as effective as continuous intravenous heparin in the treatment of venous thrombosis. The decreased mortality rates seen in two clinical trials, particularly in patients with metastatic cancer, were an unexpected but intriguing finding. This requires further confirmation, in larger prospective randomized trials.

Heparin, Low-Molecular-Weight↗
PubMed1997

Low-molecular-weight heparin: prophylaxis and treatment of venous thromboembolism.

Intravenous heparin followed by warfarin has been the classical anticoagulant therapy of acute venous thromboembolism for the last 30 years. Furthermore, low-dose unfractionated heparin given two to three times daily has been the most popular form of prophylaxis for venous thrombosis. In recent years, a number of low-molecular-weight heparins have become available for clinical trials. These agents have many advantages over unfractionated heparin and are now being used widely internationally for the prevention and treatment of venous thromboembolism. Indeed, low-molecular-weight heparin will undoubtedly replace intravenous unfractionated heparin not only in the treatment of venous thromboembolism, but in other conditions where heparin therapy is indicated. Whether or not the low-molecular-weight heparins can decrease or eliminate some of the complications of unfractionated heparin will depend on the outcome of future clinical trials.

Fibrinolytic Agents↗
PubMed1996

Aging and heparin-related bleeding.

BACKGROUND: Many studies have suggested that elderly patients are at increased risk of bleeding during heparin therapy. OBJECTIVE: To establish whether the risk of bleeding in the elderly results from concomitant risk factors or is associated with the aging process itself. METHODS: One hundred ninety-nine patients who presented with proximal deep vein thrombosis were treated with a standard intravenous heparin protocol in a double-blind, randomized, prospective study. Bleeding complications were monitored. Activated partial thromboplastin times and heparin levels were assessed 4 to 6 hours after a standard intravenous heparin bolus and infusion. Heparin doses and heparin levels were also assessed after stable therapeutic heparin infusion rates were established. RESULTS: There was an increase in total and major bleeding complications with aging (P < .05) that was not accounted for by standard risk factors for bleeding. Aging was associated with an increase in heparin levels (r = .239, P = .003) and a tendency for an increase in activated partial thromboplastin time (r = .134, P = .07) after standard heparin doses. Aging was also associated with lower heparin dose requirements (r = .267, P = .003) after therapeutic activated partial thromboplastin times were achieved. CONCLUSION: Aging is a risk for heparin-related bleeding that may be explicable by age-related changes in the pharmacologic characteristics of heparin.

Adult↗
PubMed1996

Cost-effectiveness of pulmonary embolism diagnosis.

BACKGROUND: In recent years, improvements in the methods of clinical trials and the use of objective tests to detect venous thrombosis have enhanced the clinician's ability to diagnose pulmonary embolism. OBJECTIVE: To perform a cost-effectiveness analysis of the commonly recommended strategies for pulmonary embolism diagnosis and management. METHODS: Two criteria of effectiveness were used: correct identification of pulmonary embolism and correct identification of patients in whom treatment was unnecessary. The cost of each diagnostic alternative was defined as the direct cost of administering the diagnostic test plus the treatment cost associated with a positive test result. Data derived from a decision analysis published separately on 662 patients were used for this study. RESULTS: A strategy based on the use of ventilation-perfusion lung scans, serial impedance plethysmography, and pulmonary angiography was the most cost-effective. It remained so under all possible variations within the sensitivity analysis. CONCLUSIONS: The strategy that requires pulmonary angiography in the fewest patients is a combination of ventilation-perfusion lung scans and serial impedance plethysmography. This strategy also proved to be the most cost-effective.

Angiography↗
PubMed1996

Prevention and treatment of venous thromboembolism.

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.

Anticoagulants↗
PubMed1995

The low-probability lung scan. A need for change in nomenclature.

BACKGROUND: The prognosis in patients with suspected pulmonary embolism who have a low-probability lung scan has been the focus of much clinical debate. This is particularly so in patients with underlying cardiac and pulmonary disease, because these disorders frequently cause low-probability lung scans in the absence of pulmonary embolism. Historically, the clinical response has been to exclude pulmonary embolism and withhold treatment on the basis of a low-probability lung scan, which has been regarded as synonymous with a good prognosis. METHODS: A prospective cohort-analytic study to evaluate prognosis, using long-term follow-up, in patients with inadequate cardiorespiratory reserve who have presented with suspected pulmonary embolism (inadequate cardiorespiratory reserve, ie, pulmonary edema, right-ventricular failure, hypotension, syncope, acute tachyarrhythmia, abnormal spirometry [forced expiratory volume in 1 second, < 1.0, or vital capacity, < 1.5 L], or abnormal arterial blood gases [PO2, < 50 mm Hg, or PCO2, > 45 mm Hg]). RESULTS: The outcomes of the 77 consecutive patients with low-probability lung scans, suspected pulmonary embolism, and inadequate cardiorespiratory reserve were compared with those in 711 consecutive patients with good cardiorespiratory reserve and nondiagnostic lung scans who were entered into the study over the same period of time. Six (7.8%) of the 77 patients died within days of entry with autopsy-proven pulmonary embolism compared with one (0.14%) of the 711 patients with nondiagnostic lung scans (P < .0001). CONCLUSIONS: Our findings indicate that the term low-probability lung scan should be abandoned in reference to patients with inadequate cardiorespiratory reserve, because it is not synonymous with a good prognosis and is, indeed, misleading.

