ASAIO journal : a peer-reviewed journal of the American Society for Artificial Internal Organs
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The authors developed a new membrane oxygenator (MO) for long-term respiratory support and evaluated its performance in animal experiments for as long as 336 hr. The MO, with a membrane area of 1.2 m2 and priming volume of 140 ml, is compact and designed to be interposed in a ventricular assist system (VAS) conduit. It is made with a novel hollow fiber membrane, in which micropores are blind-ended so that serum leakage can be prevented during prolonged use. ⋯ The levels of coagulation parameters including fibrinogen, fibrin degradation products (FDP), antithrombin III (AT III), antiplasmin, prothrombin time (PT) and activated partial thromboplastic time (APTT) remained within physiologic ranges and relatively constant. At the end of the evaluation, no thrombus formation was noted in three of five MOs. These results suggest that this MO is a promising device for long-term respiratory support.
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Eleven infants weighing 2.3 to 7.8 kg underwent mechanical circulatory support for post cardiotomy cardiogenic shock. Initiated pre-operatively in two patients, extracorporeal membrane oxygenation was used in a total of eight patients aged 6 days to 3 months in association with repair of cyanotic congenital heart disease with increased pulmonary blood flow or with a right sided obstructive lesion. Ventricular assist devices were used in three other patients: a centrifugal left ventricular assist device in Patient 1 (10 months, 5.7 kg) after repair of the anomalous left coronary artery, and a pneumatic biventricular assist device (stroke volume 12 ml) in Patient 2 (6 months, 7.0 kg) for cardiac arrest after closure of ventricular septal defect and in Patient 3 (10 months, 7.8 kg) for post transplant graft failure. ⋯ Support was discontinued after 45 hr in Patient 2 who exhibited irreversible brain damage. Patient 3 was weaned from a biventricular assist device after 174 hr, but suffered recurrent graft failure. Our results show that an appropriate circulatory support system should be selected according to the cardiac anatomy in infants.
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Arteriovenous carbon dioxide removal (AVCO2R) has been shown to achieve total carbon dioxide (CO2) exchange. To determine optimal blood and gas flow parameters that can provide maximal gas exchange and evaluate the utility of AVCO2R at reduced blood flow, the authors used a low resistance membrane gas exchanger within an arteriovenous shunt in mechanically ventilated sheep. Adult female sheep (n = 5) were anesthetized and underwent placement of the gas exchange device in a simple arteriovenous shunt created between the carotid artery and common jugular vein. ⋯ Optimizing AVCO2R blood and gas flow maximizes CO2 removal and allows a significant reduction in minute ventilation. In cases of severely limited blood flow, lung rest can still be realized at moderate hypercapnia. At flow rates achievable by percutaneous access, extracorporeal AVCO2R can be used to achieve lung rest during mechanical ventilation.
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Comparative Study
Hemodialysis access flow measurement. Comparison of ultrasound dilution and duplex ultrasonography.
Decreased hemodialysis access flow is associated with an increased risk of access thrombosis. Duplex ultrasonography can measure access flow and select a subset of patients at increased risk for access failure. With in-line techniques (ultrasound dilution), access flow can be measured during hemodialysis. ⋯ Regression analysis revealed a linear relationship between the two techniques described by the equation QAT = 246.14 + 0.8104(QAS) (correlation coefficient of 0.83; p < 0.0001). Measurement of hemodialysis access flow by ultrasound dilution was essentially equivalent to that obtained by duplex ultrasound. Additional studies are needed to determine if regular in-line flow measurements can predict and prevent future access thrombosis and decreased the cost of access management.
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Interleukin-6, interleukin-8, and polymorphonuclear leukocyte elastase levels in coronary sinus blood were measured and compared with those in arterial blood drawn from the radial artery before and immediately after cardiopulmonary bypass (CPB) during coronary artery bypass grafting in 20 patients. We introduced coronary sinus blood sampling as a useful method for evaluation of myocardial metabolism, myocardial protection, and reperfusion injury during CPB, especially by measurement of cytokines. ⋯ We conclude that the myocardium is not a predominant source of their release during CPB. Our results also showed that the measurement of these cytokines in systemic arterial blood reflected their levels in the whole body, including the myocardium, even during cardiac operation with CPB.