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Biomedical subjects

T L Simon

Publications and source records attributed to T L Simon.

At least 55 records · Page 3Linked to original sources
PubMed1984

Controlled trial of routine administration of platelet concentrates in cardiopulmonary bypass surgery.

Prophylactic administration of platelet concentrates to patients undergoing their first cardiopulmonary bypass operation (coronary artery bypass grafting or uncomplicated valve replacement) was evaluated in a controlled randomized study of 28 patients. Four units of platelet concentrates administered at the end of bypass prevented prolongation of the bleeding time seen in patients not receiving platelets. However, chest tube blood loss, transfusion requirements, and clinical outcome were not improved. Moreover, thrombocytopenia and prolongation of bleeding time did not correlate with blood loss or transfusion needs. Mild thrombocytopenia (to 58,000 platelets per microliter) and transient platelet dysfunction after bypass do not require administration of platelet concentrates, and prophylactic use of this blood component in the surgical setting of bypass is not indicated.

Blood Transfusion↗
PubMed1984

In vivo behavior of radioiodinated rabbit antithrombin III. Demonstration of a noncirculating vascular compartment.

Rabbit antithrombin III (AT), purified by heparin-agarose, was labeled with iodine-131 by either the glucose oxidase-lactoperoxidase or iodine monochloride techniques. When intravenously injected, the disappearance of the 131I-AT from plasma was characterized by rapid initial decreases, and three-exponential equations were required for best fit of the plasma disappearance curves. This rapid 131I-AT removal was not caused by denaturation, as shown by comparison with results obtained when 131I-AT was biologically screened (injected into a first rabbit, and then transferred 16 h later in whole plasma to a second for kinetic evaluation) before injection. Thus, the same rapid initial loss of plasma 131I-AT was observed with screened preparations, and the plasma fractional catabolic rates of 0.716 +/- 0.048 and 0.673 +/- 0.051 day-1 for unscreened and screened 131I-AT were not significantly different. These results support the hypothesis that a vascular-endothelial AT compartment is present in rabbit. The fractions of the total-body AT in the plasma, the vascular-endothelial and the extravascular compartments were 0.337 +/- 0.031, 0.178 +/- 0.056, and 0.485 +/- 0.069, respectively. Two three-compartment kinetic models are discussed. The first pictures AT as distributing independently between plasma and two other compartments, and the second sees AT as first passing to the vascular-endothelial compartment, and then directly into the extravascular compartment. The plasma 131I-AT kinetic data was consistent with both models, but the sizes of the vascular-endothelial compartments were best predicted by the second. If AT catabolism was assigned to the plasma, both models generally underpredicted the whole-body radioactivities, while assignment of breakdown to the extravascular compartment generally resulted in overpredictions. This suggests that AT catabolism occurs from both plasma and extravascular compartments.

Animals↗
PubMed1982

Normal viability of platelet concentrates obtained from CPDA-1 blood after storage in CL-3000 blood containers.

Platelet concentrates were obtained from blood anticoagulated with CPDA-1 and their viability after storage in CL-3000 containers for 72 h at 22 degrees C and for 24 and 48 h at 4 degrees C was studied using autologous reinfusion of 51Cr-labeled platelets. Yield and t1/2 values after such storage were similar to those previously reported for other containers and anti-coagulants. Survival of platelets stored at 22 degrees C for 3 days was essentially normal with the expected yields for that duration of storage. As has been described for other containers, adenine has no adverse or beneficial effect on platelet viability when assessed with these methods.

Adenine↗
PubMed1979

Hemostasis in massively transfused trauma patients.

Twenty-seven patients requiring massive transfusions were studied prospectively to determine whether administration of stored, modified whole blood induced a primary disorder of hemostasis evidenced by generalized microvascular oozing. Platelet counts fell in proportion to the number of units of blood transfused. In contrast, the levels of factors V and VIII correlated poorly with the units of blood transfused, 85% of the total variation in the levels being due to influences other than transfused blood. Levels of all other clotting factors were unrelated to the number of units of blood given. Eight patients developed abnormal bleeding. The cause appeared to be dilutional thrombocytopenia in five patients, and DIC in three. In six of the eight, bleeding was controlled with platelet concentrates alone. Two patients were given cryoprecipitate also. The most useful laboratory test for predicting abnormal bleeding was the platelet count. Fibrinogen levels should be followed as an aid in the diagnosis of DIC. The BT, PT, and PTT were not helpful in assessing the cause of bleeding, unless they were greater than 1.5 times the control value. We recommend that any patient receiving massive transfusions who develops diffuse microvascular bleeding be given platelet concentrates. Platelet counts as high as 100,000 may be required to control bleeding from surgical wounds. It is not necessary to supplement transfusions of stored, modified whole blood with fresh blood or fresh frozen plasma.

Adolescent↗
PubMed1978

Heparin pharmacokinetics: increased requirements in pulmonary embolism.

Heparin disappearance after injection and plasma levels during continuous infusion were studied in normal subjects and patients with thrombophlebitis, pulmonary embolism, renal failure, and liver failure. Heparin removal in normal subjects after 75 u/kg was nearly linear with a clearance of 0.64 ml/min/kg, SD +/- 0.11. Clearance varied inversely with dose. Heparin clearance in pulmonary embolism (0.80 ml/min/kg +/- 0.23) was significantly accelerated compared both to normals (P less than 0.005) and to thrombophlebitis patients (0.55 ml/min/kg +/- 0.19, P less than 0.01); the disappearance was more curvilinear in thrombophlebitis and pulmonary embolism than in normal subjects (P less than 0.025). Continuous infusion heparin requirements were greater in pulmonary embolism than in thrombophlebitis, in accordance with pharmacokinetic predictions. The pattern and rate of disappearance in renal disease was similar to normal subjects; in liver disease clearance was accelerated (0.86 ml/min/kg +/- 0.28) and disappearance curvilinear. Because of accelerated clearance, the initial dose of heparin in pulmonary embolism should be greater (25 u/kg/h) than in thrombophlebitis (10-15 u/kg/h). Variability within patient groups necessitates some laboratory control of dosage.

