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.
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A 39-year-old man was admitted to our hospital because of chest pain and was diagnosed with severe heart failure due to viral myocarditis. Intraaortic balloon pumping (IABP) and cardiac extracorporeal membrane oxygenation (ECMO) were employed. ⋯ Two days later, the blood flow was reversed from the thoracic to abdominal aorta; the natural flow was strengthened because the native heart had improved. The observation of this phenomenon is helpful for determining the recovery of cardiac function under cardiac ECMO support.
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A simplified extracorporeal circulation (ECC) assemblage with autogenous oxygenation (AO) using a single centrifugal pump was tested in dogs. The transpulmonary gradient was obtained by increasing pressure in the right atrium through volume expansion and decreasing it in the left atrium by collecting the blood from the pulmonary veins in a reservoir placed below the level of the animal, generating a siphon effect. This arrangement dispenses with a right side pump. ⋯ This ECC circuit allowed the maintenance of adequate hemodynamic and blood gas parameters during the bypass. The operating field and the mobility of the heart were equivalent to that of conventional cardiopulmonary bypass (CPB). We conclude that the use of a single centrifugal pump simplifies the autogenous oxygenation approach, making it a practical choice for the coronary artery bypass graft (CABG) procedure.