The Annals of thoracic surgery
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Because previous reports suggest that the linear relationship between celite activated clotting time (ACT) values and heparin sodium is disrupted if values exceed 500 to 600 seconds, this study was designed to evaluate the relationship of kaolin activated clotting time (ACT) values to high in vitro heparin concentrations. In addition, the relationship of kaolin ACT to heparin concentration as determined manually was compared with that obtained with an automated heparin dose response assay. ⋯ A variable response of kaolin ACT to heparin among patients was demonstrated in our study, especially when ACT values exceeded 500 seconds. We found that the response of kaolin ACT to higher heparin concentrations was acceptable for clinical monitoring based on good correlations obtained in individual patients. The HDR assay generally overestimates a patient's heparin requirements; most likely, this is due to a lower response of kaolin ACT to heparin concentration that is reflected in this assay. Because and exceptional correlation can be obtained between kaolin ACT values and heparin concentration using the assay, this automated assay can identify heparin-resistant patients who may need further treatment.
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Considerable controversy exists experimentally and clinically regarding adverse neurologic effects that may follow deep hypothermic circulatory arrest. Moreover, the techniques of DHCA have never been standardized. ⋯ These data suggest that neither the rate of cooling nor DHCA times between 42 and 70 minutes using profoundly low hematocrits and low ionized calcium levels has any measurable effect on neurologic outcome up to 2.5 years postoperatively. It is possible that adverse neurologic outcomes from DHCA reflect particular methods of achieving DHCA.
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Case Reports
Cardiopulmonary bypass in patients with heparin-induced thrombocytopenia using Org 10172.
In patients with heparin-induced thrombocytopenia undergoing cardiac operations, anticoagulation with heparin should be avoided. The low-molecular-weight glycosaminoglycan Orgaran has been used as an alternative, but the overall experience is limited. ⋯ Orgaran might be a useful alternative for anticoagulation during extracorporeal circulation. Adequate dosages and measurement of plasma levels are recommended for its use in cardiopulmonary bypass.
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Comparative Study
Cerebral oxygenation measured by near-infrared spectroscopy: comparison with jugular bulb oximetry.
Near-infrared spectroscopy is a potential tool for measuring adequacy of cerebral oxygenation during cardiac operations. The cerebral microcirculation is predominantly venous (by volume) and therefore regional cerebral oxygenation measured by near-infrared spectroscopy should reflect jugular bulb venous saturations. ⋯ These findings suggest that near-infrared spectroscopy may be a useful tool for assessing intravascular cerebral oxygenation during pediatric cardiac operations. Prospective studies of neurologic outcome will be required to establish the value of this technique for assessing the adequacy of cerebral protection.
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Editorial Comment
Monitoring of systemic anticoagulation during cardiopulmonary bypass.