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Biomedical subjects

J Umlas

Publications and source records attributed to J Umlas.

45 records · Page 3Linked to original sources
PubMedDate not supplied

In vivo platelet function following cardiopulmonary bypass.

In order to test the in vivo hemostatic function of platelets exposed to cardiopulmonary bypass, template bleeding times (TBT) were performed prebypass, three hours postbypass and 18 to 20 hours postoperatively in 22 patients undergoing open-heart surgery. The Harker-Slichter formula was applied to platelet counts below 100,000/cu mm to determine the expected TBT if the platelets function normally but were associated with a prolonged bleeding time merely from thrombocytopenia. Half of the patients received only frozen erythrocyte transfusions. Twenty of the 22 patients (91%) had normal or shorter than the expected TBT. Eight of the ten patients with platelet counts under 100,000/cu mm had shorter than predicted TBTs. All of the patients receiving only frozen erythrocytes had normal or shorter than predicted TBTs. It is concluded that in vivo platelet hemostatic function is usually normal postbypass, that routine platelet transfusions are therefore not necessary, and that most open-heart surgical procedures can be performed using frozen erythrocyte transfusions exclusively.

Blood Cell Count↗
PubMedDate not supplied

Fibrinolysis and disseminated intravascular coagulation in open heart sergery.

Fibrinolysis and disseminated intravascular coagulation (DIC) have been implicated as the cause or contributing mechanisms for hemorrhage during and after cardiopulmonary bypass. Even when unassociated with hemorrhage, both processes have been thought to be common occurences during open heart surgery. In order to measure the degree to which these mechanisms occur, fibrin split products (FSP) were measured simultaneously in blood and chest tube drainage of open heart surgical patients. In addition, serial measurements of platelets and fibrinogen were also measured in the blood of these patients. It is concluded that fibrinolysis invariably occurs to a high degree in the chest postoperatively but with few systemic manifestations and that fibrinolysis and/or DIC are rare causes of a hemorrhagic diathesis after cardiopulmonary bypass.

Blood Cell Count↗
PubMedDate not supplied

The use of frozen blood in neonatal exchange transfusion.

Because of inability to quickly locate donors to provide fresh heparinized blood, seven exchange transfusions were performed on four newborns with hemolytic disease due to Rhesus incompatibility using previously frozen erythrocytes suspended in albumin or heparinized, decitrated fresh frozen plasma. Platellets were added to one unit of previously frozen erythrocytes because of severe thrombocytopenia in one patient following an earlier exchange transfusion. The hematologic and bilirubin removing responses were comparable to those seen with fresh heparinized whole blood. Using this method, the safest red blood cells available, namely the mother's, can be drawn and frozen early in gestation for subsequent exchange transfusion.

Erythroblastosis, Fetal↗
PubMedDate not supplied

Use of the refractive index to measure the adequacy of glycerol removal from previously frozen erythrocytes.

A common method for measuring deglycerolization of previously frozen erythrocytes is to determine the osmolality of the supernatant fluid after completion of the wash cycle. We attempted to compare this type of examination with the simpler, faster, and cheaper determination of refractive index (RI) using the Goldberg refractometer. One hundred twenty units of deglycerolized red blood cells, some with glycerol added so as to exceed an acceptable 1% glycerol content, had measurements made of the post-wash supernatant fluid by refractive index and osmometry. The responsiveness of refractive index to residual glycerol was essentially the same as osmolality. Although there is more interference from supernatant hemoglobin, this did not preclude the use of RI to measure glycerol removal. Readings up to 28 had glycerol levels of less than 1%. Readings between 29 and 31 should be checked by osmometry, and readings over 31 should cause the unit of blood to be rejected.

Buffers↗
PubMedDate not supplied

Heparin removal in an autotransfusor device.

In order to determine the residual heparin in the supernatant fluid recovered from blood washed with increasing amounts of solution in the Haemonetics Cell Saver, various modifications of Grann's polybrene neutralization test applied. It is suggested that each 450 to 500 ml of recovered heparinized blood be washed with a minimum of 500 ml of saline, although 700 ml is advisable. The red color from hemolyzed erythrocytes may clear while unacceptably high levels of heparin remain.

Blood Transfusion, Autologous↗
PubMedDate not supplied

A simplified method for quality control of deglycerolized erythrocytes.

Quality control to detect inadequately deglycerolized red blood cells can be easily and inexpensively accomplished by suspending the deglycerolized cells in either recipient serum or normal saline in the same way in which the routine crossmatch is performed. In vitro hemolysis is readily and consistently apparent when the residual glycerol exceeds either 2.4% (in saline) or 2.5% (in serum). In contrast to generally held beliefs, the in vivo 24-hour survival of red blood cells with a residual glycerol concentration of up to 2.7% was demonstrated to be 76% of greater, a level which is well above what is usually accepted as adequate.

Blood Transfusion↗
PubMedDate not supplied

Measurement of plasma heparin levels using a fluorometric assay.

The performance of a fluorometric heparin assay system was evaluated. The system indirectly measures heparin by its inhibition of thrombin protease action on a synthetic substrate. Our results confirm that within the range of heparin concentrations recommended by the manufacturer, i.e., 0.1-0.8 units/ml, there is an excellent correlation between expected and observed values. Within-day coefficients of variation range from 1% to 2.6%; the between-day coefficient of variation is 6.5. The accuracy of the assay diminishes under 0.1 units/ml. The assay is not influenced by bilirubin, hemolysis, fibrin split products, or lipemia. Results can be generated in less than 5 min. Possible drawbacks are the wide range of acceptability for the supplied heparin standard, and the frequency of pipetting involved.

Fluorometry↗