ASAIO journal : a peer-reviewed journal of the American Society for Artificial Internal Organs
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Intravenous oxygenation represents a potential respiratory support modality for patients with acute respiratory failure or with acute exacerbations of chronic respiratory conditions. Our group has been developing an intravenous oxygenator, the IMO, which uses a constrained fiber bundle and a rapidly pulsating balloon within the fiber bundle. Balloon pulsation drives blood flow past the fibers at greater relative velocities than would otherwise exist within the host vessel, and gas exchange rates are enhanced. ⋯ Balloon pulsation eliminated much if not all of the dependence of the gas exchange rate on blood flow rate as seen in passive oxygenators. This suggests that in clinical application the IMO may exhibit less gas transfer variability due to differences in cardiac output Over the entire flow rate range studied, the CO2 and O2 gas exchange rates of the IMO at maximal balloon pulsation varied from approximately 250 to 350 ml/min/m2. At maximum balloon pulsation the IMO exchanged CO2 and O2 at rates from 50-500% greater, depending upon the blood flow rate, than the exchange rates reported for the IVOX device in ex vivo tests.
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Rotary blood pumps have been considered effective permanently implantable devices. However, control of such pumps is quite complicated. Sensorless control of pump flow is required because no invasive flow or pressure sensors are wanted. ⋯ Sensorless control of pump flow is gained by analysis of the electric motor current and speed. The required pump output flow is chosen based on heart rate, and an intelligent fuzzy logic based control mechanism is developed to adjust the motor input so that the pump output can reach required flow while also preventing the occurrence of ventricular suction or cannular collapse. Computer simulation was carried out, and the results indicate that the proposed algorithms can achieve required pump flow to obtain normal physiology, whereas overpumping can be prevented to provide safe operation.
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Cardiopulmonary bypass (CPB) is known to induce an inflammatory response in association with neutrophil mediated lung injury. P-Selectin has been reported to be involved in the initiation of this inflammatory response by promoting the adhesion of neutrophils to endothelial cells in postcapillary venules. However, the role of P-selectin in the inflammatory response induced by CPB has never been clarified. ⋯ The RI value increased in a pattern similar to that of the inflammatory cytokines and was significantly lower in group P. These data demonstrate that the addition of an anti-rat specific monoclonal antibody inhibits the abnormal release of inflammatory cytokines and attenuates CPB induced lung injury in rats. Thus, P-selectin may play a role in the augmentation of CPB induced inflammatory response, and the use of its inhibitory monoclonal antibody seems to be a promising strategy for the treatment of CPB induced lung injury.