Adult↗
PubMed1995

Hirudin and hirudin analogues as new anticoagulant agents.

Recombinant hirudin and hirudin analogues constitute interesting new antithrombotic agents that have distinct advantages over heparin. These agents specifically inhibit thrombin and all of its actions and also suppress further thrombin generation. As opposed to unfractionated heparin, hirudin and hirulog effectively suppress clot-bound thrombin, making these agents of particular interest in the treatment of arterial thrombosis, for example, following thrombolysis or percutaneous transthoracic angioplasty. The recent data derived from clinical trials supporting the use of hirudin and hirulog in the prevention and treatment of thrombotic diseases are reviewed here.

Angina, Unstable↗
PubMed1995

Current concepts of anticoagulation therapy.

The use of heparin and warfarin in the treatment of venous thromboembolism has been revolutionized by the findings of clinical trials performed over the past decade. This article addresses some unanswered questions regarding the treatment of venous thromboembolism that are the subjects of current clinical trials, such as the optimum duration of oral anticoagulant therapy in patients with idiopathic or recurrent deep vein thrombosis and the role of low-molecular-weight heparin in the short-term and long-term treatment of venous thrombosis.

Heparin↗
PubMed1995

Cost effectiveness of diagnosis of deep vein thrombosis in symptomatic patients.

BACKGROUND: The most widely used noninvasive test for deep vein thrombosis is Doppler ultrasonographic imaging of the lower extremities. The best evaluated of the noninvasive approaches are ascending contrast venography, impedance plethysmography, Doppler ultrasonography with B-mode imaging. Economic evaluation is aimed at helping decision makers to reach their goal of maximizing the health of the population served, subject to the available resources. METHODS: The data that provided the basis for this cost effectiveness analysis were derived from a prospective study of approximately 500 patients referred to a regional thromboembolism program with a first episode of clinically suspected deep vein thrombosis. The application of cost effectiveness analysis to the diagnosis of deep vein thrombosis is readily accomplished using cost minimization. This cost effectiveness technique makes it possible to rank the diagnostic approaches from "worst" to "best", with the best approach defined as that which accomplishes the desired health effect at minimum cost. Effectiveness (health benefit) may be defined in this context as the number or proportion of patients with deep vein thrombosis correctly identified by objective testing or, the number or proportion in whom treatment was correctly withheld. RESULTS: Clinical diagnosis is cost ineffective; $1,590,784 Canadian, $2,624,220 US. Outpatient diagnosis using noninvasive testing was the most cost effective. Serial Doppler ultrasonography is more costly ($618,265 Canadian, $1,326,180 US) than serial impedance plethysmography ($527,165 Canadian, $1,052,880 US). Combined Doppler ultrasonography and serial impedance plethysmography offers a less costly strategy ($551,065 Canadian, $1,124,580 US) than serial ultrasonography alone. DISCUSSION: Objective testing is mandatory. Outpatient testing is preferred, avoiding unnecessary hospital admissions. Noninvasive testing is the most cost effective. The most widely used test, serial Doppler ultrasonography, is less cost effective than serial impedance plethysmography. The combined approach of initial Doppler ultrasonography followed by serial impedance plethysmography combines the advantage of an initial ultrasound image with less costly serial impedance plethysmography.

Adolescent↗
PubMed1994

Physician-guided treatment compared with a heparin protocol for deep vein thrombosis.