Adult↗
PubMed1978

Multiple plasmacytomas with thoracic and biliary involvement.

The course of a patient who had nonsecretory multiple myeloma was characterized by extraosseous plasmacytomas that were initially limited to pleural lesions with effusion and subcutaneous masses. Subsequently, we noted the development of obstructive jaundice caused by a mass at the head of the pancreas, which was diagnosed by abdominal ultrasound and responded to radiation therapy, and bilateral pulmonary nodules, which were visualized by fiberoptic bronchoscopy. Forceps biopsy of an endobronchial lesion showed plasmacytoma similar in histologic features to her original osseous lesions. The pulmonary nodules responded to cyclophosphamide and prednisone. During her course, she had three forms of intrathoracic myeloma: rib lesions extending into pulmonary tissue, pleural disease, and multiple endobronchial masses. The biliary and pulmonary manifestations of plasmacytomas are rarely seen. Diagnosis by noninvasive procedures and rapid response to conservative therapy were important in this patient's care.

Aged↗
PubMed1977

The clinical features of submassive and massive pulmonary emboli.

Clinical findings in 167 patients with angiographically established pulmonary emboli were analyzed in detail. The clinical symptoms and physical findings in this group were compared with the findings in 160 patients (diagnosis established by angiography) from an earlier similar study. The observations from this, the largest known group of patients with documented pulmonary emboli that has been studied and reported on, revealed that many of the "classic signs and symptoms" occurred infrequently. Most patients in this study had prognostic value. The data from this study demonstrate that no clinical findings are specific for the diagnosis of pulmonary emboli, but the absence of isolated frequently occurring signs and symptoms should mitigate against the presence of pulmonary emboli.

Angiography↗
PubMed1977

Kinetic characterization of hemostasis in thermal injury.

Hemostasis has been characterized by kinetic measurements in 12 patients with severe burns. Survival and turnover of 51Cr-platelets, 131I-fibrinogen, and 125I-plasminogen were simultaneously measured in 10 patients within 24 hours of injury; the disappearance times were shortened in concert to approximately 20% of normal values, and platelet and fibrinogen turnover were increased to more than three times normal. Serial studies in five of these patients 3 and 5 weeks later showed progressive improvement in kinetic measurements ,but normal values were not achieved. Two additional patients with similar rates of consumption demonstrated localization of radiolabeled platelets and fibrinogen in the burn wound. Heparin therapy did not modify consumption significantly. Enhanced fibrinolysis was reflected by marked reduction in 125I-plasminogen survival, depletion of the plasma plasminogen levels, and elevated levels of fibrin degradation products. Initial low levels of platelets and fibrinogen were followed by compensatory elevations; factor V and prothrombin complex factors were depressed during the first five days, but factor VIII levels were not reduced. Thermal injury is characterized by marked and prolonged consumption within the wound of platelets, fibrinogen, and plasminogen that is not reversible by heparin. This process depletes hemostatic components and causes bleeding when the burn is massive or complications are severe.

Adolescent↗
PubMed1976

A comparative analysis of pulmonary perfusion scans with pulmonary angiograms.

Pulmonary angiograms and pulmonary lung perfusion scans on 162 patients with pulmonary embolism were comparatively analyzed. Among the expert angiographic panel members who independently evaluated the studies there was consistent agreement on the diagnosis, size of the emboli, and severity. Consistency of agreement among the expert pulmonary lung perfusion scan panelists was considerably less. These data demonstrate that, in addition to the lack of specificity of the lung perfusion scan for the diagnosis of pulmonary thromboemboli, there is a considerable problem of interpretation in this patient population.

Angiography↗
PubMed1975

The phase II urokinase-streptokinase pulmonary embolism trial: a national cooperative study.

The controlled clinical trials of thrombolytic agents in the United States have been carried out in two phases, under the auspices of the National Heart and Lung Institute. Phase I was devoted to the comparison of 12-hour Urokinase (12h-UK) followed by heparin (H) with heparin alone in patients with acute pulmonary embolism (Walsh et al. 1969). The results showed that pateints treated with UK had more rapid and gretaer resolution of pulmonary thromboemboli in the first twenty-four hours of therapy than patients treated with H alone, as assessed by serial pulmonary angiography, hemodynamics and lung scanning (The Urokinase Pulmonary Embolism Trial, 1970, 1973; Hyers et al. 1970). Because of the ralatively small size of the Trial and the low mor tality of treated pulmonary embolism, mortality differences were not sought-nor was one found. Although there was early difference in amount of clot resolution, patients treated with H alone showed similar improvement by two weeks. The phase II Urokinase-Streptokinase Pulmonary Embolism Trial (USPET) was begun to assess the comparative results of UK and Streptokinase (SK) therapy. Because of favorable results obtained with SK in other countries, it was deemed necessary to make this comparison (Browse and James, 1964; Hirsh et al. 1968; Miller et al. 1969, 1971; Chesterman et al. 1969). A third group, 12-hour UK, was added to relate this study (24-hour UK and SK) with the Phase I results which employed only a 12-hour infusion of UK. This Phase II Trial represents the first controlled, randomized study of UK and SK in thromboembolic disorders.

Angiography↗