Artificial organs
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Comparative Study
A centrifugal pump driven tidal flow extracorporeal membrane oxygenation system tested with neonatal mock circulation.
In 1993, Chevalier published his experiences with tidal flow venovenous extracorporeal membrane oxygenation (ECMO) featuring a single lumen cannula, non-occlusive roller pump, and alternating clamps. Using a neonatal mock circulation (NMC), which enables different hemodynamic states for neonatal ECMO research, the tested hypothesis was that it is possible to create a centrifugal pump driven tidal flow neonatal venovenous ECMO system. Additionally, the resulting hemodynamic effects in a condition of circulatory impairment were investigated. ⋯ In conclusion, a centrifugal pump driven tidal flow venovenous ECMO system can be created enabling sufficient tidal volumes. Tested in the described NMC simulating posthypoxic circulatory impairment, significant hemodynamic effects could be demonstrated. Animal experiments for confirmation are necessary.
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Comparative Study
Comparative study of biocompatibility between the open circuit and closed circuit in cardiopulmonary bypass.
The theoretical benefit of a centrifugal pump or heparin coating demonstrated through in vitro or in vivo studies is not recognizable in cardiopulmonary bypass (CPB) during chemical open heart surgery. The objective of this study was to investigate the influence of the interface of air and blood in current CPB with an open circuit system and its relative significance in relationship to the heparin dose and heparin coating. Using the same oxygenator and circuit, an open circuit and closed circuit CPB with the same priming volume were prepared for a 4 h perfusion experiment using diluted and heparinized (3.6 U/ml) fresh human blood. ⋯ We speculate that the lower blood C3a level in the open circuit suggests that C3a was taken in by the adsorbed protein. In conclusion, analysis of the adsorbed protein indicates the lower biocompatibility of the open circuit. Similar experiments with less heparin use and more severe conditions will be necessary to elucidate the essential benefit of making a CPB closed circuit.
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Recently, several types of centrifugal pumps have been widely used as the main pumps for cardiopulmonary bypass (CPB). However, according to the results of our experimental studies, after cardiogenic shock, pulsatile flow was effective in maintaining the functions and microcirculations of end organs, especially those of the liver and kidney. To estimate the effectiveness of pulsatility during CPB, cytokine and endothelin and other metabolic parameters were measured in clinical pulsatile and nonpulsatile CPB cases. ⋯ As for plasma free hemoglobin, there were no significant differences between the groups. These results suggested that even in conventional CPB, pulsatility was effective to reduce endothelial damage and suppress cytokine activation. It may play a important role in maintaining the functions and microcirculations of end organs during CPB.