BACKGROUND: Effective heparin therapy, defined by therapeutic prolongation of the activated partial thromboplastin time (APTT), decreases the risk of recurrent venous thromboembolism. Achieving therapeutic prolongation of the APTT within 24 hours of the start of heparin therapy has proved difficult. We hypothesized that a protocol that delivered high initial heparin infusions to patients without identifiable risk for bleeding complications would decrease the time to achieve a therapeutic anticoagulant effect without increasing the incidence of major bleeding complications. METHODS: To test this hypothesis, we studied concurrent patient cohorts. We defined a therapeutic anticoagulant effect (APTT > 55 seconds) to be an APTT more than 1.5 times the upper limit of normal. Twenty patients with acute symptomatic deep vein thrombosis received a 5000-U heparin bolus, followed by 1680 U/h (low risk to bleed) or 1240 U/h (high risk to bleed), adjusted by protocol-directed response to APTT results. Forty-eight patients with deep vein thrombosis were treated by their physicians. The Kaplan-Meier method was used to examine the proportion of patients who achieved an APTT greater than 55 seconds as a function of time. RESULTS: The two study cohorts did not differ with respect to age, weight, or risk factors for venous thromboembolism. Analysis of Kaplan-Meier curves showed that the heparin protocol decreased the time to achieve a therapeutic anticoagulant effect (P = .025). Ten (91%) of 11 patients (95% confidence interval, 59% to 100%) without risks to bleed who were treated by the heparin protocol and 29 (60%) of 48 patients (95% confidence interval, 45% to 74%) not treated by the protocol had an initial therapeutic APTT (P = .006). CONCLUSION: A protocol that delivers higher initial heparin infusions to patients without identifiable risks for bleeding decreases the time needed to achieve therapeutic prolongation of APTT, when compared with nonprotocol physician management.

Aged↗
PubMed1994

A noninvasive strategy for the treatment of patients with suspected pulmonary embolism.

BACKGROUND: Pulmonary embolism has historically presented a formidable diagnostic problem because of the nonspecificity of the clinical findings associated with this disorder and the diagnostic uncertainties and challenges presented by both ventilation-perfusion lung scanning and pulmonary angiography. We have reported previously that serial noninvasive leg testing provides a practical noninvasive alternative to pulmonary angiography in patients with non-high probability (nondiagnostic) lung scans and adequate cardiorespiratory reserve. We have reevaluated this observation prospectively to (1) confirm or refute our original observation in an independent cohort and (2) to increase the numbers sufficiently to provide narrow confidence limits for the observed outcomes. METHODS: A prospective comparative study in 1564 consecutive patients with suspected pulmonary embolism who underwent ventilation-perfusion lung scanning and objective testing for proximal-vein thrombosis. RESULTS: On long-term follow-up of 627 patients with the following characteristics: (1) abnormal, nondiagnostic lung scans, (2) not taking anticoagulant therapy, and (3) serial noninvasive test results negative for proximal-vein thrombosis, only 12 patients (1.9%; 95% confidence limits, 0.8% to 3.0%) had venous thromboembolism. By comparison, venous thromboembolism on follow-up occurred in four (0.7%) of 586 patients (95% confidence limits, 0.02% to 1.3%) with normal lung scans in whom anticoagulant therapy was withheld and in eight (5.5%) of 145 patients (95% confidence limits, 1.8% to 9.2%) with high probability lung scans who received anticoagulant therapy. CONCLUSIONS: Our findings indicate that the clinician has a practical noninvasive strategy in patients with adequate cardiorespiratory reserve and nondiagnostic lung scans that (1) avoids pulmonary angiography, (2) identifies patients with proximal-vein thrombosis who require treatment, and (3) avoids the need for treatment and further investigation in the majority of patients.

Adolescent↗
PubMed1994

Prophylaxis of venous thromboembolism in brain tumor patients.

Thromboembolism is a common problem in patients with brain tumors. Within this population are subpopulations of patients at varying but substantial risk for deep vein thrombosis and pulmonary embolism. Prophylactic strategies can be applied to these various risk groups that will dramatically reduce the incidence of thromboembolism, and these should be applied on a routine basis. The standard prophylactic methods for thromboembolic prophylaxis include mechanical devices (e.g., graduated leg stockings; external pneumatic calf compression) and pharmacological agents (e.g., low dose heparin). In addition, a basic knowledge of low molecular weight heparins and heparinoids is essential because these new agents have a potentially promising role in the prophylaxis of neurological disease in certain patients. The principles concerning the prophylaxis of venous thromboembolic disease in patients with brain tumors are addressed in this review.

Brain Neoplasms↗
PubMed1994

Therapeutic use of low molecular weight heparins: knowledge to date and their application to therapy.

Indeed, the accumulating evidence indicates that certain LMW heparins administered subcutaneously may replace classic intravenous heparin therapy. Certain of these subcutaneously administered LMW heparins do not require monitoring. The simplified care offered by LMW heparin therapy offers the possibility of transferring care from in to out of hospital in uncomplicated patients with deep vein thrombosis. The advantages to the patient of avoiding in-hospital care and its associated hazards are obvious. Outpatient LMW heparin therapy will likely prove to be highly cost effective. It is uncertain at present whether the findings associated with an individual LMW heparin preparation can be extrapolated to a different LMW heparins. For this reason, the findings of clinical trials apply only to the particular LMW heparin evaluated and cannot be generalized to the LMW heparins at large.

Animals↗